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
| 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 ET 19-0014 U S Nuclear Regulatory Comm1ss1on ATTN Document Control Desk Washington, DC 20555 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 Relief Request to utilize ASME Code Case N-513-4 Enclosures 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)
Enclosure I II.____
R_ec_o_rd_#_l 2_-_84_1_ __,
CASE I CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~
Approval Date: January 26, 2009 Code Cases will remain available for use until annulled by the applicable Standards Committee.
Case N-513-9 (e) The piping design Code shall be used in Evaluation Criteria for Temporary Acceptance of determining the stress indices B 1 and B 7, and stress Flaws in Moderate Energy Class 2 or 3 Piping intensification factor, i, for flaw evaluation following Section XI, Division 1 Code applicability limits in terms of component geometry, such as Ddt,____w ratio. If the piping design Inquiry: What requirements may be used for Code does not provide stress indices,Section III, 2004 temporary acceptance of flaws, including through-wall Edition or later Editions and Addenda may be used to flaws, in moderate energy Class 2 or 3 piping including define B 1 and B1~
elbows, bent pipe, reducers, expanders, and branch tees, (fd) The provisions of this Case demonstrate the without performing a repair/replacement activity? integrity of the item and not the consequences of leakage. It is the responsibility of the Owner to Reply: It is the opinion of the Committee that the demeRskate system eperability consideriflg effects of following requirements may be used to accept flaws , leakage in demonstrating system operability and including through-wall flaws, in moderate energy Class performing plant flooding analyses.
2 or 3 piping including elbows, bent pipe, reducers, (e) The eval1:1atieR peried, r""""', is the eperatieRal expanders, and branch tees, without performing a time fer whieh the tempera!)' aeeeptaRee eriteria are repair/replacement activity for a limited time, not satisfied e1:1t Ret eirneediRg 26 meRths fi:em the iRitial exceeding the e;*ah,1atieR peried as defiRed iR this diseevel)' efthe ceRditieR.
Gasetime to the next scheduled refueling outage.
2 PROCEDURE 1 SCOPE (a) The flaw geometry shall be characterized by (a) These requirements apply to the ASME Section volumetric inspection methods or by physical III, ANSI 831.1, and ANSI 831.7 piping, classified by measurement. The full pipe circumference at the flaw the Owner as Class 2 or 3 that is accessible for location shall be inspected to characterize the length and inspection. The provisions of this Case do not apply to depth of all flaws in the pipe section.
the following: (b) Flaw shall be classified as planar or nonplanar.
(1) pumps, valves, expansion joints, and heat (c) When multiple flaws, including irregular exchangers, except as provided in (b) ; (compound) shape flaws, are detected, the interaction (2) weld metal of socket welded joints; and combined area Joss of flaws in a given pipe section (3) leakage through a flange joint; shall be accounted for in the flaw evaluation.
(4) threaded connections employing (d) A flaw evaluation shall be performed to nonstructural seal welds for leakage protection. determine the conditions for flaw acceptance. Section 3 (b) This Case may be applied to heat exchanger provides accepted methods for conducting the required external tubing or piping, provided the flaw is analysis.
characterized in accordance with 2(a) and leakage is (e) Frequent periodic inspections of no more than monitored. 30 day intervals shall be used to determine if flaws are (t;_h) The provisions of this Case apply to Class 2 or growing and to establish the tim~ Q/le,+i,_at which the 3 piping in liquid systems whose maximum operating detected flaw will reach the allowable size.
temperature does not exceed 200°F (93°C) and whose Alternatively, a flaw growth evaluation may be maximum operating pressure does not exceed 275 psig performed to predict the time,-4""""', at which the (1.9 MPa). detected flaw will grow to the allowable size. The flaw (de) The following flaw evaluation criteria are growth analysis shall consider the relevant growth permitted for pipe and tube including elbows, bent pipe, mechanisms such as general corrosion or wastage, reducers, expanders, and branch tees. The straight pipe fatigue, or stress corrosion cracking. When a flaw flaw evaluation criteria are permitted for adjoining growth analysis is used to establish the allowable time fittings and flanges to a distance of (Rotf' from the weld for temporary operation, periodic examinations of no centerline. more than 90 day intervals shall be conducted to verify the flaw growth analysis predictions.
Draft 15 (05/05/14)
CASE (continued)
CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~
(I) For through-wall leaking flaws, leakage shall be When through-wall axial flaws are evaluated, the 00S0FV00 eymonitored daily walkaev.'HS to confirm the allowable flaw length is:
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 where the next scheduled refueling outage, whichever occurs p = pressure for the loading condition Note: Z has been first. Repair~ Lreplacement activities shall be in Do = pipe outside diameter added to equation accordance with IWA-4000 er IWA 7000, res13eetively, u1 = flow stress (1 ).
iR 6aitieRS QRG AaaeRaa 13rier ta the 1991 AaaeRaa; Sy = Code specified yield strength QRG, iR the 1991 AaaeRaa Qfl0 later, iR aeeeraaRee with s. = Code specified ultimate tensile strength and P.l/A 4000.
SFm = structural factor on primary membrane stress (i) Evaluations and examination shall be as specified in C-2622 documented in accordance with IW A-6300. The Owner Z = load multiplier for ductile flaw extension shall document the use of this Case on the applicable (equal to 1.0 when using limit load criteria) data report form .
Material properties at the temperature of interest 3 FLAW EVALUATION shall be used.
Planar flaws in straight pipe shall be evaluated in FIG. 1 THROUGH-WALL FLAW GEOMETRY 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 (c) For planar flaws in ferritic piping, the evaluation materials shall be evaluated in accordance with the procedure of Appendix C shall be used. Flaw depths up requirements in 3.14. to 100% of wall thickness may be evaluated. Flaw For all flaw evaluations, all Service Level load depth, a, is defined in Figures C-4310-1 and C-4310-2.
combinations shall be evaluated to determine the most When through-wall circumferential flaws are evaluated limiting allowable flaw size. in accordance with C-5300 or C-6300, the flaw depth to thickness ratio, alt, shall be set to unity. When applying 3.1 Planar Flaws in Straight Pipe the Appendix C screening criteria for through-wall axial (a) For planar flaws, the flaw shall be bounded by a flaws, alt shall be set to unity, and the reference limit rectangular or circumferential planar area in accordance load hoop stress, a1, shall be defined as cr)M2
- When with the methods described in Appendix C. IWA-3300 through-wall axial flaws are evaluated in accordance shall be used to determine when multiple proximate with C-5400 or C-6400, the allowable length is defined flaws are to be evaluated as a single flaw. The geometry by eqs. (1) through (3), with the appropriate structural of a through-wall planar flaw is shown in Fig. 1. factors from Appendix C, C-2622. When through-wall (b) For planar flaws in austenitic piping, the flaws are evaluated in accordance with C-7300 or C-evaluation procedure in Appendix C shall be used. Flaw 7400, the formulas for evaluation given in C-4300 may depths up to 100% of wall thickness may be evaluated. be used, but with values for Fm, Fb, and F applicable to When through-wall circumferential flaws are evaluated, through-wall flaws. Relations for Fm, F,,, and F that take the formulas for evaluation given in C-5320 or C-6320, into account flaw shape and pipe geometry (Rlt ratio) as applicable, of Appendix C may be used, with the flaw shall be used. The appendix to this Case provides depth to thickness ratio, alt, equal to unity. equations for Fm, Fb, and F for a selected range of Rlt.
Geometry of a through-wall crack is shown in Fig. 1.
Draft 15 (05105/14) 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.s u. ,* I... ~
, 111tA1. UT1: c. - - .111111 ~ f t l l N M * ~ ilfllt - *111 1111at 111*Mttn * -.iw*c.-iaJfl.
3.2 Nonplanar Flaws in Straight Pipe defined in Fig. 3. When the above requirement is not
__ (a) The evaluation shall consider the depth and satisfied, (J @ shall be met.
extent of the affected area and require that the wall (jiiJ) When Lm is less than or equal to 2.65 thickness exceed lm;n for a distance that is the greater of (RJm;J lll and tnom is greater than 1.13 tm;n , ta1oc is 2.5 ..JRtnom or 2Lm.avg between adjacent thinned regions, determined by satisfying both of the following where R is the mean radius of the piping item based on equations:
nominal wall thickness and Lm,avg is the average of the
~ I .5fij;;; [,- tnom] + 1.0 extent of Lm below lm;n for adjacent areas (see Fig. 2).
Alternatively, the adjacent thinned regions shall be taloc (5) considered a single thinned region in the evaluation. tmin L tmrn
__ (b) For nonplanar flaws, the pipe is acceptable when either (b)(l) and (b)(2), or (b)(2) and (b)(3) are taloc 0.353Lm (6)
->----===-
tmin - ~ Rotmin met.
(1) Tthe remaining pipe thickness (tp) is greater than or equal to the minimum wall thickness lm;n:
When the above requirements are not satisfied, (4b:) shall be met.
t . =- -pDo
~- (4) (b:4) When the requirements of (.J.D, (Jill, and nun 2(S+0.4p} (J @ above are not satisfied, laioc is determined from Curve 2 of Fig. 4. IR aelelitieR, 1""'6 shall satisfy the where fellewiRg e(lHatieR:
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& Wfll!ftHf1, is the RemiRal flifle l0Rgit1,1eliRal eeReliRg stress (3) As an alternative to (b)(l)Altematively, an res11ltiRg frem all Sep,riee Le1rel B flFimary fli13e evaluation of the remaining pipe thickness (tiJ_may be leaeliRgs.
performed as given below. The evaluation procedure is (c) When there is through-wall leakage along a a function of the depth and the extent of the affected portion of the thinned wall, as illustrated in Fig. 5, the area as illustrated in Fig. 3. flaw may be evaluated by the branch reinforcement (i+) When Wm is less than or equal to 0.5 method. The thinned area including the through-wall (R0 t) Vl , where Ro is the outside radius and Wm is defined opening shall be represented by a circular penetration at in Fig. 3, the flaw can be classified as a planar flaw and the flaw location. Only the portion of the flaw lying evaluated in accordance with 3. I(a) through 3.l(c), within tadJ need be considered as illustrated in Fig. 6.
above. When the above requirement is not satisfied, When evaluating multiple flaws in accordance with (Jill shall be met. 3.2(a), only the portions of the flaws contained within (ilJ) When Lm(t) is not greater than (RJ min ) Ill, tadj need be considered.
taioc is determined from Curve 1 of Fig. 4, where Lm(t) is Draft 15 (05/05/14) 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 ~ t-+--- Lm1,1 - -~
Transverse Lm111 (circumferential)
Axial direction direction Editor's Note: This Figure 3 is to be deleted and replaced with the Figure 3 on the following page.
Draft 15 (05/05/ 14) 4
CASE (continued)
CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-43, FIG. 3 ILLUSTRATION OF NON PLANAR FLAW DUE TO WALL THINNING
+---1.m(a)-
l lm(t)
Transverse (circumferential)
Axial direction l direction FIG. 4 ALLOWABLE WALL THICKNESS AND LENGTH OF LOCALLY THINNED AREA 1.0 0.8 0.6
..e 0.4 0.2 0
0 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 T hrough~wall t *n / opening
~ - - L axial - - - . i Transverse L.:irc (clrcumferentlal)
Axial direction direction Editor' s Note: This Figure 5 is to be deleted and replaced with the Figure 5 on the following page.
Draft 15 (05/05/1 4) 6
CASE (continued)
CASES O F ASME BOILER AND PRESSU RE VESSEL CODE N-513-4J FIG. 5 ILLUSTRATION OF THROUGH-WALL NONPLANAR FLAW DUE TO WALL THINNING
+ - - - laxia1 - - *1 i
Lcirc Transverse (circumferential)
Axial direction
! direction Draft 15 (05/05/ 14) 7
CASE (continued)
CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~
The minimum wall thickness, lm;n, shall be are adjusted, to account for the geometry differences, as determined by eq. (4). For evaluation purposes, the described below. Alternative methods may be used to adjusted wall thickness, lat1j , is a postulated thickness as calculate the stresses used in evaluation.
shown in Fig. 6. The pipe wall thickness is defined as The hoop stress, rrh, for elbow and bent pipe the *thickness of the pipe in the non-degraded region as evaluation shall be:
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: &end = elbow or bent pipe bend radius
~ = circumferential angle defined in Figure 7 1.5~Rladj (tadj - lmin) h = flexibility characteristic d adj ~ - ~ - - - - ~ (l&)
lmin
~ = resultant primary bending moment I = moment of inertia based on evaluation wall thickness, l The remaining ligament average thickness, le.avg, over the degraded area bounded by dadi shall satisfy:
Equation 9 is only applicable for elbows and bent pipe where h > 0.1.
~ 9) The axial membrane pressure stress, rrm, for elbow and bent pipe evaluation shall be:
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 where B 1 is a primary stress index as defined in Section in flaw dimensions shall consider the degradation III for the piping item. B, shall be equal to 0.5 for mechanisms as relevant to the application. The flaw is elbows and bent pipe.
acceptable when there is sufficient thickness in the The axial bending stress, rrl!., for elbow and bent degraded area to provide the required area pipe evaluation shall be:
reinforcement.
(d) Alternatively, ifthere is a through-wall opening
<rb = Bz( -D._M_b) along a portion of the thinned wall as illustrated in Fig. ~~ 21 - - - - - -----'(11) 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. where B, is a primary stress index as defined in Section The minimum wall thickness lm;n, shall be determined III for the piping item .
by eq. (4). The allowable through-wall lengths in the The thermal expansion stress, rr., for elbow and axial and circumferential directions shall be determined bent pipe evaluation shall be:
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 ~ ~ cr, =i(-D;-~-* ) ~ ~ ~ ~ ~ ~C~I=2)
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).
= stress intensification factor as defined in the 3.3 Through-wall Flaws in Elbows and Bent Pipe design Code for the piping item Through-wall flaws in elbows and bent pipe may be M.. = resultant thermal expansion moment 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) 8
CASE (continued)
CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~
3.4 Through-wall Flaws in Reducers and The axial bending stress, <Tb, and thermal expansion Expanders stress, u,, for branch tee evaluation shall be determined Through-wall flaws in reducers and expanders may from eq . {15) and eq . {16), respectively.
be evaluated using the straight pipe procedures given in
- 3. I or 3 .2( d), provided the stresses used in the 3.~ Flaw Growth Evaluation evaluation are adjusted, to account for the geometry If a flaw growth analysis is performed, the growth differences, as described below. Alternative methods analysis shall consider both corrosion and crack-growth may be used to calculate the stresses used in evaluation. mechanisms as relevant to the application.
Fig. 8 illustrates the reducer and expander zones In performing a flaw growth analysis, the discussed below. Evaluation of flaws in the small end procedures in C-3000 may be used as guidance.
transition zone is outside the scope of this Case. Relevant growth rate mechanisms shall be considered.
The hoop stress, <Th, and axial membrane pressure When stress corrosion cracking (SCC) is active, the stress, u... , for reducer or expander evaluation shall be: 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 where D 0 is the small end OD for flaws in the small end correction factor, and C and n are material constants.
and the large end OD for all other flaws.
The axial bending stress, <Tb, and thermal expansion For intergranular SCC in austenitic steels, where T -:;
stress, <Te, for reducer or expander evaluation shall be: 200°F (93°C).
C = 1.79 X 10- 8 Sr =1 n = 2.161
_ _ _ a, = {-D-;M-1_* ) ------'{...o.1=6) For transgranular SCC in austenitic steels, where T -:;
200°F (93 °C).
where I is based on the degraded section.
C = 1.79 X 10-7 3.5 Through-wall Flaws in Branch Tees Sr = 3 _71 x 108 [IO(oo1842 r - 12 2s)]
Branch reinforcement requirements shall be met in n = 2.161 accordance with the design Code. If the design Code did not require reinforcement, for evaluation purposes, a The temperature, T, is the metal temperature in reinforcement region is defined as a region of radius D, degrees Fahrenheit. The flaw growth rate curves for the of the branch pipe from the center of the branch above SCC growth mechanisms are shown in Figs. 2.+
connection. Through-wall flaws in branch tees outside and l.Q&. Other growth rate parameters in eq. (11G) may of the reinforcement region may be evaluated using the be used, provided they are supported by appropriate straight pipe procedures given in 3.1 or 3.2{d), provided data.
the stresses used in the evaluation are adjusted, to account for the geometry differences, as described 3.14 Nonferrous Materials below. Alternative methods may be used to calculate the For nonferrous materials, nonplanar and planar stresses used in evaluation. Evaluation of flaws in the flaws may be evaluated following the general approach region of branch reinforcement is outside the scope of of 3.1 through 3.~ . For planar flaws in ductile this Case. materials, the approach given iR 3 .1 (e) aRa 3 .3 for The hoop stress, <Ta, and axial membrane pressure austenitic pipe may be used; otherwise, the approach stress, u... , for branch tee evaluation shall be determined given iR 3.l(e) aRa 3.3for ferritic pipe should be from eq. {13) and eq. {14), respectively. The outside applied. Structural factors provided in 4 shall be used. It diameter for each of these equations shall be for the is the responsibility of the evaluator to establish branch or run pipe, depending on the flaw location. conservative estimates of strength and fracture toughness for the piping material.
Draft 15 (05/05/14) 9
CASE (continued)
CASES O F ASME BOILER AND PRESSURE VESSEL CODE N-513-4~
FIG. 6 ILLUSTRATION OF ADJUSTED WALL THICKNESS AND EQUIVALENT HOLE DIAMETERS Through-wall rt ,____
t m1n opening t adj T
Pipe
_! \~~..,__- ~ ,
--~.-.....1-------..........
I I
~~-t*"
I I (al Adjusted Wall Th Ckf18SS I
I I
I I
Shift figure (b) to the I
I right so that dadj Ti tmrn
- width lines up with
~~.i_e~d~~~-~--'
figure (a).
,~ ~-r-----------~
1.. dad; ---J lb) Equivalent Hole Representation FIG. 7 CIRCUMFERENTIAL ANGLE DEFINED extrados
~~~~~~
Draft 15 (05/05/14) 10
CASE (continued)
N-513-4~
CASES OF ASME BOILER AND PRESSURE VESSEL CODE FIG. 8 ZONES OF A REDUCER OR EXPANDER Large end transition zone Small end transition zone ct------
GENERAL NOTE:
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 O F 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 O F ASME BOILER AND PRESSURE VESSEL CODE N-513-4~
FIG. 103 FLAW GROWTH RAT E FOR TGSCC IN AUSTENITIC PIPING
,.~ -02
~ IIIIS11rttlc Flpl~ ,,,
Ts 20:f'
/ "'
/
l.~ -44 ii i!!
-= I." V i l.~ -05
==t T*IO~
ri 11 a:
/
,F
/ I T* 10~ f
! l.~ -06 iii (j ,F
,,:/
, .~ -07 J
~
/
! .~ -O D , 10 'JOO S1111SS. l"anSIIY Fnlar, X fbl In.LIi GENERAL ~OTE: 1,1 ~ jffif lll: 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 nondimensional stress intensity factor for through-wall circumferential flaw under Piping containing a circumferential planar flaw is membrane stress acceptable for temporary service when flaw evaluation I moment of inertia based on evaluation provides a margin using the structural factors in thickness, t Appendix C, C-2621. For axial planar flaws, the maximum stress intensity factor under structural factors for temporary acceptance are as long term steady state conditions specified in Appendix C, C-2622. Straight pP-ip~ L maximum extent of a local thinned area containing a nonplanar part=-through-wall flaw is with t < lnom acceptable for temporary service if the remaining pipe Laxia/ length of idealized through-wall planar section meets the longitudinal stress limits in the design flaw opening in the axial direction of the Code for the piping and Ip 2': latoc, where latoc is pipe, as illustrated in Fig. 5 determined from 3.2(b). Straight pP-ip~iHg containing a length of idealized through-wall planar nonplanar through-wall flaw is acceptable for temporary flaw opening in the circumferential service when the flaw conditions of 3 .2(c) or 3 .2(d) are direction of the pipe, as illustrated in Fig. 5 satisfied. An elbow or bent pipe containing a nonplanar maximum extent of a local thinned area through-wall flaw is acceptable for temporary service if with t < lmin the flaw conditions of 3.3 are satisfied. A reducer or Lm(a) axial extent of wall thinning below lm;n expander containing a nonplanar through-wall flaw is Lm(I) circumferential extent of wall thinning acceptable for temporary service if the flaw conditions below lmin of3.4 are satisfied. A branch tee containing a nonplanar average of the extent of Lm below through-wall flaw is acceptable for temporary service if lm;n for adjacent thinned areas the flaw conditions of3.5 are satisfied. Lm,i maximum extent of thinned area, i M2 bulging factor for axial flaw 5 AUGMENTED EXAMINATION 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 An augmented volumetric examination or physical R mean pipe radius measurement to assess degradation of the affected & 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 system shall be performed as follows: R0 outside pipe radius (a) From the engineering evaluation, the most S allowable stress at operating temperature susceptible locations shall be identified. A sample size SFm structural factor on primary membrane of at least five of the most susceptible and accessible stress locations, or, if fewer than five, all susceptible and Sr coefficient for temperature dependence in accessible locations shall be examined within 30 days of the crack growth relationship detecting the flaw. Code-specified ultimate tensile strength (b) When a flaw is detected, an additional sample Code-specified yield strength of the same size as defined in 5(a) shall be examined. metal temperature (c) This process shall be repeated within 15 days maximum extent of a local thinned area for each successive sample, until no significant flaw is perpendicular to Lm with t < lmin detected or until 100% of susceptible and accessible minimum distance between thinned areas i locations have been examined. andj z load multiplier for ductile flaw extension 6 NOMENCLATURE a flaw depth C half crack length fu..Jb~=-~ S~ec~t=io~n~ II=I_p=r=im =ar-y~st~re=s=s~i=n=
d '=
- c~es da/dt flaw growth rate for stress corrosion C coefficient in the crack growth relationship cracking
!1,*_---'=*n"'s=id=e'-p"'i,.,p=e-'d=i=am=e=te=r diameter equivalent circular hole at tadj D0 outside pipe diameter diameter of equivalent circular hole at F nondimensional stress intensity factor for lmin through-wall axial flaw under hoop stress h flexibility characteristic nondimensional stress intensity factor for stress intensification factor through-wall circumferential flaw under total crack length = 2c pipe bending stress allowable axial through-wall flaw length exponent in the crack growth relationship Draft 15 (05/05/ 14) 14
CASE (continued)
CASES OF ASME BOILER AND PRESSURE VESSEL CODE N-513-4~
p maximum operating pressure at flaw location evaluation wall thickness, surrounding the degraded area ladj adjusted wall thickness which is varied for evaluation purposes in the evaluation of a through-wall nonplanar flaw la/oc 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 a maximum cone angle at the center of a reducer A 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 Editor's Note: For Applicability Index, this Case shall apply to Appendix C of the 2004 Edition applicability is from 1996 Addenda to or later editions or addenda. For editions BREI--Or addenda 2013 Edition.
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) 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 Ab = -3 .26543 + 1.52784 (Rlt)- 0.072698 (R/t )2
+ 0.0016011 (Rlt)3 For through-wall flaws, the crack depth,_--fa.1 will Bb = 11.36322 - 3.91412 (Rlt) + 0.18619 (Rlt )2 be replaced with half crack length.,_-fc.1 in the stress - 0.004099 (Rlt) 3 intensity factor equations in C-7300 and C-7400 of Cb = -3.18609 + 3.84763 (Rlt)- 0.18304 (Rlt )2 Section XI, Appendix C. Also, Q will be set equal to + 0.00403 (Rlt)3 unity in C-7400.
Equations for Fm and Fb are accurate for Rlt between 5 1-2 CIRCUMFERENTIAL FLAWS and 20 and become increasingly conservative for Rlt greater than 20. Alternative solutions for Fm and Fb may For a range of Rlt between 5 and 20, the following be used when Rlt is greater than 20.
equations for Fm and Fb may be used:
1-3 AXIAL FLAWS Fm = 1 + Am (8/7,) 15 + Bm (8/ 1r)2 5 + Cm (8fa) 35 Fb = 1 + Ab (8!1r) 15 + Bb (8!1r) 25 + Cb (8/1r)3 5 For internal pressure loading, the following equation for F may be used:
where F = l + 0.0724491. + 0.64856).2 - 0.2327 ).3 8 = half crack angle = c/R + 0.038154 ).4 - 0.0023487 'A. 5 R = mean pipe radius t = evaluation pipe-wall thickness where and Am = -2.02917 + 1.67763 (Rlt) - 0.07987 (R/t )2 c = half crack length
+ 0.00176 (Rlt)3 'A. = c!(Rt) V2 Bm = 7 .09987 - 4.42394 (Rlt) + 0.21036 (R!t )2 T he equation for F is accurate for 'A. between O and 5.
- 0.00463 (Rlt) 3 Alternative solutions for F may be used when A is Cm = 7.79661 + 5.16676 (Rlt) - 0.24577 (Rlt )2 greater than 5.
+ 0.00541 (Rlt) 3 Draft 15 (05/05/14) 16
Enclosure II to ET 19-0014 Copy of N-513-4 (16 pages)
Enclosure 11 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 (e) The p1pmg design Code shall be used m determm-Evaluation Criteria for Temporary Acceptance of Flaws mg the stress md1ces B 1 and B 2 , and stress mtens1ficat10n m Moderate Energy Class 2 or 3 P1pmg factor, 1, for flaw evaluation following Code apphcab1hty Section XI, D1v1s1on l hm1ts m terms of component geometry, such as D0 /tnom ratio If the p1pmg design Code does not proVIde stress m-Inquiry What reqmrements may be used for temporary d1ces,Section III, 2004 Ed1t10n or later Editions and Ad-acceptance of flaws, mcludmg through-wall flaws, m mod- denda may be used to define B 1 and B 2 erate energy Class 2 or 3 p1pmg mcludmg elbows, bent (f) The proV1s1ons of this Case demonstrate the mteg-pipe, reducers, expanders, and branch tees, without per- r1ty of the item and not the consequences of leakage It formmg a repair/replacement act1v1ty? 1s the respons1b1lity of the Owner to consider effects of leakage m demonstratmg system operab1hty and per-formmg plant floodmg analyses 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, 2 PROCEDURE and branch tees, without performmg a repair /replace- (a) The flaw geometry shall be characterized by volu-ment act1v1ty for a limited time, not exceedmg the time metric mspect10n methods or by physical measurement to the next scheduled refuelmg outage The full pipe circumference at the flaw location shall be mspected to characterize the length and depth of all flaws m the pipe section l SCOPE (b) Flaw shall be classified as planar or nonplanar '
(a) These reqmrements apply to the ASME Sect10n III, (c) When multiple flaws, mcludmg irregular (com-ANSI B311, and ANSI B31 7 p1pmg, classified by the Own- pound) shape flaws, are detected, the mteract10n and er as Class 2 or 3 that 1s accessible for mspect10n The pro- combmed area loss of flaws m a given pipe section shall VISIOns of this Case do not apply to the followmg be accounted for m the flaw evaluat10n (1) pumps, valves, expansion 1omts, and heat exchan- (d) A flaw evaluation shall be performed to determme gers, except as proVIded m (b) the cond1t10ns for flaw acceptance Section 3 proVIdes ac-(2) weld metal of socket welded 1omts cepted methods for conductmg the reqmred analysis (3) leakage through a flange 1omts (e) Frequent periodic mspect10ns of no more than (4) threaded connect10ns employmg nonstructural 30 day mtervals shall be used to determme 1f flaws are seal welds for leakage protection growing and to establish the time, at which the detected (b) This Case may be applied to heat exchanger exter- flaw will reach the allowable size Alternatively, a flaw nal tubmg or p1pmg, provided the flaw 1s characterized growth evaluat10n may be performed to predict the time m accordance with 2(a) and leakage 1s momtored at which the detected flaw will grow to the allowable size (c) The proVIs1ons of this Case apply to Class 2 or 3 pip- The flaw growth analysis shall consider the relevant mg m hqmd systems whose maximum operatmg tem- growth mechamsms such as general corros10n or wa-perature does not exceed 200°F (93°C) and whose stage, fatigue, or stress corrosion crackmg When a flaw maximum operatmg pressure does not exceed 275 ps1g growth analysis 1s used to estabhsh the allowable time (19 MPa) for temporary operat10n, periodic exammat10ns of no (d) The followmg flaw evaluation criteria are permitted more than 90 day mtervals shall be conducted to verify for pipe and tube mcludmg elbows, bent pipe, reducers, the flaw growth analysis predictions expanders, and branch tees The straight pipe flaw evalua- (f) For through-wall leakmg flaws, leakage shall be t10n criteria are permitted for ad1ommg f1ttmgs and momtored daily to confirm the analysis cond1t1ons used flanges to a distance of (R 0 t) 1/ 2 from the weld centerlme 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- When through-wall axial flaws are evaluated, the allow-ceptable, a repair/replacement act1v1ty shall be able flaw length 1s 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 ah =pD0 /2t (2)
(1) Evaluat10ns and exammat10n shall be documented m accordance with IWA-6300 The Owner shall document (3) the use of this Case on the applicable data report form where 3 FLAW EVALUATION D O = pipe outside diameter p = pressure for the loadmg cond1t10n Planar flaws m straight pipe shall be evaluated m accor- Su = Code specified ultimate tensile strength dance with the reqmrements m 3 1 Nonplanar flaws m Sy = Code spec1f1ed yield strength straight pipe shall be evaluated m accordance with the re- SFm = structural factor on pnmary membrane stress as qmrements m 3 2 Through-wall flaws m elbows and bent specified m C-2622 pipe shall be evaluated m accordance with the reqmre- Z = load multiplier for ductile flaw extens10n (equal ments m 3 3 Through-wall flaws m reducers, expanders, to 1 0 when usmg hm1t load cntena) and branch tees shall be evaluated m accordance with the O/ = flow stress reqmrements m 3 4 and 3 5, respectively Flaw growth evaluat10n shall be performed m accordance with the re- Matenal propert:Jes at the temperature of mterest shall qmrements m 3 6 Nonferrous matenals shall be evalu- be used ated m accordance with the reqmrements m 3 7 (c) For planar flaws m fernt1c p1pmg, the evaluat10n For all flaw evaluations, all Service Level load combma- procedure of Nonmandatory Appendix C shall be used t10ns shall be evaluated to determme the most hm11:Jng al- Flaw depths up to 100% of wall thickness may be evalu-lowable flaw size ated Flaw depth, a, 1s defmed m Figures C-4310-1 and C-4310-2 When through-wall c1rcumferent1al flaws are 31 PLANAR FLAWS IN STRAIGHT PIPE evaluated m accordance with C-5300 or C-6300, the flaw (a) For planar flaws, the flaw shall be bounded by a rec- depth to thickness ratio, aft, shall be set to umty When tangular or circumferential planar area m accordance applymg the Nonmandatory Appendix C screenmg enter-with the methods descnbed m Sect10n XI Nonmandatory Ia for through-wall axial flaws, a /t shall be set to umty, Appendix C IWA-3300 shall be used to determme when and the reference hm1t load hoop stress, u 1, shall be de-multiple proximate flaws are to be evaluated as a smgle fined as uy/M 2 When through-wall axial flaws are evalu-flaw The geometry of a through-wall planar flaw 1s shown ated m accordance with C-5400 or C-6400, the allowable m Figure 1 length 1s defined by eqs (b)(l) through (b)(3), with the (b) For planar flaws m austemt1c p1pmg, the evaluation appropnate structural factors from Nonmandatory procedure m Nonmandatory Appendix C shall be used Appendix C, C-2622 When through-wall flaws are evalu-Flaw depths up to 100% of wall thickness may be evalu- ated m accordance with C-7300 or C-7400, the formulas ated When through-wall c1rcumferent1al flaws are evalu- for evaluat10n given m C-4300 may be used, but with val-ated, the formulas for evaluation given m C-5320 or ues for Fm, Fb, and F applicable to through-wall flaws Re-C-6320, as apphcable, of Nonmandatory Appendix C lat:Jons for Fm, Fb, and F that take mto account flaw shape may be used, with the flaw depth to thickness rat10, and pipe geometry (R/t rat:Jo) shall be used The appen-a /t, equal to umty 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- considered as illustrated m Figure 6 When evaluatmg tively, the adjacent thmned reg10ns shall be considered multiple flaws m accordance with (a), only the port10ns a smgle thmned reg10n m the evaluat10n of the flaws contamed w1thm tadJ need be considered (b) For nonplanar flaws, the pipe 1s acceptable when The mm1mum wall thickness, tmin, shall be determmed either (1) and (2), or (2) and (3) are met by (b)(1), eq (4) For evaluat10n purposes, the adjusted wall thickness, tadJ> 1s a postulated thickness as shown (1) The remammg pipe thickness, tp, 1s greater than m Figure 6 The pipe wall thickness 1s defined as the thick-or equal to the mm1mum wall thickness tmin ness of the pipe m the non-degraded reg10n as shown m t - pDo Figure 6, 11!ustrat10n (a) The diameter of the openmg 1s (4) mm - 2(S + 0 4p) equal to d adf as defined by tadJ as shown m Figure 6, 1!-
lustrat10n (a) The postulated value for tadJ shall be great-where er than tmin and shall not exceed the pipe wall thickness The tadJ value may be vaned between tm,n and the pipe p = maximum operatmg pressure at flaw locat10n wall thickness to determme whether there 1s a combma-S = allowable stress at operatmg temperature t10n of tadJ and dadJ that satisfies the branch remforce-(2) The remammg degraded pipe sect10n meets the ment reqmrements long1tudmal stress hm1ts m the design Code for the The values of tadJ and dadJ of Figure 6, 1llustrat10n (b) p1pmg shall satisfy (3) As an alternative to (1), an evaluat10n of the re- 15~RtadJ (tadJ - tmm) mammg pipe thickness, tp, may be performed as given be- dadJ s - ~ - ~ - - - - (7) tmm low The evaluation procedure 1s a funct10n of the depth and the extent of the affected area as illustrated m Figure The remammg ligament average thickness, tc avg over 3 the degraded area bounded by dadJ shall satisfy
(-a) When Wm 1s less than or equal to O 5 (R 0 t) 1 / 2 ,
ip where R 0 1s the outside radms and Wm 1s defmed m tc,avg ~ 0 353dad1'1's (8)
Figure 3, the flaw can be classified as a planar flaw and evaluated m accordance with 3 1(a) through 3 1(c), In add1t10n, the pipe sect10n mcludmg the eqmvalent above When the above reqmrement 1s not sat1sf1ed, (-b) hole representat10n shall meet the longitudmal stress hm-shall be met 1ts m the design Code for the p1pmg 1 2
(-b) When Lm(tJ IS not greater than (R 0 tmin) l , If a flaw growth analysis 1s performed, the growth m taioc IS determmed from Curve 1 of Figure 4, where flaw d1mens10ns shall consider the degradat10n mechan-Lm(tJ 1s defmed m Figure 3 When the above reqmrement isms as relevant to the apphcat10n The flaw 1s acceptable 1s not sat1sf1ed, (-c) shall be met when there 1s sufficient thickness m the degraded area to
(-c) When Lm 1s less than or equal to 2 65 provide the reqmred area remforcement 112 (d) Alternat1vely, 1f there 1s a through-wall openmg X (Rotm1n) and tnom IS greater than 113tmtn, taloc 1s determmed by sat1sfymg both of the followmg along a port10n of the thmned wall as illustrated m Figure equat10ns 5 the flaw may be evaluated as two mdependent planar through-wall flaws, one oriented m the axial direct10n t.,Jot, ~ 1 5 ~ [ 1 - tnom] + 10 (5) and the other oriented m the circumferential direct10n tmm L tmm 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 When the above reqmrements are not satisfied, (-d) shall be met Lax,ai and Lcirc (see Figure 5) as determmed from 3 1(a) and 3 1(b) or 31(c), as appropriate The remammg
(-d) When the reqmrements of (-a), (-b), and (-c) ligament average thickness, tc avg, over the degraded above are not sat1sf1ed, taioc 1s determmed from Curve area bounded by Laxtai and Lc,rc shall satisfy (c), eq (8) 2 of Figure 4 (c) When there 1s through-wall leakage along a portion 3 3 THROUGH-WALL FLAWS IN ELBOWS AND of the thmned wall, as illustrated m Figure 5, the flaw may BENT PIPE be evaluated by the branch remforcement method The thmned area mc!udmg the through-wall openmg shall Through-wall flaws m elbows and bent pipe may be be represented by a circular penetrat10n at the flaw loca- evaluated usmg the straight pipe procedures given m t10n Only the port10n of the flaw lymg w1thm tadf need be 31 or 3 2(d), provided the stresses used m the evaluat10n 3 (N-513-4)
CASE (continued)
N-513-4 ASME BPVC CC NC-2017 are adjusted, to account for the geometry differences, as descnbed below Alternative methods may be used to cal-described below Alternative methods may be used to cal- culate the stresses used m evaluat10n Figure 8 illustrates culate the stresses used m evaluation the reducer and expander zones discussed below Evalua-The hoop stress, uh, for elbow and bent pipe evaluat10n t10n of flaws m the small end trans1t10n zone 1s outside the shall be as follows scope of this Case The hoop stress, uh, and axial membrane pressure stress, um, for reducer or expander evaluat10n shall be (9) as follows where (13) h = flex1b11ity characteristic I = moment of mert1a based on evaluat10n wall thickness, t (14)
Mb = resultant pnmary bendmg moment Rb end = elbow or bent pipe bend radius
¢ = c1rcumferent1al angle defined m Figure 7 where Equat10n (9) 1s only applicable for elbows and bent D 0 = small-end OD for flaws m the small-end and the pipe where h ~ 0 1 large-end O D for all other flaws The axial membrane pressure stress, um, for elbow and The axial bendmg stress, ub, and thermal expans10n bent pipe evaluat10n shall be as follows stress, CJ e, for reducer or expander evaluat10n shall be as follows (10)
(15) where B 1 = pnmary stress mdex as defined m Sect10n III for the p1pmg item a:
e
= 1 (DoMe) 21 (16)
= 0 5 for elbows and bent pipe The axial bendmg stress, ub, for elbow and bent pipe where evaluat10n shall be as follows I = moment of mert1a based on degraded sect10n (11) 3 5 THROUGH-WALL FLAWS IN BRANCH TEES Branch remforcement reqmrements shall be met m ac-where cordance with the design Code If the design Code did not B 2 = primary stress mdex as defined m Sect10n Ill for the reqmre remforcement, for evaluat10n purposes, a rem-p1pmg item forcement reg10n 1s defmed as a reg10n of radms D I of the branch pipe from the center of the branch connection The thermal expans10n stress, u e, for elbow and bent Through-wall flaws m branch tees outside of the rem-pipe evaluat10n shall be as follows forcement reg10n may be evaluated usmg the straight pipe procedures given m 3 1or32(d), provided the stres-0:
e
= 1 (D 2TMe) 0 (12) ses used m the evaluat10n are adjusted, to account for the geometry differences, as descnbed below Alternative where methods may be used to calculate the stresses used m evaluat10n Evaluat10n of flaws m the reg10n of branch re-1 = stress mtens1ficat10n factor as defined m the design mforcement 1s outside the scope of this Case Code for the p1pmg item Me = resultant thermal expans10n moment The hoop stress, uh, and axial membrane pressure stress, um, for branch tee evaluat10n shall be determmed 3 4 THROUGH-WALL FLAWS IN REDUCERS AND from eq 3 4(13) and eq 3 4(14), respectively The outside EXPANDERS diameter for each of these equat10ns shall be for the Through-wall flaws m reducers and expanders may be branch or run pipe, dependmg on the flaw location evaluated usmg the straight pipe procedures given m 3 1 The axial bendmg stress, ub, and thermal expans10n or 3 2(d), provided the stresses used m the evaluation are stress, Cle, for branch tee evaluat10n shall be determmed adjusted, to account for the geometry differences, as from eq 3 4(15) and eq 3 4(16) respectively 4 (N-513-4)
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CASE (continued)
ASME BPVC CC NC-2017 N-513-4 3 6 FLAW GROWTH EVALUATION design Code for the p1pmg and tp ~ taloc, where ta1oc IS determmed from 3 2(b) Straight pipe contammg a non-
!fa flaw growth analysis 1s performed, the growth anal-planar part through-wall flaw 1s acceptable for temporary ysis shall consider both corros10n and crack-growth me-service when the flaw cond1t10ns of 3 2(c) or 3 2(d) are chamsms as relevant to the apphcat10n sat1sf1ed An elbow or bent pipe contammg a nonplanar In performmg a flaw growth analysis, the procedures m through-wall flaw 1s acceptable for temporary service 1f Article C-3000 may be used as gmdance Relevant growth the flaw cond1t10ns of 3 3 are sat1sf1ed A reducer or ex-rate mechamsms shall be considered When stress corro-pander contammg a nonplanar through-wall flaw 1s ac-s10n crackmg (SCC) 1s active, the followmg growth rate ceptable for temporary service 1f the flaw cond1t10ns of equat10n shall be used 3 4 are sat1sf1ed A branch tee contammg a nonplanar (17) through-wall flaw 1s acceptable for temporary service 1f the flaw cond1t10ns of 3 5 are satisfied 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 5 AUGMENTED EXAMINATION correct10n factor, and C and n are material constants For mtergranular SCC m austemt1c steels, where T ::;; An augmented volumetric exammat10n or physical 200°F (93°C) measurement to assess degradat10n of the affected sys-tem shall be performed as follows C = 1 79 x 10- 0 (a) From the engmeermg evaluat10n, the most suscepti-n = 2161 ble locat10ns shall be 1dent1fied A sample size of at least Sr= 1 five of the most susceptible and accessible locat10ns, or, For transgranular SCC m austemt1c steels, where T ::;; 1f fewer than five, all susceptible and accessible locat10ns 200°F (93°C) shall be exammed w1thm 30 days of detectmg the flaw (b) When a flaw 1s detected, an add1t10nal sample of the C = 1 79 X 10- 7 same size as defined m (a) shall be exammed n = 2161 ST = 3 7l X lQ8 [10(0 01842 T - 12 25)] (c) This process shall be repeated w1thm 15 days for each successive sample, until no s1gmf1cant flaw 1s de-The temperature, T, 1s the metal temperature m de- tected or until 100% of susceptible and accessible loca-grees Fahrenheit The flaw growth rate curves for the t10ns have been exammed 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 6 NOMENCLATURE data a = flaw depth 3 7 NONFERROUS MATERIALS B1 , B 2 = Sect10n III primary stress md1ces For nonferrous materials, nonplanar and planar flaws c = half crack length may be evaluated followmg the general approach of 3 1 C = coefficient m the crack growth relatJ.onsh1p through 3 6 For planar flaws m ductile materials, the ap- da/dt = flaw growth rate for stress corros10n crackmg proach given for austemt1c pipe may be used, otherwise, dad! = diameter eqmvalent circular hole at tadj the approach given for fernt1c pipe should be apphed D 1 = ms1de pipe diameter Structural factors provided m 4 shall be used It IS the re- dmin = diameter of eqmvalent circular hole at tmin spons1b1hty of the evaluator to establish conservative es- DO = outside pipe diameter timates of strength and fracture toughness for the p1pmg F = nond1mens10nal stress mtens1ty factor for material through-wall axial flaw under hoop stress F b = nond1mens10nal stress mtens1ty factor for through-wall circumferential flaw under pipe 4 ACCEPTANCE CRITERIA bendmg stress P1pmg contammg a circumferential planar flaw 1s ac- Fm = nond1mens10nal stress mtens1ty factor for ceptable for temporary service when flaw evaluation pro- through-wall circumferential flaw under mem-v1 des a margrn usrng the structural factors rn brane stress Nonmandatory Appendix C, C-2621 For axial planar h = flex1b1hty characteristic flaws, the structural factors for temporary acceptance 1 = stress mtens1ficat10n factor are as spec1f1ed m Nonmandatory Appendix C, C-2622 I = moment of mert1a based on evaluat10n thick-Straight pipe contammg a nonplanar part through-wall ness, t flaw 1s acceptable for temporary service 1f the remammg Kmax = maximum stress mtens1ty factor under long pipe sect10n meets the long1tudmal stress limits m the term steady state cond1t10ns 5 (N 513 4)
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CASE (continued)
N-513-4 ASME BPVC CC NC-2017 L = maximum extent of a local thmned area with t tmin = mm1mum wall thickness reqmred for pressure
< tnom loadmg Lax,al = length of 1deahzed through-wall planar flaw tnom = nommal wall thickness openmg m the axial direct10n of the pipe, as il- tp = mm1mum remammg wall thickness lustrated m Figure 5 Wm = maximum extent of a local thmned area per-Le ire = length of idealized through-wall planar flaw pendicular to Lm with t < tmin openmg m the circumferential d1rect10n of the X, 1 = mm1mum distance between thmned areas 1 pipe, as illustrated m Figure 5 andJ Lm = maximum extent of a local thmned area with Z = load multipher for ductile flaw extens10n t < tmin f = total crack length =2c Lm(aJ = axial extent of wall thmnmg below tmin fall = allowable axial through-wall flaw length Lm(tJ = circumferential extent of wall thmmng below c/> = circumferential angle from elbow or bend flank tmin a = maximum cone angle at the center of a reducer Lm avg = average of the extent of Lm below tmrn for ad- e = half crack angle for through-wall circumferen-Jacent thmned areas tial flaw Lm 1 = maximum extent of thmned area, 1 A = nond1mens10nal half crack length for through-M2 = bulgmg factor for axial flaw wall axial flaw Mb = resultant primary bendmg moment ab = axial bendmg stress for primary loadmg Me = resultant thermal expans10n moment a. = axial thermal expansion stress n = exponent m the crack growth relat10nsh1p af = material flow stress p = maximum operatmg pressure at flaw locat10n ah = pipe hoop stress due to pressure and bendmg R = mean pipe radms moment (for elbows and bent pipe)
Rbend = elbow or bent pipe centerlme bend radms a1 = reference hm1t load hoop stress R0 = outside pipe radms am = axial pressure stress S = allowable stress at operating temperature ay = material yield strength at temperature, as de-SFm = structural factor on primary membrane stress fined m C-4300 Sr = coefficient for temperature dependence m the crack growth relat10nsh1p 7 APPLICABILITY Su = Code-specified ultimate tensile strength Reference to Nonmandatory Appendix Cm this Case Sy = Code-specified yield strength shall apply to Nonmandatory Appendix C of the 2004 Ed1-T = metal temperature t1on or later ed1t10ns or addenda For editions or addenda t = evaluat10n wall thickness, surroundmg the de- pnor to the 2004 Ed1t10n, Class 1 pipe flaw evaluat10n graded area procedures may be used for other p1pmg classes As a tadJ = adjusted wall thickness which IS vaned for eva- matter of defimt10n, the current term "structural factor" luation purposes m the evaluat10n of a through- 1s eqmvalent to the term "safety factor," which 1s used wall nonplanar flaw m earher ed1t10ns and addenda 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 6 (N-513-4)
CASE (continued)
ASME BPVC CC NC-2017 N-513-4 Figure 1 Through-Wall Flaw Geometry (al C1rcumferent1al Flaw (bl Axial Flaw 7 (N-513-4)
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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) X 1 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)
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CASE (continued)
ASME BPVC CC NC-2017 N-513-4 Figure 3 Illustration of Nonplanar Flaw Due to Wall Thmnmg t
tnom t
Transverse (c1rcumferent1al)
Axial d1rect1on d1rect1on
,(
9 (N-513-4)
CASE (continued)
N-513-4 ASME BPVC CC NC-2017 Figure 4 Allowable Wall Thickness and Length of Locally Thinned Area 10 08 C:
06
.....E 0
- 3 04 02 0
0 2 3 4 5 6 7 8 Lm1a/~
10 (N-513-4)
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CASE (continued)
ASME BPVCCCNC 2017 N-513-4 Figure 5 Illustration of Through-Wall Nonplanar Flaw Due to Wall Thmnmg Through-wall I+--- Laxral - - -
Transverse (c1rcumferent1al)
Axial d1rect1on d1rect1on 11 (N-513-4)
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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)
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CASE (continued)
ASME BPVC CC NC-2017 N-513-4 Figure 8 Zones of a Reducer or Expander
/Large end
r-,,.--r---~-- / / trans1t1on zone
/
/ Central conical
/ section
)a
/
Small end _/
trans1t1on zone 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: /
I/
-ti /
~
i /
/
1 0 E-05 C: ,
.r::
~ /
e CJ
/
V t.)
u e ,,v 1 0 E-06
/
/
/
1 0 E-07
/
/
/
/
1 0 E-08 1 10 100 Stress Intensity Factor, K (ks1 mo 5)
O5 GENERAL NOTE (SI convers10n 1 0 ID /hr= 7 06 x 10-3 mm/sec, 1 0 ks1 ID = 1 099 MPa m 0 5, °C = [°F - 32]/18) 14 (N-513 4)
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/
.,v Austenit1c Piping 1 0 E-03 T,;; 200°F /v I/
/
1 0 E-04 ,
.,v
~
/ V "
.c C
_,,/
,, /
.,,v
/
~ 1 0 E-05 c\l' ,
"O T= 200°F , ,,, ,
i / /
a: / /
.c I T = 100°F I
~
e 1 0 E-06
/ /
(;J
(.)
/ /
~
u / ., V
,,v 1 0 E-07
/
/
V 1 0 E-08
/
1 0 E-09 1 10 100 Stress Intensity Factor, K (ks1 in o 5) 05 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 , °C = [°F - 32]/18) 15 (N-513-4}
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CASE (continued)
N-513-4 ASME BPVC CC NC-2017 MANDATORY APPENDIX I RELATIONS FOR Fm, Fb, AND F FOR THROUGH-WALL FLAWS Bb = 1136322t- 3 91412 (Rjt) + 0 18619 (R/t)2 -
1-1 DEFINITIONS 0 004099 (R/t) 3 For through-wall flaws, the crack depth, a, will be re- Cb = -3 18609 + 3 84763 (R/t) - 0 18304 (R/t) 2 +
placed with half crack length, c, m the stress mtens1ty fac- 0 00403 (R/t) 3 tor equations m C-7300 and C-7400 of Sect10n XI, In the above equatJons Nonmandatory Appendix C Also, Q will be set equal to umty m C-7400 R = mean pipe radms t = evaluat10n wall thickness e = half crack angle= c/R 1-2 CIRCUMFERENTIAL FLAWS EquatJons for Fm and Fb are accurate for R /t between For a range of R/t between 5 and 20, the followmg 5 and 20 and become mcreasmgly conservative for R/t equat10ns for Fm and Fb may be used greater than 20 Alternative solut10ns for Fm and Fb may be used when R/t is greater than 20 where 1-3 AXIAL FLAWS 2
Am = -2 02917 + 167763 (R/t) - 0 07987 (R/t) + For mternal pressure loadmg, the followmg equat10n 0 00176 (R/t) 3 for F may be used Bm = 7 09987 - 4 42394 (R/t) + 0 21036 (R/t)2 -
0 00463 (R/t) 3 F = l + 0 0724491 + 0 6485612 - 0 232713 + 0 03815414 Cm = 7 79661 + 5 16676 (R/t) - 0 24577 (R/t)2 + - 0 0023487il5 0 00541 (R/t) 3 where c = half crack length
.1 = c/(Rt) 1 / 2 where The equat10n for F 1s accurate for il between O and 5 Ab = -3 26543 + 1 52784 (R/t) - 0 072698 [R/t/ + AlternatJve solut10ns for F may be used when il 1s greater 0 0016011 (R/t) 3 than 5 16 (N-513-4)
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