ML12088A430
| ML12088A430 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 10/26/2009 |
| From: | Lo K Entergy Nuclear Operations |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| Shared Package | |
| ML12088A422 | List: |
| References | |
| RAS 22102, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01 EN-CS-S-008-MULTI, Rev 0 | |
| Download: ML12088A430 (132) | |
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{{#Wiki_filter:ENTERGY[ENGINEERINGSTANDARD EN-CS-S-008-MULTI Rev.0 PIPE WALL THINNING STRUCTURAL EvALuAtioN Page 1 of 132 Entergy ENGINEERING STANDARD EN-CS-S-008-MULTI Rev.0 Effective Date: 1-1-2010 Pipe Wall ThinninQ Structural Evaluation Applicable Sites lP-1 1P-2 1P-3 JAF PLP PNPS Effective Date Exception Applicable Sites ANO-1 ANO-2 GGNS RBS WF3 NP HON Effective Date Exception EC No(s).Safety Related: X Yes No Prepared by: Approved by: 4'4'Kai Lo-R.Drake//;f Engin'eMg StandardOwn Date:/I-Process Applicability Exclusion (ENLl1OO)/Proramrnatic Exclusion All Sites: Specific Sites: ANO U GGNS U IPECU JAF U PLP LI PNPS Li ABS[1 VY Li W3 U] CD-øC 3 CD 0 2)z CD to 0 z U)C 3 9 m z-4 m-n-U m r r-4 m x z z z C)Cl)C Cl)C)--l C Z r D rn<1 r C 0 z m 2 n-G Cfl C()CD C 0 PS)C r Ht C..)PS)33 CD 0 ENTERGY ENGINEERING SmroARD EN-CS..S-008-MULTI Rev.0 PIPE WALL THINNING SmucruRAl. Ev.tuArIoN Page 3 ot 132 TABLE OF CONTENTS Section Iii 1.0 PURPOSE..,.......................... 4
2.0 REFERENCES
4 3.0 DEFINITIONS 5 4.0 RESPONSIBILITIES 7 5.0 DETAILS 7 6.0 RECORDS 17 7.0 ATTACHMENTS 17 Attachment 7.1 Example of Wall Thinning Evaluation Based on Uniformly Thinned Section 18 Attachment 7.2 Example of Axial Stress Calculation with Actual Thinned Section 20 Attachment 7.3A Example of ASME Code Case N-513 Evaluation for a Through-Wall Flaw for Carbon Steel 22 Attachment 7.38 Example of ASME Code Case N-51 3 Evaluation for a Through-Wall Flaw for Austenitic Steel 24 Attachment 7,4 Example of Minimum Wall Evaluation at Reinforcement Area of Tee 26 Attachment 7.5 Plant Specific Allowable Stress Factors 27 Attachment 7.6 Recommendation for Safety Related Moderate Energy Class 213 and Non-Safety Related Piping 28 Attachment 7.7 Recommended Guidance and Methods for Calculation of Wear Rates 35 Attachment 7.8 Guide for using PS-S-aOl as Informational Attachment 38 Attachment 7.9 Informational Attachment 40 ENTERGV L.ENGINEERING STANDARD EN-CS-S.008-MULTI Rev.0 Pu'E WALL.THINNING STRuCTURAL EVALUATION Page 4 of 132 1.0 PURPOSE 1.1 The purpose of this standard is to provide consistent methodology for performing structural evaluations of pipe wall thinning for ASME Section Xl Class 1, 2, and 3, carbon and low ailoy steel piping.This standard is also applicable for non-safety related piping using Attachment 7.6 of this procedure. 1.2 This standard can be used for, but not limited to, evaluation of internal or external thinning due to Flow Accelerated Corrosion (FAC), Microbiologically Induced Corrosion (MIC), and general erosion/corrosion. The methodology for evaluation of thinning due to MIC and general erosion/corrosion is the same as FAG;however, wall thinning rates are different and should be calculated as shown in Section 5.1.1.3 This standard is applicable to Entergy Nuclear (EN)nuclear power plants for which the piping was designed in accordance with the ASME Section Ill, ANSI 831.7 and USAS/ANSI 831.1 code[2.1, 2.20, 2.211.1.4 This standard is applicable to piping and fittings and can not be used to evaluate other components such as valves, pump casings, etc.
2.0 REFERENCES
2.1 USAS/ANSI 831.1,"Power Piping", (For applicable code year, see indMdual plant FSAR)2.2 1P3 FSAR 2.3 JAFFSAR 2.4 ASME B&PV Code Case N-597, Rev.2 2.5 PS-S-001 Rev.I,"Localized Pipe Wall Thinning and Crack Like Flaw Evaluation Standard"2.6 ASME B&PV Code Case N-513-2 2.7 PVPVolume 264, Piping, Supports, and Structural Dynamics, ASME 1993, P51-55 2.8 lP2 FSAR 2.9 PNPSFSAR 2,10 VYFSAR 2.11 ASME 2001 8&PV Code, Section Xl, Appendix C 2.12 EN-DC-126,"Engineering Calculation Process"2.13 USNRC Regulatory Guide 1.147 2,14 EN-DC-315,"Flow Accelerated Corrosion Program"2.15 ENN-DC-185,"Through-Wall Leaks in ASME Section Xl Class 3 Moderate Energy Piping Systems"2.16 EPRI NSAC-202L-R3. "Recommandations for an Effective Flow Accelerated Corrosion Program", May 2006 2.17 EPRI CHECWORKS Steam/Feedwater Application Guidelines for Plant Modeling and Evaluation of Component Inspection Data, Report No.1009599, Final Report, Sept.2004 2.18 ASME B&PV Code Case N-661 2.19 Roark's Formulas for Stress&Strain, W.C.Young, Sixth Edition 2.20 USAS 831.7,"Nuclear Power Piping", (For applicable code year, see individual plant FSAA) rENTERGY[ENGINEER STANDARD EN-CS-S-008.-MULTI Rev, oj[PIPE WALL THINNING STRUCTURAL EVALUATION Page 5 of 132 j 2.21 ASME Boiler and Pressure Vessel Code, Section III ,(For applicable code year, see individual plant FSAR)2.22 ANO-1 FSAR 2.23 ANO-2 FSAR 2,24 GGNS FSAR 2.25 WF3 FSAR 2.26 PLP FSAR 2.27 ABS FSAR 2.28 EN-DC-i 15, Engineering Change Process 30 DEFINiTIONS 3.1 A-Additional thickness per ANSI B31.i code, (in)3.2 A-Predicted inside cross-section area with pipe wall thinning, (in 2)3.3 A,-Predicted metal cross-section area with pipe wall thinning, (in 2)3.4 A 0-Total cross-section area of pipe based on outside diameter, ie0 0 2/4, (in 2)3.5 D-Pipe outside diameter, (in)3.6 i-Stress Intensification Factor for nominal thickness (See Appendix D of Ref.2.1)3.7 i'-Stress Intensification Factor based on average measured thinned thickness 3.8 151-In-Service Inspection. Piping components are classified as 151 Class 1, 2, and 3 in accordance with Regulatory Guide 1.26, 1 OCFR5O.2V and br the ISI Program Plan 3.9 K 0-Allowable stress factor for Normal (or Design)Conditions.(See Attachment 7,5 for plant specific values)3.10 Ku 8'Allowable stress factor for Upset Conditions.(See Attachment 7.5 for plant specific values)3.11 KEm 2 Allowable stress factor for Emergency Conditions.(See Attachment 7.5 for plant specific values)3.12 KFau Allowable stress factor for Faulted Conditions.(See Attachment 7.5 for plant specific values)3.13 L-Maximum extent of a local thinned area with wall thickness less than t, (in.), (see Figure A-i of Attachment 7.6)3.14 L,-Maximum extent of a local thinned area with wall thickness less than trnfl, (in.), (see Figure A-i of Attachment 7,6)3.15 Lrna)-Maximum axial extent of a local thinned area with wall thickness less than trnfl, (in.), (see Figure A-I of Attachment 7.6)3.16 Lrna).rnax -Maximum of the axial extent of two adjacent local thinned areas with wall thickness less than tmn, (in.), (see Figure A-3 of Attachment 7.6) [ENTERGY[ENGINEERING STANDARD EN-CS-SO08-MULTI Rev.0 I Pic WALL THINNING STRUCTURAL EvAwATI0N Page 6 of 132 317 Lmti Maximum transverse extent of a local thinned area with wall thickness less than t,, (in,), (see Figure A-i of Attachment 7.6)3.18-Average of the extent of thickness less than tm,,for two adjacent thinned areas.(in.).(see Figure A-2 of Attachment 7.6)3.19 ME-Moderate Energy;Piping system operating pressure<275 psig and operating temperature <200 F 3.20 Mb-Resulting bending moment from the design analysis of record for each loading condition under consideration, (in-Ib)3.21 P-Design pressure, (psi)3.22 P-Thermal expansion stress, (ksi)3.23 Pm-Piping axial stress due to design pressure, (ksi)3.24 Pb Piping bending stress, (ksi)3.25 R-Pipe mean radius, (D.-t,)!2, (in)3.26 Rb-Pipe elbow bend radius, (in)3.27 Rmn Mean radius of piping item based on the minimum wall thickness, (in)3.28 Rn,jm-Pipe nominal radius, (in)3.29 R 0-Pipe outside radius, D 0/2, (in)3.30 S-Piping axial stress=Pm+b, (ksi)3.31 SA-Pipe thermal expansion allowable stress, (psi)3.32 Sb-Pipe axial stress due to bending moments, (psi)3.33 S 0 r Pipe axial stress at Normal Conditions or Stress Due to Sustained Loads[2.1], (psi)3.34 Smg Pipe axial stress at Emergency Conditions or Stress Due to Occasional Loads[2.1], (psi)3.35 S 3-Pipe axial stress at Faulted Conditions, (psi)3.36 S-Pipe allowable stress at operating temperature, (psi),[see Appendix A of Ref.2.1].3.37 S-Pipe thermal expansion stress or Additive Stress[2.1], (psi)3.38 S'T-Pipe thermal expansion stress for the thinned section.(psi)3.39 S-Pipe axial stress due to pressure, (psi)3,40 S-Pipe axial stress at Upset Conditions or Stress Due to Occasional Loads[2.1], (psi)3.41 SF-Safety Factor for Wear Rate, (1.1 is recommended per EN-DC-31 5)3.42 tm-Minimum measured pipe wall thickness of the latest inspection, (in)3.43 Minimum required pipe wall thickness for internal pressure, (in)3.44 t,.,-.-Minimum required pipe wall thickness for straight pipe, (in)3.45-Minimum required pipe wall thickness for axial stress, (in)3.46 t',-Minimum required pipe wall thickness required for hoop stress, axial stress and larger than[3t.,, (in) ENTERGY ENGINEERING STANDARD J EN.-CS.S-008-MULTI Rev.0 PIPE WALL THINNINO STRUcTuRAL EVALUATION Page 7 of 132 3.47 t, Pipe nominal wall thickness, (in)3.48 t Minimum predicted pipe wall thickness at the next inspection, (in)3.49 Y-Service years between the latest and the next inspections, (years, or time unit)3.50 Z,,,.Predicted minimum section modulus for the thinned pipe section, including consideration of the shift of the neutral axis of the thinned pipe section, (in 3)3.51 W,-Wear Rate, (in/year.or in/time unit)3.52 Other A factor: 0.3 for Class 1 and 0.2 for Class 2 or 3 piping The distance from the center of pipe to the center of gravity of the pipe metal thinned section, (in)'Afactorof 1.143 (=1/0.875)0 Maximum angle (in degrees)from center of outer one-half of elbow to the location of thinned area being evaluated, as measured in the pipe cross section (see Figure 2)4.0 RESPONSIBILITIES 4.1 Manager of Design Engineering at each site is responsible for assuring the proper implementation of this standard.4.2 Implementing Engineer is responsible for ensuring that calculations generated from this standard shall be performed in accordance with the EN calculation procedure, EN-DC-126. 4.3 Wear rates for inspections performed under EN-DC-31 5 is the responsibility of the FAC engineer.4.4 Civil/Mechanical Engineering Section is responsible to perform structural evaluation for pipe wall thinning and flaws.50 DETAILS The methods of pipe wall thinning evaluation in this standard are steps to assess the acceptability of the minimum predicted thickness, t (See Figure 1 for illustration). First an initial screening is performed using the t value to determine action to be taken.The actions are: Accept-as-Is, Evaluate, or Repair/Replace. If a structural evaluation is performed, it shall satisfy the pipe code stress requirements for both hoop and axial directions [2.4].The approaches of the uniformly thinned section and the actual thinned section for the structural evaluation are both provided in this standard.The uniformly thinned section methodology illustrated in Figure 4 assumes a uniformly thinned section with the minimum measured thickness. This approach is simple but it may give overly conservative results when the pipe wall thinning is localized. Re-evaluation using the actual thinned section may be required to reduce the conservatism. For non-safety related piping components, minimum wail thiCknOSs criterta that are not included n this standard can be used if it is justfed by Oocurnerted site specfic evaluations. 5.1 Predicted Thickness at Next Inspection, tp The wear rate (Wr)shall be obtained from the FAC engineer, as applicable. Otherwise, it shall be determined as provided in Attachment 7.7.Calculate t ENTERGY L ENGINEERING STANDARD EN-CS-S-0O8MULTl Rev.0 PIPE WALL THINNING STRUCTURAL EvALUA110N Page 8 of 132 tpt_SFW,Y Wall thinning (wear)rates for phenomenon other than FAC may be difficult to predict and therefore should be determined on a case-by-case basis by the engineer.5.2 Screening Rules Determine actions for the acceptability of t by the screening criteria as follows: Screening Criteria Actions tp 0.875 2 Accept as is 0,875 tnom>t>0.3*for Class 1 Evaluate>0.2*t 0 for Class 2&3 0.3 t,,,,>t for Class 1 Repair or replace 0.2*>tp for Class 2&3 (If piping meets the ANSI B31.1 code requirements, then immediate repair is not required.Repair or replace during the current operating cycle not to exceed the next refueling outage)(For moderate energy Section XI Class 2 or 3 piping, perform ASME Code Case N-513-2 evaluation for through-wall flaws, if necessary> (1)The*is the multiplication sign herein.(2)The rule is not applicable for the following cases;a.Class 1 short radius elbows, an evaluation shall be conducted to show that requirements of NB-3642.2 are met.b.Reinforcement area of tees or branch connections (see Figure 6), an evaluation of reinforcement area per ANSI 831.1 is shown in Attachment 7.4, c.Specific designed items as stated in Reference 2.4, Section 3500(a)(4>. Notes: ENTERGY ENGINEERING STANDARD EN-CS-S-O08-MULTI Rev 0 PIPE WALL THINNING STRUCTURAL EVALUA11ON Page 9 of 132 5.3 Structural Evaluation 5.3.1 Hoop Stress Requirements Minimum Wall Thickness, trnn: tmn ((P*D 0)I[2*(Sh+0.4*P)1)+A Hoop Stress Requirements Actions tp tm,i Accept for hoop stress tp<tmn Replace or repair (A local thinning evaluation can be performed based on Code Case 597, however NRC approval is required for acceptance) For Class 2/3 moderate energy pipe, ASME CC N..51 3-2 can be used without NRC approval.Note: (3)a.For reducers (see Figure 3), t shall be equal to tmfl of straight pipe connected to the reducer end.For the conical portion of the reducer, t shall be that of the larger diameter end.b.For inner portion of elbows and pipe bends (see Figure 2), excluding a region within 1.5*(R*t)OS of butt welds, t shall be equal to[0.5+0,5/(1 +(RJRb)*cos0)J*trn.,.,. c.For branch connections and tees, except at regions providing reinforcement of the opening required by 531.1 Code, tmfl shall be as required for straight pipe.Caution: When pressure is very low, t may be unrealistically low.5.3.2 Axial Stress Requirements 5.3.2.1 Uniformly Thinned Section Approach Obtain axial stresses (SNøc, SUp, SEmq SFau,&STe)and their allowable stresses[KN*Sh, (KErn*Sh, (KFau*Sh,&SA]at the thinned area due to pressure and mechanical loads for Normal (or Design).Upset, Emergency, Faulted Conditions, and Thermal Expansion. Determine the new stress intensification factor (SIF), i, if required, by using the average predicted wall thickness or conservatively using twice of the original SIF value around the thinning area of the component. The formulation of the stress intensification factors are listed in Appendix D of 531.1 Code[2.1].Select the minimum thickness required for axial stress, to calculate the ratio of old and new section modulus;7p7 rr 4'+iirr 4 ,a\4 LJnom)i'L-'o k'-'o'4.L The new stresses due to pipe wall thinning shall satisfy the following I ENTERGY L ENGINEERING STANDARD EN.CS..S-008-MUL11 Rev.0 PIPE WAIL THINNING STRucTuRAL EvALuATIoN Page 10 of 132 conditions: Normal Conditions: y'KN.,,*Sr,[P*D,.J4t,,. +U',i)(SN, P*D4t.orj*(Z!Z)J >0[Eq 11 Upset Conditions: -[P*Do/4trn,n +(i'/i)(Sup -PDo/4tnorn)*(Z/Z)1 0[Eq.2]Emergency Conditions: iKErng*Sh-[P*D 0 J4ta+(i/i)*(SErnq -P*Do/4tnorn)*(Z/Z)] 0[Eq.3]Faulted Conditions: (if required)*KFaU*Sh[p*Dcl4tarnn +(iii)*(SFau -P*D 0/4tnom)*(ZiZ)] >0[Eq.4]Normal+Thermal Expansion: +S)-[PDJ4t,+(i'/tY(S 0 ,-P*Do/4trorn +SThe)*(Z/Z)1 >0[Eq.5]The minimum of tam,n can be obtained by the Trial and Error Method"until one of the above four equations is close to zero.It is noted that if tp/tKm>0.75, and subject to no more than 150 equivalent full temperature cycles from the measurement date to the time of the next examination, then the thermal expansion stress need not to be considered. Axial Stress Requirements Actions t>ta Accept for axial stress Repair or replace, or tp<calculate stresses based on actual thinned section in accordance with paragraph 5.3.2.2;For Class 2/3 moderate energy pipe, ASME CC N-513-2 can be used.An example of the wall thinning evaluation with the uniform thinned section approach is shown in Attachment 7,1.5.3.2.2 Actual Thinned Section Approach 5.3.2 2.1 Primary Piping Stress A detailed stress analysis may be conducted based on the complete set of the wall thickness measurements around the circumferential direction of the actual thinned section of the pipe (See Figure 4).The nominal axial pressure stress, S, shall be determined by: P A/A, ENTERGY ENGRrc.SvoARD EN-CSS-OO8..MULTl Rev.0 PIPE WALL ThINNING STRUCTURAL EvALUATION Page 11 of 132 The axial bending stress, Sb, for various Loading condibons shall be determined by: Sb=(Mb+P*A)/Z The total axial stress, S, for various loading conditions shall satisfy their limits as follows;S S+Sb<K*Sh where K=yKEmq, and are for Normal (or Design), Upset, Emergency, and Faulted Conditions, respectively. The detailed methodology of this approach is described in Reference 2.4.5.3.2.2.2 Thermal Expansion Stress Determine the new thermal expansion stress as following: C"j'I'\*/'7 17'*C'*C'çThe ,I it)/Qo, An example of the detail calculation is shown in Attachment 7.2.5.4 Potential Buckling of Thinned Region When the ratio R 0 It is greater than 50, the potential for buckling of the thinned region shall be evaluated. Following criteria is recommended to be used for evaluation of buckling.Local Buckling: Buckling can only be caused by axial compressive stresses due to bending moments.Calculate local critical buckling stress as: Critical Buckling Stress 8.46*E*(taveIb) 2 (Note: This equation is based on Reference 2.19 Table 35 Case I b, square plate with all edges clamped for a Poisson's ratio equal to 0.3)where: tauC=average measured thickness in the flawed area b=length of flaw in the circumferential direction E=Modulus of Elasticity for pipe Overall Buckling: Check piping overall buckling by methodology contained in ASME B&P V code Section Ill, NB/NC-3133.6 for cylinders under compression or any equivalent methodology. 5,5 Evaluation of Through-Wall Flaws The through-wall flaw evaluation is applicable to only Class 2 or 3 moderate energy (ME)piping for through-wall flaws and flaws where t is less than the required thickness for hoop and axial stress.The geometry of through-wall planar flaws is shown in Figure 5.The flaw evaluation is based on the requirements of ASME Code Case N-SI 3[2.63 with the following limitations: 1.Specific structural factors in paragraph 4.0 of reference 2.6 must be satisfied. 2.Code Case N-513-2 may not be applied to: ENTERGY[ENGINEERING STANDARD EN-CS-SOO8-MULTI Rev.0 PIPE WALL THiNNING STRUcTURAL EVALUATION Page 12 of 1 32_J (a)Components other than pipe and tube.(b)Leakage through a flanged joint.(c)Threaded connections employing nonstructural seal welds for leakage prevention (through seal weld leakage is not a structural flaw;thread integrity must be maintained).(d)Degraded socket welds.3.Code Case N-513-2 may be applied to adjoining fittings and flanges to a maximum distance of (R 0 t)°5 from the weld centerline. 4.When the width of wall thinning Wm that exceeds tmfl, is O.5(R 0 t)°5 where W 1 is defined in Fig.A-i (partial through wall thinning), the flaw can be classified as a planar flaw, Attachment 7.3A or 7,36 can be used.If the above requirement is not satisfied, Attachment 7.6 can be used.The acceptance is limited to the next scheduled outage.The detailed methodology of the evaluation is described in Reference 2.6.ASME Code Case N-51 3 also requires augmented examinations to determine extent of condition. These requirements are covered in ENN-DC-185 [2.15].An example of a through-wall flaw evaluation is given ri Attachment 7.3A and 7.36.5.6 Remaining Service Life (RSL)Estimation The remaining service life of a thinned pipe shall be used to schedule the next inspection. Calculate RSL: RSL (teas t'r)!(SFWr) Where t'rnr, Maximum Of (tarnin,)*>5.7 Restoration of Wall Thickness for Class 2 and 3 Carbon Steel Piping If necessary, wall thickness restoration of Classes 2 and 3 carbon steel Raw Water Service piping can be performed in accordance with ASME Code Case N-661[2.18]with the limitations of Regulatory Guide 1.147[2.13]. ENTERGY ENGINEERING STANDARD EN-CS S-OO8 MULTi Rev 0 PIPE WALL THINNING STRUcmRAL EvALuATIoN Page 13 of 132 Yes Operable but monitoring required per N-513, Repair or replace at next scheduled outaqe Figure 1: Logic Diagram for Pipe Wall Thinning Evaluation ENTERGY[ENGINEERING STANDARD j EN-CS-S-008-MULT! Rev.ol I PIPEWALLThINNINGSTRUcruRALEVALuATI0N Page 14 of 132_J GENERAL NOTE: Transition zones extend from the point on the ends weze the diemeter begn8 to change to the point on the central cone where the cone angie is ccnant, Figure 2: Elbow and Nomenclature Large end transition zone Central conical section Small end transition zone Figure 3: Zone of 94er ENTERGY ENGiNEERING STANDARD EN-CS-S-008-MULTI Rev.0 PIPE WALL THINNNG STRUCmRAL EVALUATION Page 15 of 132 tIi.1.ttl.tl Figure 4: A Typical Thinned Pipe Cross-Section ()Cirtm etW iw-4--t (b)Aii flaw Figure 5: Through-Wall Flaw Geometry (T-I z Cl)a,-n 0 c.C Cl C)--4 I>C 2 0 Ill C 0 2 m z C,-o D 0 0 H-a.C., 1)m 0-i m C)-n C'3.I 33 CL>3 LIl L LI'33 I.CL CL 3 3.3.3.CL 3 3.3 C 3 3 CL 3 ENTERGY[ENGINEERING STANDARD EN-CS-S-008-MULTI Rev.U PIPE WALL THINNING STRUcTuRAL EvwAnoN Page 17 of 132 6.0 RECORDS Use of this standard in conjunction with EN-DC-i 26 and EN-DC-il 5 process.7.0 ATTACHMENTS 7.1 Example of WaB Thinning Evaluation Based on Uniformly Thinned Section 7.2 Example of Axial Stress Calculation With Actual Thinned Section 7.3A Example of ASME Code Case N-513 Evaluation for A Through-Wall Flaw for Carbon Steel 73B Example of ASME Code Case N-513 Evaluation for A Through-Wall Flaw for Austenitic steel 7.4 Example of Minimum Wall Evaluation at Reinforcement Area of Tee 7.5 Plant Specific Allowable Stress lactors 7,6 Recommendation for Safety Related Moderate Energy Class 213 and Non-Safety Related Piping 7.7 Recommended Guidance and Methods for Calculation of Wear Rates 7.8 Guide for using PS-S-OOl as Informational Attachment 7.9 Informational Attachment ENTERGY ENGINEERING STANDARD EN-CS-S-008-MULTI Rev.0 PIPE WALL THINNING SrRucTURAL EvALUATIoN Page 18 of 132 Attachment 7.1 Example of Wall Thinning Evaluation Based on Uniformly Thinned Section Sheet 1 of 2 1.Design Parameters D 0: Outside Diameter, (in)Nominal Thickness, (irrl Material P: Design Pressure.(psi)T Design Temperature, (CF)_________S 5 Allowable Stress at Design Temperature.(psi)___________________ Thermal Expansion Allowable Stress (psi)______A An additional thickness per Section 106.1 of 831,1, (in)2.PredictIon of Mm.Thickness at Next Inspection, tp_____________________ tms: Measured thickness of latest inspection, (in>____________________ W: Wear Rate (in/yr)__________ Y: Service years between the latest and next inspections, (yr)_______________________ SF: Safety factor________________ Projected thermal cycles between the latest and next inspections _________________ tp=tnea-SFWrY, (in)RcJtp 50, OK;or>50, 8uckling Evaluation Required 3.Screening Rules for Pipe Wall Thinning Rule 1: Acceptance Standard=O.875t 2, t3)Rule 2: Minimum Required Thickness 0.3t for Class 1 for Class 2 or 3 Rule 3: Between the above two limits, wall thinning can be accepted by a structural evaluation Action required based on the above screening rules for the inspected thinned pipe Class I piping Structural Evaluation Req'd Class 2 or 3 piping Structural Evaluation Req'd 4.Structural Evaluation a.Minimum Thickness for Hoop Stress: tmn=PD 0 J[2).+.4P)j+/-A (in)0038 b.Mrnmum Thickness for Axial Stress Is the lhermal expansion stress requred to be evaluated 9 (No for t O.75t and cycles<150: Yes for otherwise) Ailowable stress increase factor for Normal Condition K 0: AIlowab stress ncrease laclor for Upset Condtion Allowabre stress increase factor for Emergency Condition y: Allowable stress norease factor for CC'N-597 Boxed values are input)3.5 0.216 (See App.A of 831.1)A106 GB, SML32528015000 22500 0 0.080 0.00250 2 1.1 70 (I I flit 5=23 0.0745 OK 0.189 0,065 0.043 Yes______1.0 1.2: 1.8 h-1143 [ENTERGY[ENGINEERING STANDARD EN-CS-S-008-MULTI Rev 0[j PIPE WALL THINNING STRucTuRAL EVALUATION Page 19 of 132 Attachment 7i Example of Wall Thinning Evaluation Based on Uniformly Thinned Section Sheet 2 of 2 Original Piping Stresses S 5: Normal Condition Stress, (psi)2500 Upset Condition Stress.(psi)5600 Strn 5 Emergency Condition Stress, (psi)_________Sm: Thermal Expansion Stress.(psi)8000 Let ,O53 (1 1 i/i I Z/Z[D 0 4 (Oo"2tnom) 4 1/[D 0 4 (Do2tmm)4 1 3.55 Allowable Stress-Axial Stress>0 Normal conditions: y*Ke 0*Sm PDJ4t+(iVi)(S P*Dj4t)(Z/Z)] >0 7568 Upset conditions: ymKup'Sm (PDcJ4tm+(lVl)(Sup P*Dm/4troRJ2)) 0 0 Emergency conditions: KEmgS-[P*Do/4t++(i'Il)'(Sr,re P*DmJ4tr)*(Z/Z)] 0 2483 Normal and Ther.Expansion conditions: 1 (S+/-S)[PD,14tm+(i/i)*(So PDi4t÷ST>*(Z/Z>0 4907 c.Minimum Required Thickness Class 1: t, Max.(in): Acceptable if t>0065 Yes Class 2&3: t',,=Max.(in);Acceptable if Ip>0.053 Yes 5.RemainIng Service Life (RSL)Class 1;RSL=[t tJ/(SF*Wj, (yr)5.5 Class 2&3: ASL=[tm-tj/(SF*W,), (yr)9,9 Notes: (1)The wear rate will be obtained from Responsible FAC Engineer or based on the Attachment 7.7.(2)The acceptance standard (0.875L)can not be applied to: 1.Class 1 short radius elbows, 2.Reinforcement area of a tee or branch connection, and 3.For regions of piping designed to specific wall thickness requirements, such as counterbores or weld attachments. (3)For the small end of reducers, the standard shall be based on the of the pipe size at the small end.For the large end, the large end transition and the conical portion, it shall be based on the t of the pipe size at the larger end.(4)The formula is applicable for straight pipes, bends, and elbows.For reducers, t at each end shatl be equal to of straight pipe of the same nominal size as the reducer end.For the conical portion and transition at larger end of reducers, t shall be that of the large diameter pipe end.For branch connections and tees, the reinforcement area of the opemng shall be based on the 831.1 code.(5)can be obfained by the Trial and ErrorS method until the Allowable Stress Axial Stress due to Normal, Upset, Emergency, and combined Normal and Thermal Expansion conditions are all positive and one of them shall be close to zero.(6)(i)can be calculated from Appendix Dot ANSI B31.1.(i')needs to be adjusted for the pipe wall thinning.lt is suggested that the average thickness or 2 times of the original value be used for the 1'calculalion.
- I ENGINEERING STANDARD EN-CS-S008-MULTI Revision 0 Jntergy I PIPE WALL THINNING STRUCTURAL EVALUATION Page 20 of 132 Attachment 7.2 Example of Axial Stress Calculation With Actual Thinned Section Sheet 1 of 2 (Boxed values are input.l 0314 Where ii Icenirficalion ot measurement nd around crrcumference Mm.thickness measured in nth grid Mm.oredicted thiesness of nIb grid at next insoection.(t.)..-SPVW..where W,=it (t..,,.'V*(ns;de thinned radius A, t.-of nth grid 9;Circumferential angle clockwise of nth grid if rote verlical axis of pipe sectionl=1 R-Rn 2 Y(;\9)12.A R'..O)/2 B,.=R'cos)0.)(.\9)J3, Bvr=Rr*sin(9r(,X0)!3,=lR-R 4 ycoS 2 (O$(\0):4,=(R-Rsin 2 (O 0 (;\O)4, l=(Rr 4 RsIn(0)*coS(0(.\9)/4.
A,,., similar for A,.B, 84, t, L.and I..(The origin of x-y coordinates is at the center of pipe section.)D 4: Pipe OD.(in)R..: Pipe outside radius.D 1/2.lin)L,,, Pipe nominal wall thickness, (in)V Total service years up to latest Inspection, (yr)V Service years between latest inspection and next inspection, (yr;r N Tota!no.of thickness measurements (equal grid)in circumferential direction.O=2mN, angle of each grid, (tad)(where it=3.142 fl (tmnm)n tt,jn Rn On A Am,, B 14 ,, Inn L I,,,, (in.)(in.)(rad)(in 2)(in 2)(in 3)(in 3)(in 4)(in 4)(in 4)1[21 0.207 8.79 0.00 12.1 0.58 71.2 0.0 45.8 0.0 0.0 2 0.226 0.212 8.79 0.31 12 1 0.59 67.6 22.0 42.5 4.5 13.8 3 0.222 0.208 8.79 0.83 12.1 0.58 57.6 41.8 30.1 15.9 21.9 4 0280 0.271 8.73 0.94 12.0 0.76 40.9 56.3 20.5 38.9 28.2 5 0.295 0.288 8.71 1.26 11.9 0.80 21.4 65.9 6.0 56.8 18.5 6 0.297 0.290 8.71 1.57 119 0.81 00 69.2 0.0 63.2 0.1)7 0.294 0.287 8.71 1.88 11.9 0.80-21.4 65.9 6.0 56.6-18.4 8 0.292 0.284 8.72 2.20 11.9 0.79-40.8 58.1 21.5 40.7-29.5 9 0.292 0.284 8.72 2.51 11.9 0.79-56.1 40.8 40.7 21.5-29.5 10 0.283 0.275 8.73 2.83 12.0 0.76-66.2 21.5 54.3 5.7-17.7 11 0.314 0.308 8.69 3.14 11.9 0.86-68.8 0.0 67.1 0.0 0.0 12 0.304 0.297 8.70 3.46 11.9 0.83-65.6-21.3 58.6 6.2 19.1 13 0.304 0.297 8.70 3.77 11.9 0.83-55.8-40.6 42.4 22.4 30.8 14 0.138 0.116 8.88 4.08 12.4 0.33-43.2-59.4 9.0 17.1 12.4 15 0.137 0.115 8.88 4.40 12.4 0.32-22.7-69.9 2.5 23.4 7.6 16 0.139 0.117 8.88 4.71 12.4 0.33 0.0-73.4 0.0 26.4 0.0 17[0.140 0.118 8.88 5.03 12.4 0.33 22.7-69.8 2.5 24.1-7.8 18 0.130 8.87 5.34 12.4 0.37 42.9-59.1 10.1 19.1-13.9 19 i 0.161 I 0.141 8.86 5.65 12.3 0.40 58.9-42.8 20.7 10.9-15 0'I 20 0.309)0.303 8.70 5.97 11.9 0.84 65.5-21.3 59.7 6.3-19.4 tvlin.0.137 0.115 Ave.0.240 0.228 Total A Am B 1 B, 241.8 12.7 8.2-18.1 539.9 459.6 1.0 I,, I I,,,, Eri STANDARD EN-CS-S-008-MULTI Revision 0 Entergy PIPE WALL THINNING STRuCmRAL EVALUATION Page 21 of 132çment72ExamleofialStres8 Calculation With Actual Thinned Section SHEET 2 OF 2 Gravity center of pressure area Y, B, A Xi,-B/A On)Gravity center of metal area X'-A,A,,X 1 ,;Y,,-A/A,,Y,,: (rr)Moment nertias at C.G.of metal area I, I,-A,,Y, 1 , ti I,&I,, Ixy-Ai, X,Y,, on Actual thinned Section.Nominal sectiorr Uniformly thinned section.2.AxIal Stress tor Actual Thinned Section P: Design pressure.(psi)L.jci-PAJA./1000 Axial stress for pressure based on the actual thinned section, (ksi)Eccentricity of thinned section, (in)Mi,=(1r*Ro 2 yP3/1 000, Bending moment due to eccentricity of pressure force, (k-in)Operating Condition S: Pipe axial stress based on nominal thickness[From Piping Stress Reporti, (ksi)0.75i:[I Stress Intensification for nominal thickness] Mi, (S-P*D,i4t,J1 000)*Zi,i,,/(0,75i): Bending moment due code loadings, (k-in)=Mi,+Mi, Total bending moment for thinned section, (k-in)0,75i[I'Stress Intensification for average thinned thickness} 5'=Si,+(075i)*M/Zi,,,: Actual stress based on the actual thinned section, (ksi)yS,,i,,,,,: Allowable stress, (ksi)Acceptable if ySi,,,>S Normal U set 376 466 735 436 526-795 EZo 13.5 157 22.3 L 7 lj 20.6 I Yes Yes Yes Cyclic Operation Smi,: Thermal stress range (ksi)(l i)Srio*(Z,om/Zrn,n);(ksi)Thermal allowabe stress: (ksi)Acceptable if ySi, 10 1 219 25,7 I Yes I,.,-{ti÷l,-[(I-l,)+4i9'[/2, R, ,=B+(X,,+Y,', I i,i,, B Z, (for t,,i,,,=0375 in);(in', in, in 2)I, R 0 , Z (for (t,)0115 in);(In 2 , in, in')0 034 0075 1425 0649 5346 4338 1274 4322 1057 40.9 806.6 900 89.6 258.8 900 28.8 2.86 1 57 59.8 Notes: (1)It is recommended at least 18 measured wall thickness points around the circumference (2)y=1.l43isused. ATTACHMENT 7.3A EXAMPLE OF ASME CODE CASE N-513 EvALuATIoN FOR A TI-IROuGH-WALL FLAw FOR CARBON STEEL Sheet I of 2 A.Pipe Parameters 0 Pine 00 On)=Pipe wall thickness at flaw location un)=average wall thickness of pipe circumference based on UT report (in)=nominal pipe wall thickness (in)p 5=Design Pressure (psi)p 0 Operational Pressure Ipsi)I Metal Temperature at evaluation(0 F)1<200'Fl E=elastic modulus at I (ksi)v poison ratio J 1.material toughness (lb/in)S=allowable stress for pipe (ksi)=SIP=stress intensification factor used in the stress analysis Service Level pD')t)or loom stress summery'Axial stress due to desiqri pressure lksil s p 5 fl,/(4t)÷(O.75i)u: Piping Axial Stress (ksi, from stress output)SF 0 Level A=27;Level B=2.4;Level c 1.8;Level D=1.3 SF 5.Level A 0023;Level B=2.0;Level c=1.6: Level 0=1.4=pipe mean radius (in)=(D 0 t)/2 E=E/(1-v 2)K 10 material critical stress intensity factor=J 10 0 E/1 000)°(ksilin)O0) 015 at section 150 H 45.too A B C 0 TT F F 1 278 J 3.18-.3.18]27 24 1.8 13 2.3 20 1.6 1.4 9.925 30549 37.08 B.Evaluate as a planar flaw in axial direction Service Level o 00 00 Half axial flaw length (in)p pressure for the service level condition pDj(2t)/1 000 (l<si)For through wall flaw, a C:?oc:(tP.)'F=1÷A+8÷C 3÷D÷EX Where A=00724 K K 00K 0.K 00 00 flaw length 020 A B C D tty'c to make K 5-K>=r I 0.0 L ilL On l0 iSO 150 60 10.00 10.00 10.00 0.76 0.47 0.68 0.96 1.34 1.15 1.28 1.49 E=00023 0.00 0.00 (<275 psig)(C-2621&2622][C-2621](Based on LEFM C-7400&N513.-2, 1-3.0)8=06486 C=02327 000 00382 (ksilirr)°°) 0.00 1.86 1.14 1.65 11.14 0.00 2.33 Allowable Axial Flaw LengTh Smaller 2c"of four service levels (in.)= ATrAcHMENT 7.3A ExAMPLE OF ASME CODE CASE N-513 EVALUATION FOR A THROUGH-WALL FLAW FOR CARBON S'rEEL Sheet 2 of 2 C.Evaluate as a planar flaw in circumferential direction=pDdI2(S+0 4p)](inch)L=length of through wall crack for the hole penetration in the axial direction of the pipe (inch)-length of through wall crack for the hole penetration in the circumferential direction of the pipe (inch)A=flow area of pipe (in>)A>=flow area per CC N-513-2 (in>)A.allowable flow area smaller of A.and A A.-fowaieaof hole Service Level A B C D 10 750>=1.0 1.00 1.00 1.00 1 00 Ot=19 p,D,i(4t)>(0.,5r1 ksi)0.15 0.78 1.18 1.18 o ojD>-(DC-2t l']!lD-ID.-2t,l)1kw)0.221 1.148 1 737 1 737 p=pressure at the service level 90 1 50 150 150 a,=pDJ(4L): Axial stress due to service pressure (ksi)1 80 3.00 3.00 3.00 K=37.1 37.1 37.1 37.1 For through wail flaw, based on a=C C: Half circumferential flaw length try'c'to make K-K 1>0.0 0.045 0.030 0.034 0.041 r=R,,/t 662 66.2 66.2 662=0 1 A.,,=A,,--A.,r+A.,'r' ÷A, 3'r>A.,, 1 20292 269.1 269.1 8,,=B,-'-B,,r+B.,>'r> +B,,,>'r 1 B,, 70999-706-706 C=C,,>+C'r+C,,r> +C,,,, 1'r C,,, 77966 8408 8408 A=A,,>+A 1 ,*r-f A,,,r 4 A 1 ,>'r 3 A 3 2654 243.4 243.4 Bf=B,,,,+B,,,'r+E3,,>'r+Br Bb1 11 363-620-620 Cr>'C>,,÷C,, 1 r+C 1 ,,r>+C,,.r'C,,-3 1861 617.5 617.5 F>r 1+Arn*csl+B,,'cz>+C,.rx> 5 3,30 2.30 F,,=1+A,,'r,,>B,,*a>+Ct,*c,,>> 3.09 2.18 K 1 ,,-K 1 K,,-)(SFm)(1tC)°'C1,,F,,) +SF 1 (rtc)°(a,F,,)] >0.0 0.0 0.0 Flaw length (2c)=2.82 1.88 Allowable Circumferential Crack Length Smaller"2c>of 4 service levels (in.)=I 1.88 I 2 3 1 6776-4 4239 S 1668 1.5278-3.9141 3.8476-0.0799 0.2104-0 2668-00727 0 1862 0.1830 00018-00046 0.0064 0.0016-0.0041 0.0040 269.1-706 840.8 24.3.4-620 617.5 2.54 2.39 0.0 211 D.Check the hole penetration flow area 269.1-706 840.8 24.3.4-620 617 5 100 2 81 00 255 0.100 20 20 0 72 Yes ENGINEERING STANDARD PIPE WALL THINNING SimIcTURAL EvALuATIoN EN-CS-S-008 Revision 0 Page 24 of 132 ATTACHMENT 7.3B ExAMPLE OF ASME CODE CASE N-51 3 EvALuATION FOR A THROUGH-WALL FLAW FOR AOSTENrnc STEEL Sh.1 of 2 K material cutical stress Intensity factor.d*E/1 000)05 (ksi(in)°B.Evaluate as a planar flaw in axial direction LBased on ASME CC N513-2 3b, eqn 1,2&3]Service Level A B p=pressure at service level pD/t2t)(psi)=(S 5÷S)i2 tpsb=allow through wall axial flaw (inch)=1'({o./SF,)aj" -Allowable Axial Flaw Length=I of four service levels (in.)=90 150 6000 10000 47500 47500 5.3 3.3 I I A.Pipe Parameters D..Pipe 00 (in)Pipe wall thickness at flaw location (In)average wall thickness of pipe circumferential based on UT report(in) =nominal pipe wall thickness (in)p Design Pressure (psi)p=Operational Pressure pm (<275 psig)T=Metal Temperature at evaluation(5 F)(.r 200SF)E elastic modulus at T (ksi)V poison ratio=material toughness (lb/in)=Material yield stress at T (ksi)S=Material ultimate tensile strength at T (ksi)=SIF=stress intensification factor Service Level pD='(4 ffl.)or from UE&C stress summery, Axial stress due to design pressure Ike)s=p, 1 DJ(4t)+(0 75l)a 5: Piping Axial Stress (ksi, from stress output)SF,,,: LevelA=2.7;Level8=2.4; Levelc=1,8;LevelD=I[0-2621&2622)SF 5'Level A=23;Level B=2.0 Level c=1.6;Level D=1[0.2621]a/t=depth of flaw to wall thickness ratio (for through wall flaw, a/t=1.0)A,,.=pipe mean radius (in)=(Do'((/2=EI(1-v 2)at scction 0S1 1Q A B C 0 aDo 20O 2.00 1 aO aa 1 7.00 7.B2 I 27 24 18 13 23 20 16 14 1,00 9.925 30549 37.06 0 150 10000 47500 6.8 C 150 10000 47500 4.7 ENGINEERING STANDARD EN-CS-SOO8 Revision 0 PIPE WALL THINNING SmUCTURAL EVALUATION Page 25 of 132 Attachment 7.38 Example of ASME Code Case N-513 Evaluation for a Through-Wall Flaw for Austenitic_Steel Sh.2 of 2 C.Evaluate as a planar flaw in circumferential direction Service Level lO.75i)>ic 1.0 crc'pcDd(4 i..(I:iO.75)(0,-2,j,(D-(0--2t.4]p pressure at the service level (psi)-pDJ(4t)Axial stress due to internal pressure lksi)C half crack length, trial S errol until a Ic appears for both primary bendnq and membrane stress 0=c/R,, (radtan)(S+S)/2 (psi)If 13+/-(ft<=it then flaws not penetrating the compresstve side of pipe=0.5[it.(ait)0-rc/43.4]=(2a/st)[2sin(lf (alt)sind](psi)1119÷[1)>it then flaws penetrating the compressive side of pipe (1=ir(1-aft-O/Oi}!(-alt)crC=(2cry3t)(2 -(alt))sin() pat)Use&Check primary bending stress Allowable bending stress S-a 1 jSF 5[1 it (psi)Sc O,>0 Check primary membrane stress arcsin[0.5(a/t)sin9(=cr41-(a/t)i9 it)-2qs it)(pail Allowable membrane stress=S S 1-0,,.>lrc 0 Flaw length (2c)=A B C 0 1.00 100 100 100 1 88 5.06 5 82 5.82 2.763 7.442 8564 8.564 90 150 150 150 1.80 3.00 3.00 3.00 I.i.H 125[1 1.592 1.179 1.259 1.360 47500 47500 47500 47500 0,71 0.87 0.83 0.78 9175 18388 15945 13053-0.12-0.20-0.20-0.20 16760 27817 27817 27817 I'm[s.sj I 13853j 2856 7444 8633 8631 93 2 68 67 o.k.o.k.o.k.o.k.0.52 0.48 0.50 0.51 7601 15151 13457 11485 2815 6313 7476 8835 1015 3313 4476 5836 o.k.o.k.o.k.o.k.31.6 23,4 25.0 27 0 23.4 0.100 1=.p,,Dj2S 0.4p.;(tnch, L length of through wall flaw for the hole penetration to the axial deection of the pipe (Inch)length o t through wall flaw for the hole penelrahen n the circumferential direction of the p pa inich)A-flow area cf p'pe ()-flow area per CC N-513-2 (to I A=Oi(CwablC flow area smaller of A.and A:.A.=flow area.f hole=LL,.(Based on Limit Load C-5320)Allowable circumferential Flaw Length Smaller"2c'of four service levels (in.)F.Check the hole penetration flow area G.6 20 20 0.72 A<=Aa Yes PIPE WALL THINNING SWucTURAL EvALuATIoN Attachment 7.4 Example of Minimum Wall Evaluation at Reinforcement Area of Tee Sheet 1 of 1 1.Branch Connection Dimensions (See Figure 6 for nomenclature and dimensions) (5 Angle between axes of run and branch, (Deg.)ci ID of branch, (in)d 0: 00 of branch, (in)Mm, predicted branch wall thickness, (in)tm mm Mm.required branch wall thickness, (in)0, 00 of run, (in)T 0: Mm.predicted run wall thickness, (in)Tm: Mm, required run wall thickness, (in>2.Reinforcement Area Dimensions d 1 d/sin(o,), (in)d 2°Haif width of reinforcing zone=Max(di, t÷T÷di2)but not more d (in)L: Altitude of reinforcement zone outside of run=2.5t 9 , (in)te Thickness of reiniorcement ring, pad or saddle, (in)OD of reinforcement ring, pad or saddle (Effective only up to 2*d 2): (in)3.Reinforcement Area Required for Pressure (Boxed values are input.)90 25.25 26 r 0.244 0.244 0.092 A,=1.07*Tmfl*d,*[2510((5)], (in 2)2.486 4.Reinforcement Area Provided A 1: Excess wall thickness in run=d 2 (T (in 2)A 2 Excess wall thickness in branch=2L*(tp (in 2)A, 3 Area provided by deposited weld metal beyond 00 of run and branch, (in 2)A 4: Area provided by a reinforcing ring or pad=(D-d 1)mm t (in 2)A 5 Area provided by a reinforcing saddle (D m dc)tmm (in 2)Total Area Provided A,.., A,+A 2+A 3+(A.m or Ar.)(in)4.11 5.Acceptability of Thinning at Reinforcement Area ENGINEERING SmroARo EN-CS-SOO8 Revision 0 Page 26 of 132 25.25 25.25 0.61 0.0 L0.0 3.838 0.206 LfJ 0 0 Acceptable if A 5..>A.'mm Yes ENGINEERINc STANDARD EN-CS-S-008-MULTI Revision 0 Entergy PIPE WALL THINNING STRUCTURAL EVALUATt0N Page 27 of 132 Attachment 7.5 Plant Specific Allowable Stress Factors Sheet 1 of 1 The following plant specific factors are for a typical piping system.It should be noted that some particular piping systems mght have different factors.In such case, the particular factors for that piping system shall be used.Allowable Stress Factors Normal Upset Emergency 1 fiie1 Site KNOr KEmq KFau Notes lP2 1.0 1.2'1.8 1.812)1.0 t2 1.8 JAF'1.0 1.2 1.8 PNPS 1.0 1.2 1.8 2.4 VY 1.0 1,2 1.8'i'"(1)The typical load combinations for various operating conditions are defined as follows;-Normal (or Design)Pressure+Dead Weight,-Upset=Normal÷Operational Basis Earthquake,-Emergency Normal+Design Basis Earthquake or Safe Shutdown Earthquake Loadings such as pressure transient or pipe rupture, etc.should be added to the appropriate load combination according to the individual plant design basis.(2>Also see Table 1.11-2 of P2 UFSAR.(3)Also see Table 16.1-2 of 1P3 FSAR.(4)Use of this factor is acceptable for piping included in the Mark I Program Analysis.Otherwise, use 1.8. I ENGINEERING STANDARD EN-CS-S-OO841ULTI Revision 0-Entergy i--j PIPE WALL THINNING STRUCTURAL EVALUATION Page 28 of 132 Attachment 76 Recommendation for Safety Related Moderate Energy Class 213 and NoN-SAFry RELATED PIPING Sheet 1 of 7 For non-safety-related piping, the following restrictions of Code Case N-597 and Regulatory Guide 1.147 can be ignored.(1)Thermal expansion stress need not be considered. (2)Localized wall thinning evaluation is acceptable. It is noted that NRC approval is required to apply the local thinning evaluation to Class 1, 2,&3 piping.For moderate energy Class 2&3 piping, NRC granted unconditional acceptance to evaluation method prescribed in ASME CC N-513-2, Acceptable Local Wall Thickness, t 0[2.41 A.t can be equal to O.9 tm,fl without further calculation, or perform following steps B.Obtain local thinning area dimensions: L, Lm, Lmt 5;, L 1>(See Figure A-i)C.Calculate pipe characteristic length, (Rrnritmm)°, where R, 5=A 5-0, Calculate Lmiar/(Rsn*tmn)O E.Determine taioc/trnir, by performing Case 1 and 2 in order.If the limits of Case 1 and 2 are not satisfied, determine tacjtrn,fl from Column 3622.4 of Table A1 2, Case Conditions Applicable Limits Limited i Transverse Extent (Rrn;s*tm;n )>Lm From Column 3622.2 of Table A-i Limited Axial 2.65*(Rm*t )05 Larger value of&2 Transverse Extent and 1-1)05(t,,,.Jt,-.-1)/L arid t,>1.13*tm;s O,353*L 5 1(R,nt>0.5 3 Unlimited Transverse Case 1 or Case 2 not met I From Column 3622.4 of Table A-i Extent-F.Local Wall Thickness Requirements Hoop Stress Criteria Actions tp>ta Accept for Hoop stress tp<t Repair or replace An example of local thinning evaluation for hoop stress is shown in this Attachment [ShI 6&71 Notes: (1)For multiple thinned areas, tOe wail thickness is required to exceed for a distance that is the greater of 2.5(Rt.r,-.) or 2L...between adjacent th;nned reg;ons.Otherwise, the adjacent thinned ewes shall be considered as a single thinned region in the evaluation. (2)For mu tiple thinned a;sos the e a I thickness shat exceed t for n axial d stan..e the greater of a 5(R t)or 2L between adjacent thinned regions.Otherwise, the adjacent thinned areas shalt be considered as a single thinned region in the evaluation.
- ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0-"I!th?rgy
---..PIPE WALL THINNING STRUCTURAL EVALUATION Page 29 of 132 Attachment 7.6 Recommendation for Safety Related Moderate Energy Class 2/3 and NoN-SAFETY RELATED PIPING Sheet 2 of 7 AllvabI*LDc Thlcknes 4*PI*ft4e 3622 2---3622 4 0 0.100 0.100 0.20 0.100 0261 0.23 0.100 0.300 0.26 0.100 0.373 032 0,100 0.477 0.38 0.100 0.531 0.45 0300 0.616 0.30 0.100 0.651 0.60 0.100 0.703 0.70 0.182 0,742 0.83 0300 0.778 0.83 0.315 0.782 0.90 0.349 0.7 L00 0.410 0.813 1.20 0.505 0.841 1.40 0.572 0.860 1.60 0.622 0.873 1.80 0.659 0.883 2.00 0.687 0.891 2.25 0.714 0.897 2.50 0.734 0.900 2.73 0.750 0,900 3.00 0.763 0.900 3.50 0.787 0.900 4.00 0.811 0.900 4.50 0.834 0.900 5.00 Q.:58 0.900 3.50 0.882 0.900 oo 0.900 o.oo>6.00 0.900 0.900 GENERAL NOTE: lnterpotatlon may be used for intermedl.ate aIueL Table A-i ENGINEERING STANDARD EN Cs S 008 MULTI Revision 0 Lrztergy PIPE WALL THINNING STRUCTURAL EVALUATION Page 30 of 132 Attachment 7.6 Recommendation for Safety Related Moderate Energy Class 213 and NoN-SAFElY RELATED PIPING Sheet 3 of 7 SAcioii A-A N Aa freclofl 4 Figure A-i Illustration of Nonpianar Flaw Due To Wall Thinning ENGINEERING STANDARD EN-CS-S..008.MULTI Revision Eritergy-____PIPE WALL THINNING STRUCTURAL EVALUATiON Page 31 of 132 Attachment 7.6 Recommendation for Safety Related Moderate Energy Class 2/3 and NoN-SAFETY RELATED PIPING Sheet 4 of 7 minimumdtancebeiweenaeasiand/ Area S (-maxrniurn axta4e of ihinnad area i G4Lm.NRAL Nbt Cembiiaton of da*t areea into an equvalnt srne aroa sali be based on metsions end axten4s pro to cornbnation f n aucount.nq area 3 Figure A-2: Separation Requirements for Adjacent Thinned Areas
- ENGINEERING STANDARD I EN-CS-SOO8-MULTI Revision 0'Entergy-----I PIPE WALL THINNING STRucrunAL EVALUATION Page 32 of 132 Attachment L6 SHEET 5 OF 7 Recommendation for Safety Related Moderate Energy Class 213 and NON-SAFETY RELATED PIPING-minimum distanc, between areas I dj at any d.c ferantial location on pipe*maximum ext*of thinned area i in axial direction*maximum of the extents and two adjacent areas NOTES: (1)Areas need not be eomblned into skile areas based on separation in the transverse dwection provided Ikat tranwerse axtaMa of indMdul adjacent thinned areas do nat overlap Combination of adjacent areas Into an equivalent
- inQla area shaH be based on dimensions and etante prier to ao cembinmon o a4acent areas.Axial Direction r in surrounding area INote I2 Figure A-3: Separation Requirements for Adjacent Thinned Areas I I ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0 I Entergy I-Pipe WAu.THINNtNG STRUCTURAL EVALUATION Page 33 of 132 Attachment 7.6 Recommendation for Safety Related Moderate Energy Class 2/3 and NoN-SAFETY RELAmD PIPING Sheet6of7 Attachment 7.6: RECOMMENDATION FOR SAFEtY RELATED MODERATE ENERGY CLASS 213 AND NON-SAFETY RELATED PIPING (NRC review and approval is required for Class 1 and High Energy Piping>*1 Design Parameters
.(Boxed values are nput):______D 0:Outside Diameter, (in)16 tflom Pipe nommal thtcknes'i Un)0 5 p design pressure[for N597-21 or mamum operating pressure at flaw location (for N-Si 31 275 S: allowable stress for pipe (psi)is000 tmIf Mnimurn thickness required for hoop stress due to pressure,=pOdt2(S+/-O4p)](in)0.146.tP: Mnimum predicted walithickness at next inspeciion, (in)0.330-,: nominal pipe longitudinal bending stress resulting from all primary pipe loading (psi)7000 R: is used for CC N-597-2;R 0 is used for CC N-51 3-2 R 0 Pipe mean radius=(0 t)/2 (in)7 93 R 0:Piperadius,=D 0/2,(in)8.00:2 Local Thinning Area Dimensions (See FIgure 2 for illustration) The following dimensions shall be the dimensions predicted at the next inspection,: ______L Maximum length of area where thickness is less than t,, (in)4 Maximum length of area where thickness is less than t,, (in)2 L: Maximum length in transverse direction of area where thickness is less than (in)1.5 L,,: Maximum length in axial direction of area where thickness is less than t, (in)1.2 L,/(R*t,)05.Dimensionless length of local thinning in axial direction 1.12 Is CC N51 3 2 applicable input s or no L no Note For CC N 5132 applyto pipe&fitting ata distance<=(R 0 t)°'from weld center line 3.Acceptance Thickness for Local Thinning, t N-597-2 N-513-2: (Rtj°: Pipe characteristic length, (in)1.07 1.08 Case 1: Local Thinning for Limited Trasverse Extent Applicable if (Fi tj°5>L Na nla C 1 (tai/t,,): see note 1 0.90 n/a Note 1: N513-2:trc'mcurve 1 of 15g.3 it applicable; N597-2: fromtable 3622-1,-3622.2 ii applicable Case 2: Local Thinning for Limited Axial arid Transverse Extent Applicable if 2.65*(Rt)O> L,, and I>1.13t, Yes n/a (1 5*(R*.)O.&.L)(1 -tJt,)+1.0 0.019 n/a c=0 353 L,,,(R I.)°0657 nfl c-.Larger of'c c if applic3ble jr 1 0 if nO 0657 n a Case 3: Unlimited Transverse Extent C 1 (t+r,t=,.) see note 2 na+(t)(cx/S)}/1 .8 Larger of (631, c)0.830 n/a t"bte 2: N513-2: fromcurve 2 of Fig.3;N597-2: from table 3622-1,-3622.4 taj=Mfl(Ci. c 2 ,c 3 r t,,(in)0096 ,Aceptabte if t Yes b.Elbow and 8ent Pipe______ 1 ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0 Entergy F---PIPE WALL THINNING STRUcTuRAL EvALuATIoN Page 34 of 132 Attachment 7,6 Recommendation for Safety Related Moderate Energy Class 213 and NON-SAFETY RELA1tO PIPING Sheet 7 OF 7 b.Elbow and Bent Pipe_______R 0 Elbow radius, (in)24 O: Thinning location angle, See Fig.2 for illustration (Deg.)0 (05-fO5/(1+(RP.RbcosO)
- t, (in>0128 Acceptable if t>yes c.Reducer d 0: Maximum outside diameter of piping item at the thinned location, (in){24 Reducer larger end outside diameter (xD 0 assumed), (in)24 a: Maximum cone angle at the center of a reducer, (degree>L=(d,/Di)/cosa
- trO, (in>0103 Acceptable if t>yes Notes applicable to Code Case N5972: (1)Local thinning evaluation shall not be allowed for the following:
At the reinforcement area of opening for any branch connection or tee on the run piping.The reinforcement area is a region adjacent to the branch connection on the run piping, unless the distance between the center of the branch connection and the edge of thinned area predicted to be less than trnfl exceeds D, where D is the nominal inside diameter of the branch connection. 2.At the small end transition of a reducer.3.Inner portion of elbows, tr.0.5[1+11(1+(RbIR)*COS9)]*tmn,ppe, see details in Section 36221(3)of[2.4].(2>Case I shall not be used to evaluate a reducer.For the rule of the separation, see details in Section 3622.2(a)of[2.4.(3)Case 2 is not applicable for the following conditions: 1 Thinned area overlaps the reinforcement of the branch connection. 2.Thinned area lies on the conical or small diameter transition zone of a reducgr 3, Adjacent thinned area qualified by this approach when the reinforcement zones associated with each area would overlap.(4)As an alternative, C21 1-0.935A&r/(Lt.,*): where=the reinforcement area available in the pipe wall based on t distribution in excess of and within the limits of reinforcement of B31.1 Code, see Section 3622.3(d)of[2.41.(5)Case 3 shall not be used to evaluate a reducer.For the rule of the separation requirements for adjacent thinned area, see details in Section 36225(a)of[2.41.
- ENGINEERING STANDARD EN..CS-S-OO8-MULTI Revision 0 Lntergy-___________
PIPE WALL THINNING STRUcmRAi.. EVALUATION Page 35 of 132 Attachment 7.7 Recommended Guidance and Methods for Calculation of Wear Rates Sheet 1 of 3 Wear rate calculations fall into two categories. The first category is for components without baseline or previous inspection data (Le, no initial thickness data is available for the component). rhe second category is for components which have initial (baseline> thickness data or data is available from previous inspections. Due to uncertainties in original thickness, operating history, UT measurement errors, and other factors, establishing accurate wear rates can be difficult. it requires some judgment.EPRI has developed methodologies for wear rate calculations on both initial and repeat inspections. These are described in detail in Section 4.6 of Reference 2.16.There are four methods commonly used for determining wear of piping components from UT inspection data.The methods are: Band Method The band method is based on the assumption that wear caused by FAC is localized and the thickness variations observed around circumferential bands is an indication of wear experienced by the component. The inspection data is divided into circumferential bands of one grid width each.The initial thickness (t)of each band is assumed to be the larger of the nominal thickness or the maximum thickness found in each band (tm).The band wear is the initial thickness minus the minimum thickness found in the band (tm).For each band: t larger of tflm or tmax Wear=t-The component maximum wear is the largest of the individual band wear values.The component initial thickness is than taken as the initial thickness of the band of maximum wear.The use of the nominal wall thickness in the calculations above address the possibility that the entire band may have thinned uniformly, which may have caused most or all of the thickness to be under nominal wall thickness. Area Method The area method uses a local rectangular region, identified as the wear region.It is based on the assumption that the entire wear area, and a thickness representative of the initial thickness, is encompassed within the rectangular region.More than one area can be defined for a given component. The initial thickness (t)of each area is assumed to be the larger of the nominal thickness or the maximum thickness found in each area.(t.aj.For each area: t=arger of t or t Wear=-tfl The component maximum wear is the largest of the individual area wear values.The component initial thickness is than taken as the initial thickness of the area of maximum wear.The use of the nominal wall thickness in the calculations above address the possibility that the entire area may have thinned uniformly, which may have caused most or all of the thickness to be under nominal wall thickness.
- ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 01 Lntery PIPE W,L THINNING STRUCTURAL EvALUArI0N Page 36 of 132 Attachment 7.7 Recommended Guidance and Methods for Calculation of Wear Rates Sheet 2 of 3 Moving Blanket Method The moving blanket method in CHECWORKS is a refinement of the Area Method.It automates the process of identifying the region of maximum wear and attempts to minimize the effect of measurement errors.The method uses a predetermined size wear area or'blanket".
The data within the blanket is evaluated to estimate both the initial thickness and the wear.The blanket is then moved to another location on the component and the process is repeated.The process continues until all possible locations on the component have been covered.Point to Point Method The Point to Point Method can be used when data taken at the same grid locations exists from two or more outages (or baseline data plus data from one or more outages).The wear at each location is the thickness taken at the earlier inspection minus the thickness taken at the later inspection. The largest of the grid wear values is the component maximum wear between the two outages.The Point to Point Method does not estimate the initial component thickness. Wear Rates for Components Without Prior Inspection Data (Initial Inspections) When no initial thickness data is available some value must be used for the initial wall thickness in the wear rate calculation, Variations in the component wall from the manufacturing process can impact the wear rate calculations. This is most evident in reducers and in 90 degree wrought elbows.The Band Method, Area Method, and the Moving Blanket Method can be used to evaluate components with single inspection data.All the methods are based on the theory that the wear caused by FAC is typically found in a localized area or region.The following table taken partially from Reference 2.17 shows the recommended methods and the limitations for each method to determine wear on components with single outage inspection data.Only methods marked'YES'in the table below are recommended to be used for components with single outage inspection data.TABLE 1 Component Type Band Method Area Method Moving Blanket Method Elbow NO NO YES Tee YES ()NO htPi YES NO YES Concentric YES NO NO Reducer4ggander
.-.---
Eccentric NO NO YES ReduceriExder Nozzle Initial thickness and measured wear determined from single outage inspection data should be interpreted conservatively and only be used for structural integnty.Alternately, a conservative Wear and Wear Rate may be calculated as follows: ENGINEERING STANDARD EN-CS-S-0O8MULTI Revision 0 Enteny--PIPE WALL THINNING STRucTuRAL. EvALuArioN Page 37 of 132 Attachment 7.7 Recommended Guidance and Methods for Calculation of Wear Rates Sht 3 of 3 The lowest recorded thickness value for all grid points is used as the measured thickness (t-as)=larger of t.1., 1 Of VV ear=-Wear Rate (Wr)=Wear/Time Wear Rate for Components With Baseline or Prior Inspection Data (Repeat Inspections) Multiple inspection data are considered valid only if the identical grids were used for each inspection. The"point-to-point" method is used to calculate the component wear rate.The wear at each grid location is the thickness taken at the earlier inspection minus the thickness taken at the later inspection The largest of the grid wear values is the component maximum wear between the two outages.The following methods for calculating total wear from multiple inspections are recommended by EPRI in Reference 2.17 TABLE 2 Cases Moving Blanket Point-to-Point Baseline data and subsequent NO YES outages No baseline data with 1 or 2 YES YES LU qes__-No baseline data with more than[1]Point-to-point method can be used when there is data trom at east two outages.However, the wear rate should be compared to the lifetime wear rate obtained from single inspection (Table 1).The maximum wear rate obtained from Table 1 and 2 should be used to determine acceptability of the component. Care must be taken when using the point to point method in cases where the wear between the outages is small.Two large numbers (wall thickness> are subtracted to obtain a small number (wear since previous outage)and then divided by another relatively small number tinterval between outages>to determine the wear rate UT measurement inaccuracies could cause significant calculation error with this method.However, in most cases where inspection data from several inspection outages is available, the point to point method will provide more accurate determinations of wear than other methods[2J Use single inspection method (Table 1)at first inspection plus Pcint-to-Point method thereafter
- I ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0-Lritergy 1----__-----
--H PIPE WALL THINNING STRUCTURAL EVALUATiON Page 38 of 132 Attachment 7.8: Guide for using PS-S-O01 as informational attachment Page 1 of 2 PS-S-OOi Title Acceptability -Remark Attachment I References for pipe wall Yes References are either built into thinning PWT)and crack-like (see Attachment section 2.0 or the spread flaw eva[uation (CLF_-7.9)-sheets in the EN standard.II Terminology and Nomenclature Yes Nomenclature s either built for PWT and CLFE (see Attachment into section 3.0 or the spread 7.9)sheets in the EN standard.Ill Inputs/Requirements common Yes Inputs are built into the spread for PWT and CLFE (see Attachment sheets in the EN standard.-__IV Inputs I Requirements for Yes Inputs are built into the spread evaluation of PWT (see Attachment sheets in the EN standard.7.9)V Inputs I Requirements for CLFE Yes Inputs are built into the spread (see Attachment sheets in the EN standard.7.9)VI Definition of PWT and CLFE Yes (see Attachment VII PWT Evaluation: Code No See Figure 1, Att.7.1, 7.2, 7.6 (removed)Evaluation Procedure CC N-480 was in the EN standard.superseded VIII PWT Evaluation: NRC Generic No.See Figure 1, Att 7.1, 7.2, 7.6 (removed)Letter 90-05 Methods CC N-480, for wall thinning, Att.7.3 for methodology through-wall flaw in the EN required NRC standard.Unconditional NRC approval acceptance using CC N-51 3-2 for moderate energy class 2&n.IX PWT Evaluation: Alternate No EN standard is based on CC (removed)Methods CC N-480 was N-597-2.The code is superseded applicable to non-planar flaws.Att.7.6 need NRC approval when Class 1, 2&3 piping local thinning tac<tp<trnn evaluation. Moderate energy class 2&3 piping does not need to have NRC approval. ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0 En!ergy-___PIPE WALL THINNiNG STRUCTURAL EVALUATION Page 39 of 132 Attachment 7.8: Guide for using PS-S-OO1 as informational attachment Page 2 of 2 X PWT Evaluation: Finite Element Yes See Ati.7.2 in the EN Analysis Methods (see Attachment standard.2D finite element 7.9)need method will solve majority of___________________ edoalup the case-Xl CLFE: Section XL Flaw Yes Evaluation Standards (see Attachment 7.9)From EPRI&Sect.XI documents XII CLFE: Procedure for Austenitic Yes For moderate energy piping, Piping (see Attachment use ATT.7.3B in the EN 7,8)standard for through-wall flaw, Safety factor changed (use as ence__XIII Flaw Evaluation Procedure for Yes For moderate energy piping, Ferritic Piping (see Attachment use ATT.7.3A in the EN 7.9)standard for through-wall flaw.Safety factor changed (use as jence_XIV CLFE: Fracture Mechanics Yes Software (see Attachment 7.9)Safety factor changed (use as ence)XV CLFE: Alternate Fracture Yes Mechanics Solutions XVI Derivation of Approaches for No (removed)PWT Evaluation Given in CC N-480 was Attachment VII prseded XVII Figures Yes, Fig.1&3 Use figure 1 of the EN Figure 2 is no standard instead of Figure 2 of longer valid and PS-S-OO1 k vuechqd [Entergy[..ENGINEERING STANDARD I EN-CS-S-oo8-MULTI Revision a I LL THINNING STRUCTURAL EVALUATION Page 40 of 132 j Attachment 7.9: Informational Attachment Page 1 of 93 Attachment I: References for Pipe Wall Thinning and Crack-Like Flaw Evaluation REFERENCES A.Additional References Used in This Standard and Attachments: A.1 ASME Boiler and Pressure Vessel Code, Section III, Subsections NB, NC.and ND 1974 Edition through Summer 1975 Addenda.A,2 ASME Boiler and Pressure Vessel Code, Section Ill, Subsections NB.NC, and ND 1971 Edition with Winter 1972 Addenda.A.3 ASME Boiler and Pressure Vessel Code, Section III, Subsections NB, NC.and ND 1971 Edition with Summer 1971 Addenda.A.4 USAS 831.7-1969 Edition and"Nuclear Power Piping,"with Addenda through Summer 1971.A.5 ANSI B31.1-1973, with all Addenda through and including Summer 1974.AG ANSI 831.1-1973, through Summer Addenda 831.lb-1973.A.7 ANSI 831.1-1973, with all addenda up to and including Winter 1973 Addenda.A.8 USAS 8311.0-1967. A.9 USAS B31 1.0-1967 and Addenda ANSI 831.7b-1971.A.9a USAS 831.1.0-1967 and Addenda ANSI 831.7b-1973 to ANSI B31,1-1973.A.10 ASME Section XI, IWB-3000, 1986 Edition, without Addenda.A.1 1 ASME Section Xl.1980 Edition with Winter 1981 Addenda.A.12 ASME Section XI, 1977 Edition through Summer 1979 Addenda.A.13 EPRI Report No.NP-6045, Evaluation of Flaws in Ferritic Piping, Novtech Corporation, Rockville. MD, 1988.A.14 EPRI Report No.NP-5911 SP&M."Acceptance Criteria for Structural Evaluation of Erosion/Corrosion Thinning in Carbon Steel Piping,'Structural Integrity Associates, San Jose, CA, July 1988.A,15 EPRI Report NP-3607,"Advances in Elastic Plastic Fracture Analysis'General Electric Company, Schenectady. NY, August 1984.A.16 l.S.Raju and J.C.Newman, Jr.."Stress Intensity Factor inf'uence Coefficients for Internal and External Surface Cracks in Cylindrical Vessels,"ASME PVP-Vol.58, Aspects of Fracture Mechanics in Pressure Vessels and Piping.1982, pp.37-48.A.17 J.C.Newman, Jr.and IS.Raju,"Stress-intensity Factors for Circumferential Surface Cracks in Pipes and Rods Under Tension and Bending Loads."Special Technical Publication 905.ASTM, Philadelphia. PA.1986.A,18 EPRI Report NP-1406-SR,"Nondestructive Examination Acceptance Standards, Technical Basis and Development for Boiler and Pressure Vessel Code, ASME Section Xl.Division 1,"Special Report, May 1980.A.19 Section Xl Task Group for Piping Flaw Evaluation. ASME Code.'Evaluation of Flaws in Austenitic Steel Pipno.'Journal of Pressure Vessel Technology. Vol.108.August 1986. A.20 NUREG-0313, Rev.2, Technical Report on Material Selection and Processing Guideilnes for BWR Coolant Pressure Boundary Piping,'USNRC, January 1988.A21 NUREG-1061, Volume 1,'Report of the U.S.Nuclear Regulatory Commission Piping Review Committee-investigation and Evaluation of Stress Corrosion Cracking in Piping of Boiling Water Reactor Plants,"August 1984.A.22 F,P.Ford and P.L.Andresen, The Theoretical Prediction of the Effect of System Variables on the Cracking of Stainless Steel and Its Use in Design,"Corrosion'87, Paper No.83, Moscone Center, San Francisco, CA, March 9-13, 1987.A.23 H.Tada, P.C.Paris.and G.R.Irwin,'The Stress Analysis of Cracks Handbook," Paris Productions Inc.and Del Research Corporation, St.Louis, Missouri, Second Edition, 1985.A.24 G.C.Shih,"Handbook of Stress Intensity Factors,"Lehigh University, Bethelham. PA, 1973.A.25 0.P.Rooke and D.J.Cartwright,"Compendium of Stress Intensity Factors,"The Hillingdon Press, Uxbridge, Middx, England, 1976.A.26 EPRI NP-5596,"Elastic-Plastic Fracture Analysis of Through-Wall and Surface Flaws in Cylinders," January 1988.A.27 EPRI NP.6301.D,"Ductile Fracture Handbook," Vols.I, II, and III, 1990.A.28 A.
Deardorfi,
G.Randall, and B.Chexal,"An Update on Section Xl Approach for Evaluation of Piping Thinning Due to Flow Accelerated Corrosion," PVP-VoI.264, American Society of Mechanical Engineers, 1993.A.29"Specification for Evaluation and Acceptance of Local Areas of Material, Parts, and Components that are Less Than the Specified Thickness," Reedy Associates. July 28, 1993.A.30 N.Cofie and C.Froehlich,"Plastic Collapse Analysis of Pipes with Arbitrarily Shaped Circumferential Cracks,"in PVP-Volume 135, Fracture Mechaj Creep and Fatique Analysis, ASME, 1988, A.31 ASME Journal of Pressure Vessel Technology,"Evaluation of Flaws in Austenitic Piping,"Vol.108, August 1986.A,32 ASME Cases of B&PV Code, Code Case N-480,"Examination Requirements for Pipe Wall Thinning Due to Single Phase Erosion and Corrosion, Section XI, Division 1.'pp.787-795, Approval date May 10.1990.A.33 ANSI/ASME B31G."Manual for Determining the Remaining Strength of Corroded Pipelines.' 1984.A.34 EPRI 6793-CCML,"CHECK-T Software for the Evaluation of Pipe Wall Thinning: Description and User's Manual,"Structural Integrity Associates, Inc., San Jose.CA.and Miller-Norris Associates. Santa Cruz.CA, April 1990.A.35 intentionally Left Blank.A.36 Warren C.Young,"Roarks Formulas (or Stress and Strain", McGraw-Hill Book Co., 6th ed, A.37 ASME Boiler and Pressure Vessel Code.Section Xl.1989 Edition.A.38 ASME Boiler and Pressure Vessel Code, Section Ill Appendices, 1989 Edition.Attachment 7.9: Informational Attachment Page 2 of 93
- ENGINEERING STANDARO EN-CS-S-008-MULTI RevIsion 0-En!ergy'>PIPE WALL THINN1NG STRUCTURAL EVALUATION Page 42 of 132 Attachment 7.9: InformatIonal Attachment Page 3 of 93 A.39 BWR Vessel and Internal Project-Topical Report: Evaluation of Crack Growth in BWR Stainless Steel RPV Internals (Proprietary Information prepared by BWR Vessel and Internals Project Crack Growth Working Group, SIA, GE, EPRI, Entergy Operations, Inc.et a!), 1955.A.40 US Nuclear Regulatory Commission Generic Letter 88-01: NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping, Jan 25, 1988.A.41 John M.Barsom and S.T.Rolfe, Fracture and Fatigue Control in Structures
-Applications of Structural Mechanics," Prentice Hall, Inglewood Cliffs, NJ, 2nd Ed., 1987 A.42 EPRI Report No.NP-1931, An Engineering Approach for Elastic-Plastic Fracture Analysis," V.Kumar, M.D.German, and C.F.Shih, July 1981, A.43 NAVCO Piping Datalog, ed.No, 10, 1974.National Valve and Manufacturing Co., Pittsburgh, PA B.References Provided For Information: B.1 M.F.Kanninen and C.H.Popelar,"Advanced Fracture Mechanics," Oxford University Press, New York, N.Y., 1985.8.2 EPRI Document NP-5064M,"Corrosion-Assisted Cracking of Stainless and Low Alloy Steels in LWR Environments," February 1987, 8.3 EPRI Document TR-100399, Volume 2,"Stress Corrosion Monitoring and Component Life Prediction in SWAs,"March 1992.8.4 P.L.Andresen, L.F.Coffin, and F.P.Ford,"Corrosion Cracking Monitor-Feasibility Il,"EPRI Contract RP2006-14, GE CR0 Report 87SRD022, Final Report, February 1988.8.5 EOl formulations using Fracture Mechanics Approach.8.6"pc-CRACK Fracture Mechanics Software User's Manual,"Structural Integrity Associates, Version 2.1, 1991.8.7"ENDURE"-Users Manual for Fatigue and Fracture Analysis, Engineering Mechanics Research Corporation, Troy, Ml. f ENGINEERING STANDARD EN-Cs-soo8-MULTI Revision 0 I ALL THINNING STRUCTURAL EvALuATIoN Page 43 of 132 j Attachment 7.9: Informational Attachment __________________Page 4 of 93 Attachment II: Terminology and Nomenclature for Pipe Wall Thinning And Crack-Like Flaw Evaluation a Maximum depth of surface flaw.inch a Final flaw size, inch A Corrosion allowance. inch (includes any additional wall thickness for general loss)A 1 Area of wall thinning that exceeds tm.inch 2 A 2 Compensating area for local wall thinning, inch 2 A, Internal Area of pipe, in 2 a Coefficient of thermal expansion of pipe;Maximum cone angle at the center of the reducer, degrees B 1.B 2 Primary stress indices Angle to neutral axis of flawed pipe, radians c Half length of surface flaw, inch CVN Charpy V-notched absorbed energy, ft-lb d 1.d 2 Depth of flaws as shown in figures of generic letter 90-05 evaluations. inch d Distance from the pipe nominal center to the center of pressure for the thinned section, inch Distance from the pipe nominal center to the centroid of the pipe wall metal at the thinned section, inch Da Mean Diameter of corroded pipe and outer pipe, inch D Nominal pipe internal diameter, inch D Nominal pipe diameter, inch DN Inside diameter of corroded pipe, inch Outside pipe diameter, inch D Inside pipe diameter based on projected pipe wall thickness, inch D 1 Outside diameter at the large end of the reducer, inch D 2 Outside diameter at the small end of the reducer.inch E Modulus of elasticity or weld joint efficiency. psi E Modulus of elasticity at room temperature, psi E 1 Modulus of elasticity at pipe temperature, psi Stress range reduction factor for cyclic conditions F Boundary correction factor or a parameter for normalized (axial)flaw stress intensity factor F ENGINEERING STANDARD I EN-CS-S-0O8-MULTI Revision 0 Lntery PIPE WALL THINNING STRucTURAL EVALUATION Page 44 of 132 Attachment 7.9: Informational Attachment ________________________ Page 5 of 93 F A parameter for circumferential flaw bending stress intensity factor F A parameter for circumferential flaw membrane stress intensity factor FAC Flow Accelerated Corrosion Flaw Generic term used to describe cracking or locally thinned area of a pipe wall GTAW Gas Tungsten Arc Welding GMAW Gas Metal Arc Welding Code stress intensification factor, 0.75i 1 Predicted minimum centroidal moment of inertia at the pipe section, in 4 Measure of material toughness due to crack extension at upper shelf, transition, and lower shelf temperatures, J integral at first flaw extension, in-lb/in 2 Jlairn Measure of fracture toughness at 1 mm of crack growth at upper shelf temperature, in-lb/in 2 Kia Applied Fracture Toughness, ksi in Kib Mode I stress intensity factor for bending loading, ksi'din.Critical Fracture Toughness, ksi Iin A component of the screening criterion (SC), the ratio of the stress intensity factor to material toughness Mode I stress intensity factor for membrane loading, ksi'/in.Total flaw length, inch L Length of locally thinned area less than t, inch L Maximum length of thinned area less than tm.inch La Axial length of locally thinned area less than t,,, inch L 1 Tangential (transverse) length of locally thinned area in less than tm, inch Ln.m..Minimum Lrn measured.inch L Length of reinforcement area, inch M Margin of stress M Resultant moment loading due to weight and other sustained loads, in-I b M Resultant loading moment due to occasional load, in-lb M Range of resultant moment due to thermal expansion. in-lb MIC Microbiologically Induced Corrosion N Number of cles P Internal (or external)design pressure, psi ENGINEERING STANDARD I EN-CSS-OO8MULTl Revision 0 Entergy-----I PIPE WALL ThINNING STRUctuRAL EvALuA'rIoN Page 45 of 132 Attachment 7.9: Informational Attachment Page 6 of 93 Total axial load including pressure, kip (see Att.XIII)P Applied pnmary bending stress, psi Applied expansion stress.psi Primary membrane stress at flaw location, psi P Normal operating pressure, psi P Maximum internal operating pressure (peak pressure), psi Total axial load on pipe including pressure, lb r Radius of opening in a pipe (br pipe branch reinforcement), inch R Mean pipe radius, inch Rb Elbow bend radius, inch R Outside pipe radius.inch RatiooiZntoZi Ratio of tn to R Internal Radius, inch R Mean pipe radius based on nominal pipe diameter, inch Rm Mean pipe radius based on minimum pipe wall thickness as determined for hoop pressure, inch Rrn,r Mean pipe radius based on wall thickness t.S Maximum allowable stress at design temperature in ASME Code hoop stress equation, psi Allowable stress range for expansion stress in Code stress equations 10 and 11, psi SAW Submerged Arc Welding SMAW Shielded Metal Arc Welding S Basic material allowable stress at cold temperature. psi SC Screening Criterion SE Marnum allowable stress in material due to internal presure at design temperature and joint efficiency E.psi S Basic material allowable stress at design (hot)temperature in ASME Code stress equations 8, 9 and 11 psi Distance between multiple flaws in GL 90-05 evaluation, inch Longitudinal pressure stress from internal pressure, psi S, Design stress intensity at design'operating temperatures, psi Maximum design stress due to occasional loads, psi I ENGINEERING STANDARD I EN-CS-S-008-MULTI RevIsion 0 I Entergy F--------------
H PirE WALL THINNING STRucTURAL EvALUATIoN Page 46 of 132 Attachment 7.9: Informational Attachment Page 7 of 93 S A component of screening critera (SC), the ratio of the sum of primary bending and expansion stresses to the bending stress at limit load Maximum design stress due to sustained loads, psi S 5 Thermal expansion stress, psi STE Maximum design stress due to sustained loads plus thermal expansion, psi a bending stress at the flawed location for dead weight, pressure, thermal expansion, and SSE as used in GL 90-05, psi a 1 , Reference bending stress at the limit load, psi a Material ultimate strength, psi a Material yield stress.psi a 1 Material yield stress at temperature, psi Nominal pipe wall thickness, inch Allowable local wall thickness, inch aoc Average projected thickness remote from flaw location, inch Uniform thickness of piping with outside diameter D required to withstand sustained and occasional bending loadings as considered in the design analysis of record, in the absence of pressure, anchor movement and thermal expansion loadings, inch tm Code minimum wall thickness satisfying hoop stress criteria, inch tm Minimum pipe wall thickness based on Code Equations for axial pressure and bending, inch tM Larger of tm and trn , inch tm t for large end of reducer, inch t, for small end of reducer, inch Nominal pipe wall thickness, inch t Minimum projected pipe wall thickness at the next scheduled inspection, inch T Ppe design temperature.
F T,,ijL)Range of temperatute on side a(b)of gross structural discontnuity or material dscontinuity. F (see ASME Section Ill NB 3653)9 One-half of the final flaw angle, radian v Poisson Ratio x at'1'Coefficient 0.4 for temperature 900 F and below Z Section modulus based on projected pipe wall thickness t.inch 3 ZM Predicted minimum secto'i modulus for the thinned section, inch I ENGNEEnING STANDARD I EN-CSS-OO8MULTi Revision 0'Lntery I----------- I PIPE WALL THINNING STRUcmRAL EvALuAIi0N j Page 47 of 132 Attachment 79: Informational Attachment ________Page 8 of 93 Z Secton modu'us based on nomInal waU thIckness t, Inch 3
- I ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0-Entergy Ptc'WALL THINNING STRUCTURAL EvALUATIoN Page 48 of 132 Attachment 7.9: informational Attachment Page 9 of 93 Attachment Ill: Inputs!Requirements Common For Pipe WaH Thinning and Crack-Like Flaw Evaluation The information contained in the following tables is considered as given conditions and known values.The lurPose of collecting this information is to perform an acceptability evaluation of locally thinned areas (indications) and crack-like flaws.Table 1: Location and Other Piping Information Relating to the Indication or Flaw Component or Subeomponeni Location: Location: Plant System Location: Building Location: Elevation Location;Other Details, if any Piping or Component-Description:
Pipe I Branch I Tee/Elbow/-Rducer or other Line Class: ASME Class 1, 2, 3 or ANSI B31i ANSI B31.7 Class 1,2,3 or Section Xl Line Class: Class 1, 2, 3 Non-Safety iso brawing No.P&IDor Other Id No.Stress Problem No.Line No.Node No(s)Used In the Stress Math Model Type of Piping: CS I SS Component Identification No.
- ENGINEERiNG STANDARD EN-CS-S-008-MULTI Revision 0 Lritery Pipe WALL ThINNING STRuCTURAL EvALuATIoN Page 49 of 132 Attachment 7.9: Informational Attachment
_________Page 10 of 93 Table 2;Other Piping Related Information Required for Localized Pipe Wall Thinning and Crack Like Flaw Evaluation: Material Ultimate Strength (c)psi Material Yield Stress by)psi Material Yield Stress at Temperature (a)psi Modulus of Elasticity (E)psi Mocfulus of Elasticity at Room Temperature (Es)psi Modulus of Elasticity at Pipe Temperature (Et)Psi Coefficient of Thermal Expansion of Pipe Material over a range from 70°F to Temperature (a)Poissofls Ratio (v)at ati Temperatures Applied Fracture Toughness (Kia)ksiJ*Critical Fracture Toughness{Kj)ks[v**Information required for Fracture Mechanics Evaluation of Crack-like Flaws ENGINEERING STANDARD j ENCSSOO8MULTl RevIsion 0 Entergy PIPE WALL THINNING STRUCmRAL EVALUATION j Page 50 of 132 Attachment 79: informational Attachment ____________________ Page 11 of93 Table 3: MaterIal and Geometry of the Pipe and Description of Weld: Material of Pipe ficaon Type or Grade Class ProdUct Form GeometrV of Pipe Nominal diameter (d)inch Schedtiie Pipe 0.0,{D 0)inch Nominal Thickness (t)inch if Weld l Involved for Pipe Wall thinning or Cvack-lfle Flaw Evaluation: Loation of Weld with respect to the Pipe Flaw and any Pipe Discontinufty Type of Weld I ENGINEERING STANDARD I EN-CSS-OO8-MULTI Revision 0 Enterf2y I------H PIPE WALL THINNING STRUCTURAL EVALuATIoN Page 51 of 132 Attachment 7.9: Informational Attachment Page 12 of 93 Table 4: Loading Parameters: PIPING PRESSURES (psi): Normal Operating (Pr.)Maximum Operating (P 0)-______________________ Internal Design 1P)External Design, if applicable (P)(eci..Condenser Lines.)PIPING TEMPERATURES (F): Duerating Maximum Operating Design T)HIGH ENERGY PIPING CONSIDERATIONS Is Pip;rig Hgn Energy (1?0OF and P 275 nsiq or Moderate_Energy jT 200'F or P275 pic SEISMIC CATEGORY: (I.II.tIll.III)RESULTANT MOMENT LOADINGS (in-tb)(For Class 2&3 and B31.*Due to Weight and Other Sustained Loans (i1)Due 10 Occasional Loads IM.,)Due to Thermal Expans'on Loads M)RESULTANT MOMENT LOADINGS (in-tb)(ForClass1) -________________
- In some cases there may he multiple loading conditions that have to he considered.
ENGINEERING STANDARD I EN-CS-SOO8MULTI Revislon]Entey----1 PipE WALL THINNING STRucTuRAL EvALUATIoN Page 52 of 132 Attachment 79: Informational Attachment Page 13 of 93 Table 5: DesIgn Allowables: ALLOWABLE PIPING STRESSES (psi): Class 1 and B31 I Piping: Design Stress Intensity (Sm)at Design I Operating Temperature Class 2, 3 and B 31.1 Piping Maximum Allowable Stress at Design Temperature in Code Hoop Stress Equations (S)Basic Material Stress at Cold Temperature (Sc)Basic Material Allowable Stress at Design (hot)Temperature (Sh)in Code Stress Equations 8, 9 and 11 Allowable Stress Range for Expansion Stress (SA)in Code Stress Equations 10 and 11 Weld Joint Efficiency (E)**Required For Pipe Wall Thinning (Indication) Evaluation ENGINEERING STANDARD EN-CS-S-O08-MULTI Revision 0 PIPE WALL THINNING S'rsiucmnAL EVALUATION Page 53 of 132 Attachment 7.9: Informational Attachment Pagel4of93 Table 6: Applicable Codes for the Evaluation of Indications and Flaws: PLANT: ReL CbD Check No Applicable
- Code ANO-1 A 4 USAS Bl.7-1969 Piping Classes I, ti, and III with Addenda through Summer 1971 (Per Piping Spec: ANSI Bat.7c I 971, ASME-71 Winter 1972 Addenda)ANO1 A.9a tJSAS 8311.0 1967 (Par Piping Spec: ANSI 831 lb-1373to ANSi 831.1-1973).ANO-1 All 1St: ASME Section Xl, 19S0d.with WInter 1981 Addnda.4.10 Repair&Replacement:
ASME Section Xl, 1986 Ed.wlb Addenda ANO-2 4.3 ASME Boiler and Ptessra Vessel Code, Section III, Subsections 148, NC, Nt)1971 with Sn1mer 1971 Addenda ANO-2 A 9 1JSAS 831.1.0-1967 and Addenda ANSi 831.1 b-1971 ANO-2 A.l0 ISI: ASME Section Xl, 1986 Ed.wfo Addenda.Repair&Replacements: AS14E Section XI, 1986 Ed.wlo Addenda.GGNS A.l ASME Boiler and PressUre Vessel Code, Section lii, Subsections NB, NC, Nt)1974, tWough Summer 1975 Addenda.GGNS A.7 ANSI 831.1-1973 , thtough Winter 1973 Addenda GGNS A.12 ASME Section XI, 1977 Ed.through Summer 1979 Addenda R Al ASME Boiler and Pressure Vessel Code, Section 111.Subsections NB, NC, ND 1974, through Summer 1975 Addenda RBS 4.5 ANSI 931,1-1973 ,lhrough Summer 1974 Addenda fiBS All ASME Section XI, 19B0 Ed: through Wirifer 1981 Addenda W-3 A.I ASME Boiler and Pressure Vessel Code, Section III Subsection NB 1974.with Summer 1975 Addenda.W-3 A.2 ASME Boiler and Pressure Vessel Code, Section III.Subsections NC, ND 1971 with Winter 1972 Addenda.W4 A.5 ANSI 831.1-1973 , with All Addenda through and including Summer 1974 W4 A.11 ASME Section Xl, 1980 Ed.with Winter 1581 Addenda,
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PIPE WALL Ti-fINNING STRUCTURAL EvALUATION Page 54 of 132 Attachment 7.9: Informational Attachment ______Pagel5of93 -Attachment IV: Inputs/Requirements for Evaluation of Pipe Wall Thinning Table 1: Description of Locally Thinned Area: Define initiating Mechanism: Corrosion Mechanisms such as: (1)Flow Accelerated Corrosion (FAC)r (2)Microbilogically Induced Corrosion (MIC), Solid Particle Impingement &Fouling in SSW (3)Cavitation &Flashing Downstream of Orifices.Flow Control Valves And Level Control Valves (4)Mechanical Abrasion, Manufacturing Process, Pipe Wall Gnnding and (5)Environmental Conditions. Geometry of Locally Thinned Area: (see Figure 1)Internal or External Minimum Projected WaN Thickness (tn), inch Length of Locally Thinned Area Less Than t,, (L), inch Maximum Length of Thinned Area Less Than t, (Lw), inch Axial Length of Locally Thinned Area Less than t,, L,, inch Tangential (transverse) Length of Locally Thinned Area Less Thaii tm, L, inch Additional Information Required for Local Pipe Wall Thinning Evaluation: Location of locally thinned area with respect to a fitting or weld on a specific isomelric drawing.4.Orientation circumfercntiallv. looking downstream, with"0"being at the top and the measured length clockwise around ihe pipe to the center of the locally thinned area.Orientation to show the view north, south, east, or west has"0"at the north when viewed 1mm above (plan view).3.Detailed results of pipe wall inspection, including both asmeasured arid prolecled pipe wall thickness in both the axial and circumferential direction. The extent of the thickness mapping shall he at least+/-R in the axial direction and shall include all of the thinned location in the circumferential direction. m Entergy ENGINEERING STANDARD EN-CSS-OO8-MULTI Revision 0 PIPE WALL THINNING STRUcTuRAL EVALUATION Page 55 of 132 Attachment 79: Informational Attachment Pagel6of93 Attachment V: Inputs/Requirements for CrackLike Flaw Evaluation A Lm transverse 1 (Hoop>4 Direction Lm(t)L Figure 1: Local Pipe Wall Thinning Parameters [I ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0 I in!ergy PIPE WALL THINNING STRuc'rURAL EVALUATION Page 56 of 132 Attachment 7.9: Informational Attachment ________Page 17 of 93 Attachment V: Inputs!Requirements for Crack-Like Flaw Evaluation Table 1:Description of the Flaw Location: Define Initiating Mechanism: Fatigue/SCC/FAC/MIC I Other such as Mechanical abrasion, Manufacturing process, Pipe wall surface grinding.Environmental conditions or Other________________ Geometry of Flaw Location: Pipe OD (Do).inch Nominal Pipe Wall Thickness ft).inch Flaw Orientation Flaw Length (If), inch Maximum Flaw Depth for Surface Flaws (a).nch Maximum Flaw Depth for Subsurface Flaws (2a).inch Figures Describing Cracklike Flaws: 1.l..ocalion of flawed area ith lespecilo a fitting or weld on a specific isometric dra lug.2.Orientation circumferentially, looking downstream, with"0"being at the top and the measured length clockwise around the pipe to the center of the locally thinned area.Orientation to show the view north, south, east.or west has"0 at the north when viewed from above (plan view).3.Exact description of the flawed area (e.g., depth versus position along flaw, depth within the wall, etc.)4.For multiple flaws, a map showing the location of the flaws (start and end points of the individual flaws)should be provided.
- .I ENGINEERING STANDARD[EN-CS-S-DaB-MULTI Revision 0 Lntergy H------------H f PwE WALL THINNING SmUcruAL EVALUATION Page 57 of 132 Attachment 7.9: Informational Attachment
____Page 18 of 93 Attachment VI: Definition of Pipe Wall Thinning and Crack-Like Flaw Evaluation 1.0 CharacterIzation of Flaws and Wall Thinning I.I Flaws and/or wall thinning may occur in nuclear plant piping due to a number of degradation mechanisms. Pipe wall degradation may occur in many different forms, ranging from general thinning (uniform loss of wall thickness) to local cracking (e.g., due to fatigue or intergranular stress corrosion cracking). This section provides guidance on how to characterize pipe wall degradation and recommends which sections of this manual may be appropriate for evaluation of the flaw or wall thinning detected by inspections. 2.0 Wall Thinning 2.1 Pipe wall thinning is characterized by a general loss of pipe wall thickness. The most common form of wall thinning is that due to erosion-corrosion (flow-accelerated corrosion). This type of degradation occurs due to a wearing away of protective metal oxides at the pipe wall, and is localized due to local flow turbulence or lack of alloying in carbon steel piping.Wall thinning can also result from general corrosion and wastage, due to wet steam erosion, flashing downstream of orifices or valves, or solid particle erosion.2.2 The degradation can generally be quantified by a predicted minimum wall thickness at the location of interest.ri cases of severe thinning, additional information may be required to quantify the transverse and axial extent of the thinning that is less than that required to meet minimum pipe wall thickness requirements. 2.3 Evaluation of wall thinning is addressed in Attachments VII to X.3.0 Cracking 3.1 Cracking is the breakdown of the metal structure due to fatigue cycling or intergranular attack.leading to crack-like detects.There is no observable degradation at the surface of the metal, except for the evidence of cracking intersecting the metal surface.Pure cracking produces very localized stresses in the vicinity of the crack tip which lead to further growth of the cracks due to fatigue cycles (for fatigue cracking)or constant applied stresses (for intergranular stress corrosion cracking). Cracking may be either surface connected or sub-surface. 3.2 Cracks are characterized by a crack depth, crack length and orientation relative to the axis of the pipe.With this characterization, appropriate fracture mechanics models may be used to determine future crack growth and the allowable flaw size.3.3 Attachments Xl to XV address evaluation of crack-like defects.4.0 Other Pipe Degradation 3.1 There are other corrosion mechanisms that produce pipe wall degradation that is neither thinning nor cracking. Page 19 of 93 Attachment VI: Definition of Pipe Wall Thinning and Crack-Like Flaw Evaluation 4.2 Pitting corrosion may occur as a result of certain material and water chemistry combinations. It is generally characterized by relatively deep local defects, although there may also be some general loss of pipe wall thickness, In many cases, the presence of pitting is discovered by local leakage through the pipe wall.The pits may be extremely localized or they may exhibit characteristics of a general indentation of the wall surface.In general, there will be adjacent areas which are affected by the pitting phenomenon, such that inspection of adjacent areas is required when pitting is discovered. 4.3 Microbiologically induced corrosion (MIC)is another form of degradation caused by microbial action at the pipe inside surface.The effect may be a general loss of pipe wall material beneath microbial scale or tubercles. For some cases, MIC may produce local pits that will lead to through-wall leakage.4.4 In general, these other types of local wall degradation can be evaluated as wall thinning as described in Attachments VII to X.Of special interest would be evaluations using local wall thinning concepts of area reinforcement (such as is used for branch piping connections). However, in certain cases, evaluating the defect as a crack-like defect may also produce an acceptable answer (such as is used in the through-wall flaw approach in Attachment VIII).Attachment 7.9: Informational Attachment
- ENGINEER1NG SrANDAAD EN-CS-S-008-MULTI Revi&on 0 Enterjy PIPE WALL THlNNNG STRucTuRAL EVALUATION Page 59 of 132 Attachment 7.9: Informational Attachment Page 20 of 93 Attachment X: Pipe Wall Thinning Evaluation:
Finite Element Analysis Methods
1.0 INTRODUCTION
.1 The option of using finite element element analysis is provided primarily as a'last gasp alternative when the methods described in Attachments VII through lX are either not applicable or because they fail to provide adequate relief due to conservative simplifying assumptions which form the basis of these methods.The following conservatisms regarding calculation of hoop stresses in the EPRI NP-59I1SP methodology, which also exist in Code Case N-480, and Generic Letter 90-05 can be reduced by use of finite element analysis: 1.1.1 The Local Membrane and B31.G methods are based on the assumption that the nominal pipe wall thickness t, is equal to the minimum wall thickness required for internal pressure, tM, and no credit for t>t is taken.1.1.2 As can be seen in Figure 5 attachment IX, it is assumed in the Branch Reinforcement method that the area which must be replaced (A,)is equal to (tm tjLm.Depending on the shape of the locally thinned area, the true value of A 1 may be significantly less than this.In addition, the area available for reinforcement, A, is conservatively calculated, with not all of the local area with a projected wall thickness greater than trn being included.1.2 For the calculation of axial stresses due to internal pressure and bending moment, it is assumed in NP-591 iSP, Code Case N-480, and Generic Letter 90-05 that the pipe wall is uniformly thinned to the projected wall thickness t for the entire 360 degree circumference. If a three dimensional (3D)finite element model is used, the variation of wall thickness around the pipe circumference can be accurately modeled.I.3 Figure 1 shows a flow chart which describes the recommended procedure for evaluation of locally thinned areas by finite element analysis.The first step is to develop a finite element model of the locally thinned area.The type of model used will be dependent on the shape and extent of the locally thinned area.If the locally thinned area has a fairly constant t, around the pipe circumference, an axisymmetric (20)finite element model should be used.A 3D finite element is best suited for locally thinned areas that are limited in the transverse extent or in the transverse and axial extent.1.4 After development of the finite element model, internal pressure and bending moment loads are applied to the model.It is suggested that the following separate load cases be run: 1.4 1 Load Case 1: Internal pressure with no'end cap"loadings for hoop stress.I.4.2 Load Case 2: Axial end cap'loadings from internal pressure.I.4.3 Load Case 3: Moment loadings from axial bending stresses.
- I ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0 Eritergy i---------PIPE WALL THINNING STRUCTURAL EVALUATION Page 60 of 132 Attachment 7.9: InformatIonal Attachment Page 21 of 93 Attachment X: Pipe Wall Thinning Evaluation:
Finite Element Analysis Methods 1.4,4 For the first case (hoop stress), some normalized value of internal pressure, such as 1, 100 or 1000 psi, is applied to the inside surface of the piping model.The ends of the piping model must be open.One end is'free"(no restraints) and the other is'fixed (all degrees of freedom restrained), The axial length of the model should be sufficiently long so that the boundary conditions at either end will not affect the stress distribution at the locally thinned area.The only significant stresses calculated by the model for this load case will be hoop stresses, since there is rio applied axial loading.1.4.5 The second load case (for longitudinal pressure stresses>, is the axial loading due to the internal pressure"end cap"force.This force is equal to the normalized internal pressure used in the first load case times the actual (effects of thinning included)inside area of the pipe.It is applied to the free end of the model as a uniformly distributed force/unit length around the full pipe circumference. It is important that the free end be at least one pipe diameter from the near edge of the locally thinned area so that accurate local stresses are calculated in the thinned area.This is also true for additional resultant bending moment loading, where the resultant bending moment is applied at the free end.A normalized value such as 1000 in-lbs is recommended. The stress analysis will typically provide actual moments on each side ot the thinned region.The larger of the two moments should be applied to the finite element analysis normalized stress when performing the actual stress analysis.
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Finite Element Analysis Methods 1.5 Once the stress results for the three"normalized" load cases have been obtained, the maximum hoop and axial stresses at the locally thinned areas due to design and operational loadings can be obtained.Hoop stresses due to design pressure can be obtained by ratioing the results from the first load case.Axial stresses due to internal pressure.primary (mechanical> bending moments and secondary (thermal expansion, thermal anchor movements and seismic anchor movements) can be obtained by ratioing the results of the second and third load cases.Axial and hoop stresses can be obtained in this manner for all design and operating conditions defined in the licensing basis documentation for the piping.1.6 Once the maximum hoop and axial stresses have been calculated, they must be compared with the allowable values defined in the Code of Construction. Since ASME Class 1 requires the evaluation of through.'wall thermal bending stresses and a fatigue evaluation for cyclic operation, Figure 1 defines a separate evaluation procedure for Class 1 piping.This procedure is described in Section 2.The evaluation procedure recommended for ASME Class 2 and Class 3 piping and ANSI B31.1 piping is included in Section 3.2.0 CLASS 1 PIPING EVALUATION PROCEDURE 2.1 The first step defined in Figure 1 for the Class 1 piping evaluation procedure is to check that the stress requirements for the design conditions have been met.Hoop stresses are calculated for design internal pressure using the finite element model in the manner described above.The hoop stresses can be evaluated for acceptance by use of paragraph NB-3213.10 of the ASME Code.Figure 2 illustrates the concept of local primary membrane stress which is defined by this paragraph of the Code.From the Code, a stressed region may be considered local if the distance over which the membrane stress intensity exceeds l.lSm does not extend in the meridional direction more than 1.0(Rt 1)°5.For application to locally thinned pipes, the meridional direction is axial to the pipe, and t is t,.N8-32 13.10 also sets a limit on the proximity of areas where membrane stresses can be considered as local.Regions of local 2.2 primary stress intensity involving axisymmetric membrane stress distributions which exceed 1.1S, shall not be closer in the meridional direction than 2.5(Rt,)°". If both of these conditions are met by the hoop stress distribution calculated by the finite element analysis, then the allowable stress of 1.5S defined in Figure NB-3221-1 of the ASME Code for local membrane stresses can be used to qualify the hoop stresses resulting from design pressure.2.3 Axial stresses due to design conditions are checked by equation (9)of NB-3652 of the ASME Code (see Attachment VII).The PDJ2t portion of the first term in this equation is replaced by the maximum axial stress in the locally thinned area calculated by the finite element model for the second load case described above, The D 0 M 1/2l portion of the second term is replaced by the maximum axial stress obtained from the finite element model for the third load case.The finite element stresses implicitly include stress concentration effects, and stress intensification terms in the Code equations should be set to unity, i.e..the finite element stresses should not be modified by a stress intensification factor.if the limitations of equation (9)of NS-3652 are met, the axial stresses in the locally thinned area meet the Class 1 requirements for design conditions. I ENGINEERING STANOARD I EN-CS-S-008-MLJLTI Revision 0 En!ergy F----PIPE WALL THINNING STrnJcThRAL EVALUATiON Page 62 of 132 Attachment 7.9: Informational Attachment Page 23 of 93 Attachment X: Pipe Wall Thinning Evaluation: Finite Element Analysis Methods 23 For Service Level A and B conditions, equation (10>of NB-3653 must be met.This equation includes the temperature ranges Ta-Tb and AT 1.These terms can be taken from the original piping evaluation. The smaller thickness will result in smaller temperature gradient across the thickness, and therefore, it is conservative to use the AT 1 from the original piping evaluation. The thinning also decreases the stiffness of the pipe which makes it conservative to use the Ta-Tb terms from the original analysis.In general, it is not expected that local thinning will have a significant effect on the AT 1 and Ta-T, stresses.The first two terms are evaluated in the same manner as in equation (9), with the exception that operating pressure and moment ranges resulting from the Service Level A and B loading conditions are substituted in the pressure and bending moment terms.2.5 If the Service Level A and B stress requirements are met, the Class 1 fatigue requirements for cyclic operation must also be checked.The basis of this fatigue evaluation for Class 1 piping is Code equation (11)of NB-3653.The additional through-wall thermal term corresponding to AT 2 should be taken from the original piping evaluation, since the thinned pipe will have actual AT 2 c the original AT 2.The pressure and M, terms from Code equation (10)are the same except they are multiplied by l<1 and K 2 , respectively, in Code equation (11).The K 1 and K 2 terms are used to multiply the finite element stresses if the model is not expected to include all necessary details (stress concentrations at butt weld).For a very refined model that is expected to accurately model all stress concentration effects, it may be justified to set K 1=K 2=1.0.The remainder of the fatigue evaluation is the same as in the original piping evaluation. 3.9 EvaluatIon Procedure for Non-Class 1 Piping 3.1 For ASME Class 2 and 3 piping, and ANSI 831.1 piping, hoop stresses calculated by the finite element model may be evaluated using the same method as described above, except the allowable stress for local membrane stresses is taken as I.5S instead of 1.5Sm.For the axial stresses due to internal pressure and primary bending moments, the PD 0!4t, MAJZ and (MA÷M 5)/Z terms in the Code of Construction piping equations are replaced with the corresponding results from the finite element analysis.The finite element stresses implicitly include stress concentration effects, and stress intensification terms in the Code equations should be set to unity, i.e., the finite element stresses should not be modified by a stress intensification factor.Axial stresses due to secondary loadings (thermal expansion. thermal anchor movement and seismic anchor movement)are checked for compliance with the original Code of Construction by substituting the appropriate results from the finite element analysis into the M/Z term in the Code equations for thermal expansion. 3.2 To determine if an evaluation for cyclic operation is necessary. use the criteria described in Section 3.7 of Attachment IX, ENGINEERING STANDARD j ENCS-S-OO8MULTI Revision 0 Entergy PIPE WALL ThINNING STRUCTURAL EvALuATIoN Page 63 of 132 Attachment 79: Informational Attachment ________Page 24 of 93 Attachment X: Pipe Wall Thinning Evaluation: Finite Element Analysis Methods ervice Level A&B Stress No-H Requirements Met?Yes rements for Primary Stresses Met?Yes rements for Secondary Stresses Met?Yes ation for Cyclic Operation Required?Yes 0 Finite Element Analysis Methods[Develop Finite Element Model Mechanical and Thermal Bending Moments Calculate Maximum Hoop and Axial Stresses 4[ternal in Locally Thinned Area Pressure Yes No I Monitor>Figure 1: Finite Element Analysis Method 1 ENGINEERING STANDARD EN-CSS-OO8MULTI Revision]Lntergy H-PIPE WALL THINNING STRUCTURAL EVALUATION Page 64 of 132 Attachment 7.9: Informational Attachment Page 25 of 93 Attachment Xc Pipe Wall Thinning Evaluation: Finite Element Analysis Methods 4 2.5\Rt 4 I 0 SIll S 1.5 rn'm___1____?ial Dim.=(Lm+L 1)/2=Larger of L 1 , Lm2 Figure 2: Illustration of Local Primary Membrane Stress 0 1 ENGINEERING STANDARD 1 EN-CS-SOO8-MULTI RevisIon 0-En!ergy[---------1 PIPE WAL.L THINNING STRucTuRAL EVALUATION j Page 65 of 132 Attachment 7.9: Informational Attachment _________________ _____________ Page2Sof93 Attachment Xl: CLFE: Section Xl Flaw Evaluation Standards.
1.0 INTRODUCTION
.1 This attachment utilizes later editions of the Section Xl Codes, as detailed below, which may not be addressed in the Codes referenced by Table 6 in Attachment Ill.Approval from the plant licensing department, and/or NRC, may be required prior to utilizing the provisions of this attachment. .1,1 Tables 3 and 4 may not be addressed in the Codes referenced by Table 6 in Attachment Ill for ANO-1 (IS I), GGNS, R8S and W3.1.2 Flaw indications in piping which are characterized as cracklike should be evaluated in accordance with ASME Section Xi.The steps in the process include: 1.2.1 Flaw characterization and sizing to determine its length and depth in accordance with ASME Section Xi Article IWA-3300.1.2.2 Comparison of the flaw dimensions to the appropriate acceptance standards of Section Xl Articles IWB-3500, IWC-3000, or IWD-3000 as appropriate. 1.2.3 Analytical evaluation for flaws which exceed the acceptance standards. 1.2.4 This attachment provides a detailed standard for characterizing cracklike flaws in Entergy nuclear plant piping and for determining their acceptability in accordance with ASME Section Xl acceptance standards, Analytical evaluation procedures for flaws which exceed the standards are provided in Attachments XII through XV.The technical basis for the standards is documented in Reference A.18 of Attachment I.2.0 FLAW CHARACTERIZATION AND SIZING 2.0,1 Cracklike flaws should first be characterized as planar, laminar, or linear flaws, in accordance with the following definitions. 2.0.2 Planar flaws are flaws which are cracklike in nature and oriented, at least partly, in the through-walt direction of the pipe.They are planar in nature, possessing only two dimensions, length and depth, and the depth dimension has a significant component which is perpendicular to the inside or outside surfaces of the pipe (see figure 1). I ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0 Entergy 1-j Pp WALL THINNING STRUCTURAL EvALuATioN Page 66 of 132 Attachment 7.9: lnformation& Attachment ______________________ Page 27 of 93 2.02.1 Planar flaw indications are further characterized as surface or subsurface flaws depending upon their proximity to the nearest surface of the pipe.Flaws which intersect the surface, or are within a prescribed distance'5"from the surface are classified as surface flaws, see figures 1 and 2.All other planar flaws are considered subsurface flaws.Non-cracklike flaws.such as weld porosity or slag, which are volumetric in nature (possess three dimensions), may be conservatively assumed to be planar flaws for purposes of evaluation. In this case, the minimum of the three directions is ignored, and the other two dimensions are assigned as the flaw length and depth, in accordance with the planar flaw sizing rules.The ultrasonic examination techniques used for inservice inspections are in general incapable of distinguishing between volumetric and planar defects, so this assumption is a common one.2.03 Laminar flaws are similar to planar flaws, but are oriented in a plane that is essentially parallel (within 10)to the inside or outside surface of the pipe (see figure 6), 2.04 Linear flaws are planar flaws which have been detected by radiography (RT)or surface examination (PT or MT), such that the depth dimension has not been measured and only the length dimension is known.2.05 The basic flaw sizing approach consists of bounding the observed flaw with a rectangle that fully contains the area of the flaw, as illustrated in Figure 1.The length of the flaw'I"corresponds to the length dimension of the rectangle, which is parallel to the surface of the pipe.The depth dimension corresponds to the through-wall component of the rectangle, which is perpendicular to the surface of the pipe.For surface flaws, the depth of the rectangle is denoted"a", while for subsurface flaws, the through-wall depth is denoted'2a"(see Figure 1).The"a"and"I"dimensions are assumed to correspond to the minor half-axis and major axis of an ellipse for purposes of fracture mechancis analysis.Special rules are provided for determining "a"and"I'in the case of multiple flaws, flaws which are close to the pipe surface, or flaws oriented in curved or parallel planes.These are described in the following paragraphs. 2.1 Surface Flaw Proximity Rules 2.1.1 Characterization of planar flaws which are close to the surface of a component, but do not intersect the surface is illustrated in Figure 2.ln this case, the non-destructive examination technique is used to determine the minimum separation distance'S'from the surface to the closest point of the flaw.The through-wall depth of the flaw is then determined, which is temporarily denoted"2d".If S is greater than or equal to 0.4d.then the flaw is a subsurface flaw, and the characteristic flaw depth a is set equal to d.If S is less than 0.4d, then the flaw must be assumed to be a surface flaw, and the uncracked ligament S is added to the crack depth to create a total surface flaw depth a 2d+S.Note that for cases in which the uncracked ligament S is between 0.4d and d, the flaw is classified as subsurface, but there is an adjustment to the subsurface flaw acceptance standards using a'Y"factor as described in section 3,1.2.1.2 In the case of clad piping, proximity to the clad surface is determined assuming the clad-base metal interface to be the inside surface of the pipe.The location of the clad-base metal interface may be determined by non-destructive testing.or estimated from design drawings. 10 ENGINEERING STANDARD I EN-CS-S-OOB-MULTI Revision 0[--Entergy PIPE WALL THINNING STRUCTURAL EvuA'noN Page 67 of 132 Attachment 7.9: Informational Attachment Page 28 of 93 2.2 Multiple Flaw Proximity Rules 2.2.1 Characterization of multiple, closely-spaced planar fiaws is also performed using proximity rules, as illustrated in Figure 3.Each individual flaw is characterized in terms of a through-wall depth dimension d,.(i=1.2,...n.where n is the total number of flaws).The largest characteristic depth is used as the basis for the proximity rules.If the spacing between the flaws, S.is less than twice the largest characteristic depth, 2 dmax, either in the length or depth direction, then the flaws must be combined into a single planar flaw with length and depth equal to the complete flawed area, as illustrated in the figure.If the flaw spacing is greater than 2 dmdx, then each flaw may be individually sized with its own length and depth dimension, and evaluated separately. 2.3 Skewed or Non-planar Flaws 2.3.1 Flaws which are not oriented perpendicular to one of the principal stress directions (axial or hoop)may be evaluated based on their projected areas (I and a dimensions) in the principal stress plane closest to the actual plane of the flaw.This rule also applies to flaws in a curved or non-planar surface (Figure 4).2.4 Flaws in Multiple Planes (see IWA-3300)2.4.1 Proximity rules for flaws in multiple planes are illustrated in Figures 5 and 6.For planar flaws, the multiple flaw proximity rules must be applied for combining flaws if the two planes are within a 1/2 inch spacing of one another at the flaw locations (Figure 5).If the spacing of the planes is greater than 1/2 inch, the flaws do not need to be combined.2.4.2 For laminar oriented flaws (i.e., within 1OC of parallel to the pipe surface), flaws in any plane between the front and back surface must be combined if their projections are within a 1 inch spacing (Figure 6). Attachment 7.9: Informational Attachment Page 29 of 93 3.0 FLAW ACCEPTANCE STANDARDS 3.0.1 Acceptance of flaws in piping is governed by ASME Section Xl Paragraph lWB-3514 for Class 1 piping, IWC-3514 for Class 2 piping and IWD-3000 for Class 3 piping.At the present time, however, Section Xl states that the Class 2 and Class 3 Standards are'in the course of preparation, and that the Standards of IWB-3514 may be applied to these classes of piping.'3.1 Acceptance of Planar Flaws 3.1.I The ASME Section Xl acceptance standards for planar flaws detected during inservice inspection are reproduced in Table 1 and 2.and are illustrated graphically in Figures 7 and 8.Table 1 and Figure 7 apply to ferritic steel piping with a specified minimum yield strength of 50 ksi or less, and which met the ASME Section III minimum fracture toughness requirements of NB-2300, NC-2300, or ND-2300, as applicable, Table 2 and Figure 8 apply to austenitic steel piping with a specified minimum yield strength of 35 ksi or less.Standards are not provided for other piping materials or for materials which do not satisfy these restrictions. In such cases, component specific standards must be developed, or the evaluator must proceed directly to analytical evaluation as described in Attachments XII and XIII.Dissimilar metal welds, such as nozzle safe-ends, are governed by the appropriate piping standards for the side of the weld being evaluated. Flaws in the carbon or low-alloy steel side of a dissimilar metal weld are evaluated by the ferritic steel standards, and flaws on the high alloy steel side, including the weld metal (typically> are evaluated by the austenitic steel standards. 3.1.2 The standards consist of allowable values of normalized flaw depth (alt)in percent, versus flaw aspect ratio (all), where a and I are the flaw depth and length, determined in accordance with the rules of section 2.0, and t is the piping wall thickness at the location of the observed flaw.The piping wall thickness may be determined by nor-destructive testing or estimated from design drawings.Separate columns of allowable flaw depth are provided for different piping wall thicknesses, and for surface and subsurface flaws.For near-surface flaws, the subsurface flaw allowables are modified with a Y factor.3.1.3 Application of the standards is straightforward. Simply compute alt and all for the observed flaw, and compare it to the appropriate column in the tables (or curve in the figures).If the pipe wall thickness or flaw aspect ratio falls between any of the specified values, interpolation is permitted. If the flaw is a subsurface flaw, with distance, S.from the nearest surface in the range of 0.4a<S<a, then multiply the allowable flaw depth by the ratio Y S/a.For S<0.4a the flaw is classified as a surface flaw, and a new a is defined as described in section 2.1 and Figure 2.If S>a, set V 1.0.3 1.4 Example applications of the acceptance standards to some typical piping problems are discussed in section 3.4.3.2 Acceptance of Laminar Fiaw 3.2.1 Acceptance standards for laminar flaw indications (laminations) are governed by a single set of standards for both types of material.These standards are presented in Table 3, and consist of allowable lamination areas as a function of pipe wall thickness. The areas are determined in accordance with the characterization rules of section 2.0 above.Once again, interpolation is permitted for intermediate ope thicknesses. ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0 Eritergy PIPE WALL THINNING STRUCTURAL EvALuATIoN Page 69 of 132 Attachment 7.9: InformatIonal Attachment __________ _______________ Page 30 of 93 3.3 Acceptance of Linear Flaws 3.3,1 Acceptance standards for linear flaws in ferritic and austenitic steel piping are presented in Table 4.These are presented in the form of allowable lengths for various pipe wall thicknesses. These are further broken down into allowable lengths of surface flaws (typically from surface examinations such as PT or MT).and allowable lengths for subsurface flaws (typically from radiography, RT, by which method depth generally is unavailable). The linear flaw acceptance standards are generally more conservative than the planar flaw acceptance standards described in section 3.1 because of the uncertainty of the depth dimension. An acceptable option, for flaws which fail to meet these standards, is to perform augmented inspections (typically UT), to define both the length and depth of the observed indication, following which the flaw can be evaluated by the planar flaw standards. 3.4 Example applications 3.4.1 Figure 9 illustrates two typical subsurface flaw indications in a nominally 1-inch thick, carbon steel pipe weld.Flaw A is a typical subsurface flaw, located along a weld fusion line essentially at the mid-wall of the pipe.It is 0.5 inches long, circumferentially oriented, and has a through-wall depth of 0.14 inches.Evaluation of this flaw in accordance with the acceptance standards is illustrated by the calculations in the lower portion of the figure.Since it is a subsurface flaw, the total through-wall depth is denoted'2a", and the flaw depth dimension to be used for evaluation purposes is one-half this value, or 0.07 inches.The normalized flaw evaluation parameters are all=0.14 and a/t=0.07.Referring to the 1-inch wall thickness subsurface flaw column of Table 1, and interpolating for the aspect ratio of 0.14 (between 0.10 and 0.15), the allowable flaw depth is 15,4%or 0.154.Note that the Y factor is set equal to 1.0 in this case, since the flaw is well removed from the surface (S/a>>1).Therefore, flaw A is acceptable by a comfortable margin (a/t of 0.07 versus an allowable of 0.154).3.4.2 Flaw B (Figure 9)is located fairly close to the surface of the pipe, such that application of the surface proximity rule is required.This flaw is 2.7 inches long, with a through wall dimension of 0.1 inches, but is located 0.03 inches from the inside surface of the pipe.The through-wall dimension is temporarily denoted"2d"(since we are not yet sure whether this will be the depth used for evaluation). S/d is thus equal to 0,6, from which we conclude that the flaw may be evaluated as a subsurface flaw.but that the standards must be adjusted via a Y-factor.Since the flaw is subsurface, a"may be set equal to d.or 0.05 inches.from which the flaw evaluation parameters are all=0.019 and alt=0.05.Again referring to the 1-inch wall thickness, subsurface flaw column of Table 1, and interpolating for a/l 0.019 (between 0.0 and 0.05)yields an allowable flaw depth of 12.75%.which must be multiplied by Y of 0.6.Thus the actual allowable flaw depth is 7.6%or 0.076, and the observed flaw, with a't of 0.05 is acceptable. Note however, that the combined effects of surface proximity and the longer flaw length considerably reduced the allowable flaw size relative to Flaw A. ENGINEERING STANDARD EN-CS-S-008-MULTI flevision 0 iJziitergy [,__PIPE WALL THINNING STRucTURAL EvALUATION Page 70 of 132 Attachment 7.9: Informational Attachment Page 31 of 93 3.4.3 Figure 10 illustrates a pair of near-surface indications (Flaw C>in a 1.75 inch thick stainless steel pipe, which are close enough to the surface and to each other to require checking in accordance with the proximity rules of sections 2.1 and 2.2.To provide a basis for comparison, the two individual flaws are sized exactly the same as Flaws A and B of Figure 9, but they have been placed closer together, with only a 0.02 inch spacing between the flaws.The near surface flaw is also 0.03 inches from the surface, identical to Flaw B.Denoting the two flaw depth dimensions, d 1 0.07 inches and d 2=0.05 inches, the proximity rules require the two flaws to be combined, since the 0.02 inch spacing is less than 2d.Thus the combined depth, 2d, is the sum of the two flaw depths plus the spacing, or 0.26 inches, and the flaw length is the combined length of 3.2 inches.Next the surface flaw proximity must be checked.S/d=0.231 which is less than 0.4, so that Flaw C must be treated as a surface flaw.3.4.4 As a surface flaw, the flaw evaluation depth'a"is the total through-wall dimension, 0,26 inches, plus the surface spacing dimension 0.03 inches, or 0.29 inches.The flaw evaluation parameters are thus a/l=0.091, and a/t 0.166, Referring to Table 2 for austenitic steel piping, and interpolating both for the 1.75 inch thickness (between 1-inch and 2-inch)and for the 0.091 aspect ratio (between 0.05 and 0.10), yields an allowable surface flaw depth of a/t.=0.105.Thus Flaw C is unacceptable, and detailed fracture mechanics evaluation or repair is required.This example illustrates the importance of multiple flaw and surface proximity rules.Two flaws which were acceptable by comfortable margins (in a 1-inch thick pipe), became unacceptable (even in a 1.75-inch thick pipe>when they were moved close enough together that they had to be combined, and thus became close enough to the surface that they had to be treated as surface flaw.3.4.5 Figure 10 also illustrates a lamination in the base metal adjacent to the weld, Flaw D, which must be evaluated in accordance with the laminar flaw standards. The total cross-sectional area of this lamination, assuming it to be rectangular, is 3 in 2.Referring to Table 3, for a 1.75-inch thick pipe (between 0.625-inch and 3.5-inch). the allowable lamination area is 7.5 in 2 , (using ref.A.37), so the lamination is acceptable. 3.4.6 As a final example, it is instructive to assume that Flaws A, B, and C were detected by radiography, and that depth information is therefore unavailable. The flaws must thus be evaluated using the linear flaw acceptance standards of Table 4.Referring to these tables, Flaw A for 1"pipe thickness, is unacceptable (0.5-inch length versus an allowable of 3/8-inch), flaw B is unacceptable (2.7-inch length versus an allowable of 3/8-inch), and for 1.75"pipe wall thickness Flaw C is also unacceptable (3.2-inch length, versus an interpolated allowable of 0.656-inch). This example illustrates the advantage of performing supplemental examinations to define flaw depth in the case of unacceptable linear indications. Two of the three indications were acceptable when the depth dimensions were defined. F*ENGiNEERiNG STANDARD EN-CS-S-008-MULTI Revision U Eritergy PIPE WL THINNING STRUCTURAL EvALuATIoN Page 71 of 132 Attachment 7.9: Informational_Attachment _____Page 32 of 93 TABLE 1: ASME Section Xl Allowable Flaw Size Standards (alt%)Planar Flaws in Ferritic Steel Piping (with minimum yield strength of 50 ksi or less at 1000 F)r t=0.312 t 1.0 in.t 2.0 in.surface subsurf.I surface I subsurf.surface I subsurf.--.----I-0.00 11.1 13.8Y 10.0 12.6Y 8.5 lO.8Y 0.05 11,8 14,4Y 10.8 13.OY 9.3 1l.2Y 0.10 13.0 15.6Y 11.8 14.2Y 10.2 12.1Y 0.15 14.4 17.2Y 13.2 15,7Y 11.2 13.5Y 0.20 14.4 17.2Y 14.8 17.7Y 12.6 15.1Y 0.25 14.4 17.2Y 14.8 17.7Y 14.2 17.1Y 0.30 14.4 17.2Y 14.8 17.7Y 14.2 17.1Y 0.35 14.4 17.2Y 14.8 17,7Y 14,2 17.1Y 0.40 14.4 17.2Y 14.8 17.7Y 14.2 17.1Y 0.45 14.4 17.2Y 14.8 17.7V 14,2 17.1Y 0.50 14.4 17.2Y 14.8 17.7Y 14.2 17.1Y Notes: Y s/a.If S<0.4d, the flaw is classified as a surface flaw.If Y>1.0, use V=1.0.Source: Inservice Inspection Table IWB-3514-2[All]and Table lWB-3514 1[A.10]=3.0 in.surface subsurf.7.0 8.7Y 7.5 9.1Y 8.2 9.9V 9.1 10.9Y 10.3 12.3Y 11.7 13.9Y 13.2 15.7Y 13.2 17.7Y 13.2 17.7V 13.2 17.7Y 13.2 17.7Y m ENGINEERING STANDAr1D I EN-CS-S-008-MULTI Revision 0-Enteigy Pipe WALL THINNING STRucTURAL EVALUATION Page 72 of 132 Attachment 7.9: Informational Attachment Page33of93 TABLE 2: ASME Section Xl Allowable Flaw Size Standards (alt%)Planar Flaws in Austenitic Steel Piping (with minimum yield strength of 35 ksi or less at 1000 F)all I t 0.312 in.t 1.0 in.t 2.0 In.I=3.0 in.surface I subsurf.surface iubsurf.j,urface subsurt.I__1 I I surface subsurt.000 11,7 11.7Y 10.6 10,6Y 10.0 10,0'?9.5 9.5Y 0.05 12.0 12.0'?10.7 10.7'?10.2 10.2Y 9.6 9.6Y 0.10 12.2 12.2'?11,0 11.0'?10.4 10.4Y 9.7 9.7Y 0.15 12.4 12.4'?11.1 11.1'?10.5 10.5'?9.9 9.9'?0.20 12.5 12.5'?11.4 11.4'?10.7 10.7'?10.1 10.1'?0.25 12.5 12.5'?11.5 11.5'?10.9 10.9'?10.2 10.2'?0.30 12.5 12.5'?11.7 11.7'?11.1 11.1'?10.4 10.4'?0.35 12.5 12.5'?11.9 11.9'?11.2 11.2'?10.6 10.6'?0.40 12.5 12.5'?12.1 12.1'?11.4 11.4'?10.7 10.7Y 0.45 12.5 12.5'?12.2 12.2'?11.6 11.6'?10.9 10,9'?0.50 12.5 12.5'?12.5 12.5'?11.7 11.7'?11.1 11.1'?Notes: Y=s/a.If S<0.4d, the flaw is classified as a surface flaw.If Y>1.0, use Y=1.0.Source: Inservice Inspection -Table IWB-3514-2 [A.10]and Table IWB-3514-3[A.11j. I ENGINEERING STANDARD ENCS-S-O08-MULTl Revision 0/Entery----------- L PIPE WALL THINNING STRucTuRAL EvALuATioN Page 73 of 132 Attachment_7.9: Informational Attachment ___________________ _________Page 34 of 93 TABLE 3: ASME Section Xl Allowable Flaw Size Standards Laminar Flaws in Piping (Allowable Areas, sq.in.)Nominal Pipe Laminar Area Walt Thickness sqin.0.625 in,&less 1.25 (7,5*)2.0 in.(3.5*)4.0 (7.5)6.0 in.12.0 Notes: Linear interpolation with respect to nominal pipe wall thickness is permissible to determine value of allowable laminar area;see IWA-3200(c). Source: Table lWB-3514-6 [All]and Table lWB-35143[A.10J Since References A.10 and A.11 provide conservative values in lieu Reference A.37, Table IWB-3514.3 can be used.TABLE 4: ASME Section Xl Allowable Flaw Size Standards Linear Flaws in Piping (Allowable Lengths, in)r Nominal Pipe Ferritic Steel Austenitic Steel 2 Wall Thickness Surf.}Subsurf.Surf.Subsurf.0.312 in.0.1875 0.25 0.2 0.25 1.0 in.0.3125 0.375 0.25 0.375 2.0 in.0.625 0.75 0.45 0.75 3.0 in.0.875 1.2 0.65 t2 4,0 in.0.875 1.4 0.65 1.4 Notes: For intermediate values of nominal pipe wall thickness. interpolation with respect to linear interpolation is permissible, see IWA-3200(c). Source: 1 Table IWB-3514-4 IA 101.(Applicable to Ferritic steelsith yield strength of 50 ksi or less at 100*F)2 For Auslenitic steels in the absence of allowable flaw size standards for linear flaws standards use allowable flaw size standards for allowable planar flaws.References A.10: Table lWB36142.Also, in the absence of information of subsurface flaws conservatively use same as ferritic steels.
- I ENGINEERING STANDAIRD EN-CS-S-008-MULTI Revision 0 Eritery I-_------_-
PIPE WALL THINNING STRUCTURAL EvALUA110N Page 74 of 132 Attachment 7.9: Informational Attachment Page 35 of 93 Unclad Surface Clad Surface surface flaws a-Pressure retaining surface of unclad component or clad S 4 2a4 S base metal interface or clad component subsurface flaw"4-wall thickness t Figure'1 Basic Flaw Sizing Method tram ASME Section Xl Source: Ref.A.iO and All, Fig.IWA-33l0-1.
- I ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0 ri k'ry H------------------I PIPE WALL THINNING SilIUcTURAL EVALUATION Page 75 of 132 Attachment 79: Informational Attachment Page 36 of 93 If S 04d, Flaw is subsurface, a=d If S<O4d, Flaw is surface, a=2d+S Pressure retaining surface of unclad component or ciad base metal interface of clad component Figure 2 Near-Surface Flaw Proximity Rule from ASME Section XI 4-S-4-2d-4-S-*4 S 4-4 Clad Surface wail thickness t Source: Ref.AlO and All, Fig IWA3310-l and IWA-3320-1 F ENGlNEERIN STANDARD I EN-CS-S-008-MULTI Revision Lntergy PIPE WALL THINNING STRUCTURAL EvALuATIoN Page 76 of 132 Unclad Surface Pressure retaining surface of unclad component or clad base metal interface of clad component S 2d 1 or 2d 2 (whichever is greater)Figure 3 Flaw-to-Flaw Proximity Rule from ASME Section Xl S 2d 3 or2d 2 (whichever is greater>Attachment 7.9: Informational Attachment Page 37 of 93 S2d 1 S O.4a Surface (whichever is greater)I wall thickness t Sourrce: Ret.A.1O and A.1 1 Figure lWA-333O1.
0 I ENGINEERING STANDARD I EN-CS-S-008-MULTI Revisionj-Eritergy i-------------i j PIPE WALL THINNING SmUcTURAL EVALUATION Page 77 of 132 Attachment 7.9: Informational Attachment Page 38 of 93 GENERAL NOTE: Flaw area shall be projected in planes normal to principal stresses a 1 and a 2 to determine critical orientation for comparison with allowable indication standards. FIgure 4: Flaw Sizing Method for Skewed or Non-Planar Flaws from ASME Section Xl circular plane Flaw#1 plane Source: Ref.A.lO and All, Fig.IWA-3340-l.
- I ENGINEERING STANDARD I EN-CS-S-GOB-MULTI Revis]--Enteigy h-----1 j Pi WALL THINNING STRUCTURAL EvALuATIoN Page 78 of 132 Attachment 7.9: Informational Attachment Page 39 of 93 Surface Flaws Figure 5: Flaw Sizing Rules for Planar Flaws in Multiple Planes Source: Ref.A.lOancl All.Fig.IWA-3350-l, ENGNEERING STANDARD j EN.CS-SOO8-MULTI Revision 0 j Lnteigy PIPE WALL THINNING STRucTuRAl.
EvALuATioN Page 79 of 132 Attachment 79: Informational Attachment Page 40 of 93 Figure 6: Flaw Sizing Rules for Laminar Flaws in Multiple Planes Source: Ret, AlO and All Fig.IWA-336Oi. Back Surface a plane C Figure 7A Ferritic Flaw Standards Source: See Table 1
Reference:
AlO and All, Table lWB3514l.Inservice Inspection. Attachment 79: Informational Attachment Page 41 of 93 Surface Flaws 16 14 12 10 8 8 4 2 0-.-tO312 in-a-1.0 in-*-2.()in--3.0 in 0 005 0.1 015 0.2 0.25 0.3 0.35 0.4 045 0.5 Aspect Ratio (all)
- ENGINEERING STANDARD I EN-CS-S-DOS-MULTI Revisio]En!ergy PIPE WALL THINNING STRUCTURAL EVALUATION Page 81 of 132 Attachment 79: Informational_Attachment Page 42 of 93 14 J)Subsurface Flaws 20 18 16 12 10 8 6-'---1=0.312 in---l.Oin-*-2.O in-*-3.Oin 4 2 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 GA 0.45 0.5 Aspect Ratio (a/I)Figure 78 Ferritic Flaw Standards Source: See Table 1
Reference:
Inservice Inspection -Table lWB-3514-1 [A 10]and Table IWB-3514-2 [A.11j. ENGINEEriNG STANDARD EN-CS-S-OO84vIULTI Revision 0-Entergy--PIPE WALL THINNING SmucTuRAt. EVALUATION Page 82 of 132 Attachment 7.9: Informational Attachment Page 43 of 93 Surface&Subsurface Flaws 6-.--tO.312in.I =4 2--3.Oin.0 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Aspect Ratio (a/1 Figure 8 Austenitic Flaw Standards Source: See Table 2
Reference:
Inservice Inspection-Table IWB-3514-2 [AlO]and Table 1W8-3514-3 [A.111. Page 44 of 93 2a=0.14"a=0.07"=0.5"a/I 0.14"alt=0.07 Allowable alt=0.154 (see table 1)Flaw is acceptable 2d 0.1"d 0.05";0.4d=.02"S=0.03".4d>S<d;Subsurface Flaw;>d=a;=0.05""Subsurface Flaw S/a=0.6=V=1"aJl=0.019 a/t=0.05 Allowable alt=0.127Y=0,076 (see table 1)Flaw is acceptable Attachment 7.9: Informational Attachment Inside Pipe Surface Flaw A (Subsurface) Flaw B (Subsurface) Figure 9: Subsurface Flaw Evaluation Examples , ENGINEERING STANDARD I EN-CS.S-008-MULTI Rovisio]I nIer&y--I PIPE WALL THINNING STRUCTURAL EvALuAnoN Page 84 of 132 Attachment 7.9: Informational Attachment ____________Page 45 of 93 Type 304 Stainless Steel Pipe FiawDt75"Flaw C (Subsurface) Flaw D (Near Surface)2d 1=0.14";d 1 0.07";Area=3.0 in 2 (=2.0 x 15)2d 2=0.1';d 2=0.05";Allowable Area 7.5 in S 0.02"<2d 1 (greater of d 1 and d 2)Flaw is Acceptable 2d=0.26"(=2d 1+2d 2+S)d=0.13"=3.2"(=2.7"+0.5")S=0.03"to surface Sld=0.231 Surface flaw (i S<0.4)a=surface flaw depth=2d+S=0.26+0.3 a=0.29"I=3.2"all=0.091 alt=0.166 Allowable alt=0.105 (from table 2)Flaw is unacceptable Figure 10: Surface and Laminar Flaw Evaluation Examples ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0 Entergy-___PiPE WALL THINNING STRucTuRAL EVALUATION Page 85 of 132 Attachment 7.9: Informational Attachment _______________ ____________ ____Page 46 of 93 Attachment XII: CLFE: Procedure for Austenitic Piping
1.0 INTRODUCTION
.1 This attachment utilizes the 1989 Edition of the Section Xl Code which is not addressed in the Codes referenced by Table 6 in Attachment Ill.Approval from the plant licensing department, and/or NRC, may be required prior to utilizing the provisions of this attachment. 1.2 This attachment provides for evaluations of crack-like flaws in austenitic steels, a formalized approach to explain the terminology and salient equations in select references available for such evaluations. A case by case approach and appropriate methodology has to be selected to solve an individual problem.Since most of the problems involving crack-like flaw evaluations in stainless steel are of an extremely complex nature, it is not recommended to select any approach without first understanding the root cause and nature of the crack-like flaw.For example inter-granular stress corrosion cracking (IGSCC)is a phenomenon most common to crack-like flaws occurring in austenitic steel, and considering the complexities of this phenomenon this has been excluded from the scope of this attachment except for occasional references to this phenomenon, Thus, this atlachment should be used as an introductory material and needs to be supplemented from other sources.This attachment can be used after it has been determined that the Code approaches discussed In this attachment are appropriate for any particular problem.1.3 The procedure for evaluation of flaws in austenitic stainless steel piping material is provided in Subsection IWB-3640 and Appendix C of the ASME Code, Section Xl[A.37J for Class 1 piping.Currently, there are no evaluation procedures in the Code for Class 2 and 3 piping.so the procedure for Class 1 is generally applied to Class 2 and 3 piping systems.The procedure is summarized in the flow chart presented in Figure 1.The technical basis for the evaluation procedure is provided in Reference A.19, I ,4 Austenitic stainless steel piping material can be classified into two basic groups.The first group consists of wrought product and non-flux welds.Experimental studies have shown that these materials have adequate toughness such that in the presence of a flaw they fail by net section collapse (limit load)when subjected to piping loads.The second group consists of the flux weldments (shielded metal arc weidments (SMAW)and submerged arc weidments (SAW).Experimental studies have shown that materials in this group have lower toughness compared to the wrought material and the non-flux welds, These materials fail by unstable ductile tearing prior to reaching limit load.Because of this, allowable flaw sizes for flux welds were developed from elastic-plastic fracture mechanics using the J-integral and ductile tearing modulus instability criterion. 1.5 It is to be noted that as indicated in the flow chart for evaluation of crack-like flaws.Figure 7.3 of this DEAM.if evaluation methods using IWB-3600 (Class 1)or IWC 3600 (Class 2)and IWD 3600 (Class3)are used.a prompt reporting has to be submitted for regulatory concurrence. The system, however can be operable until the regulatory approval. ENGINEERING STANDARD EN-CSS-008-MULTI Revision 0 Enfergy PIPE WALL THINNING STRucnJRAL EVALUATION Page 86 of 132 Attachment 7.9: InformatIonal Attachment _____________Page 47 of 93 1.6 The evaluation procedures in this attachment are applicable to pipes NPS 4 in, or greater.In general, crack-like defects are found in welds and the adjacent discontinuities or heat-affected zones.The evaluation procedures are applicable to a distance of from the centerline of a girth butt weld, where R 0 is the nominal outside radius and t is the nominal pipe wall thickness. Components /fittings outside these limitations should be treated on a case-by-case basis.2.0 STRESSES 2.1 Stresses are provided separately for allowable flaw size determination and flaw growth analysis.For allowable flaw size determination (section 2.2)primary stresses are considered, and in some cases secondary stresses may be considered. For flaw growth analysis (section 2.3)secondary stresses are considered in addition to the piping and expansion stresses.2.2 Stresses for Allowable Flaw Size Determination 2.2.1 In the evaluation of flaw in austenitic piping, three classes of stresses are required: 2.2.1.1 Primary membrane stress(Pm) 2.2.1,2 Primary bending stress(Pb) 2.2.1.3 Thermal expansion stress(P)2.2.2 These stresses can be obtained from the piping stress report.m is associated with pressure stress, Pb is generally associated with dead weight and seismic loads, and Pe is restraint stresses arising from thermal expansion. 2.2.3 The above Pm and b stresses correspond to unconcentrated (without stress intensification factors)primary stress intensity values defined in Equation 9 of ASME Section III NB-3650.P is unconcentrated stress intensity value for moment loads defined in Equation 10 of ASME Section Ill, NB-3650.2.3 Stresses and Flaw Growth 2.3.1 It is important to determine the loads that contribute to the flaw growth.2.3.1.1 For fatigue.both the magnitude of the stress and cyclic information should be obtained from the stress report or any supplementary evaluation that may have been performed as part of the root cause evaluation. 2.3.1.2 For IGSCC evaluation, the sustained stress which contributes to 5CC must be considered. The sustained stresses consist of Pm.r and P from section 2.2 above and weld residual stresses, when applicable. [*ENGINEERING STANDARD I EN-CS-S008-MULT1 Revision 0 I Ltteiy------__L PIPE WALL THINNING STRUCTURAL EVALUATION I Page 87 of 132 Attachment 7.9: Informational Attachment ___________________ Page 48 of 93 2.3.2 Butt weld residual stresses play a major role in flaw growth evaluation. A through-wall butt welding residual stress profile has been provided in NUREG-0313 IA.20]and shown in Figure 2.This residual stress profile is appropriate for large diameter piping (thickness greater than 1.0 inch>and is consistent with note 3 of the figure.For small diameter piping, linear through-wall bending residual stress distribution provided in Reference A.19 and NUREG-1061 [A.211 is recommended. 3.0 LOAD COMBINATION 3.1 For allowable flaw size determination, two load combinations are considered in ASME Section XI[A.371 3.1.1 Normal operating (including Upset and Test>Level NB 3.1.2 Emergency/faulted Level C/D 3,2 The load combinations are generally reported in the piping Stress Report but, in general, the following load combinations are typical.3.2.1 LeveIA/B Pm Pressure Deadweight +OGE Seismic Pe-Thermal expansion 3.2.2 Level CID Pm-Pressure Pb-Deadweight +SSE Seismic-Thermal expansion 3.3 For fatigue crack growth analysis, only the cyclic loads in the above load combinations are considered. 3.4 For 1GSCC crack growth evaluation, only the sustained stresses are considered. This generally includes a combination of Pressure, Deadweight, Thermal Expansion and Weld Residual Stress.4.0 Material Properties 4.In performing ASME Section Xl allowable flaw size evaluation, the important material property is the ASME Section Ill allowable stress intensity limit: Sm.The value of S, for various types of austenitic stainless steel is provided in Table-1.2 of the ASME Section Ill appendices. for Class 1 materials[A.38j.
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___________________________ Page 49 of 93 4.2 When a J-lntegral/ Tearing Modulus analysis is performed for the flux weld, additional material properties are required.These include the Rarnberg-Osgood stress-strain curve parameters a and n, the yield stress cs, the flow stress i.Modulus of Elasticity E, and the fracture toughness J..Typical values for SAW and SMAW welds have been provided as follows[A.19): Submerged Shielded metal Parameter arc weld arc weld a 11.0 9.0 6.9 9.8 CT 2 , ksi 33.7 49.4 , ksi 42.1 55.4 E, ksi 25,000.0 25,000.0 J, in-lb/in 2 650.0 990.0 4.3 In addition, the JT material resistance curve will also be required.Typical curves used in Reference A.19 are shown in Figures 3 and 4.4.4 The material properties used for flaw growth evaluation are discussed in Section 7.4.5 Attachment XV, Section 3,0 provides the methodology for performing elastic plastic fracture mechanics (EPFM)analysis using the J-integral /Tearing Modulus Approach.5.0 Initial Flaw Size and Flaw Orientation 5.1 Initial flaw size and flaw orientation are obtained from ISI reports.Flaws can be either axial or circumferentially oriented.Flaws can also be surface or subsurface. Rules for determining flaw orientation and flaw type are provided in ASME Section Xi, IWA-3000.5.2 In some cases, multiple flaws are encountered. Rules for combining multiple flaws are also provided in IWA-3000.Additional rules for combining multiple IGSCC flaws are provided in NUREG-0313, Rev.2[A.20].6.0 Determination of Stress Intensity Factor (Kl)versus Flaw SIZE 6.1 Determine the fracture mechanics model for calculation of stress intensity factor (K)as a function of flaw size.This is determined from the knowledge of the pipe geometry and the flaw orientation. Use of select computer software is pertinent as mentioned in Attachment XIV or methodology provided in Attachment XV.7.0 Flaw Growth 7.1 The mechanisms for flaw growth should be established from the root cause evaluation. The flaw growth mechanism in austenitic stainless steels could be attributed to either 1GSCC or fatigue from cyclic loadings.7.2 lntergranular Stress Corrosion Cracking (IGSCC)7,2.1 IGSCC in general occurs in BWR austenitic stainless steel piping.
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____________ Page 50 of 93 7.2.2 The procedure for performing IGSCC flaw growth evaluation is beyond the scope of this attachment and thus is excluded due to the extremely complex nature of the flaw growth from IGSCC.The procedure for performing flaw evaluation in BWR austenitic stainless steel piping is provided in NRC documents Generic Letter 88-01[A.40]and NUREG-0313 Rev.2[A.201.The BWR Vessel and Internals Project is in the process of developing a Topical Report on 1GSCC crack growth rate[A.39j.On approval from the USNRCC this information will be helpful in developing this subsection. 7,2.3 Other methods consider the environment as well as the material condition of the austenitic stainless steel.A detailed discussion regarding these is beyond the scope of this attachment, but references are provided in A.22 and 8.2.7.3 Fatigue 7.3.1 ASME Code Section Xl currently has a fatigue crack growth law for air environment but does not have one for water environment. 7.3.2 The ASME Section XI, Appendix C fatigue crack growth law for air is given as: Eqn.2 d 2 V where: n=3.3.and C,,=C(S)Eqn.3 and C is a scaling parameter to account for temperature, which is given by C=Eqn.4 Kmx-Kmin, ksi 7.3.3 Tis the metal temperature in F (T 800 CF).S is a scaling parameter to account for the R ratio (Krn,/K.11.), and is given by: S 1.0 whenR 0 1.0+1.8R when 0<A 0.79-43,35+57.9Th when 0.79<A<1.0 ENGINEERING STANDARD EN.CS-S-008-MULTI Revision 0 a Entergy-------PIPE WALL THINNING SmUcTuRAL EvALuATIoN Page 90 of 132 Attachment 7.9: Informational Attachment Page 51 of 93 7.3 4 For water environment, the fatigue crack growth law provided in Reference A.19 can be used, However, due to the complexity of this method its recommended that all the ramifications are completely understood before this can be applied This subsection has been provded for information for an understanding of the basic material required in case of any review.This law is based on work sponsored by the Pressure Vessel Research Committee and Metals Properties Council and has the form: da/dN C E S(.\K)'Eqn.5 where: LIaJ'dI=change in crack depth.a, per fatigue cycle.in/cycle C, a=material constants 1=3.3 C=2 x 10 S=R ratio correction factor=11.0 05R}4 R=Knvi/Krna=environmental factor (equal 1.0, 2.0, and 10.0 for air.PWR, and BWR environments, respectively) JK Kmax-Kmin, ksi(in)Kmin.K 1 ,,,,=minimum and maximum values, respectively, of applied stress intensity factor 7.3.5 There are currently efforts in the ASME Code Working Group on Flaw Evaluation to provide an environment fatigue crack growth law for stainless steel.8.0 Determination of Allowable Flaw Size 8,1 Determination of allowable flaw size for austenitic stainless steel piping is provided in IWS 3640 and Appendix C of Section Xl.Allowable flaw sizes for base metal and non-flux welds (GTAW and GMAW>are based on plastic collapse (limit load>Allowable flaw sizes for flux welds (SAW and SMAW)are based on ductile tearing (J-lntegral Tearing Modulus analysis>. 8.2 The first step in determining the allowable flaw size is to use the tables provided in IWB-3640.The flow chart (Figure 5)provdes guidance for use of these tables.The tabies are also summarized below'82.1 IWB-3641-l -Circumferential Flaws,Normal and Upset$2.2 IWB-3641-2 -Crcurnferential Flaws/Emergency and Faulted I ENGINEERING STANDARD ENCS-SOOa-MULTI RevisIon 0 Entergy-________P1PE WALL THiNNING STRucTuRAL EvALuAI10N Page 91 of 132 Attachment 7.9: Informational Attachment __________________________ Page 52 of 93 8.2.3 IWB-3641-3 Axial Flaws/Normal and Upset 8.2.4 IWB-3641-4 -Axial Flaws, Emergency and Faulted 8.2.5 IWB-3641-5 -Circumferential Flaws/Normal and Upset (SMAW/SAW) 8.2.6 IWB-3641-6 -Circumferential Flaws/Emergency and Faulted (SMAW/SAW) 8.3 Table IWB-3641-1 The following are the applicability and assumptions used in developmg this table[A.19J.The differences between the base metal, flux and non-flux weld are provided in Section 1 3.Non-fluxed weidments have more toughness than fluxed weldments 8.3.1 Circ.Flaws-Normal Operating (including Upset and Test>Conditions 8.3.2 For Base Metal and Non-flux GTAW and GMAW Weldments 8.3.3 Based Purely on Plastic Collapse (Limit Load Source Equations> 8.3,4 Only Primary Stresses (No Secondary-Thermal Stresses>8.3.5 ljnintensified Stresses 8.3.6 Safety Factor=277 8.3.7 Assumes cy=3S 8.3.8 Assumes Pm0.5Sm 8.3.9 Maximum Allowable alt=0 75 8.4 Table IWB-3641-2 8.4.1 Circ.Flaws-Emergency and Faulted Conditions 8.4.2 For Base Metal and Non-flux GTAW and GMAW Weldments 8.4 5 Based Pure y on Plastic Collapse (Limit Load Source Equations 8.4 4 Only Primary Stresses (No Secondary-Thermal Stresses)8.4.5 Unintensified Stresses 8.4 (Safety Factor 1 39 8.4.7 Assumes n 3S. I ENGINEERING STANDARD ENCS-S-008-MULTI Revision 0 Entergy i--_---------- PIPE WALL THINNING STRUCTURAL EVALUATION Page 92 of 132 Attachment 7,9: InformatIonal Attachment ______Page 53 of 93 8.4.8 Assumes Pm 1.0S.8.4 q Maximum Allowable au 0.75 8 5 Table IWB-3641-3 8.5.1 Axial Flaws-Normal Operating (including Test and Upset)Conditions 8.5.2 For Base Metal and Non-fluxed GTAW and GMAW Weldments 8.5.3 Based on Plastic Collapse 8.5.4 Only Primary Hoop Stress 8.5.5 Unintensified Stresses 8.5.6 Safety Factor=3.0 8.5.7=3S 8.5.8 Maximum a/t 0.75 8.6 Table IWB-3641-4 8.6.1 Axial Flaws-Emergency and Faulted Conditions 8.6.2 For Base Metal and Non-Flux GTAW and GMAW Weldments 8.6.3 Based on Plastic Collapse 8.6.4 Only Primary Hoop Stresses 8.6.5 Unintensified Stress 8.6.6 Safety Factor 1 5 8.6.7 (T 3Srn 8.6,8 Maximum a/t=0.75 8.7 Table 1WB-3641-5 8.I Circumferential Flaws-Normal Operating (including Upset and Test)Conditions 8.7.2 For Fluxed SAW and SMAW Weldments s,"3 Based on Elastic-Plastic Fracture Mechanics (J T anaysis -I ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0 Lnteigy 1-------___Pp WALL THINNING STRUCTuRAL EVALUATION Page 93 of 132 Attachment 7.9: Informational Attachment _____________________________________________ Page 54 of 93 8.7.4 Stress Muhiphers Provided to Convert to Equivalent Plastic Collapse Analysis 8.7.5 Both Primary and Secondary Stresses Considered. For non-fluxed welds, only primary stresses are considered. 8.7.6 Safety Factor 2.77 for Primary Loads 8.7.7 Safety Factor=1.0 for Thermal Loads 8.7.8 Maximum Allowable alt 0.60 8.8 Table IWB-3641-6 8.8.1 Circumferential Flaws Emergency and Faulted Conditions 8.8.2 For fluxed SAW and SMAW Weidments 8.8.3 Based on Elastic-Plastic Fracture Mechanics (J/T Analysis>8.8.4 Stress Multipliers Provided to Convert to Equivalent Plastic Collapse analysis 8.8,5 Both Primary and Secondary Stresses Considered. For non-fluxed welds, only primary stresses are considered. 8.8.6 Safety Factor=1.39 for Primary Loads 8.8.7 Safety Factor=1.0 for Thermal Loads 8.8.8 Maximum Allowable alt 0.60 8.9 The above tables 1 through 6 are the Code allowable tables.No tables are provided in the Code for axial flaws for fluxed weldments. ENGINEERING STANDARD I ENCS-SOO8-MULTI Revision 0 Entergy---H PIPE WALL THINNING STRUCTURAL EvALuATIoN Page 94 of 132 Attachment 7.9: Informational Attachment ______Page 55 of 93 8.10 When more relief is desired than by using the preceding tables in IWB-3640, the source equations provided in Appendix C of Section Xl[A.37]can be used directly.These source equations are based on plastic collapse with adjustments for the flux welds.The stress distribution of a circumferential flawed pipe at plastic collapse is shown in Figure 6.The plastic collapse equations for circumferential flaws are given as: For 0+[1 it=--2sinflsin&? Eqn, 6 a Eqn.7 2.z 3S,:}For 0+11>it 6S,, (u I,=__2_-jsan/i Eqn.8 it (a/1=jl--------l Eqn.9)-t 3Sf,,)where all the terms are shown in Figure 6 and o=3S, Eqn.10 8.11 For base metal and non-flux welds, the relationship between the failure bending stress Pb'and the applied stresses (P and Pb)is given as: f,=SF(f+1,)F Eqn.11 8.12 For the flux welds (SAW and SMAW weldments), from Appendix C of Section Xl[A,37]Pb'SF(P+Pb+PC I SF)J Eqn.12 1,15[i+0.013(D-4) firSMAW Eqn, 13 1.31)[I+0,Ol0(D-4)]fr SAW where D s the nominal pipe size.NPS and for NPS'24 in.: use D=24. I ENGINEERING STANDARD EN-CS-S-COB-MULTI Revision;] Enfer&y F--.------PIPE WALLTHINNINGSTRUCTIJRALEVALUATION Page 95 of 132 Attachment 7.9: Informational Attachment ______Page 56 of 93 8.13 For axial Part-through Flaws: 35, F t/a1 I=-H-Lqn.14 Sf[1 I (1-1/M.where:=[i+L611f I(4Rt)J=nominal hoop stress PD/21 1)nominal outside diameter of the pipe=total flaw length a flaw depth.The flaw depth is limited to 75%of thickness R=mean radius of the pipe=nominal thickness SF=Safety Factor: 3.0 for Level A and B Service Loadings, 1.5 for Level C and D Service Loadings 8.14 The evaluation can also be performed using appropriate computer programs.Alternate methods for plastic collapse which take into account the shape of the flaw and also cases involving multiple flaws are discussed in Attachment XV Section 4.0. I ENGINEERING STANDARD I EN-CSS-OO8-MULTl Revision 0 Entergy[--------j____PIPE WALL THINNING S1-fucTuRAL EVALUATION Page 96 of 132 Attachment 7.9: Informational Attachment Page 57 of 93 Austenftic Stainless Steni Piping WE3-3640/Appendnc C termine Stresses Normal Operating (NOC)F (Including Test/Upset)Determine Load Combinations L_Emergency Faulted (EOC)j Determine Material Properties Zj Sm Circumferential i Determine Flaw Orientation Axial Initial Flaw Size q Determination of K Fatigue Flaw Growth Analysis ioscc Other Inspection Interval Final Flaw Size Yes j Determine Allowable Flaw Size: NOC and EOC See Figure 5 LeOfienN No Yes E H Repair/Replace inued Orateptable, Figure 1: Flaw Evaluation Procedure for Austenitic Steel Piping
- ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision biteigy PIPE WALL THINNING STRUCTURAL EvALUATIoN Page 97 of 132 Attachment 7.9: Informational Attachment Page 58 of 93 Through-Wail Residual Stress Wail Thickness Axial Circumferential'
<1 inch o ID ID 1 inch See Note 3 0 1 S=30 ksi 2 Considerable variation with weld heat input.y[1.0-6.91 (alt)+8.69 (alt)2-0.48 (alt)3-2.03 (alt)4 1=stress at inner surface (a=0)Figure 2 Residual Stress Distribution in Large and Small Diameter Piping Welds[A.19, A.21] I ENGINEERING STANDARD EN-CS-S008-MULTI Revision 0 DIntergy[---j PIPE WALL THINNING STRUCTURAL EVALUATION Page 98 of 132 Attachment 7.9: Informational Attachment Page 59 of 93 6000 5000 4000-z 3000-4 2000 1000 0 0 100 200 300 T, t)F Figure 3: Material J-R Resistance Curve for SAW Weldment at 5500 F[A19]100 200 300 400 500 Figure 4 Material J-R Resistance Curve for SMAW Weldment at 55OF[A.1 9]Regkrn Material J=65O 400 500 600 6000 4000 Extrapolated 3000 2000 1000 ria1 3 lc=990 0 1, F
- I ENGINEERING STAr.oARD EN-CS-S-008-MULT1 RevIsion 0 Entergy I-PIPE WALL.THINNING STRUCTURAL EVALUATION Page 99 of 132 EOC EC}C Figure 5 How Chart for Allowable Size Determination of ustenitic Stainless Steel Piping Attachment 7.9: Informational Attachment Page 60 of 93.J 31 JI V NOC F0C COO EO'V4Mi2 641-1__*36413 ENGINEERING STANDARD EN-CS-S-OO8-MLJLTI Revision 0 Entergy PIPE WALL THINNING STRUCTURAL EVALUATION Page 100 of 132 Attachment 7.9: Informational Attachment Page 61 of 93]Nominal stress in the Figure 6: Stress Distribution In a Cracked Pipe Basis for Net Section Collapse Criteria for Austenitic Steel Pipe[N Pm:: e 7xis-Limit Load (Net section plastic collapse)
- .ENGINEERING STANDARD EN-CSS-0O8-MULTI Revision 0-Lntergy->PIPE WALL THINNING STRUCTURAL EvALuAT10N Page 101 of 132 Attachment 7.9: Informational Attachment Page 62 of 93 Attachment XIII: Flaw Evaluation Procedure for Ferritic Pipmg 10 INTRODUCTiON
.1 This attachment utilizes later editions of the Section Xl Code which may not be addressed in the Codes referenced by Table 6 in Attachment III.Approval from the plant licensing department. and/or NRC, may be required prior to utilizing the pertinent provisions of this attachment. 1.2 This attachment provides for evaluations of crack-like flaws in ferritic steels, a formalized approach to explain the terminology, and salient equations in select references available for such evaluations. A case by case approach and appropriate methodology has to be selected to solve an individual problem.Since problems involving crack-like flaw evaluations could be of a complex nature, it is not recommended to select any approach without first understanding the root cause and nature of the crack-like flaw.Thus, this attachment should be used as an introductory material and needs to be supplemented from other sources.This attachment can be used after it has been determined that the Code approaches discussed in this attachment are appropriate for any particular problem.1.3 The procedure for evaluation of flaws in Class 1 ferritic piping is provided in Subsection IWB 3650 and Appendix H of ASME Code Section XI[A.37].The technical basis for the procedure is provided in EPRI Report No.NP-6045[A.13].The flow chart shown in Figure 1 summarizes the procedure. There are currently no rules for Class 2 and 3 piping, therefore, the rules of Class 1 piping are generally used for Class 2 and 3.1.4 As explained in Reference A.13, the load carrying capacity of flawed ferritic piping can vary significantly within the LWR operating temperature range.This temperature dependence results in three distinct regions of fracture behavior, hence each requires a different fracture mechanics analysis technique. 1.4.1 The"lower shelf"region, where the fracture toughness of the material is a minimum and does not change significantly with increasing temperature. In this region, the behavior of the material is generally assumed to be linear elastic because ductility is negligible and therefore, linear elastic fracture mechanics (LEFM)techniques are applicable. 1.4.2 The"transition temperature" region where the fracture toughness increases significantly above the lower shelf value with increasing temperature. In this region, elastic-plastic fracture mechanics (EPFM)techniques involving the use of the J-lntegral/Tearing Modulus analyses are typically employed.1.4,3 The'supper shelf"region, where the fracture toughness reaches a maximum and ideally remains constant with increasing temperature. in this region, the material is very ductile and limit load (net section plastic collapse)analyses are employed in fracture mechanics evaluation. ENGINEERING STANDARD EN-CS-SO0B-MULTl Revision 0 Irttergy-PIPE WALL THINNING STRucTuRAL EvALuATIoN Page 102 of 132 Attachment 79: Informational Attachment ________________ Page 63 of 93 1.5 To determine which regions and analyses methods to use, the flow chart shown in Figure 2 is provided in ASME Code.Section XI.Appendix H.The key to the determination of the analysis method is the determination of a screening criterion (SC).For an exp:anation of screening criteria see section 2.1.1.Figure 2 indicates that if SC is below 0.2.limit load analysis shall be used.If SC falls between 0.2 and 1.8.elastic-plastic fracture mechanics (EPFM)techniques shall be used.Linear elastic fracture mechanics techniques are used if SC is greater than or equal to 1.8.The computational method for calculating SC is provided in ASME Section Xl Appendix H, (ref.A.37).1.6 The evaluation procedures in this attachment are applicable to pipes NPS 4"or greater.In general, crack-like defects are found in welds and the adjacent discontinuities or heat-affected zones.The evaluation procedures are applicable to a distance of from the centerline of a girth butt weld, where R is the nominal outside radius and t is the nominal pipe wall thickness. Components /fittings outside these limitations should be treated on a case-by-case basis.2.0 STRESSES 2.1 Screening Criteria and Allowable Flaw Size 2.1.1 Screening criterion (SC)parameter to define the applicable failure mode is[A.37: H-4421 and A.13]: sc=[]Eqn.I where K=F-_1 Eqn,2=J.,.E'/100() J ksi-"/in.Equ.3=Measure of material toughness due to crack extension at upper shelf, transition, and lower shelf temperatures. J integral at first flaw extension. in-lh/in E=IE/(1v 2)1 ksi Eqo.4 wlwre E=Modulus of Elasticity V=Poisson Ratio
- I ENGINEERING STANDARD EN-CSS.008MULTI Revision 0 1 Lntergy[-------[PE WALL THINNING STRucTuRAL EvALuATIoN Page 103 of 132 Attachment 7.9: Informational Attachment Page 64 of 93 K 1=Total applied stress intensity factor (as defined in sections 7.4.1 and 7.4.2 for circumferential and axial flaws)ksi-in For circumferential flaws, (see section 7.4.1);-'1 ,'=I Eqn.where:=Eqn.6a=bending stress at limit load Eqn.6h For axial flaws.(see section 7.4.2): Sr Eqn.7[J 1 J where: Eqn.7a 0',=reference stress at limit load Eqn.7b 2.1.2 For determination of the screening criterion (SC)and allowable flaw size, three classes of stresses are required: 2.1.2.1 Primary membrane (Pm)2.1.2.2 Primary bending (Pb)2.1.2.3 Thermal expansion (Pe)2.1.3 These stresses are obtained from the piping Stress Report, P.is associated with pressure stress, Pb is generally associated with dead weight and seismic loads, and P is restraint stresses arising from thermal expansion.
2.1.4 The above P.and Pr stresses correspond to unconcentrated (without stress intensification factors)primary stress intensity values defined in Equation 9 of ASME Section Ill NB-3650.Pr is unconcentrated stress intensity value for moment loads defined in Equation 12 of ASME Section Ii, N8-3650.2.1.5 When LEFM analysis is performed. butt weld residual stresses should also be considered in the determination of allowable flaw size, since these stresses are not expected to relax under LEFM condition. Through-wall butt weld stress distribution for ferritic piping recommended in Reference A.13 is shown in Figure 3. [ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0 iLritergy[PIPE WALL THINNING STRUCTURAL EVALUATION Page 104 of 132 Attachment 7.9: Informational Attachment Page 65 of 93 2.2 Flaw Growth 2.2.1 For ferritic piping.the predominant flaw growth mechanism is fatigue.Ferritic piping is generally immune from intergranular stress corrosion cracking (IGSCC).In flaw growth evaluation, it is important to determine the loads that contribute to the flaw growth.For fatigue, both the magnitude of the stresses and expected number of cycles for all normal and upset operating conditions must be included.This information should be obtained from the stress report or from any supplementary evaluation that may have been performed as part of the root cause evaluation. Butt weld residual stresses should also be considered in the evaluation. 3.0 LOAD COMBINATION 3.1 For allowable flaw size determination, two load combinations are considered in ASME Section Xl: 3.1.1 Normal operating (including Upset and Test)Level A/B 3.1.2 Emergency and Faulted Level C/D 3.2 The load combinations are generally reported in the piping Stress Report but, in general, the following load combinations are typical.3.2.1 Level NB m-Pressure Pb-Deadweight +OBE Seismic Pe-Thermal expansion 3.2.2 Level C/D Pm Pressure Pb-Deadweight +SSE Seismic-Thermal expansion 3.3 For fatigue crack growth analysis.all the cyclic loads which contribute to the crack growth must be considered. 4.0 MATERIAL PROPERTIES 4.1 For the purpose of determining material properties. ferritic piping materials are categorized into two groups in ASME Section Xi, Appendix H, also see ref.A,13, 4.1.1 Material Category 1: Seamless or welded wrought carbon steel pipe and pipe fittings that have a specified minimum yield strength not greater than 40 ksi and we[ds made with E7015.E7016, and E7018 electrodes in the as-welded or post weld heat treated conditions. ENGINEERING STANDARD EN-CS-S-DUB-MULTI Revision 0 Entery--PIPE WALL THINNING STRUcTuRAL EvALUATIoN Page 105 of 132 Attachment 7.9: Informational Attachment Page 66 of 93 4.1.2 Material Category 2: All other ferritic shielded metal arc and submerged arc welds with specified minimum tensile strengths not greater than 80 ksi in the as-welded or post weld heat treated conditions. 4.2 In determining the screening criteria and allowable flaw size.certain material property data is required.This includes: Yield Stress, a, Ultimate Strength, a Young's Modulus.E Poisson Ratio.V Design Stress Intensity. S Fracture roughness. J 1 4.3 The values of rr a 1.E, and Sm are provided in Appendix I of ASME Section III[A.38}.The value of v is typically taken as 0.3.Minimum values of Jare provided in ASME Section Xl Appendix H if actual values are not available for the evaluation. J.shall be obtained directly from heat-specific J experiments, or correlations with heat-specific Charpy V-notched absorbed energy (CVN)data or reasonable lower bound CVN data.4.4 The correlation at upper shelf temperatures for use with CVN data for circumferential flaws is given as: 10 CVN Eqn.8 where, is flaw extension in in-lb/in 2 and CVN is heat specific energy in ft-lb units.Note that the operating temperature is considered as greater than 200°F.If actual CVN values are available, correlation between fracture toughness and CVN values provided in literature (e.g., ref.A.41)can be used.4,5 In the absence of specific data, the upper shelf temperature for terrific piping is specified as 2O0F, -I ENGINEERING STANDARD ENCS-S-008-MULTI Revision 0 Lntery J PIPE WALL THINNING StRucTuRAL EvALUATIoN Page 106 of 132 Attachment 79: Informational Attachment __________ ____Page 67 of 93 4.6 When a J-integraUTearing Modulus analysis is performed, additional material properties are required.These include the Ramberg-Osgood stress-strain curve parameters a and n, and reference stress a,.Lower bound values for these parameters were determined in Reference A.13 for A106 Gr.B and SA-333-6 materials based on the lower bound stress-strain curve shown in Figure 4.Parameter Submerged arc weld 251 n 4.2 at,, ksi 27.1 4.7 In addition, the J-T material resistance curve will also be required.Typical curves used in Reference A.13 are shown in Figures 5 through 8.5.0 INITIAL FLAW SIZE AND FLAW ORIENTATION 5.1 Initial flaw size and flaw orientation are obtained from lSi reports.Flaws can be either axial or circumferentially oriented.Flaws can also be surface or subsurface. Rules (or determining flaw orientation and flaw type are provided in ASME Section Xl, IWA-3000.In some cases, multiple flaws are encountered. Rules for combining multiple flaws are also provided in IWA-3000.6.0 FLAW GROWTH 6.1 The mechanisms for flaw growth should be established from the root cause evaluation. The flaw growth mechanism in ferritic steels is attributed mainly to fatigue.Per Appendix H of Section XI, the fatigue crack growth law for ferritic vessels in Appendix A of Section Xl is used.Separate laws are provided for air and water environments. These crack growth laws are included in software programs which address these applications, see attachment XIV.7.0 DETERMINATION OF ALLOWABLE FLAW SIZE 7.1 The first step in the allowable flaw size determination is to determine the appropriate analysis method for using the screening criteria (SC>provided in Appendix H of ASME Section XI and shown in Figure 2.The screening criteria and the allowable flaw size can be determined using software programs which address these applications, see attachment XIV.7.2 If SC<0.2, the limit load analysis technique should be used in determining the allowable flaw size.Flow chart for materials meeting the limit load criteria is provided in Section Xl, Appendix H.Article H-5000 and shown in Figure 9.As can be seen from this flow chart, tables are provided in Appendix H as follows: 7.2.1 Table H-5310-1-Circ.Flaws-Normal/Upset/Test Conditions 7.2.2 Table H-5410-2-Circ.Flaws-Emergency/Faulted Conditions 7.2.3 Table H-5410-3-Axial Flaws-Normal/Upset/Test Conditions 7.2.4 Table H-5310-4-Axial Flaws-Emergency/Faulted Conditions
- I ENGiNEERING STANDARD FCS-S0O8-MULT)
Revision 0 I Entery[---_------- PIPE WALL THINNING STRucWRAL EvALuATIoN Page 107 of 132 Attachment 7.9: Informational Attachment _______Page 68 of 93 7.2.5 In lieu of usina the above tables, the source equations given in Appendix H may be used.These equations are given as follows: 7.2.5.1.For circumferential flaws[A.37: H-5320]ForO+it 2o J,---2.sin,6--'sin?j Eqn.9 (I P Eqn.1O For 0+[3>it 2=__+/-.2--Jsin/i Eqn.11 it (a l--------j Eqn.12 2-I O)where all the terms are shown in Figure 9 and a shall be taken as the average of yield and ultimate stress, or 2.4 S 1 when these values are not available. 7.2.5.2 The above formulas are valid for Pb/Pm 1.0 and P,,, 0.5 S 1 for normal operating (including upset and test>conditions or Pm 1.0 Sm for emergency and faulted conditions. 7.2.5.3 The allowable bending stress S is given as: r i (SF)1l/.)]Eqn.13 where: SF=safety factor=2,77 for normal operating condition (including upset at test)conditions =1.39 for emergency and faulted conditiOnS 7.2.5.4 The maximum allowable flaw depth is limited to 75%of pipe wall thickness. For axial flaws[A.37: H-54201 r i/a-I°'ir l11 14 Sf It/a-li MI ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0-Eritergy PIPE WALL THINNING STRUCTURAL EvALUATIoN Page 108 of 132 Attachment_7.9: Informational Attachment Page 69 of 93 where:=[i+1.6 I//(.4R1)J Fqn.15=2.4S 01=nominal hoop stress=PD/2'I)=nominal outside diameter of the pipe=total flaw length a=flaw depth R=mean radius of the pipe=nominal thickness SF=Safety Factor: 3.0 for Level A and B Service Loadings.1.5 for Level C and D Service Loadings 7.2.5.5 Furthermore i<l where l is determined by the condition for the stability of through-wall flaws o.=Tf I M 2.72.5.6 Note flaw depths a 0 and a 0 , determined from eqn.14 shall be used in the acceptance criteria of IWB 3652(a)[A,37}to determine the acceptability of the flawed pipe for continued service.7.3 If 0.2 SC<1.8, elastic-plastic fracture mechanics (EPFM)techniques should be used in determining the allowable flaw size.Flow chart for materials meeting the EPFM criteria is provided in Section Xl, Appendix H Article H-6000 and shown in Figure 10, Tables are provided in Appendix H for the determination of allowable flaw size.These tables are based on limit load analyses.but stress multipliers are provided to convert the EPFM analyses to equivalent limit load analyses using Z-factors provided in the Code.7.3.1 Table H-5310-1 (Modified) -Circ.Flaws-Normal/Upset/Test Conditions 7.3.2 Table 1+/-5310-2 (Modified) -Circ.Flaws-Emergency/Faulted Conditions 73.3 Table H-6410-1-Axial Flaws-Norma['UpsetiTest Conditions 7.34 Table H-6410-2-Axial Flaws-Emergency/Faulted Conditions F I ENGINEERING STANDARD ENCS-S-008-MULT! Revision 0 I Erileray F----------- -L PIPE WALLTHINNINGSTRUCTURALEVALuATION Page 109 of 132 Attachment 7.9: Informational Attachment Page 70 of 93 7.3.5 Circumferential Flaws: In using Tables H-53 10-1 aiid H-53 10-2 for circumfercntiallv flawed welds, the primary membrane stress Pm, primary bending stress Ph, and expansion stress PC are considered in the load combination. The Stress Ratio (SR)for normal operating/upset/test conditions is calculated as: Eqn.16 Equ.17 7.3.6 The stress ratio for emergency/faulted condition is calculated as: SR=Z(I.++/1.39)/S, where Z is the Z-faetor provided in Tables 11-6310-1 or Table 63 10-2 of ASME Section Xl.Appendix H.7.3.7 In lieu of using these tables, an analytical solution based on modified limit load analysis may be used.The limit load equations provided in Section 7,2.5 are used.The allowable bending stress S is determined as: I JP___(SF)Z J Z(SF))Equ.18 where: SF safety factor 2.77 for normal operating/upset/test conditions 1.39 for emergency and faulted conditions. =E3ending stresses at limit load for primary and expansion loads 7=Load multiplier For ductile flaw extension 7.3.8 If more margin in the allowable flaw size is desired for territic pipe material exhibiting EPFM characteristics (0.2SC<1.8). actual J-IntegraliTearing Modulus instability analysis can be performed. Models for performing such analyses are discussed in Attachment XV and provided n software programs which address these applications, see attachment Xlv, 7.4 If SC>1.8, linear elastic fracture mechanics (LEFM)techniques should be used in determining the allowable flaw size.A flow chart for materials meeting the LEFM criteria is provided in Section Xl, Appendix H, Article 7000 and shown in Figure 11.This involves the evaluation of the applied stress intensity factor (K)and comparing it to allowable stress intensity factor (K).7.4.1 For circumferential flaws,[A.37.H-7300, H-4221)K, K,.+/-K,.+K..K Eqn.1 9 ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0 Entergy PIPE WALL THINNING STRUCTURAL EVALUATION Page 110 of 132 Attachment 7.9: Informational Attachment ___________ Page 71 of 93 where: E'/l00(ksi in Eqn.3=Measure of material toughness due to crack extension at upper shelf, transition, and lower shelf temperatures. J integral at first flaw extension, in-lh/in=IE/(1-v)1ksi Eqn.3 Kim=(SF)[J(,i)°5!'.ksiin Eqn.20 where.=ksi Eqn.21 2gRi where P=Total axial load on pipe including pressure.kips Kb Eqn.22=[sF{ah}+J(i) 5 , ksi v'Kir=stress intensity factor due to residual stress with a safety factor of 1.0, ksi in K 1 total applied stress intensity factor, ksi'qin F 1 1.10+x 10.15241+16.722 (xO/lt)°855-14.944 Cr0/it)]Eqn.23=1,10+x 1-0.09967+5.0057 (x0I)5-2.8329 Cr0/it)]Eqn.24=a/t Eqn.25 9/it=ratio of crack length to pipe circumference iSF)=Salery Factor=2.77 for normal operating/upset 1.39 for emergency/faulted Note: K from transients are not considered per Code,]A.37 J.7.4.2 For axial flaws.[A.37.H-7400.H-4221]: ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0 Entergy----------__--l PIPE WALL THINNING SrRucTuRAL EVALUATION Page 111 of 132 Attachment 7.9: Informational Attachment _______________ Page 72 of 93 K 1=K+K 1 K 1 Eqn.26 where: pR Kim=(SF)-(ita/Q) F ksitn Eqn.27 here (SF)=Safety factor=3.0 for not mal operating (including upset and test)conditions =1.5 for emergency and faulted conditions Q=1+4.593() Eqn.28 F=1.12÷0.053+0,0055a 2-f(l.0+0,02(+0.0l91)(20-R/t 2/1400 Eqn.29=(alt)(afl) Eqn.30 K 1 ,=stress intensity factor due to residual stress with a safety factor of 1.0, ksi Jin K 1=(Ji E'/l000)15 ksi in Eqn.3 $U I 0 I.9 UI 0 U b a 0 C,, l. ENGINEERING STANoAR EN-CS-S-OO8MULTI Revision 0 Entergy--______PIPE WALL THINNING STRUcTURAL EvALuATIoN Page 113 of 132 Obtain J from Article H4210 (SC)>=1.8 LEFM Ho Figure 2: ASME Code Section XI Appendix H Flow Chart for Screening Criteria to Establish the Analysis Method[A37J Page 74 of 93 Attachment 79: Informational Attachment r Is J.available?-No Use actual JiG T Usea=27.1 ksi and=181 ksi Screening Criterion (SC)1 Sjr TØ-I ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0 i Entergy i----------------i [jIPE WALL THINNING STRUCTURAL. EvALuATIoN Page 114 of 132 Attachment 79: Informational Attachment ge 75 of 93 1 s Yield stress Considerable variation with weld heat input.a=a,[1.0-6.91 (alt)+&69 (alt)2-0.48 (alt)3 2.03 (a/t)j Figure 3: Recommended Axial and Circumferential Residual Stress Distributions for Circumferential Welds in Ferritic Pipe[Al 3]Through-Wall Residual Stress Wall Thickness Axial Circumferential S S<1 inch IDND 0 ID 1 inch See Note 3 0 a=stress at inner surface (a 0) TRUE STRAIN, PERCENT Figure 4: True Stress-Strain Curves for SAl 06 Gr.B and SA333 Gr.6 at 5500 F[A.13]Attachment 79: Informational Attachment Page 76of 93 90 80 70 60 6 5 30 Ramherg-Osgood Fit 20 10 0 1, 2, 4, 5.aii 7: SAIO6GrB, Different Heats 3 and 6: SA333-6, Different Heats 0 1 2 3 4 5 6 ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0 j Entergy PIPE WALL TaNNING STRUCTURAL EVALUATION Page 118 of 132 Attachment 7.9: Informational Attachment Page 77 of 93 4500 4000 3500 3000 2500-c 2000 1500 1000 500 0 0 0,05 0.1 0.15 0.2 0.25 0.3 Crack Growth.a-inches 0.35 Figure 5: J-Resistance Behavior for A106 Gr.B (L-C Orientation) and A51 6 Gr.70 (T-L Orientation) at 550°F[A.13]4 k=1050©jI°A106 GrB Gr70 F*I ENGINEERING STANDARD I EN-CS-S-008MULTI Revision 0 Lntergy I----------------.1 -PIPE WALL THINNING S11ucTuRAL EVALUATION j Page 117 of 132 Attachment 79: Informational Attachment Page 78 of 93 5000 4500 A J=105()4000*J 14=6OO 3500 3000 2500 2000 1500 1000 500 0 0 100 200 300 400 500 600 T°F Figure 6: J iT Curves for Category 1 Materials[A.131 ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0: hriIery.y-1 PIPE WALL.THINNING STRUCTURAL EvALuATIoN Page 118 of 132 Attachment 79: Informational Attachment Page 79 of 93 2000 (800*J350 1600 200 0.0&0S 0.1 0.15 Crack GTowth, inch Figure 7: J.R Curve for Category 2 Matenals[A.1 31
- ENGINEERING STANDARD I EN-CS-S-GOB-MULTI Revision 0 Entergy--------------i PIPE WALL THINNING STRUCTURAL EVALUATION Page 119 of 132 Attachment 79: Informational Attachment
_____Page 80 of 93 2500 2000 1500 0 100 200 300 400 500 600 TF Figure 8: jir Curve for Category 2 Materials[Ai3] [ENGINEERING STAtDARD EN CS S 008 MULTI Revision 0 Ii1tPr/y----PIPE WALL THINNING STRucTuRAL EvALuATIoN Page 120 of 132 Attachment 79: Informational Attachment Page 81 of 93 Figure 9: Flow Chart for Materials Meeting the Load Limit Criteria[A.37] I ENGINEERING STANDARD 1 EN-CS-S-008-MULTI Revision 0 tEntr'y 1----PIPE WALL THINNING STRUCTURAL EVALUATION Page 121 of 132 Attachment 7.9: Informational Attachment Page 82 of 93 Flgur.10: Row Chart for Materiats for which Ouctile Flaw Extension May Occur Prior to Limit Load (EPFM)(k371 14 ENGINEERING STANDARD I EN-CS-S-OO8MULTl Revision iEnfeigy-1[PIPE WALL THINNING STRUcmRAL EvALUATIoN Page 122 of 132 Attachment 7.9: Informational Attachment Page 83 of 93 Figure 11: Flow Chart for Materials Meeting the Linear Elastic Fracture Mechanics (LEFM)Criteria[A.37] Nominal stress in the uncracked section of pipe Limit Load (Net section plastic collapse)Figure 12: Stress Distribution In a Cracked Pipe--Basis for Net Section Collapse Criteria for Austenitic Steel Pipe F I ENGINEERING STANDARD j ENCSS-OO8-MULTl Revision 0 Entrgy i-------------------i PIPE WALL THINNING STRucTURAL EvALuAiioN Page 123 of 132 Attachment 7.9: Intormational Attachment Page 84 of 93+Pb N I I I axis Pm-Flow stress T I ENG1NEERING STANDARD I EN-CS-S-OO8MULTI Revision 0 Entergy I---------------j[PIPE WALL THINNING STRucTuRAL EVALUATION Page 124 of 132 Attachment 7.9: lnformationa) Attachment _____________________Page 85 of 93 Attachment XIV: CLFE: Fracture Mechanics Software 1.0 Several personal computer-based software programs for performing fracture mechanics analysis of a wide variety of structural components and materials are available. The programs usually have many features and capabilities which are directly applicable to piping flaw and wall thinning evaluations addressed by this standard.These programs can be covered under vendor's nuclear quality assurance programs'safety related applications. Software programs can be used to perform fracture mechanics-based pipe flaw and wall-thinning evaluations described in this standard.2.0 Typically the capabilities of these programs include: 2.1 Codes and Standards Evaluation 2,2 Linear Elastic Fracture Mechanics (LEFM)2.3 Elastic Plastic Fracture Mechanics (EPFM)3.0 Generally these software packages have major modules listed above which contain numerous sub-modules and options.These allow the user to input specific problem parameters, to perform the necessary analyses, to save all relevant data from the analyses for future use, and to obtain tabular and graphical output of results.They also contain detailed program description, including sample problems and a program verification manual in the program users manual.4.0 Two of such software programs are mentioned in the list of references as B.6 and B.7 F I ENGINEERING STANDARO I EN-CS-S-008-MULTI Revision 0 Enteçgy l-.--------__---------_--I PIPE WALL THINNING STRUcTuRAL EvALuATION Page 125 of 132 Attachment 7.9: Informational Attachment ____Page 86 of 93 Attachment XV: CLFE: Alternate Fracture Mechanics Softitions
1.0 INTRODUCTION
I I The evaluation procedures provided in Attachments XII and XIII are based on ASME Code Section Xl, Appendices C and H, respectively. It should be recognized that these appendices are non-mandatory, hence, alternate solutions can be obtained elsewhere in the literature. However, the acceptance criteria of IWB-3640 and IWB-3650 must be satisfied. The acceptance criteria can be satisfied by ensuring that the Code safety margins presented in Attachments XII and XIII are maintained at all times if alternate methods are used.In this attachment, alternate solutions are provided for linear elastic fracture mechanics (LEFM), elastic-plastic fracture mechanics (EPFM)and limit load analysis.2.0 LINEAR ELASTIC FRACTURE MECHANICS 2.1 Linear elastic fracture mechanics (LEFM)is used for the determination of allowable flaw size for ferritic steels for which the screening criteria discussed in Attachment Xlll is greater than or equal to 1.8.LEFM is also used to perform crack growth evaluations for both ferritic and austenitic stainless steel pipe.2.2 LEFM assumes elastic behavior of the stresses in the pipe, including the region around the crack tip.The stress distribution near the crack tip depends on a single quantity termed"the stress intensity," generally designated as K.For loadings which produce an opening mode of displacement between the crack surfaces, the stress intensity factor is further designated as K 1.Expressions have been developed in the literature for the calculation of the value of K 1 in terms of the applied load and the crack size for various combinations and shapes, and types of applied loading.All of these equations have an identical format: K, Ccr-.L Eqn.1 where: a=nominal applied stress a=characteristic crack dimension such as crack depth for surface cracks C=non-dimensional constant whose value depends on crack geometry, the ratio of the crack size to the size of the structural member and tYpe of loading (tension, bending, etc.) I ENGINEERING STANDARD EN-CS-S-008-MULTI Revision Entergy F------J PIPE WALL THINNING SmUcWRAL EVALUATION Page 126 of 132 Attachment 7.9: Informational Attachment Page 87 of 93 2.3 Formulations for K 1 for various surface, subsurface and throughwall geometnes have been presented in several sources[A.23 to A.271.Some of these references have K 1 solutions for cases where the stress varies through the thickness of pipe.One of the most widely used solutions for K 1 are the formulations developed by Raju and Newman[A.16 and A.17].The formulations assume an elliptical surface flaw in a cylinder in tension and bending.The advantage of Raju-Newman solution is that K can be determined at various locations on the crack front.There are also several software programs to solve for K (see Attachment XIV).In fact.solutions for K versus crack size found in References A.23 through A.27 can be imported directly to the calculation procedure in Reference A.37 to perform fracture mechanics evaluations such as crack growth.2.4 The basic principle of LEFM is that unstable propagation of an existing flaw will occur when the value of K 1 attains a critical value designated as K 1.The K 1 , generally called the fracture toughness of the material, is a temperature-dependent material property.The value of K 1 recommended for use by ASME Section XI for ferritic materials in the LEFM regime is presented in Attachment XIII.Recommendations for K 1 values for ferritic steels in the LEFM regime are provided in ASME Section Xl, Appendix H, Article H-4000[A.37].Other values for K 1 are provided in Reference A.27.In some cases, the value of K 1 for a material is not readily available. However, in LEFM regime only, another parameter called J (the elastic-plastic fracture toughness) when available can be converted to K 1 using the relationship K 1_(EJ ksi Eqn.2 where, is in in-lb/in 2 units 2.5 In summary, the implementation of alternate LEFM fracture mechanics concept for evaluation of flawed piping consists of two steps: 2.5.1 Determine K properties of the material from the Code or from other references such as Reference A.27, 2.5.2 Determine the anticipated flaw size in the pipe and calculate the value of K 1 from the References A.23 through A.27.Safety factors shall be applied to the stresses to maintain Code safety margins.Compare K to K to ensure K 1 is less than K 1.3.0 ELASTIC-PLASTIC FRACTURE MECHANICS 3,1 Background 3.1.I Elastic-plastic fracture mechanics principles are used for determination of allowable flaw sizes for austenitic stainless steel piping flux weidments and ferritic piping for which the screening criterion discussed in Attachment XIII is between 0.2 and 1.8.These materials are ductile such that there is significant plastic deformation around the crack tip while the rest of the structure exhibits elastic behavior. T-I ENGINEERING STANDARD EN-CS-S-O08-MULTI RevIsion 0[ntPrgy[-------------- PIPE WALL THINNING STRUCTURAL EVALUATIoN Page 127 of 132 Attachment 7.9: Informational Attachment _________Page 88 of 93 3.1.2 In the presence of the crack, the stress and strain at the tip can be characterized by a parameter called J, where J is a path independent integral which is a measure of the work done around the vicinity of the crack under the applied loading.For loadings which produce an opening mode of displacement between the crack surfaces.the J-integral is further designated as J,.3.1.3 For linear elastic cases, K, J 1---(1--tI) Eqn.3 3.1.4 Similar to the LEFM case, there is a parameter designated as J 1 which measures the fracture toughness of the material.The values of K 1 can be converted to using the above expression. However, unlike the linear elastic case, unstable crack growth does not occur when the value of J is reached.Figure 1 shows the crack growth behavior of a typical ductile material.Upon reaching J, there is a region of stable crack growth before unstable growth occurs.3.2 Engineering Approach for Calculating J 3.2.1 In lieu of determining the value of J using very sophisticated finite element analyses, several simple expressions have been enveloped for various cracked pipe configurations in References A.15, A,26, A.27 and A.42.The formulations in all these references assume that the material stress-strain behavior can be represented by the Ramberg Osgood power law equation of the form: e (V Eqn.4 E,, O\7)where: s and=strain and stress, respectively e and o=yield strain and yield stress.respectively aand n Ramherg--Osgood material coefficients 3.2.2 Values of aand n for typical piping materials used in the nuclear industry have been provided in Reference A.27, 323 For materials that can be represented by the Ramberg-Osgood stress-strain relationship, j is generally represented as[A.42J: I=L+,J Eqn.5 where:=the elastic contribution =the plastic contribution rm ENGINEERING STANDARD I EN-CS-S-008-MULTI Revision 0--Eritergy PIPE WALL THINNING STRUCTURAL EvALUATION Page 128 of 132 Attachment 7.9: Informational Attachment __________________Page 89 of 93 3.2.4 The expressions for Je and J have been provided in References A.15, A.26, A.27 and A.42 for various cracked pipe and loaduiq configurations as listed below: 36O part-wall crack in a cylinder under remote tension[A.27.A.42J 32.4.1 Through-wallflaws in a cylinder under remote tension.[A.15j;3.2.4.2 Through-wall flaws in a cylinder under remote bending.[A.15]: 3.2.4.3 Through-wallflaws in a cylinder subjected to combined, tension and bending,[A,26J: 3.2.4.4 Internally pressurized cylinder with an internal axial crack,[A.42].3.2.5 Some of the J expressions have been incorporated into computer programs and are readily available for use.As a first step in the EPFM evaluation, the J calculated from the above references can be compared to J 1.It should be emphasized though that the Code safety factors should be applied to the piping loads to maintain Code margins.Values of J 1 for typical piping materials have been provided in Reference A.27.3.3 Tearing Modulus Concept 3.3.1 Referring to Figure 1, it can be seen that even if the applied J from the piping loads is greater than J 1 , there is a region of stable crack growth that can be sustained by the cracked piping before instability occurs.The three regions shown in Figure 1 can be summarized as follows: 3.3.2 For Equilibrium: Jk.d=='(No Crack Propagation) Eqn, 8 3,3.3 For Stability: >Crack Propagation Eqn.9 di di=Stability Eqn.10 da (1(1 (LI L1 ,,->...cW='Instability Eqn.11 do (1(1 3.3.4 For convenience, a parameter called the Tearing Modulus (T)is defined as (see figure 2): di E Eqn.12 dr 3.3.5 Hence, if the relationship between J and a has been computed for the applied loading using the handbook solutions from References A.15, A.26, A.27 and A,42.the relationship between J and T for the applied loading can be determined. 3.3.6 The relationship between J and the crack extension a such as that shown in Figure 1 for a material is known as the J-R curve.The J-R curve is a material property that describes the resistance of a given material to continued ductile, stable crack extension under monotonic loading.From the J-R curve, a J-T curve can be constructed for the material using the above expression as shown in Figure 2.The J-T curve is appied to determine the instability point as shown in Figure 2.The J-R curve is generally represented as: I=Cf Au)'Eqn.13 where C and N are Power Law material coefficients dependent on the type of material.The typical values of C and N used for austenitic piping flux welds and ferritic piping are provided in Reference A.27, It should be cautioned again that in performing a J-T analysis in lieu of using the acceptance criteria of lWB-3640 or IWB 3650, the Code safety factors must be applied to the piping loads.J-T analyses can be performed using computer programs.4.0 LIMIT LOAD ANALYSIS 4.1 Limit load analysis is used for the determination of allowable flaw size for base metal and non-flux weldments in austenitic stainless steel piping as well as ferritic piping for which the screening criterion, discussed in Attachment XIII, is less than 02.These materials are very tough, and therefore there is no crack extension until the flawed pipe fails by collapse of the net section.The allowable flaw sizes for austenitic stainless steel piping in Attachment XII and ferritic piping in Attachment XIII are based on the procedures of ASME Section Xl, Appendices C and H.In the development of the allowable flaw sizes in these appendices, it is assumed that the flaw geometry can be represented by a single flaw with constant depth (rectangular flaw>along the entire length.In the case where the actual shape of the flaw is not rectangular, the flaw shape conservatism in the Code procedures can be reduced.Some studies have shown that some relief in the allowable flaw size can be obtained if the flaw shape is assumed to be elliptical or parabolic[A,30].An example of the comparison of allowable flaw size with various flaw shapes is shown in Figure 3.When multiple flaws are encountered during inspection, the conservative way to treat them is to assume a 360°flaw with the maximum depth associated with the flaws.However, it can also be shown that this conservatism can be reduced by treating these flaws as individual flaws[A.301.The evaluation methodology presented in Reference A.30 is only applicable to flaws with symmetrical shapes.4.2 For non-symmetric flaws and also for cases involving multiple flaws, development of the limit load equations becomes slightly complicated because a closed form solution is not possible.Hence, in these cases.an iterative process is used to determine the allowable plastic collapse bending moment on the cross section for a given axial load.For any arbitrary angle, the tension-to-compression axis can be determined and the two orthogonal moments can be calculated by integrating over the cross section.The resultant moment can be calculated as the square of the sum of these two moments.This process can be repeated at various discrete angles around the circumference of the pipe.The collapse moment is the minimum of all the resultant moments.This can be compared with the applied bending load to determine the safety margin which should be equal to or greater than the Code allowable for acceptance. 5.0 FINITE ELEMENT ANALYSIS 5.1 The methods presented in this section as well as in Attachment XII through XV can be used to solve almost all flawed pipe configurations that are encountered in nuclear power plant piping.Most of the solutions presented in this attachment were developed as a result of very sophisticated finite element analyses.in a very extreme case.finite element analysis can be used to add margins beyond the solutions presented in this attachment. In such analyses 5.2 special elements with very fine mesh refinements are required around the crack tip to Attachment 79: Informational Attachment Page 90 of 93 determine K 1 orJ 1. rn-I ENG1NEERNG STANDARD EN-CS-S-008-MULTI Revlsion 0 Entergy 1---_-------------_-_.i PIPE WALLTHINNINGSTRUCTVRALEvALUATION Page 130 of 132 Attachment 7.9: Informational Attachment Page 91 of 93 XVI: Figures 1'Rvp.(ir Vm Covered in this QEAM--&ept ithContintedJ Accepiablc Yes-..No_-.-j.1'ignre I: Overall Flow Chart For Evaluations I ENGINEERING STANDARD EN-CS-S-008-MULTI Revision 0--Entergy---------------- [PE WALL THINNING STRUCTURAL EvALUATIoN Page 131 of 132 Attachment_79: Informational Attachment Page 92 of 93 EEEE'Accept"As-ISa L LocthZedi'ipeWaIlThinningEvaIuatR)nAttuchmcnts III X)oted below No sfyicensingodeEquation_ in Global Pipe Section using ropeies (Aff.VII)No Code}Repairl I Replace/Notes: k=0.3 for Class 1 and 2 Piping (ref.A.32 of Aft.1)or k 0.2 for Class 3 High Energy Piping (ref.A.14 of Aft, I)or kt,=lesser of 0.3t and 0.5 t, for Class 3 Low Energy and B31.1 Piping (non-safety)(ref.A.28 of AU.I)Fgure 2: Flow Chart for EvaIt,atin 'f Localized Pipe Wall Thinnini ENGINEEFuNG STANDARD I ENCSSOO8MULTl Revision 0-Iinterty PIPE WALL THINNING SmUcTURAL EVALUATION Page 132 of 132 Attachment 79: Informational Attachment Page 93 of 93 Determine Operability and Operate until NRC Appmval (Ref.2.11: GL 9118)I-Repair I Replace--()I For FERRITIC STEEL PIPING: Class 1 Pimng Att.XIII (ASME Sec.Xl IWB 3650&App.H)Class 2 Piping Art.XIII (ASME Sec.Xl IWC 3650&App.H)Class 3 Piping: (Same as Class 2&Mod, Energy Piping GL 90.05)831 1 831.7 Piping: Att.XIII (Same as ASME Class 3 wiO GL 90.05)For AUS.STAINLESS STEEL PIPING: Class 1 Piping Ati.XII: ASME Sec Xl IWB 3640&App.Ci Class 2 Piping Att.Xli (ASME Sec.XI IWC 3640&App.C)Class 3 Piping Ati.Xll (ASME Sec.Xl IWO 3640&App.C)831.1 1831.7 Piping Art.XII: (Same as ASME CIass3)Figure 3: Flow Chart for Evaluation of Crack-like Flaws}}