Astm stp 1298 1997

STP 1298 Effects of the Environment on the Initiation of Crack Growth W Alan Van Der Sluys, Robert S Piascik, and Robert Zawierucha, Editors ASTM Publication Code Number (PCN): 04-012980-30 ASTM 100 Barr Harbor Drive West Conshohocken, PA 19428-2959 Printed in the U.S.A Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Library of Congress Cataloging-in-Publication Data Effects of the environment on the initiation of crack growth / W Alan Van der Sluys, Robert S Piascik, and Robert Zawierucha, editors p cm (STP : 1298) Includes bibliographical references ( p ) and index ISBN 0-8031-2408-2 Metals Corrosion fatigue Metals Cracking Metals-Environmental aspects Nuclear reactors Materials Cracking I Van der Sluys, William Alan II Piascik, Robert S II1 Zawierucha, Robert, 1941TA462.E38 1997 620.1 '66 dc21 97-12774 CIP Copyright 1997 AMERICAN SOCIETY FOR TESTING AND MATERIALS, West Conshohocken, PA All rights reserved This material may not be reproduced or copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of the publisher Photocopy Rights Authorization to photocopy items for internal, personal, or educational classroom use, or the internal, personal, or educational classroom use of specific clients, is granted by the American Society for Testing and Materials (ASTM) provided that the appropriate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, Tel: 508-750-8400; online: http://www.copyright.com/ Peer Review Policy Each paper published in this volume was evaluated by two peer reviewers and at least one of the editors The authors addressed all of the reviewers' comments to the satisfaction of both the technical editor(s) and the ASTM Committee on Publications To make technical information available as quickly as possible, the peer-reviewed papers in this publication were prepared "camera-ready" as submitted by the authors The quality of the papers in this publication reflects not only the obvious efforts of the authors and the technical editor(s), but also the work of the peer reviewers The ASTM Committee on Publications acknowledges with appreciation their dedication and contribution of time and effort on behalf of ASTM Printed in Ann Arbor April 1997 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Foreword This publication, Effects of the Environment on the Initiation of Crack Growth, contains papers presented at the symposium of the same name held in Orlando, Florida, on 20-21 May 1996 The symposium was sponsored by ASTM Committee E-08 on Fatigue and Fracture, G01 on Corrosion of Metals, and Subcommittees E08.06 on Crack Growth Behavior and G01.06 on Stress Corrosion Cracking and Corrosion Fatigue The symposium was chaired by W Alan Van Der Sluys, Babcock & Wilcox; Robert S Piascik, NASA Langley Research Center, and Robert Zawierucha, Praxair, Inc They also served as editors of this publication Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Contents vii Overview STRESS CORROSIONCRACKINGINITIATION The Role of Stress-Assisted Localized Corrosion in the Development of Short Fatigue CrackS~ROBERT AKID Pitting Corrosion a n d Fatigue Crack Nucleation~GIM s CHEN, CHI-MINLIAO, KUANG-CHUNGWAN, MINGGAO,AND ROBERTP WEI 18 Initiation of Stress-Corrosion Cracking on Gas T r a n s m i s s i o n P i p i n g ~ B R I A N N LEIS AND JEFFERYA COLWELL 34 CRACK INITIATION IN AGING AIRCRAFT O n the R e q u i r e m e n t for a Sharp Notch or P r e c r a c k to Cause E n v i r o n m e n t a l l y Assisted C r a c k Initiation o f / ] - T i t a n i u m Alloys Exposed to Aqueous Chloride EnvironmentsmDAViD G KOLMANAND JOHN R SCULLY Corrosion-Fatigue C r a c k Nucleation in Alclad 2024-T3 Commercial A i r c r a R Skin CHARLES G SCHMIDT,JAMESE CROCKER,JACQUESH GIOVANOLA, CHRISTINEH KANAZAWA,DONALDA SHOCKEY,AND THOMASH FLOURNOY 61 74 Effect of P r i o r Corrosion on the S/N Fatigue P e r f o r m a n c e of A l u m i n u m Sheet Alloys 2024-T3 a n d 2524-T3mGARY a BRAY, ROBERTJ 8UCCI, EDWARD L COLVIN, AND MICHAEL KULAK 89 STRESS CORROSION CRACK INITIATION IN NUCLEAR ENVIRONMENTS Influence of a Mixed Nitrate Solution on the Initiation a n d Early G r o w t h of Stress Corrosion Cracks in a Low Alloy SteeI REDVERS N PARKINS AND MAHVASH MIRZAI 107 E n v i r o n m e n t a l l y Assisted C r a c k i n g of 3.5NiCrMov Low Alloy Steel U n d e r Cyclic Straining YOSHiYUKIKONDO, MASARU BODAI, MAO TAKEI, YUJI SUGITA, AND HIRONOBU INAGAKI 120 C r a c k Initiation in Low Alloy Steel in High T e m p e r a t u r e W a t e r n HARVEY D SOLOMON, RON E DELAIR, AND ANDY D UNRUH A Process Model for the Initiation of Stress-Corrosion Crack G r o w t h in B W R P l a n t MaterialS MASATSUNEAKASHIAND GUENNAKAYAMA 135 150 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized MODELING Strain Energy Density Distance Criterion for the Initiation of Stress Corrosion Cracking of Alloy X-750mMERYL M HALL,JR AND DOUGLAS M SYMONS Molecular Modeling of Corrosive Environments in Cracks OTAKAR JONAS 167 182 CRACK INITIATION IN CORROSION F A T I G U E - - I Interactive Effect of Dynamic Strain Ageing with High Temperature Water on the Crack Initiation Behaviour of Reactor Pressure Vessel Steels-JOHN D ATKINSON, ZHI-JUN ZHAO, AND JIAN YU 199 Effects of Strain Rate Change on Fatigue Life of Carbon Steel in HighTemperature WatermMAKOTO HIGUCHI,KUNmIROnDA, AND YASUHIDE ASADA 216 Effects of Temperature and Dissolved Oxygen Contents on Fatigue Lives of Carbon and Low Alloy Steels in LWR Water Environments-GENROKU NAKAO, MAKOTO HIGUCHI, HIROSHI KANASAKI, KUNIHIRO IIDA, AND YASUHIDE ASADA 232 CRACK INITIATION IN CORROSION F A T I G U E - - I I Evaluation of Effects of L W R Coolant Environments on Fatigue Life of Carbon and Low-Alloy Steels OMESH K CHOPRAAND WILLIAMJ, SHACK 247 Corrosion Fatigue Behavior and Life Prediction Method Under Changing Temperature Condition H1ROSHl KANASAKI, AKIHIKO HIRANO, KUNIHIRO IIDA, AND YASUHIDE ASADA 267 Advances in Environmental Fatigue Evaluation for Light Water Reactor Components KAZUO KISHIDA,TOSHIMITSU UMAKOSHI, AND YASUHIDE ASADA Indexes 282 299 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Overview The initiation stage of environmentally assisted cracking can have a profound effect on the life of a component Little is known about the damage mechanisms that occur during the important early stages of crack formation, e.g., nucleation and small crack growth, compared to the crack propagation regime This Special Technical Publication reviews current understanding on the effects of the environment on the initiation of crack growth relating to specific areas, including: (1) mechanistic modeling, (2) life prediction, (3) nuclear industry environmental cracking, and (4) recent aging aircraft durability issues The following is a brief overview of the symposium papers included in this topical volume Session h Stress Corrosion Cracking Initiation Akid discussed the role of stress-assisted localized corrosion on the development of short fatigue cracks Corrosion experiments were conducted under cyclic and static stress, using low and high strength steels and stainless steels in chloride environments Surface film breakdown, pit development and growth, pit/crack transition, and environment-assisted Stage I and Stage II crack growth were monitored Each process is considered to be of primary importance during the early stages of stress corrosion and corrosion fatigue cracking Chen, Liao, Wan, Gao, and Wei assess two proposed pit to crack transition criteria: (1) the stress intensity factor for an equivalent crack, equal, or exceeded the threshold stress intensity factor for corrosion fatigue crack growth (CFCG), and (2) the time-based CFCG rate exceeded the pit growth Validation of a proposed pitting corrosion/fatigue crack nucleation criterion is presented and discussed in terms of open hole alloy 2024-T3 experiments conducted in 0.5M NaC1 solution Leis and Colwell studied the processes leading to the formation of crack-like features as well as early crack growth of stress-corrosion cracking on the exterior of gas transmission piping Observations show that cracks with dense spacing tend towards dormancy, whereas the sparsely spaced cracks continue to grow Fracture mechanics based analysis is used to rationalize the crack pattern observations Session II: Crack Initiation in Aging Aircraft Kolman and Scully examined the effects of a sharp notch or crack tip on cation accumulation-hydrolysis-acidification, potential drop in solution and resulting hydrogen production, and localization on dynamic strain in titanium alloys exposed to 0.6 M NaCI It was shown that the drop in potential down a sharp crack is severe enough to enable hydrogen production, even when the applied potential is more positive than the reversible potential for hydrogen production The effects of a sharp notch on the interplay of mechanics, film rupture, and hydrogen uptake are also examined Schmidt, Crocker, Giovanola, Kanazawa, Shockey, and Flournoy investigated the processes that influence the transition from salt water corrosion pit development to fatigue crack formation in Alcad 2024-T3 Results suggest that the nucleation of corrosion fatigue cracks involves two competing mechanisms: hydrogen effects in the cladding and electrochemical dissolution at constituent particles in alloy 2024 Cracks not necessarily nuclevii Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized viii EFFECTS OF THE ENVIRONMENT ON THE INITIATION OF CRACK GROWTH ate at the largest corrosion pit, suggesting that a contributing factor to crack nucleation from a pit may be the creation of a local region of weakness Bray, Bucci, Colvin, and Kulak evaluate the effect of prior corrosion on the S/N fatigue performance of 1.60 and 3.17-mm-thick aluminum sheet alloys 2524-T3 and 2024-T3 The fatigue strength of alloy 2524 was approximately 10% greater and the lifetime to failure, 30 to 45% longer than alloy 2024 Two main factors are believed to have contributed to the better performance of 2524: less damaging configuration of corrosion pits and its better fatigue crack growth resistance Session III: Stress Corrosion Crack Initiation in Nuclear Environments Parkins and Mirzai provide a database that will allow prediction of stress corrosion cracking failures in nuclear reactor components exposed to the radiolysis of moist air which produce nitric acid environments Constant strain stress corrosion tests, at 50 or 100% yield stress, were conducted on welded nickel based steel samples exposed to a mixed nitrate solution for various times Selective attack at relatively short exposure times was observed where grain boundaries intersected the specimen surfaces Kondo, Bodai, Takei, Sugita, and Inagaki studied environmentally assisted cracking of 3.5NiCrMoV low alloy steel under cyclic straining in water at 60~ Test results showed that higher strain range, lower strain rate, longer strain hold times, and higher electric conductivity caused increased charge transfer, which resulted in shorter crack initiation life A prediction model tbr crack initiation life was proposed based on observed charge transfer Soloman, DeLair, and Unruh investigated the fatigue crack initiation of WB36, a German low alloy steel (LAS), tested in high-temperature high-purity water The tests were performed at 177~ in water containing ppm 02 H2504 additions were also used in some tests to raise the conductivity of the water from 0.06 to 0.4-0.5 ~xS/cm The crack initiation and growth data are correlated with water chemistry Akashi and Nakayama investigated the initiation of stress corrosion cracking in boiling water reactor materials They suggest that stress corrosion cracking can be divided into six (three deterministic and three stochastic) separate processes The paper examines the influence of three stochastic processes: (1) nucleation of corrosion pits, (2) initiation of micro cracks, and (3) the coalescence of microcracks, on the stress corrosion cracking initiation process Session IV: Modeling Hall and Symons showed that the initiation of stress corrosion cracking in alloy X-750 exposed to high-temperature-deaerated water occur at a variable distance from the notch or crack tip The initiation site varies from very near the crack tip, for loaded sharp cracks, to a site that is one grain diameter from the notch, for lower loaded, blunt notches The existence of hydrogen gradients, which are due to strain-induced hydrogen trapping in the strain fields of the notch and crack tips of the SCC test specimens, is argued to be responsible for variation in the crack initiation site O Jonas presented a corrosion model for iron-based alloys Interactions of aqueous environments in cracks are expressed as relative bonding energies for individual molecules and other parameters The results indicate relative aggressiveness of environments, types of chemical/corrosion reactions, and the rate of mass transport to the crack-tip Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized OVERVIEW ix Session V and Vh Crack Initiation in Corrosion Fatigue Atkinson, Zhao, and Yu investigated the effect of dynamic strain aging (DSA) on stress corrosion cracking of reactor pressure vessel steels exposed to 250~ water Results support the coincidence of temperature and strain rate between the DSA hardening and the susceptibility to environment-assisted cracking of reactor pressure steels The mechanistic role of DSA and its interpretation with other influential variables in the enhancement of stress corrosion cracking are discussed Higuchi, Iida, and Asada studied the effect of strain rate on the fatigue life of carbon steel exposed to high-temperature water containing dissolved oxygen A series of strain-controlled fatigue tests were conducted with strain rate changed stepwise or continuously A method using the product of the environmental effect and the strain increment within a unit time interval in a transient period is integrated from the minimum strain to the maximum This modified strain rate approach method is discussed in detail Nakao, Higuchi, Kanasaki, Iida, and Asada investigated the fatigue design of pressure vessel components They show that decreased fatigue life of STS410 carbon in simulated boiling water reactor water is dependent on temperature and dissolved oxygen An environment parameter ratio, Rp, is proposed for the estimate of the fatigue life at a certain temperature and dissolved oxygen content Chopra and Shack summarized the available data on the effects of various material and loading variables such as steel type, dissolved oxygen level, strain range, strain rate, and sulfur content on the fatigue life of carbon steel and low-alloy steels The data have been analyzed to define the threshold values of the five critical parameters Methods for estimating fatigue lives under actual loading histories were discussed Kanasaki, Hirano, Iida, and Asada performed strain controlled low cycle fatigue tests of a carbon steel in oxygenated high-temperature water The corrosion fatigue life prediction method was proposed for changing temperature conditions The method is based on the assumption that the fatigue damage increased linearly with the fatigue cycle strain increment The fatigue life predicted by this method was in good agreement with the test results Kishida, Umakoshi, and Asada proposed a method for evaluating the environmental fatigue lives tbr the Class I reactor pressure A revised simplified method is developed Ibr the determination of a fatigue usage factor for a component in which loading transients include variation of temperature, strain rate, and oxygen content in addition to the strain range A number of examples are presented in which an environmental effect correction factor is determined for components in a nuclear pressure boundary W Alan Van Der Sluys Babcock & Wilcox; Alliance Ohio; symposium chairman and STP editor Robert S Piascik NASA Langley Research Center; P.O Box MS 188E, Hampton, Virginia; symposium cochairman and STP editor Robert Zawierucha Praxair, Inc., Tonawanda, New York; symposium co-chairman and STP editor Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Stress Corrosion Cracking Initiation Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions a 288 EFFECTS OF THE ENVIRONMENT ON INITIATION OF CRACK GROWTH TABLE Detailed Calculations of Fen for each load set of BWR reactor pressure vessel feedwater nozzle Load set hair NO Turbine roll Turbine trip Turbine roll Shut down BWR4 Shut down Shut down Shut down Shut down Shut down Turbine generator trip Shut down Turbine roll Hot standby Shut down Hot standby Shut down Turbine trip Shut down BWR5 Shut down Scram Shut down Shut down Shut down Hot standby Shut down Turbine roll Shut down Feedwater pump trip 10 Shut down Turbine generator trip 11 TABLE Detailed Calculations of Fen for each load set of PWR steam generator feedwater nozzle Load set )air NO Cooldown Heatup Loop Hot standby Turbine roll Leak test Cooldown Hot standby Reactor trip Loop Turbine roll Depressurization Reactor trip Cooldown Heatup Hot standby Reactor trip Loop Depressurization Turbine roll Inadvertent safety injection actior Upset Upset Upset Upset Upset Upset Upset Upset Upset Upset Upset Upset Upset Upset Upset Upset Upset Upset F~n 1.27 1.27 1.29 1.61 1.43 1.73 1.33 1.33 1.49 1.4S 1.43 1.43 1.4~ 1.42 1.4"; Fen 1.79 2.05 1.79 1.79 2.17 2.17 i ! 2.17 2.17 2.17 !.8{} 2.05 1.8{} 1.83 1.81 1.80 1.80 We have done this as follows: Calling the load set that gives rise to the maximum strain 'i', and that which is for the minimum strain 'j', letting the strain rate, assumed constant in each for the rising phase of straining, be (de / dt)i and (dr / dr)j, respectively, using the maximum value encountered in the rising phase o f straining both for the temperature and for the DO content (this is to ensure the P factor become to assume the maximum for every load set), and letting such P factors be Pi and Pj, respectively, we write: Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authoriz KAZUO ET AL ON ADVANCES IN ENVIRONMENTAL FATIGUE E max E start F e n = Feni + Fenj (1~ max ~ start ) "l" ( E end ~ ) E end E mm 289 (5) (E maX I~ start ) "F ( E end E rain ) where Feni,j = ( d E / d ~ ) i , j P m a x i ' j , Pmax i,j = f ( Tm= ~,j , DOm~x i,j ) , e,~o.is the strain at the moment the load set which gave rise to the maximum strain has started, and e end is the minimum strain counterpart of it As eq (5) is evidently much simpler than eq (2), we shall designate it as the simplified method We have duly applied this method to the parts shown in Tables and 4, and have obtained Fen's as presented in Table for BWR and in Table for PWR It will be noticed that where Table gives Sa, Fen, (de /dt)i,j , maximum temperature, maximum DO, and the largest P factor for each of the load sets, Table lacks the maximum temperature and maximum DO in reflection of the fact that in PWR the DO concentration is so low that P is assigned with a constant value regardless the temperature It will be further noted that the strain rate is faster for BWR than for PWR, for which the strain rates are all smaller than the saturation value of 0.001%/s Finally, we observe that all the Fen's, both for BWR, which is 1.4 to 1.9, and for PWR, which is 2.2, are higher than those that have been obtained in the detailed evaluation T A B L E S i m p l i f i e d Calculations o f F e n for e a c h load set p a i r o f B W R r e a c t o r p r e s s u r e v e s s e l f e e d w a t e r nozzle NO Load set pair Sa MPa) 662 Turbine roll Turbine trip Turbine roll 505 Shutdown Shut down 480 Shutdown Shut down 287 Shutdown Shutdown 819 Turbine senerator trip Shut down 555 BWR5 Turbine roll Shut down 48C Hot standby Shut down 466 Hot standby Shutdown 502 Turbine trip Shutdown 502 Scram Shut down 465 Shut down Hot standby 465 Shut down Turbine roll 448 Shut down 10 Feedwater pump trip 449 Shutdown 11 Turbine generator trip 345 Shut down Note: If the strain rate is less than 1.0E-03(%/sec), the BWR4 Strain rate Tmax DOmax Pmax Fen i,j Fen (%/see) (C) (ppm) 9.72E-02 283 0.04 0.112 1.30 1.36 1.15E-03 166 0.04 0.112 2.13 9.72E-02 283 0.04 0.112 1.30 1.36 1.15E-03 166 0.04 0.112! 2.13 9.64E-.02 286 0.04 0.112 1.30 1.3~ 1.15E-03 166 0.04 0.112 2.13 7.93E-02 199 0.04 0.112 1.33 1.6& 1.15E-03 166 0.08 0.208 4.10 2.98E-02 289 0.04 0.112 1.48 1.53 2.72E-04 214 0.04 0.112 2.17 2.98E-02 289 0.04 0.112 1.48 1.88 1.28E-04 215 0.08 0.208 4.22 2.98E-02 289 0.04 0.112 1.48 1.4/4 3.71E-01 289 0.04 0.112 1.12 2.98E-02 289 0.04 0.112 1.48 1.44 3.71E-01 289 0.04 0.112 1.12 2.98E-02 289 0.04 0.112 1.48 1.52 4.94E-04 215 0.04 0.112 2.17 2.98E-02 289 0.04 0.112 1.48 1.52 4.94 E-04 215 0.04 0.112 2.17 2.98E-02 289 0.04 0.112 1.48 1.54 4.26E-05 273 0.04 0.112 2.17 2.98E-02 289 0.04 0.112 1.48 1.54 4.26E-05 273 0.04 0.112 2.17 2.23E-02 287 0.04 0.112 1.53 1.58 4.26E-05 273 0.04 0.112 2.17 2.98E-02 289 0.04 0.112 1.48 1.54 4.26E-05 273 0.04 0.112 2.17 2.02E-02 214 0.04 0.112 1.55 1.5-~ 4.26E-05 289 0.04 0.112 2.17 strain rate for the calculations is taken as 1.0E-03(%/sec.) Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 19:39:25 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 290 EFFECTS OF THE ENVIRONMENT ON INITIATION OF CRACK GROWTH TABLE SimplifiedCalculationsof Fen for each load set pair of PWR steam ~edwaternozzle NO Load set pair Sa (MPa) 349 Strain rate Pmax Fen i,j Fen (~ Cooldown 3.30E-07 0.112 2.17 2.17! Upset 1.78E-O5 0.112 2.17 L~x~p Heatup 347 2.12E-05 0.112 2.17 2.17 Upset 1.78E-05 0.112 2.17 Hot standby 340 0.00E+00 0.112 2.17 2.17 Upset 1.78E-05 0.112 2.17 Turbine roll 208 0.00E+00 0.112 2.17 2.17 Upset 1.78E-O5 0.112 2.17 Leak test 332 4.32E-07 0.112 2.17 2.17 Upset 6.86E-06 0.112 2.17 Ctxddown 327 2.47E-07 0.112 2.17 2.17 Upset 6.86E-06 0.112 2.17 Hot standby 310 0.00E*00 0.112 1.00 2.17 Ltx~p Upset 6.86E 06 0.112 2.17 Reactor trip 251 4.24E-05 0.112 2.17 2.17 Upset 6.86E-O6 I 12 2.17 Turbine roll 209 0.00E +00 I 12 1.00 2.17 Upset 6.86E-O6 0.112 2.17 Depressurization 205 8.47E-06 0.112 2.17 2.17 Upset 6.86E-O6 I 12 2.17 Reactor trip 196 2.36E-04 I 12 2.17 2.17 Upset 6.86E-06 0.112 2.17 ttot standby 333 2.04E-07 0.112 2.17 2.17 Upset 1.78E-05 I 12 2.17 Heatup 332 1.90E 05 0.112 2.17 2.17 Upset 1.78E-05 0.112 2.17 L~a~p Hot standby 330 0.00E~O0 0.112 1.00 2.17 Upset 1.78E-05 0.112 2.17 Reactor trip 252 3.29E-05 0.112 2.17 2.17 Upset 1.78E-05 0.112 2.17 Depressurization 215 ! 1.86E-05 0.112 2.17 2.17 Upset 1.78E-O5 0.112 2.17 Turbine roll 201 0.00E+O0 0.112 1.00 2.17 Upset 1.78E-05 0.112 2.17 Inadvertent safety injection action 191 6.30E-O6 0.112 2.17 2.17 Upset 1.78E-05 0.112 2.17 o Note: If the strain rate is less than 1.0E-03(~ the strain rate fiw the calculations is taken as 1.0E-03( Fdsee FATIGUE EVALUATION FOR PIPING The current practice of fatigue evaluation for Class piping is accorded to the NB3600 of Section III, the ASME Boiler & Pressure Vessel Code Though it is essentially the same as for Class vessels, difference lies in the way Sp, the peak stress intensity, is determined Here, Sp is defined as [!]: Sp = KICI DoPo + K2C2 Do Mi + K3CsEabJo ar~ -~brbJ 2t 2I 1 + K,E