1、DEVELOPMENT OF WELD STRENGTH REDUCTION FACTORS AND WELD JOINT INFLUENCE FACTORS FOR SERVICE IN THE CREEP REGIME AND APPLICATION TO ASME CODESSTP-PT-077STP-PT-077 DEVELOPMENT OF WELD STRENGTH REDUCTION FACTORS AND WELD JOINT INFLUENCE FACTORS FOR SERVICE IN THE CREEP REGIME AND APPLICATION TO ASME CO
2、DES Prepared by: J. Shingledecker, Electric Power Research Instiitute B. Dogan, Electric Power Research Instiitute J. Foulds, Clarus Consulting, LLC R. Swindeman, Cromtech, Inc. D. Marriott, Stress Engineering Services P. Carter, Stress Engineering Services Date of Issuance: June 26, 2017 This publi
3、cation was prepared by ASME Standards Technology, LLC (“ASME ST-LLC”) and sponsored by The American Society of Mechanical Engineers (“ASME”) and the Electric Power Research Institute (“EPRI”). Neither ASME, ASME ST-LLC, the author, nor others involved in the preparation or review of this publication
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10、itten permission of the publisher. ASME Standards Technology, LLC Two Park Avenue, New York, NY 10016-5990 ISBN No. 978-0-7918-7126-3 Copyright 2017 by ASME Standards Technology, LLC All Rights Reserved STP-PT-077: Development of Weld Strength Reduction Factors and Weld Joint Influence Factors for S
11、ervice in the Creep Regime and Application to ASME Codes iii TABLE OF CONTENTS Foreword ix PART 1: Development and Application of Weld Strength Reduction Factors Guideline 1 1 APPLICATION GUIDELINE . 2 1.1 Overview 2 1.2 Application Guideline 4 1.2.1 Step 1: Develop Database . 5 1.2.2 Step 2: Analyz
12、e Data 6 1.2.3 Step 3: Base Material Strength Factor 7 1.2.4 Step 4: Application to Welded Structure 8 1.2.5 Step 5: Design Strength Ratio . 9 1.3 New Materials 10 1.3.1 Comments on Specimen Size 10 1.3.2 Data Requirements 11 2 APPLICATION TO CHROMIUM-MOLYBDENUM LONGITUDINAL SEAM WELDS 13 2.1 Step 1
13、: Grade 22 Database (b) weld joint influence factors that capture specifics of the structure; and (c) guidance for application of the weld strength reduction factor and the weld joint influence factor in design rules. Consistent with these needs as identified in ASME ST-LLCs request for proposal, th
14、is document is presented in three separate parts (reports) as follows. Part 1: Development and Application of Weld Strength Reduction Factors Guideline (Task 1b/3 project report) This report ties the elements of Parts 2 and 3 into an application guideline. The guideline includes description of a fra
15、mework for analyzing laboratory data and using the weld joint influence factor development methods. The Part 1 report provides examples of application to two weld/weldment databases for longitudinal seam welds, illustrating the usefulness of the methodology. The examples are for Grade 91 steel that
16、is susceptible to weld heat-affected zone failure, and Grade 22 steel that has and continues to be used in long seam-welded piping construction. The results are compared with current Code rules, literature findings, and experience. Part 2: Literature Review, Industry Approach, and Data Compilation i
17、n Support of WSRF Development (Task 1a project report) This report includes a compilation of laboratory and experience data on weldments for select materials of common use and interest carbon steel, low alloy CrMo steels, austenitic stainless steels, Alloy 800/800H, and Grade 91. A critical part of
18、this extensive database development was collecting relevant information not available to the ASME Code committees when allowable stresses were set for some of these materials. Also given in this report is a summary of approaches that have been taken in establishing weld strength reduction factors wo
19、rldwide. Part 3: Development of Weld Joint Influence Factors (Task 2 project report) The report describes an analysis tool to evaluate the creep rupture strength of a weldment relative to that of base metal, benchmarked against select cases of field experience and laboratory component testing. The m
20、ethodology can be used for calculating weld joint influence factors for any practical combination of materials and weldment geometries in a relatively quick and computationally efficient manner, also allowing for use of relatively simple materials models readily available to designers. This publicat
21、ion references the original project task reports that have been reproduced here in the three parts as identified above: Part 1-Tasks 1b and 3; Part 2-Task 1a; Part 3-Task 2. (EPRI is acknowledged for supporting this publication. EPRI conducts research and development relating to the generation, deli
22、very and use of electricity for the benefit of the public. An independent, non-profit organization, EPRI brings together its scientists and engineers as well as experts from academia and industry to help address challenges in electricity, including reliability, efficiency, affordability, health, STP
23、-PT-077: Development of Weld Strength Reduction Factors and Weld Joint Influence Factors for Service in the Creep Regime and Application to ASME Codes x safety and the environment. EPRIs members represent approximately 90 percent of the electricity generated and delivered in the United States, and i
24、nternational participation extends to more than 30 countries. Established in 1880, the ASME is a professional not-for-profit organization with more than 135,000 members and volunteers promoting the art, science and practice of mechanical and multidisciplinary engineering and allied sciences. ASME de
25、velops codes and standards that enhance public safety, and provides lifelong learning and technical exchange opportunities benefiting the engineering and technology community. Visit (https:/www.asme.org/) for more information. ASME ST-LLC is a not-for-profit Limited Liability Company, with ASME as t
26、he sole member, formed in 2004 to carry out work related to new and developing technology. The ASME ST-LLC mission includes meeting the needs of industry and government by providing new standards-related products and services, which advance the application of emerging and newly commercialized scienc
27、e and technology, and providing the research and technology development needed to establish and maintain the technical relevance of codes and standards. Visit (http:/asmestllc.org/) for more information. STP-PT-077: Development of Weld Strength Reduction Factors and Weld Joint Influence Factors for
28、Service in the Creep Regime and Application to ASME Codes 1 PART 1: DEVELOPMENT AND APPLICATION OF WELD STRENGTH REDUCTION FACTORS GUIDELINE STP-PT-077: Development of Weld Strength Reduction Factors and Weld Joint Influence Factors for Service in the Creep Regime and Application to ASME Codes 2 1 A
29、PPLICATION GUIDELINE 1.1 Overview The purpose of the ASME-EPRI research project is to develop the methodology and data to help establish weld strength reduction factors (WSRF) for service in the creep regime for a wide range of materials with applicability to various sections of ASME Boiler for exam
30、ple, two weldments made by the same process with the same filler metal heat will count as one lot, but if two different heats of filler metal are utilized for the same process each weldment will count as one lot b) Weld metal can be removed from a weldment or taken from a weld pad build-up provided
31、specimens are taken such that any chemical dilution in the weld metal is not included in the tests and (if applicable) post-weld heat-treatment is performed c) Longer test durations are advantageous with the goal of facilitating estimated 100,000 hour life for comparison with base metal dataset d) S
32、tandard cross-weld specimens meet the requirements for base metal specimens tested to a recognized international standard such as ASTM with either the weldment in the center of the gauge or the fusion-line centered in the gauge with weld metal comprising of the specimen length. When the weld is cent
33、ered in the gauge, to ensure sufficient base metal is present on each side of the weldment, the length of base metal (l) plus the width of the weld metal (w) should meet/exceed the typical ASTM requirement of gauge length (L) equal to four times the specimen gauge diameter as follows: L = (l + w) 4d
34、 e) Details on reporting specimen failure location and/or metallographic assessment of failure modes is encouraged STP-PT-077: Development of Weld Strength Reduction Factors and Weld Joint Influence Factors for Service in the Creep Regime and Application to ASME Codes 13 2 APPLICATION TO CHROMIUM-MO
35、LYBDENUM LONGITUDINAL SEAM WELDS This chapter describes the evaluation of the EPRI Grade 22 weld/weldment database, an analysis of the database, the application of the modeling tool/procedure to evaluate the cross-weld data, a comparison with data on large cross-weld specimens, and implications for
36、WSRFs. 2.1 Step 1: Grade 22 Database 0.2 in. (6); 0.32 in. (65); 0.38 in. (6); and 0.51in. (1). Figure 7: Grade 22 Base Metal Stress Rupture Data from EPRI TR-110807 10 Notes: Note the relatively low scatter below about 20 ksi. 25000300003500040000450001 10 100L M P ( C = 2 0 )S t r e s s ( k s i )G
37、 r a d e 2 2 B MSTP-PT-077: Development of Weld Strength Reduction Factors and Weld Joint Influence Factors for Service in the Creep Regime and Application to ASME Codes 15 Figure 8: Grade 22 Weld Metal Stress Rupture Data from EPRI TR-110807 10 Figure 9: Grade 22 Cross-Weld (X-W) Specimen Stress Ru
38、pture Data from EPRI TR-110807 10 Notes: Note the generally consistent trend exhibited with the service-relevant failure location data (WM, FL, WM/FL and HAZ). 25000300003500040000450001 10 100 1000L M P ( C = 2 0 )S t r e s s ( k s i )G r a d e 2 2 W M25000300003500040000450001 10 100L M P ( C = 2
39、0 )S t r e s s ( k s i )G r a d e 2 2 X - W _ Fa il L o c N o t R e p o r t e dG r a d e 2 2 X - W Fa il L o c : B MG r a d e 2 2 X - W Fa il L o c : W M , FL & W M /FLG r a d e 2 2 X - W Fa il L o c : H A ZSTP-PT-077: Development of Weld Strength Reduction Factors and Weld Joint Influence Factors f
40、or Service in the Creep Regime and Application to ASME Codes 16 2.2 Step 2: Grade 22 Data Analysis A preferred analysis method was first developed through exploration of the base metal database. Following this, the same method was employed for the weld metal and the cross-weld databases. The approac
41、h and results are briefly summarized below. 2.2.1 Base Metal Data Analysis First, two fitting functions were explored: ASME Code-typical (log stress polynomial) : log tR = a0 + a1/T + a2(logS)/T + a3(logS)2/T +a4(logS)3/T Spera function, as used in 1990 by the ASME Code for Grade 22 11: log tR = b0
42、+ b1/T + b2(logS)/T + b3(S)/T +b4(S)2/T where tR is the rupture time, T is the test temperature in absolute units, S is the test stress, and the coefficients, a0 through a4 and b0 through b4 are coefficients determined through a regression curve-fitting procedure. In each case, in order to examine t
43、he behavior in comparison with that expected from experience, a0 and bo were allowed to float and their best-fit values checked against the expected LMP constant C=20 value (a0 and b0 = -20). The final regression fits used in this study were developed by constraining the a0 and b0 to -20. For a firs
44、t view of the behavior, all of the data were analyzed. Both curve-fits gave floating a0 and b0 values that were significantly lower in magnitude than the expected 20, suggesting that this database exhibits behavior different from that used in development of the ASME Code allowable (b0 close to -20).
45、 However, constraining the fits to a0=b0=-20 did not reduce the quality of the fits by much. The Spera function fit gave a lower standard error of the estimate (SEE) for log tR. Based on the overall fitting capability for the data sets examined here, it was decided to use the Spera function througho
46、ut the remainder of this Grade 22 data analysis. As noted earlier, a case may be made for censoring the data above 20 ksi. Further, a re-analysis of the censored data (245 data points) gave a vastly improved quality of fit, reducing the log tR SEE from 0.44 to 0.12 for the Spera function fit. Figure
47、 10 shows the data and corresponding curve-fit to the base metal data at 20 ksi and below. The best-fit function is: log tR = -20 + 43009.92/T 2884.39(logS)/T - 338.394(S)/T + 4.094(S)2/T (1) with tR in hours, T in degree R, S in ksi and a log tR SEE of 0.118. 2.2.2 Weld Metal Data Analysis The weld
48、 metal data exhibited considerably more scatter than did the base metal data (compare Figs. 8 and 9). As a result, the curve-fits gave significantly higher standard errors. As with the base metal data analysis, the analyzed data were restricted to 20 ksi and below. The data scatter increases with st
49、ress, and the extent of scatter above 20 ksi (see Figure 9) is such that restricting the analysis to data at 20 ksi and below significantly improved the curve-fit. As with the base metal, the floating LMP constant fit produced a value for C of about 13, significantly lower than the value of 20 typical and expected for base metal. Constraining the fit to C=20 increased the SEE (from about 0.33 to 0.39). For consistency with the base metal data STP-PT-077: Development of Weld Strength Reduction Factors and Weld Joint Influence Factors for Service in the Creep Regime and
