ET 19-0014, Lnserv1ce Inspection (ISI) Program Relief Request Number 14R-07, to Utilize Code Case N-513-4, Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping Section XI, D1v1s1on 1

Lnserv1ce Inspection (ISI) Program Relief Request Number 14R-07, to Utilize Code Case N-513-4, Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping Section XI, D1v1s1on 1

ML19232A139
Person / Time
Site:	Wolf Creek
Issue date:	08/15/2019
From:	Shawn Smith Wolf Creek
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
ET 19-0014
Download: ML19232A139 (41)

Text

W$LFCREEK

'NUCLEAR OPERATING CORPORATION August 15, 2019 Stephen L Smith Vice President Engmeenng U S Nuclear Regulatory Comm1ss1on ATTN Document Control Desk Washington, DC 20555 ET 19-0014 SubJect Docket No 50-482 lnserv1ce Inspection (ISi) Program Relief Request Number 14R-07, to Utilize Code Case N-513-4, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping Section XI, D1v1s1on 1" To Whom It May Concern Pursuant to 10 CFR 50 55a(z)(2), Wolf Creek Nuclear Operating Corporation (WCNOC) hereby requests the Nuclear Regulatory Comm1ss1on (NRC) approval of a proposed alternative to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, "Rules for lnserv1ce Inspection of Nuclear Power Plant Components," on the basis that compliance with the spec1f1ed requirements of this section would result 1n hardship or unusual difficulty without a compensating increase 1n the level of quality and safety Approval of this request would allow use of an acceptable alternative analysis method in lieu of 1mmed1ate action for a degraded cond1t1on, and would allow WCNOC to perform add1t1onal extent of cond1t1on examinations on the affected systems while allowing time for safe and orderly long term repair actions, 1f necessary Actions to remove degraded p1p1ng from service could have a detrimental overall risk impact by requmng a plant shutdown, thus requmng use of a system that 1s in standby during normal operation Spec1f1cally, WCNOC 1s requesting to apply the evaluation methods of ASME Code Case N-513-4, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping Section XI, D1v1s1on 1," to Class 2 and 3 moderate energy piping including elbows, bent pipe, reducers, expanders, and branch tees This relief request to utilize Code Case N-513-4 will only be applied to systems/components that meet the applicability cond1t1ons m Code Case N-513-4 The attachment to th1s letter provides the reason for the request and the proposed alternative Enclosure I provides a marked up copy of N-513-3 h1ghlight1ng the changes between 1t and N-513-4 Enclosure II provides a copy of N-513-4 for reference We request your review and approval of this request by June 1, 2020 PO Box 411 / Burlington, KS 66839 / Phone (620) 364-8831 An Equal Opportunity Employer M/F/HCNET

ET 19-0014 Page 2 of 3 There are no regulatory commitments contained in this submittal If you have any questions concerning this matter, please contact me at (620) 364-4093, or Ron Benham at (620) 364-4204 Sincerely, Stephen L Smith SLS/rlt

ET 19-0014 Page 3 of 3 Attachment Enclosures Relief Request to utilize ASME Code Case N-513-4 I

Marked up copy of N-513-3 h1ghllghtmg the changes II Copy of N-513-4 cc S A Morns (NRC), w/a, w/e N O'Keefe (NRC), w/a, w/e B K S1ngal (NRC), w/a, w/e Senior Resident Inspector (NRC), w/a, w/e

Attachment to ET 19-0014 Page 1 of 4 Wolf Creek Nuclear Operating Corporation 10 CFR 50 55a Request 14R-07 I

Relief Requested In Accordance with 10 CFR 50 55a(z)(2)

Attachment to ET 19-0014 Page 2 of 4 10 CFR 50 55a Request Number 14R-07 Relief Requested In Accordance with 10 CFR 50 55a(z)(2)

Proposed Alternative m Accordance with 10 CFR 50 55a(z)(2)

Alternatives to codes and standards requirements.

1. ASME Code Component(s) Affected.

All American Society of Mechanical Engineers (ASME),Section XI, Class 2 and 3 components that meet the operational and conf1gurat1on hm1tat1ons of Code Case N-513-4, paragraphs 1 (a), 1 (b), 1 (c), and 1 (d) 2 Applicable Code Ed1t1on and Addenda The applicable code ed1t1on and addenda for the Fourth lnserv1ce Inspection Interval at Wolf Creek Generating Station 1s the 2007 Ed1t1on with 2008 Addenda of ASME Section XI (Reference 1) 3

Applicable Code Requirement

ASME Code,Section XI, IWC-3120 and IWC-3130 require that flaws exceeding the defined acceptance criteria be corrected by repair/replacement act1v1t1es or evaluated and accepted by analytical evaluation ASME Code,Section XI, IWD-3120(b) requires that components exceeding the acceptance standards of IWD-3400 be subject to supplemental examination, or to a repair/replacement act1v1ty 4

Reason for Request

In accordance with 10 CFR 50 55a(z)(2), Wolf Creek Nuclear Operating Corporation (WCNOC), 1s requesting a proposed alternative to the ASME Boiler and Pressure Vessel Code,Section XI, "Rules for lnserv1ce Inspection of Nuclear Power Plant Components," and the requirement to perform repair/replacement act1v1t1es for degraded Class 2 and 3 piping whose maximum operating temperature does not exceed 200°F and whose maximum operating pressure does not exceed 275 ps1g Moderately degraded piping could require a plant shutdown within the required action statement t1meframes to repair observed degradation Plant shutdown act1v1t1es result in add1t1onal dose and plant risk that would be inappropriate when a degraded cond1t1on 1s demonstrated to retain adequate margin to complete the component's function The use of an acceptable alternative analysis method in lieu of 1mmed1ate action for a degraded cond1t1on will allow WCNOC to perform add1t1onal extent of cond1t1on examinations on the affected systems while allowing time for safe and orderly long term repair actions, 1f necessary Actions to remove degraded piping from service could have a detrimental overall risk impact by requmng a plant shutdown, thus requmng use of a system that 1s in standby during normal operation Accordingly, compliance with the current Code requirements results in a hardship without a compensating increase in the level of quality and safety

Attachment to ET 19-0014, Page 3 of 4 ASME Code Case N-513-3 does not allow evaluation of flaws located away from attaching c1rcumferent1al piping welds that are in elbows, bent pipe, reducers, expanders, and branch tees (as defined 1(c) of the Case) ASME Code Case N-513-3 also does not allow evaluation of flaws located in heat exchanger external tubing or piping ASME Code Case N-513-4 provides guidance for evaluation of flaws in these locations 5

Proposed Alternative and Basis for Use WCNOC 1s requesting approval to apply the evaluation methods of ASME Code Case N-513-4, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 P1p1ng Section XI, D1v1s1on 1," to Class 2 and 3 components that meet the operational and conf1gurat1on llm1tat1ons of Code Case N-513-4, paragraphs 1 (a), 1 (b), 1 (c), and 1 (d) in order to avoid accruing add1t1onal personnel rad1at1on exposure and increased plant risk associated with a plant shutdown to comply with the cited Code requirements The Nuclear Regulatory Comm1ss1on (NRC) issued Generic Letter 90-05, "Guidance for Performing Temporary Non-Code Repair of ASME Code Class 1, 2, and 3 Piping (Generic Letter 90-05)," (Reference 2), addresses the acceptability of limited degradation in moderate energy piping The generic letter defines conditions that would be acceptable to utilize temporary non-code repairs with NRC approval The ASME recognized that relatively small flaws could remain in service without risk to the structural integrity of a piping system and developed Code Case N-513 NRC approval of Code Case N-513 versions in Regulatory Guide 1 147, "lnserv1ce Inspection Code Case Acceptability, ASME Section XI, D1v1s1on 1,"

(Reference 3) allows acceptance of partial through-wall or through-wall leaks for an operating cycle provided all cond1t1ons of the Code Case and NRC cond1t1ons are met The Code Case also requires the Owner to demonstrate system operability considering the effects of leakage The ASME recognized that the llm1tat1ons in Code Case N-513-3 were preventing needed use in piping components such as elbows, bent pipe, reducers, expanders, and branch tees and external tubing or piping attached to heat exchangers Code Case N-513-4 was approved by the ASME to expand use on these locations and to revise several other areas of the Code Case Enclosure I provides a marked-up N-513-3 version of the Code Case to highlight the changes in N-513-4 compared to the NRC approved N-513-3 version Enclosure II provides the ASME approved Code Case N-513-4 The following provides a high l~vel overview of the Code Case N-513-4 changes 1

Revised the maximum allowed time of use from no longer than 26 months to the next scheduled refueling outage 2

Added applicability to piping elbows, bent pipe, reducers, expanders, and branch tees where the flaw 1s located more than (Rot)112 from the centerline of the attaching circumferential piping weld 3

Expanded use to external tubing or p1p1ng attached to heat exchangers 4

Revised to limit the use to hqu1d systems 5

Revised to clarify treatment of Service Level load combinations 6

Revised to address treatment of flaws in austenit1c pipe flux welds 7

Revised to reqwre minimum wall thickness acceptance criteria to consider longitudinal stress in add1t1on to hoop stress 8

Other minor editorial changes to improve the clarity of the Code Case

Attachment to ET 19-0014 Page 4 of 4 WCNOC will apply ASME Code Case N-513-4 to evaluation of Class 2 and 3 components that are w1th1n the scope of the Code Case Code Case N-513-4 utilizes technical evaluation approaches that are based on principals that are accepted in other Code documents already acceptable to the NRC The application of this Code Case will maintain acceptable structural and leakage integrity while m1mm1zing plant nsk and personnel exposure by m1mm1z1ng the number of plant transients that could be incurred 1f degradation 1s required to be repaired based on ASME Section XI acceptance cntena only 6

Duration of Proposed Alternative n

/

The proposed alternative 1s for use of Code Case N-513-4 for Class 2 and Class 3 components within the scope of the Code Case A Section XI compliant repair/replacement will be completed pnor to exceeding the ne,xt' refueling outage or allowable flaw size, whichever comes first This relief request will be applied for the duration of the inserv1ce inspection interval defined in Section 2 of this request or such time as the NRC approves Code Case, N-513-4 in Regulatory Gwde 1 147 or other document If a flaw 1s evaluated near the end of the interval and the next refueling outage 1s in the subsequent interval the flaw may remain in service under this relief request until the next refueling outage 7

Precedent None 8

References 1 ASME Code,Section XI, 2007 Ed1t1on with 2008 Addenda 2

NRC Generic Letter 90-05, "Guidance for Performing Temporary Non-Code Repair of ASME Code Class 1, 2, and 3 Piping (Generic Letter 90-05) "

3 Regulatory Guide 1 147, "lnserv1ce Inspection Code Case Acceptability, ASME Section XI, D1v1s1on 1" J

Enclosure I to ET 19-0014 Marked up copy of N-513-3 highlighting the changes (16 pages)

II.____R_ec_o_rd_#_l 2_-_84_1 _

Enclosure I CASE N-513-4~

I CASES OF ASME BOILER AND PRESSURE VESSEL CODE Approval Date: January 26, 2009 Code Cases will remain available for use until annulled by the applicable Standards Committee.

Case N-513-9 Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping Section XI, Division 1 Inquiry: What requirements may be used for temporary acceptance of flaws, including through-wall flaws, in moderate energy Class 2 or 3 piping including elbows, bent pipe, reducers, expanders, and branch tees, without performing a repair/replacement activity?

Reply: It is the opinion of the Committee that the following requirements may be used to accept flaws, including through-wall flaws, in moderate energy Class 2 or 3 piping including elbows, bent pipe, reducers, expanders, and branch tees, without performing a repair/replacement activity for a limited time, not exceeding the e;*ah,1atieR peried as defiRed iR this Gasetime to the next scheduled refueling outage.

1 SCOPE (a) These requirements apply to the ASME Section III, ANSI 831.1, and ANSI 831.7 piping, classified by the Owner as Class 2 or 3 that is accessible for inspection. The provisions of this Case do not apply to the following:

(1) pumps, valves, expansion joints, and heat exchangers, except as provided in (b);

(2) weld metal of socket welded joints; (3) leakage through a flange joint; (4) threaded connections employing nonstructural seal welds for leakage protection.

(b) This Case may be applied to heat exchanger external tubing or piping, provided the flaw is characterized in accordance with 2(a) and leakage is monitored.

(t;_h) The provisions of this Case apply to Class 2 or 3 piping in liquid systems whose maximum operating temperature does not exceed 200°F (93°C) and whose maximum operating pressure does not exceed 275 psig (1.9 MPa).

(de) The following flaw evaluation criteria are permitted for pipe and tube including elbows, bent pipe, reducers, expanders, and branch tees. The straight pipe flaw evaluation criteria are permitted for adjoining fittings and flanges to a distance of (Rotf' from the weld centerline.

Draft 15 (05/05/14)

(e) The piping design Code shall be used in determining the stress indices B1 and B7, and stress intensification factor, i, for flaw evaluation following Code applicability limits in terms of component geometry, such as Ddt,____w ratio. If the piping design Code does not provide stress indices,Section III, 2004 Edition or later Editions and Addenda may be used to define B1 and B1~

(fd) The provisions of this Case demonstrate the integrity of the item and not the consequences of leakage. It is the responsibility of the Owner to demeRskate system eperability consideriflg effects of leakage in demonstrating system operability and performing plant flooding analyses.

(e) The eval1:1atieR peried, r""""', is the eperatieRal time fer whieh the tempera!)' aeeeptaRee eriteria are satisfied e1:1t Ret eirneediRg 26 meRths fi:em the iRitial diseevel)' efthe ceRditieR.

2 PROCEDURE (a) The flaw geometry shall be characterized by volumetric inspection methods or by physical measurement. The full pipe circumference at the flaw location shall be inspected to characterize the length and depth of all flaws in the pipe section.

(b) Flaw shall be classified as planar or nonplanar.

(c)

When multiple flaws, including irregular

( compound) shape flaws, are detected, the interaction and combined area Joss of flaws in a given pipe section shall be accounted for in the flaw evaluation.

(d) A flaw evaluation shall be performed to determine the conditions for flaw acceptance. Section 3 provides accepted methods for conducting the required analysis.

(e) Frequent periodic inspections of no more than 30 day intervals shall be used to determine if flaws are growing and to establish the tim~

Q/le,+i,_at which the detected flaw will reach the allowable size.

Alternatively, a flaw growth evaluation may be performed to predict the time,-4""""', at which the detected flaw will grow to the allowable size. The flaw growth analysis shall consider the relevant growth mechanisms such as general corrosion or wastage, fatigue, or stress corrosion cracking. When a flaw growth analysis is used to establish the allowable time for temporary operation, periodic examinations of no more than 90 day intervals shall be conducted to verify the flaw growth analysis predictions.

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

(I) For through-wall leaking flaws, leakage shall be 00S0FV00 eymonitored daily walkaev.'HS to confirm the analysis conditions used in the evaluation remain valid.

(g) If examinations reveal flaw growth rate to be unacceptable, a repair--ei=-Lreplacement activity shall be performed.

(h) Repair~Lreplacement activities shall be performed no later than when the predicted flaw size from either periodic inspection or by flaw growth analysis exceeds the acceptance criteria of 4, or during the next scheduled refueling outage, whichever occurs first. Repair~Lreplacement activities shall be in accordance with IWA-4000 er IWA 7000, res13eetively, iR 6aitieRS QRG AaaeRaa 13rier ta the 1991 AaaeRaa; QRG, iR the 1991 AaaeRaa Qfl0 later, iR aeeeraaRee with P.l/A 4000.

(i)

Evaluations and examination shall be documented in accordance with IW A-6300. The Owner shall document the use of this Case on the applicable data report form.

3 FLAW EVALUATION Planar flaws in straight pipe shall be evaluated in accordance with the requirements in 3.1. Nonplanar flaws in straight pipe shall be evaluated in accordance with the requirements in 3.2. Through-wall flaws in elbows and bent pipe shall be evaluated in accordance with the requirements in 3.3. Through-wall flaws in reducers. expanders. and branch tees shall be evaluated in accordance with the requirements in 3.4 and 3.5, respectively. Flaw growth evaluation shall be performed in accordance with the requirements in 3.~. Nonferrous materials shall be evaluated in accordance with the requirements in 3.14.

For all flaw evaluations, all Service Level load combinations shall be evaluated to determine the most limiting allowable flaw size.

3.1 Planar Flaws in Straight Pipe (a) For planar flaws, the flaw shall be bounded by a rectangular or circumferential planar area in accordance with the methods described in Appendix C. IWA-3300 shall be used to determine when multiple proximate flaws are to be evaluated as a single flaw. The geometry of a through-wall planar flaw is shown in Fig. 1.

(b) For planar flaws in austenitic piping, the evaluation procedure in Appendix C shall be used. Flaw depths up to 100% of wall thickness may be evaluated.

When through-wall circumferential flaws are evaluated, the formulas for evaluation given in C-5320 or C-6320, as applicable, of Appendix C may be used, with the flaw depth to thickness ratio, alt, equal to unity.

Draft 15 (05105/14)

When through-wall axial flaws are evaluated, the allowable flaw length is:

where p

= pressure for the loading condition Note: Z has been Do = pipe outside diameter u1 = flow stress Sy = Code specified yield strength added to equation (1 ).

s. = Code specified ultimate tensile strength and SFm = structural factor on primary membrane stress as specified in C-2622 Z

= load multiplier for ductile flaw extension (equal to 1.0 when using limit load criteria)

Material properties at the temperature of interest shall be used.

FIG. 1 THROUGH-WALL FLAW GEOMETRY (c) For planar flaws in ferritic piping, the evaluation procedure of Appendix C shall be used. Flaw depths up to 100% of wall thickness may be evaluated. Flaw depth, a, is defined in Figures C-4310-1 and C-4310-2.

When through-wall circumferential flaws are evaluated in accordance with C-5300 or C-6300, the flaw depth to thickness ratio, alt, shall be set to unity. When applying the Appendix C screening criteria for through-wall axial flaws, alt shall be set to unity, and the reference limit load hoop stress, a1, shall be defined as cr)M2* When through-wall axial flaws are evaluated in accordance with C-5400 or C-6400, the allowable length is defined by eqs. (1) through (3), with the appropriate structural factors from Appendix C, C-2622. When through-wall flaws are evaluated in accordance with C-7300 or C-7400, the formulas for evaluation given in C-4300 may be used, but with values for Fm, Fb, and F applicable to through-wall flaws. Relations for Fm, F,,, and F that take into account flaw shape and pipe geometry (Rlt ratio) shall be used. The appendix to this Case provides equations for Fm, Fb, and F for a selected range of Rlt.

Geometry of a through-wall crack is shown in Fig. 1.

2

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

FIG. 2 SEPARATION REQUIREMENTS FOR ADJACENT THINNED AREAS 1c,-......_.. __,...,

L. 1 *am........,.._,...,

.r...... -o.su.,* I...~

, 111tA1. UT1: c.--.111111~ftll N M *

~

ilfllt -

• 111 1111at 111*Mttn *-.iw*c.-iaJfl.

3.2 Nonplanar Flaws in Straight Pipe

__ (a) The evaluation shall consider the depth and extent of the affected area and require that the wall thickness exceed lm;n for a distance that is the greater of 2.5..JRtnom or 2Lm.avg between adjacent thinned regions, where R is the mean radius of the piping item based on nominal wall thickness and Lm,avg is the average of the extent of Lm below lm;n for adjacent areas (see Fig. 2).

Alternatively, the adjacent thinned regions shall be considered a single thinned region in the evaluation.

__ (b) For nonplanar flaws, the pipe is acceptable when either (b)(l) and (b)(2), or (b)(2) and (b)(3) are met.

(1) Tthe remaining pipe thickness (tp) is greater than or equal to the minimum wall thickness lm;n:

pDo t. =--~-

nun 2(S+0.4p}

(4) where p

= maximum operating pressure at flaw location S

= allowable stress at operating temperature (2) The remaining degraded pipe section meets the longitudinal stress limits in the design Code for the Pin.in&

(3) As an alternative to (b)(l)Altematively, an evaluation of the remaining pipe thickness (tiJ_may be performed as given below. The evaluation procedure is a function of the depth and the extent of the affected area as illustrated in Fig. 3.

(i+) When Wm is less than or equal to 0.5 (R0t)Vl, where Ro is the outside radius and Wm is defined in Fig. 3, the flaw can be classified as a planar flaw and evaluated in accordance with 3.I(a) through 3.l(c),

above. When the above requirement is not satisfied, (Jill shall be met.

(ilJ) When Lm(t) is not greater than (RJ min )Ill, taioc is determined from Curve 1 of Fig. 4, where Lm(t) is Draft 15 (05/05/14) defined in Fig. 3. When the above requirement is not satisfied, (J@ shall be met.

(jiiJ) When Lm is less than or equal to 2.65 (RJm;J lll and tnom is greater than 1.13 tm;n, ta1oc is determined by satisfying both of the following equations:

taloc ~ I.5fij;;; [,- tnom] + 1.0 tmin L

tmrn (5) taloc 0.353Lm

->----===-

tmin -

~ Rot min (6)

When the above requirements are not satisfied,

( 4b:) shall be met.

(b:4) When the requirements of (.J.D, (Jill, and (J@ above are not satisfied, laioc is determined from Curve 2 of Fig. 4. IR aelelitieR, 1""'6 shall satisfy the fellewiRg e(lHatieR:

Wfll!ftHf1, is the RemiRal flifle l0Rgit1,1eliRal eeReliRg stress res11ltiRg frem all Sep,riee Le1rel B flFimary fli13e leaeliRgs.

(c) When there is through-wall leakage along a portion of the thinned wall, as illustrated in Fig. 5, the flaw may be evaluated by the branch reinforcement method. The thinned area including the through-wall opening shall be represented by a circular penetration at the flaw location. Only the portion of the flaw lying within tadJ need be considered as illustrated in Fig. 6.

When evaluating multiple flaws in accordance with 3.2(a), only the portions of the flaws contained within tadj need be considered.

3

CASE ( continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

FIC. 3 ILLUSTRATION OF NONPLANAR FLAW DUE TO WALL THINNING

.1T ~

Axial direction Draft 15 (05/05/14) t-+--- Lm1,1--~

Lm111 Transverse (circumferential) direction Editor's Note: This Figure 3 is to be deleted and replaced with the Figure 3 on the following page.

4

.$.. e -!!

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-43, FIG. 4 1.0 0.8 0.6 0.4 0.2 0

0 FIG. 3 ILLUSTRATION OF NON PLANAR FLAW DUE TO WALL THINNING Axial direction

+---1.m(a)-

l lm(t) l Transverse (circumferential) direction ALLOWABLE WALL THICKNESS AND LENGTH OF LOCALLY THINNED AREA Draft 15 (05/05/14) 5

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

FIG. 5 ILLUSTRATION OF THROUGH-WALL NONPLANAR FLAW DUE TO WALL THINNING Axial direction t *n Draft 15 (05/05/1 4)

Through~wall

/

opening

~ --Laxial ---.i Transverse L.:irc (clrcumferentlal) direction Editor's Note: This Figure 5 is to be deleted and replaced with the Figure 5 on the following page.

6

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4J FIG. 5 ILLUSTRATION OF THROUGH-WALL NONPLANAR FLAW DUE TO WALL THINNING Axial direction Draft 15 (05/05/14)

+--- laxia1--*1 i

Lcirc !

Transverse (circumferential) direction 7

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

The minimum wall thickness, lm;n, shall be determined by eq. (4). For evaluation purposes, the adjusted wall thickness, lat1j, is a postulated thickness as shown in Fig. 6. The pipe wall thickness is defined as the *thickness of the pipe in the non-degraded region as shown in Fig. 6(a). The diameter of the opening is equal to d at1i as defined by lat1i as shown in Fig. 6(a). The postulated value for lat1i shall be greater than lmin and shall not exceed the pipe wall thickness. The ladj value may be varied between lm;n and the pipe wall thickness to determine whether there is a combination of lat1i and dadi that satisfies the branch reinforcement requirements.

The values of ladj and dadi of Fig. 6(b) shall satisfy:

1.5~ Rladj (tadj - lmin) d adj ~-~----~

lmin (l&)

The remaining ligament average thickness, le.avg, over the degraded area bounded by dadi shall satisfy:

~ 9)

In

addition, the pipe section including the equivalent hole representation shall meet the longitudinal stress limits in the design Code for the Qill.!.!!&

__ If a flaw growth analysis is performed, the growth in flaw dimensions shall consider the degradation mechanisms as relevant to the application. The flaw is acceptable when there is sufficient thickness in the degraded area to provide the required area reinforcement.

(d) Alternatively, ifthere is a through-wall opening along a portion of the thinned wall as illustrated in Fig.

5 the flaw may be evaluated as two independent planar through-wall flaws, one oriented in the axial direction and the other oriented in the circumferential direction.

The minimum wall thickness lm;n, shall be determined by eq. (4). The allowable through-wall lengths in the axial and circumferential directions shall be determined by varying ladi shown in Fig. 5 from lnom to lmin* The allowable through-wall flaw lengths based on lat1i shall be greater than or equal to the corresponding L ax;a/ and L c;rr: (see Fig. 5) as determined from 3.l(a) and 3.l(b) or 3.l(c), as appropriate. The remaining ligament average thickness, le.avg, over the degraded area bounded by Laxial and L c;rr: shall satisfy eq. ~ 9).

3.3 Through-wall Flaws in Elbows and Bent Pipe Through-wall flaws in elbows and bent pipe may be evaluated using the straight pipe procedures given in 3. l or 3.2(d), provided the stresses used in the evaluation Draft 15 (05/05/14) are adjusted, to account for the geometry differences, as described below. Alternative methods may be used to calculate the stresses used in evaluation.

The hoop stress, rrh, for elbow and bent pipe evaluation shall be:

&end = elbow or bent pipe bend radius

~

= circumferential angle defined in Figure 7 h

= flexibility characteristic

~ = resultant primary bending moment I

= moment of inertia based on evaluation wall thickness, l Equation 9 is only applicable for elbows and bent pipe where h > 0.1.

The axial membrane pressure stress, rrm, for elbow and bent pipe evaluation shall be:

where B1 is a primary stress index as defined in Section III for the piping item. B, shall be equal to 0.5 for elbows and bent pipe.

The axial bending stress, rrl!., for elbow and bent pipe evaluation shall be:

<rb = Bz ( -D._M_b )

(11)

~~

21 where B, is a primary stress index as defined in Section III for the piping item.

The thermal expansion stress, rr., for elbow and bent pipe evaluation shall be:

~

~

cr, =i(-D;-~-* ) ~~~~~~C~I=2)

= stress intensification factor as defined in the design Code for the piping item M.. = resultant thermal expansion moment 8

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

3.4 Through-wall Flaws in Reducers and Expanders Through-wall flaws in reducers and expanders may be evaluated using the straight pipe procedures given in

3. I or 3.2( d), provided the stresses used in the evaluation are adjusted, to account for the geometry differences, as described below. Alternative methods may be used to calculate the stresses used in evaluation.

Fig. 8 illustrates the reducer and expander zones discussed below. Evaluation of flaws in the small end transition zone is outside the scope of this Case.

The hoop stress, <Th, and axial membrane pressure stress, u..., for reducer or expander evaluation shall be:

where D0 is the small end OD for flaws in the small end and the large end OD for all other flaws.

The axial bending stress, <Tb, and thermal expansion stress, <Te, for reducer or expander evaluation shall be:

___ a, = {-D-;M-1_* ) ------'{...o.1=6) where I is based on the degraded section.

3.5 Through-wall Flaws in Branch Tees Branch reinforcement requirements shall be met in accordance with the design Code. If the design Code did not require reinforcement, for evaluation purposes, a reinforcement region is defined as a region of radius D, of the branch pipe from the center of the branch connection. Through-wall flaws in branch tees outside of the reinforcement region may be evaluated using the straight pipe procedures given in 3.1 or 3.2{d), provided the stresses used in the evaluation are adjusted, to account for the geometry differences, as described below. Alternative methods may be used to calculate the stresses used in evaluation. Evaluation of flaws in the region of branch reinforcement is outside the scope of this Case.

The hoop stress, <Ta, and axial membrane pressure stress, u..., for branch tee evaluation shall be determined from eq. {13) and eq. {14), respectively. The outside diameter for each of these equations shall be for the branch or run pipe, depending on the flaw location.

Draft 15 (05/05/14)

The axial bending stress, <Tb, and thermal expansion stress, u,, for branch tee evaluation shall be determined from eq. {15) and eq. {16), respectively.

3.~ Flaw Growth Evaluation If a flaw growth analysis is performed, the growth analysis shall consider both corrosion and crack-growth mechanisms as relevant to the application.

In performing a

flaw growth analysis, the procedures in C-3000 may be used as guidance.

Relevant growth rate mechanisms shall be considered.

When stress corrosion cracking (SCC) is active, the following growth rate equation shall be used:

(1.79) where da/dt is flaw growth rate in inches/hour, Kmax is the maximum stress intensity factor under long-term steady state conditions in ksi in.0 5, Sr is a temperature correction factor, and C and n are material constants.

For intergranular SCC in austenitic steels, where T -:;

200°F (93°C).

C

= 1.79 X 10-8 Sr = 1 n

= 2.161 For transgranular SCC in austenitic steels, where T -:;

200°F (93°C).

C

= 1.79 X 10-7 Sr = 3_71 x 108 [IO(oo1842 r - 12 2s)]

n

= 2.161 The temperature, T, is the metal temperature in degrees Fahrenheit. The flaw growth rate curves for the above SCC growth mechanisms are shown in Figs. 2.+

and l.Q&. Other growth rate parameters in eq. (11G) may be used, provided they are supported by appropriate data.

3.14 Nonferrous Materials For nonferrous materials, nonplanar and planar flaws may be evaluated following the general approach of 3.1 through 3.~. For planar flaws in ductile materials, the approach given iR 3.1 (e) aRa 3.3 for austenitic pipe may be used; otherwise, the approach given iR 3.l(e) aRa 3.3for ferritic pipe should be applied. Structural factors provided in 4 shall be used. It is the responsibility of the evaluator to establish conservative estimates of strength and fracture toughness for the piping material.

9

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

FIG. 6 ILLUSTRATION OF ADJUSTED WALL THICKNESS AND EQUIVALENT HOLE DIAMETERS Through-wall tm1n opening rt, ___ _

tadj T

_! \\~~..,__-~,

Pipe

--~.-.....1-------.......... ~~-t*"

I I

I I

(al Adjusted Wall Th Ckf18SS I

I I

I I

I I

Shift figure (b) to the right so that dadj tmrn width lines up with Ti figure (a).

,~~-r-----------~

~~._ie~d~~~-~--'

1..

dad;---J lb) Equivalent Hole Representation FIG. 7 CIRCUMFERENTIAL ANGLE DEFINED extrados

-- - -~~~~~~

Draft 15 (05/05/14) 10

CASES OF ASME BOILER AND PRESSURE VESSEL CODE FIG. 8 ZONES OF A REDUCER OR EXPANDER ct------

GENERAL NOTE:

Large end transition zone Small end transition zone CASE (continued)

N-513-4~

Tranaitio~ zonH extend from the point on the ends where the diameter begins to change to the point on the central cone where th*e cone angle is constant.

Draft 15 (05/05/14) 11

CASE ( continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

FIG. i.1-FLAW GROWTH RATE FOR IGSCC IN AUSTENITIC PIPING H

Aus111nn1c Plpll'f'il T;; 20C'f i.,

V

_/

.... v I.,

~

,I

/

/

/

,.cE.as

'I 10

'100 511'ffl lnlll"dll:y Rlidnr,K 1'.t51 ln.D.5l

~ENE RJ.L NOTE: IS[ o~umt.11: u I :hr * 'l'.~

11 ui' e : L.O ks! In."'

• LAM MP.1 11 C * ['f

• 2l1Li! :'.

Draft 15 (05/05/1 4) 12

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

FIG. 103 FLAW GROWTH RATE FOR TGSCC IN AUSTENITIC PIPING ii i!!

-= i ri 11 a:... !

iii ;

(j

,.~ -02

~

IIIIS11rttlc Flpl~

Ts 20:f' l.~ -44 l.~ -05

==t T*IO~

l.~ -06

,.~ -07

!.~ -OD,

,F

,F

/

J

~

/

/

/

I."

V

/

I T* 10~ f

,,:/

10 S1111SS. l"anSIIY Fnlar, X fbl In.LIi

'JOO GENERAL ~OTE: 1,1 ~

jffiflll: L.O 11, r

• 7.111> I L~**

~--i L.O In.... Lon MP; 11... ; C

• t<f - J 2].'L,I).

Draft 15 (05/05/1 4) 13

CASE ( continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

4 ACCEPTANCE CRITERIA Piping containing a circumferential planar flaw is acceptable for temporary service when flaw evaluation provides a margin using the structural factors in Appendix C, C-2621. For axial planar flaws, the structural factors for temporary acceptance are as specified in Appendix C, C-2622. Straight pP-ip~

containing a nonplanar part=-through-wall flaw is acceptable for temporary service if the remaining pipe section meets the longitudinal stress limits in the design Code for the piping and Ip 2': latoc, where latoc is determined from 3.2(b). Straight pP-ip~iHg containing a nonplanar through-wall flaw is acceptable for temporary service when the flaw conditions of 3.2( c) or 3.2( d) are satisfied. An elbow or bent pipe containing a nonplanar through-wall flaw is acceptable for temporary service if the flaw conditions of 3.3 are satisfied. A reducer or expander containing a nonplanar through-wall flaw is acceptable for temporary service if the flaw conditions of3.4 are satisfied. A branch tee containing a nonplanar through-wall flaw is acceptable for temporary service if the flaw conditions of3.5 are satisfied.

5 AUGMENTED EXAMINATION An augmented volumetric examination or physical measurement to assess degradation of the affected system shall be performed as follows:

(a) From the engineering evaluation, the most susceptible locations shall be identified. A sample size of at least five of the most susceptible and accessible locations, or, if fewer than five, all susceptible and accessible locations shall be examined within 30 days of detecting the flaw.

(b) When a flaw is detected, an additional sample of the same size as defined in 5(a) shall be examined.

(c) This process shall be repeated within 15 days for each successive sample, until no significant flaw is detected or until 100% of susceptible and accessible locations have been examined.

6 NOMENCLATURE fu..Jb~=-~S~ec~t=io~n~ II=I_p=r=im=ar-y~st~re=s=s~i=n=d'=* c~es C

coefficient in the crack growth relationship

!1,*_ ---'=* n"'s=id=e'-p"'i,.,p=e-'d=i=am=e=te=r D0 outside pipe diameter F

nondimensional stress intensity factor for through-wall axial flaw under hoop stress nondimensional stress intensity factor for through-wall circumferential flaw under pipe bending stress Draft 15 (05/05/14)

I L

Laxia/

Lm(a)

Lm(I) nondimensional stress intensity factor for through-wall circumferential flaw under membrane stress moment of inertia based on evaluation thickness, t maximum stress intensity factor under long term steady state conditions maximum extent of a local thinned area with t < lnom length of idealized through-wall planar flaw opening in the axial direction of the pipe, as illustrated in Fig. 5 length of idealized through-wall planar flaw opening in the circumferential direction of the pipe, as illustrated in Fig. 5 maximum extent of a local thinned area with t < lmin axial extent of wall thinning below lm;n circumferential extent of wall thinning below lmin average of the extent of Lm below lm;n for adjacent thinned areas Lm,i maximum extent of thinned area, i M2 bulging factor for axial flaw Af.b ___ ~re=s=u=lta=n=t..,.p=ri=m=a=ry--'-"b=e=n=d=in""g"'"""m=o=m=e=n=t

~----'-r""es=u=l=ta=n=t-"th=e=r=m=a=l-'e""x"'p~a=n=si=o=n=m=o=m=e=nt R

mean pipe radius

& eool---~e=lb=o~w~o~r =b=en=t~p"'i"'p=e-'c=e=n=te=r=li=n=e-'b=e=n=d-'r=a=d=iu=s R0 outside pipe radius S

allowable stress at operating temperature SFm structural factor on primary membrane Sr z

a C

da/dt h

stress coefficient for temperature dependence in the crack growth relationship Code-specified ultimate tensile strength Code-specified yield strength metal temperature maximum extent of a local thinned area perpendicular to Lm with t < lmin minimum distance between thinned areas i andj load multiplier for ductile flaw extension flaw depth half crack length flaw growth rate for stress corrosion cracking diameter equivalent circular hole at tadj diameter of equivalent circular hole at lmin flexibility characteristic stress intensification factor total crack length = 2c allowable axial through-wall flaw length exponent in the crack growth relationship 14

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

p maximum operating pressure at flaw location ladj la/oc a

A evaluation wall thickness, surrounding the degraded area adjusted wall thickness which is varied for evaluation purposes in the evaluation of a through-wall nonplanar flaw allowable local thickness for a nonplanar flaw average remaining wall thickness covering degraded area with through-wall leak bounded by dadj minimum wall thickness required for pressure loading nominal wall thickness minimum remaining wall thickness maximum cone angle at the center of a reducer nondimensional half crack length for through-wall axial flaw

¢ ___

~c=ir~c=um=fe=r~e=n=ti=al~an""g""l=e~fi=ro=m~e=l~bo~w~o=r~b=e=n=d flank

!4 axial bending stress for primai:y loading f4.

axial thermal expansion stress u1 material flow stress uh pipe hoop stress due to pressure and bending moment {for elbows and bent pipe) 61, RemiRal leRgitt:11:iiRal eeREliRg stfess fer 13rimary leaai.Rg witheut stress iRteRsiii eatieR faster u1 reference limit load hoop stress

!Im axial pressure stress

<Iy material yield strength at temperature, as defined in C-4300

'f..u-:

time reEjuirea fer the aeteetea flaw te grew te the allewaele flaw si2:e, eut Ret ex:eeeaiRg 2e meRths frem the iRitial aisee,*ery efthe 60R8iti0R e

half crack angle for through-wall circumferential flaw 7

APPLICABILITY This Case is a1313liea0le frem the 1983 BaitieR with the WiRter 1985 AaaeRaa, thfeugh the 2007 EaitieR with the 2008 AaaeRaa. Reference to Appendix C in this Case shall apply to Appendix C of the 2004 Edition or later editions or addenda. For editions BREI--Or addenda prior to the 2004 Edition, Class 1 pipe flaw evaluation procedures may be used for other piping classes. As a matter of definition, the current term "structural factor" is equivalent to the term "safety factor," which is used in earlier editions and addenda.

Draft 15 (05/05/14)

Editor's Note: For Applicability Index, applicability is from 1996 Addenda to 2013 Edition.

15

CASE (continued)

CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~

MANDATORY APPENDIX I RELATIONS FOR Fm, Fb, AND F FOR THROUGH-WALL FLAWS 1-1 DEFINITIONS For through-wall flaws, the crack depth,_ --fa.1 will be replaced with half crack length.,_ -fc.1 in the stress intensity factor equations in C-7300 and C-7 400 of Section XI, Appendix C. Also, Q will be set equal to unity in C-7400.

1-2 CIRCUMFERENTIAL FLAWS For a range of Rlt between 5 and 20, the following equations for Fm and Fb may be used:

Fm = 1 + Am (8/7,) 15 + Bm (8/1r)25 + Cm (8fa)35 Fb = 1 + Ab (8!1r) 15 + Bb (8!1r)25 + Cb (8/1r)3 5 where 8 = half crack angle = c/R R = mean pipe radius t = evaluation pipe-wall thickness and Am = -2.02917 + 1.67763 (Rlt) - 0.07987 (R/t )2

+ 0.00176 (Rlt)3 Bm = 7.09987 - 4.42394 (Rlt) + 0.21036 (R!t )2

- 0.00463 (Rlt)3 Cm = 7.79661 + 5.16676 (Rlt) - 0.24577 (Rlt )2

+ 0.00541 (Rlt)3 Draft 15 (05/05/14)

Ab = -3.26543 + 1.52784 (Rlt)- 0.072698 (R/t )

2

+ 0.0016011 (Rlt)3 Bb = 11.36322 - 3.91412 (Rlt) + 0.18619 (Rlt )2

- 0.004099 (Rlt)3 Cb = -3.18609 + 3.84763 (Rlt)- 0.18304 (Rlt )2

+ 0.00403 (Rlt)3 Equations for Fm and Fb are accurate for Rlt between 5 and 20 and become increasingly conservative for Rlt greater than 20. Alternative solutions for Fm and Fb may be used when Rlt is greater than 20.

1-3 AXIAL FLAWS For internal pressure loading, the following equation for F may be used:

F = l + 0.0724491. + 0.64856).2 - 0.2327 ).3

+ 0.038154 ).4 - 0.0023487 'A.5 where c = half crack length

'A. = c!(Rt) V2 The equation for F is accurate for 'A. between O and 5.

Alternative solutions for F may be used when A is greater than 5.

16

Enclosure II to ET 19-0014 Copy of N-513-4 (16 pages) 1 CASE ASME BPVC CC NC-2017 N-513-4 Approval Date May 7, 2014 Code Cases will remain available for use until annulled by the appl,cable Standards Committee Case N-513-4 Evaluation Criteria for Temporary Acceptance of Flaws m Moderate Energy Class 2 or 3 P1pmg Section XI, D1v1s1on l Inquiry What reqmrements may be used for temporary acceptance of flaws, mcludmg through-wall flaws, m mod-erate energy Class 2 or 3 p1pmg mcludmg elbows, bent pipe, reducers, expanders, and branch tees, without per-formmg a repair /replacement act1v1ty?

Reply It 1s the opm10n of the Committee that the follow-mg reqmrements may be used to accept flaws, mcludmg through-wall flaws, m moderate energy Class 2 or 3 pip-mg mcludmg elbows, bent pipe, reducers, expanders, and branch tees, without performmg a repair /replace-ment act1v1ty for a limited time, not exceedmg the time to the next scheduled refuelmg outage l SCOPE (a) These reqmrements apply to the ASME Sect10n III, ANSI B311, and ANSI B31 7 p1pmg, classified by the Own-er as Class 2 or 3 that 1s accessible for mspect10n The pro-VISIOns of this Case do not apply to the followmg (1) pumps, valves, expansion 1omts, and heat exchan-gers, except as proVIded m (b)

(2) weld metal of socket welded 1omts (3) leakage through a flange 1omts (4) threaded connect10ns employmg nonstructural seal welds for leakage protection (b) This Case may be applied to heat exchanger exter-nal tubmg or p1pmg, provided the flaw 1s characterized m accordance with 2(a) and leakage 1s momtored (c) The proVIs1ons of this Case apply to Class 2 or 3 pip-mg m hqmd systems whose maximum operatmg tem-perature does not exceed 200°F (93°C) and whose maximum operatmg pressure does not exceed 275 ps1g (19 MPa)

(d) The followmg flaw evaluation criteria are permitted for pipe and tube mcludmg elbows, bent pipe, reducers, expanders, and branch tees The straight pipe flaw evalua-t10n criteria are permitted for ad1ommg f1ttmgs and flanges to a distance of (R 0 t) 1/ 2 from the weld centerlme (e) The p1pmg design Code shall be used m determm-mg the stress md1ces B 1 and B 2, and stress mtens1ficat10n factor, 1, for flaw evaluation following Code apphcab1hty hm1ts m terms of component geometry, such as D0 /tnom ratio If the p1pmg design Code does not proVIde stress m-d1ces,Section III, 2004 Ed1t10n or later Editions and Ad-denda may be used to define B 1 and B 2 (f) The proV1s1ons of this Case demonstrate the mteg-r1ty of the item and not the consequences of leakage It 1s the respons1b1lity of the Owner to consider effects of leakage m demonstratmg system operab1hty and per-formmg plant floodmg analyses 2 PROCEDURE (a) The flaw geometry shall be characterized by volu-metric mspect10n methods or by physical measurement The full pipe circumference at the flaw location shall be mspected to characterize the length and depth of all flaws m the pipe section (b) Flaw shall be classified as planar or nonplanar '

(c) When multiple flaws, mcludmg irregular (com-pound) shape flaws, are detected, the mteract10n and combmed area loss of flaws m a given pipe section shall be accounted for m the flaw evaluat10n (d) A flaw evaluation shall be performed to determme the cond1t10ns for flaw acceptance Section 3 proVIdes ac-cepted methods for conductmg the reqmred analysis (e) Frequent periodic mspect10ns of no more than 30 day mtervals shall be used to determme 1f flaws are growing and to establish the time, at which the detected flaw will reach the allowable size Alternatively, a flaw growth evaluat10n may be performed to predict the time at which the detected flaw will grow to the allowable size The flaw growth analysis shall consider the relevant growth mechamsms such as general corros10n or wa-stage, fatigue, or stress corrosion crackmg When a flaw growth analysis 1s used to estabhsh the allowable time for temporary operat10n, periodic exammat10ns of no more than 90 day mtervals shall be conducted to verify the flaw growth analysis predictions (f) For through-wall leakmg flaws, leakage shall be momtored daily to confirm the analysis cond1t1ons used m the evaluat10n remam valid The Committee's function is to estabhsh rules of safety relating only to pressure mtegnty govemmg the construction of b01lers pressure vessels transport tanks and nuclear components and mservtce mspect!on for pressure mtegnty of nuclear components and transport tanks and to mterpret these rules when questions anse regardmg their mtent This Code does not address other safety issues relating to the constructrnn of boilers pressure vessels transport tanks and nuclear components and the mservtce mspect!on of nuclear components and transport tanks The user of the Code should refer to other pertinent codes standards laws regulations or other relevant documents 1 (N-513-4)

FDR ASME COMMITTEE USE ONLY

CASE (continued)

N-513-4 ASME BPVC CC NC 2017 (g) If exammat10ns reveal flaw growth rate to be unac-ceptable, a repair/replacement act1v1ty shall be performed (h) Repair/replacement act1v1t1es shall be performed no later than when the predicted flaw size from either penod1c mspect10n or by flaw growth analysis exceeds the acceptance cntena of 4, or dunng the next scheduled refuel mg outage, whichever occurs first Repair /replace-ment act:Jv11:Jes shall be m accordance with IWA-4000 (1) Evaluat10ns and exammat10n shall be documented m accordance with IWA-6300 The Owner shall document the use of this Case on the applicable data report form 3 FLAW EVALUATION Planar flaws m straight pipe shall be evaluated m accor-dance with the reqmrements m 3 1 Nonplanar flaws m straight pipe shall be evaluated m accordance with the re-qmrements m 3 2 Through-wall flaws m elbows and bent pipe shall be evaluated m accordance with the reqmre-ments m 3 3 Through-wall flaws m reducers, expanders, and branch tees shall be evaluated m accordance with the reqmrements m 3 4 and 3 5, respectively Flaw growth evaluat10n shall be performed m accordance with the re-qmrements m 3 6 Nonferrous matenals shall be evalu-ated m accordance with the reqmrements m 3 7 For all flaw evaluations, all Service Level load combma-t10ns shall be evaluated to determme the most hm11:Jng al-lowable flaw size 31 PLANAR FLAWS IN STRAIGHT PIPE (a) For planar flaws, the flaw shall be bounded by a rec-tangular or circumferential planar area m accordance with the methods descnbed m Sect10n XI Nonmandatory Appendix C IWA-3300 shall be used to determme when multiple proximate flaws are to be evaluated as a smgle flaw The geometry of a through-wall planar flaw 1s shown m Figure 1 (b) For planar flaws m austemt1c p1pmg, the evaluation procedure m Nonmandatory Appendix C shall be used Flaw depths up to 100% of wall thickness may be evalu-ated When through-wall c1rcumferent1al flaws are evalu-ated, the formulas for evaluation given m C-5320 or C-6320, as apphcable, of Nonmandatory Appendix C may be used, with the flaw depth to thickness rat10, a /t, equal to umty When through-wall axial flaws are evaluated, the allow-able flaw length 1s ah = pD0 /2t (2) where D O = pipe outside diameter p = pressure for the loadmg cond1t10n Su = Code specified ultimate tensile strength Sy = Code spec1f1ed yield strength (3)

SFm = structural factor on pnmary membrane stress as specified m C-2622 Z = load multiplier for ductile flaw extens10n (equal to 1 0 when usmg hm1t load cntena)

O/ = flow stress Matenal propert:Jes at the temperature of mterest shall be used (c) For planar flaws m fernt1c p1pmg, the evaluat10n procedure of Nonmandatory Appendix C shall be used Flaw depths up to 100% of wall thickness may be evalu-ated Flaw depth, a, 1s defmed m Figures C-4310-1 and C-4310-2 When through-wall c1rcumferent1al flaws are evaluated m accordance with C-5300 or C-6300, the flaw depth to thickness ratio, aft, shall be set to umty When applymg the Nonmandatory Appendix C screenmg enter-Ia for through-wall axial flaws, a /t shall be set to umty, and the reference hm1t load hoop stress, u 1, shall be de-fined as uy/M2 When through-wall axial flaws are evalu-ated m accordance with C-5400 or C-6400, the allowable length 1s defined by eqs (b)(l) through (b)(3), with the appropnate structural factors from Nonmandatory Appendix C, C-2622 When through-wall flaws are evalu-ated m accordance with C-7300 or C-7400, the formulas for evaluat10n given m C-4300 may be used, but with val-ues for Fm, F b, and F applicable to through-wall flaws Re-lat:Jons for Fm, F b, and F that take mto account flaw shape and pipe geometry (R/t rat:Jo) shall be used The appen-dix to this Case provides equat10ns for Fm, Fb, and F for a selected range of R /t Geometry of a through-wall crack 1s shown m Figure 1 3 2 NONPLANAR FLAWS IN STRAIGHT PIPE (a) The evaluat10n shall consider the depth and extent of the affected area and reqmre that the wall thickness ex-ceed tmin for a distance that 1s the greater of 2 5.JRtnom or 2Lm avg between adJacent thmned reg10ns, where R 1s the mean rad ms of the p1pmg item based on nommal wall thickness and Lm avg IS the average of the extent of Lm 2 (N-513 4)

FOR ASME COMMITTEE USE ONLY

CASE (continued)

ASME BPVC CC NC-2017 N-513-4 below tmin for adjacent areas (see Figure 2) Alterna-tively, the adjacent thmned reg10ns shall be considered a smgle thmned reg10n m the evaluat10n (b) For nonplanar flaws, the pipe 1s acceptable when either (1) and (2), or (2) and (3) are met (1) The remammg pipe thickness, tp, 1s greater than or equal to the mm1mum wall thickness tmin t

pDo mm -

2(S + 0 4p) where p

= maximum operatmg pressure at flaw locat10n S

= allowable stress at operatmg temperature (4)

(2) The remammg degraded pipe sect10n meets the long1tudmal stress hm1ts m the design Code for the p1pmg (3) As an alternative to (1), an evaluat10n of the re-mammg pipe thickness, tp, may be performed as given be-low The evaluation procedure 1s a funct10n of the depth and the extent of the affected area as illustrated m Figure 3

(-a) When Wm 1s less than or equal to O 5 (R 0 t) 1/ 2, where R 0 1s the outside radms and Wm 1s defmed m Figure 3, the flaw can be classified as a planar flaw and evaluated m accordance with 3 1(a) through 3 1(c),

above When the above reqmrement 1s not sat1sf1ed, (-b) shall be met

(-b) When Lm(tJ IS not greater than (R 0 tmin)1l 2, taioc IS determmed from Curve 1 of Figure 4, where Lm(tJ 1s defmed m Figure 3 When the above reqmrement 1s not sat1sf1ed, (-c) shall be met

(-c) When Lm 1s less than or equal to 2 65 X (Rotm1n)112 and tnom IS greater than 113tmtn, taloc 1s determmed by sat1sfymg both of the followmg equat10ns t.,Jot, ~ 15~[1-tnom] + 10 (5) tmm L

tmm When the above reqmrements are not satisfied, (-d) shall be met

(-d) When the reqmrements of (-a), (-b), and (-c) above are not sat1sf1ed, taioc 1s determmed from Curve 2 of Figure 4 (c) When there 1s through-wall leakage along a portion of the thmned wall, as illustrated m Figure 5, the flaw may be evaluated by the branch remforcement method The thmned area mc!udmg the through-wall openmg shall be represented by a circular penetrat10n at the flaw loca-t10n Only the port10n of the flaw lymg w1thm tadf need be considered as illustrated m Figure 6 When evaluatmg multiple flaws m accordance with (a), only the port10ns of the flaws contamed w1thm tadJ need be considered The mm1mum wall thickness, tmin, shall be determmed by (b)(1), eq (4) For evaluat10n purposes, the adjusted wall thickness, tadJ> 1s a postulated thickness as shown m Figure 6 The pipe wall thickness 1s defined as the thick-ness of the pipe m the non-degraded reg10n as shown m Figure 6, 11!ustrat10n (a) The diameter of the openmg 1s equal to d adf as defined by tadJ as shown m Figure 6, 1!-

lustrat10n (a) The postulated value for tadJ shall be great-er than tmin and shall not exceed the pipe wall thickness The tadJ value may be vaned between tm,n and the pipe wall thickness to determme whether there 1s a combma-t10n of tadJ and dadJ that satisfies the branch remforce-ment reqmrements The values of tadJ and dadJ of Figure 6, 1llustrat10n (b) shall satisfy 15~RtadJ (tadJ - tmm) dadJ s -~-~----

tmm (7)

The remammg ligament average thickness, tc avg over the degraded area bounded by dadJ shall satisfy ip tc,avg ~ 0 353dad1'1's (8)

In add1t10n, the pipe sect10n mcludmg the eqmvalent hole representat10n shall meet the longitudmal stress hm-1ts m the design Code for the p1pmg If a flaw growth analysis 1s performed, the growth m flaw d1mens10ns shall consider the degradat10n mechan-isms as relevant to the apphcat10n The flaw 1s acceptable when there 1s sufficient thickness m the degraded area to provide the reqmred area remforcement (d) Alternat1vely, 1f there 1s a through-wall openmg along a port10n of the thmned wall as illustrated m Figure 5 the flaw may be evaluated as two mdependent planar through-wall flaws, one oriented m the axial direct10n and the other oriented m the circumferential direct10n The mm1mum wall thickness tmin, shall be determmed by (b)(1), eq (4) The allowable through-wall lengths m the axial and c1rcumferent1al direct10ns shall be deter-mmed by varymg tadJ shown m Figure 5 from tnom to tmin The allowable through-wall flaw lengths based on tadJ shall be greater than or equal to the correspondmg Lax,ai and Lcirc (see Figure 5) as determmed from 3 1(a) and 3 1(b) or 31(c), as appropriate The remammg ligament average thickness, tc avg, over the degraded area bounded by Laxtai and Lc,rc shall satisfy (c), eq (8) 3 3 THROUGH-WALL FLAWS IN ELBOWS AND BENT PIPE Through-wall flaws m elbows and bent pipe may be evaluated usmg the straight pipe procedures given m 31 or 3 2(d), provided the stresses used m the evaluat10n 3 (N-513-4)

F"OR ASME COMMITTEE USE ONLY

CASE (continued)

N-513-4 ASME BPVC CC NC-2017 are adjusted, to account for the geometry differences, as described below Alternative methods may be used to cal-culate the stresses used m evaluation The hoop stress, uh, for elbow and bent pipe evaluat10n shall be as follows (9) where h = flex1b11ity characteristic I = moment of mert1a based on evaluat10n wall thickness, t Mb = resultant pnmary bendmg moment Rb end = elbow or bent pipe bend radius

¢ = c1rcumferent1al angle defined m Figure 7 Equat10n (9) 1s only applicable for elbows and bent pipe where h ~ 0 1 The axial membrane pressure stress, um, for elbow and bent pipe evaluat10n shall be as follows (10) where B 1 = pnmary stress mdex as defined m Sect10n III for the p1pmg item

= 0 5 for elbows and bent pipe The axial bendmg stress, ub, for elbow and bent pipe evaluat10n shall be as follows (11) where B 2 = primary stress mdex as defined m Sect10n Ill for the p1pmg item The thermal expans10n stress, u e, for elbow and bent pipe evaluat10n shall be as follows 0: = 1 (D0Me) e 2T (12) where 1 = stress mtens1ficat10n factor as defined m the design Code for the p1pmg item Me = resultant thermal expans10n moment 3 4 THROUGH-WALL FLAWS IN REDUCERS AND EXPANDERS Through-wall flaws m reducers and expanders may be evaluated usmg the straight pipe procedures given m 3 1 or 3 2(d), provided the stresses used m the evaluation are adjusted, to account for the geometry differences, as descnbed below Alternative methods may be used to cal-culate the stresses used m evaluat10n Figure 8 illustrates the reducer and expander zones discussed below Evalua-t10n of flaws m the small end trans1t10n zone 1s outside the scope of this Case The hoop stress, uh, and axial membrane pressure stress, um, for reducer or expander evaluat10n shall be as follows (13)

(14) where D 0 = small-end OD for flaws m the small-end and the large-end O D for all other flaws The axial bendmg stress, ub, and thermal expans10n stress, CJ e, for reducer or expander evaluat10n shall be as follows (15) a: = 1 (DoMe) e 21 (16) where I = moment of mert1a based on degraded sect10n 3 5 THROUGH-WALL FLAWS IN BRANCH TEES Branch remforcement reqmrements shall be met m ac-cordance with the design Code If the design Code did not reqmre remforcement, for evaluat10n purposes, a rem-forcement reg10n 1s defmed as a reg10n of radms D I of the branch pipe from the center of the branch connection Through-wall flaws m branch tees outside of the rem-forcement reg10n may be evaluated usmg the straight pipe procedures given m 3 1or32(d), provided the stres-ses used m the evaluat10n are adjusted, to account for the geometry differences, as descnbed below Alternative methods may be used to calculate the stresses used m evaluat10n Evaluat10n of flaws m the reg10n of branch re-mforcement 1s outside the scope of this Case The hoop stress, uh, and axial membrane pressure stress, um, for branch tee evaluat10n shall be determmed from eq 3 4(13) and eq 3 4(14), respectively The outside diameter for each of these equat10ns shall be for the branch or run pipe, dependmg on the flaw location The axial bendmg stress, ub, and thermal expans10n stress, Cle, for branch tee evaluat10n shall be determmed from eq 3 4(15) and eq 3 4(16) respectively 4 (N-513-4)

FOR ASME COMMITTEE USE ONLY

CASE (continued)

ASME BPVC CC NC-2017 N-513-4 3 6 FLAW GROWTH EVALUATION

!fa flaw growth analysis 1s performed, the growth anal-ysis shall consider both corros10n and crack-growth me-chamsms as relevant to the apphcat10n In performmg a flaw growth analysis, the procedures m Article C-3000 may be used as gmdance Relevant growth rate mechamsms shall be considered When stress corro-s10n crackmg (SCC) 1s active, the followmg growth rate equat10n shall be used (17) where da/dt 1s flaw growth rate m mches/hour, Kmax 1s the maximum stress mtens1ty factor under long-term steady state cond1t1ons m ks1 m O 5, ST 1s a temperature correct10n factor, and C and n are material constants For mtergranular SCC m austemt1c steels, where T ::;;

200°F (93°C)

C = 1 79 x 10-0 n = 2161 Sr= 1 For transgranular SCC m austemt1c steels, where T ::;;

200°F (93°C)

C = 1 79 X 10-7 n = 2161 ST = 3 7l X lQ8 [10(0 01842 T - 12 25)]

The temperature, T, 1s the metal temperature m de-grees Fahrenheit The flaw growth rate curves for the above SCC growth mechamsms are shown m Figures 9 and 10 Other growth rate parameters m eq (17) may be used, provided they are supported by appropriate data 3 7 NONFERROUS MATERIALS For nonferrous materials, nonplanar and planar flaws may be evaluated followmg the general approach of 3 1 through 3 6 For planar flaws m ductile materials, the ap-proach given for austemt1c pipe may be used, otherwise, the approach given for fernt1c pipe should be apphed Structural factors provided m 4 shall be used It IS the re-spons1b1hty of the evaluator to establish conservative es-timates of strength and fracture toughness for the p1pmg material 4 ACCEPTANCE CRITERIA P1pmg contammg a circumferential planar flaw 1s ac-ceptable for temporary service when flaw evaluation pro-v1 des a margrn usrng the structural factors rn Nonmandatory Appendix C, C-2621 For axial planar flaws, the structural factors for temporary acceptance are as spec1f1ed m Nonmandatory Appendix C, C-2622 Straight pipe contammg a nonplanar part through-wall flaw 1s acceptable for temporary service 1f the remammg pipe sect10n meets the long1tudmal stress limits m the design Code for the p1pmg and tp ~ taloc, where ta1oc IS determmed from 3 2(b) Straight pipe contammg a non-planar part through-wall flaw 1s acceptable for temporary service when the flaw cond1t10ns of 3 2(c) or 3 2(d) are sat1sf1ed An elbow or bent pipe contammg a nonplanar through-wall flaw 1s acceptable for temporary service 1f the flaw cond1t10ns of 3 3 are sat1sf1ed A reducer or ex-pander contammg a nonplanar through-wall flaw 1s ac-ceptable for temporary service 1f the flaw cond1t10ns of 3 4 are sat1sf1ed A branch tee contammg a nonplanar through-wall flaw 1s acceptable for temporary service 1f the flaw cond1t10ns of 3 5 are satisfied 5 AUGMENTED EXAMINATION An augmented volumetric exammat10n or physical measurement to assess degradat10n of the affected sys-tem shall be performed as follows (a) From the engmeermg evaluat10n, the most suscepti-ble locat10ns shall be 1dent1fied A sample size of at least five of the most susceptible and accessible locat10ns, or, 1f fewer than five, all susceptible and accessible locat10ns shall be exammed w1thm 30 days of detectmg the flaw (b) When a flaw 1s detected, an add1t10nal sample of the same size as defined m (a) shall be exammed (c) This process shall be repeated w1thm 15 days for each successive sample, until no s1gmf1cant flaw 1s de-tected or until 100% of susceptible and accessible loca-t10ns have been exammed 6 NOMENCLATURE a = flaw depth B 1, B 2 = Sect10n III primary stress md1ces c = half crack length C = coefficient m the crack growth relatJ.onsh1p da/dt = flaw growth rate for stress corros10n crackmg dad! = diameter eqmvalent circular hole at tadj D 1 = ms1de pipe diameter dmin = diameter of eqmvalent circular hole at tmin DO = outside pipe diameter F = nond1mens10nal stress mtens1ty factor for through-wall axial flaw under hoop stress F b = nond1mens10nal stress mtens1ty factor for through-wall circumferential flaw under pipe bendmg stress Fm = nond1mens10nal stress mtens1ty factor for through-wall circumferential flaw under mem-brane stress h = flex1b1hty characteristic 1 = stress mtens1ficat10n factor I = moment of mert1a based on evaluat10n thick-ness, t Kmax = maximum stress mtens1ty factor under long term steady state cond1t10ns 5 (N 513 4)

FOR ASME COMMITTEE USE ONLY

CASE (continued)

N-513-4 ASME BPVC CC NC-2017 L = maximum extent of a local thmned area with t

< tnom Lax,al = length of 1deahzed through-wall planar flaw openmg m the axial direct10n of the pipe, as il-lustrated m Figure 5 Le ire = length of idealized through-wall planar flaw openmg m the circumferential d1rect10n of the pipe, as illustrated m Figure 5 Lm = maximum extent of a local thmned area with t < tmin Lm(aJ = axial extent of wall thmnmg below tmin Lm(tJ = circumferential extent of wall thmmng below tmin Lm avg = average of the extent of Lm below tmrn for ad-Jacent thmned areas Lm 1 = maximum extent of thmned area, 1 M 2 = bulgmg factor for axial flaw Mb = resultant primary bendmg moment Me = resultant thermal expans10n moment n = exponent m the crack growth relat10nsh1p p = maximum operatmg pressure at flaw locat10n R = mean pipe radms Rbend = elbow or bent pipe centerlme bend radms R0 = outside pipe radms S = allowable stress at operating temperature SF m = structural factor on primary membrane stress Sr = coefficient for temperature dependence m the crack growth relat10nsh1p Su = Code-specified ultimate tensile strength Sy = Code-specified yield strength T = metal temperature t = evaluat10n wall thickness, surroundmg the de-graded area tadJ = adjusted wall thickness which IS vaned for eva-luation purposes m the evaluat10n of a through-wall nonplanar flaw taloc = allowable local thickness for a nonplanar flaw tc avg = average remammg wall thickness covermg de-graded area with through-wall leak bounded by dadj tmin = mm1mum wall thickness reqmred for pressure loadmg tnom = nommal wall thickness tp = mm1mum remammg wall thickness Wm = maximum extent of a local thmned area per-pendicular to Lm with t < tmin X, 1 = mm1mum distance between thmned areas 1 andJ Z = load multipher for ductile flaw extens10n f = total crack length = 2c fall = allowable axial through-wall flaw length c/> = circumferential angle from elbow or bend flank a = maximum cone angle at the center of a reducer e = half crack angle for through-wall circumferen-tial flaw A = nond1mens10nal half crack length for through-wall axial flaw ab = axial bendmg stress for primary loadmg

a. = axial thermal expansion stress a f = material flow stress ah = pipe hoop stress due to pressure and bendmg moment (for elbows and bent pipe) a1 = reference hm1t load hoop stress am = axial pressure stress ay = material yield strength at temperature, as de-fined m C-4300 7 APPLICABILITY Reference to Nonmandatory Appendix Cm this Case shall apply to Nonmandatory Appendix C of the 2004 Ed1-t1on or later ed1t10ns or addenda For editions or addenda pnor to the 2004 Ed1t10n, Class 1 pipe flaw evaluat10n procedures may be used for other p1pmg classes As a matter of defimt10n, the current term "structural factor" 1s eqmvalent to the term "safety factor," which 1s used m earher ed1t10ns and addenda 6 (N-513-4)

F"OR ASME COMMITTEE USE ONLY

ASME BPVC CC NC-2017 Figure 1 Through-Wall Flaw Geometry (al C1rcumferent1al Flaw (bl Axial Flaw 7 (N-513-4)

FDR ASME COMMITTEE USE ONLY CASE (continued)

N-513-4

CASE (continued)

N-513-4 ASME BPVC CC NC 2017 Figure 2 Separation Requirements for Adjacent Thinned Areas t <!:tmm 1n surrounding area Area3 tp 3< tmm Legend Lm avJ = 0 5 (Lm 1 + Lm 1)

X1 1 = m1mmum distance between areas I andJ Lm, = maximum extent ofthmned area I GENERAL NOTE Combmat10n of adjacent areas mto an eqmvalent smgle area shall be based on dimens10ns and extents pr10r to combmatlon 8 (N-513-4)

FOR ASME COMMITrEE USE ONLY

t tnom t

Axial d1rect1on

,(

ASME BPVC CC NC-2017 Figure 3 Illustration of Nonplanar Flaw Due to Wall Thmnmg 9 (N-513-4)

F"OR ASME COMMITrEE USE ONLY CASE (continued)

N-513-4 Transverse (c1rcumferent1al) d1rect1on

CASE (continued)

N-513-4 ASME BPVC CC NC-2017 Figure 4 Allowable Wall Thickness and Length of Locally Thinned Area 1 0 08 C:

06

.....E 0

3 04 02 0

0 2

3 4

5 6

7 8

Lm1a/~

10 (N-513-4)

FOR ASME COMMITTEE USE ONLY

CASE (continued)

ASME BPVCCCNC 2017 N-513-4 Figure 5 Illustration of Through-Wall Nonplanar Flaw Due to Wall Thmnmg Axial d1rect1on Through-wall I+--- Laxral ---

11 (N-513-4)

FDR ASME COMMITTEE USE ONLY Transverse (c1rcumferent1al) d1rect1on

CASE (continued)

N-513-4 ASME BPVC CC NC 2017 Figure 6 Illustration of Adjusted Wall Thickness and Equivalent Hole Diameter T

Pipe

~~--~~lwall (a) Ad1usted Wall Thickness (bl Equivalent Hole Representation Figure 7 C1rcumferent1al Angle Defined extrados

_____________ Cr____

~

mtrados 12 (N-513-4)

FOR ASME COMMITTEE USE ONLY

ASME BPVC CC NC-2017 Figure 8 Zones of a Reducer or Expander

/Large end

---

r-,,.--r---~-- /

/

trans1t1on zone

/

/

Central conical

/

section

)a

/

Small end

_/

trans1t1on zone CASE (continued)

N-513-4 ct---------------------------

GENERAL NOTE Trans1t1on zones extend from the pomt on the ends where the diameter begms to change to the pomt on the central cone where the cone angle 1s constant.

13 (N-513-4) f"DR ASME COMMITTEf:. USE ONLY

CASE (continued)

N-513-4 ASME BPVC CC NC-2017 Figure 9 Flaw Growth Rate for IGSCC m Austemt1c P1pmg 1 0 E-02 Austenit1c Piping T-:5 200°F 1 0 E-03

'/

/

/

1 0 E-04

/

L..

,E_

C:

/

-ti

~

i 1 0 E-05 I/

/

/

/

C:

.r::

~

/

e

/

CJ V

t.) e u

1 0 E-06

,,v

/

/

/

1 0 E-07

/

/

/

/

1 0 E-08 1

10 100 Stress Intensity Factor, K (ks1 mo 5)

GENERAL NOTE (SI convers10n 1 0 ID /hr= 7 06 x 10-3 mm/sec, 1 0 ks1 ID O 5 = 1 099 MPa m0 5, °C = [°F - 32]/18) 14 (N-513 4)

F"OR ASME COMMITTEE USE ONLY

CASE (continued)

ASME BPVC CC NC-2017 N-513-4 Figure 10 Flaw Growth Rate for TGSCC m Austemt1c P1pmg 1 0 E-02 I/

Austenit1c Piping

.,v 1 0 E-03 T,;; 200°F

/v I/

/

1 0 E-04

.,v

~

/

V

.c --

/

/

C

~

1 0 E-05 c\\l' "O

i a:

.,,v

_,,/

T= 200°F

/

/

/

/

.c

~

1 0 E-06 e

/

/

I T = 100°F I

(;J

(.)

~

u

/

/

/

V 1 0 E-07

,,v

/

/

V 1 0 E-08

/

1 0 E-09 1

10 100 Stress Intensity Factor, K (ks1 in o 5)

GENERAL NOTE (SI conversmn 1 0 m /hr= 7 06 x 10-3 mm/sec, 1 0 ks1 m O 5 = 1 099 MPa m 0 5, °C = [°F - 32]/18) 15 (N-513-4}

FDR ASME COMMITTEE USE ONLY

CASE (continued)

N-513-4 ASME BPVC CC NC-2017 MANDATORY APPENDIX I RELATIONS FOR Fm, Fb, AND F FOR THROUGH-WALL FLAWS 1-1 DEFINITIONS For through-wall flaws, the crack depth, a, will be re-placed with half crack length, c, m the stress mtens1ty fac-tor equations m C-7300 and C-7400 of Sect10n XI, Nonmandatory Appendix C Also, Q will be set equal to umty m C-7400 1-2 CIRCUMFERENTIAL FLAWS For a range of R/t between 5 and 20, the followmg equat10ns for Fm and F b may be used where Am = -2 02917 + 167763 (R/t) - 0 07987 (R/t) 2 +

0 00176 (R/t)3 Bm = 7 09987 - 4 42394 (R/t) + 0 21036 (R/t)2 -

0 00463 (R/t) 3 Cm = 7 79661 + 5 16676 (R/t) - 0 24577 (R/t)2 +

0 00541 (R/t)3 where Ab = -3 26543 + 1 52784 (R/t) - 0 072698 [R/t/ +

0 0016011 (R/t)3 Bb = 1136322t-3 91412 (Rjt) + 0 18619 (R/t)2 -

0 004099 (R/t)3 Cb = -3 18609 + 3 84763 (R/t) - 0 18304 (R/t) 2 +

0 00403 (R/t)3 In the above equatJons R = mean pipe radms t = evaluat10n wall thickness e = half crack angle= c/R EquatJons for Fm and F b are accurate for R /t between 5 and 20 and become mcreasmgly conservative for R/t greater than 20 Alternative solut10ns for Fm and F b may be used when R/t is greater than 20 1-3 AXIAL FLAWS For mternal pressure loadmg, the followmg equat10n for F may be used F = l + 0 0724491 + 0 6485612 -

0 232713 + 0 03815414

- 0 0023487il5 where c = half crack length

.1

= c/(Rt)1/ 2 The equat10n for F 1s accurate for il between O and 5 AlternatJve solut10ns for F may be used when il 1s greater than 5 16 (N-513-4)

FOR ASME COMMITTEE USE ONLY