Introduction of CASS Pipe Flaw Evaluation of JSME Rules on Fitness for Service

2019 ◽  
Author(s):  
Kiminobu Hojo
Keyword(s):  
Stainless Steel ◽  
Evaluation Method ◽  
Limit Load ◽  
Evaluation Procedure ◽  
Screening Criteria ◽  
Steel Pipes ◽  
Evaluation Procedures ◽  
Degradation Models ◽  
Fracture Tests ◽  
Cast Stainless Steel

Abstract This paper summarizes the revised flaw evaluation procedures for cast austenitic stainless steel (CASS) pipe of the Japan Society of Mechanical Engineers (JSME) rules on fitness for service (FFS) in 2018 addenda. The revision includes the introduction of thermal aging degradation models for stressstrain curve and fracture resistance (J-R) curve, application of a screening criteria for the fracture evaluation procedure of cast stainless steel pipes, and introduction of a new critical stress parameter for the limit load evaluation method of a shallow flaw with a flaw depth to thickness ratio of less than or equal to 0.5. These revisions are based on a large database of specimen tests and several fracture tests of flat plate and large pipe models using thermally aged material, which have already been published.

Evaluation Procedure of Limit Load for Non-Aligned Multiple Flaws

2013 ◽  
Author(s):  
Fuminori Iwamatsu ◽  
Katsumasa Miyazaki ◽  
Hidekazu Takazawa ◽  
Koichi Saito
Keyword(s):  
Correlation Coefficients ◽  
Limit Load ◽  
Evaluation Procedure ◽  
Collapse Load ◽  
Evaluation Procedures ◽  
Direct Distance ◽  
Fracture Tests ◽  
Almost All ◽  
Technical Basis

The fitness-for-service codes such as the ASME Boiler and Pressure Vessel Code Section XI require the characterization of non-aligned multiple flaws for flaw evaluation, which is performed using a flaw alignment rule. Worldwide, almost all such codes provide their own alignment rule, often with an unclear technical basis regarding the application of the rule to plastic collapse due to ductile fracture as prescribed by limit load analysis based on a net-section approach. Therefore, evaluation procedures to calculate collapse load for non-aligned multiple flaws have been proposed in various experimental and analytical studies. In these proposals, a collapse load for non-aligned multiple flaws is evaluated using the net-section stress approach in consideration of the ratio of a distance between flaws to a flaw length parameter. However, because each study proposes its own appropriate length and distance parameters, which are based on a few experimental results limited to that study, the applicability of the proposed parameters to evaluation of collapse load for arbitrary flaw sizes and locations is unclear. In this study, we performed fracture test result on a flat plate with two through-wall flaws in order to determine appropriate parameters for the evaluation procedure of the collapse load for non-aligned multiple flaws. Appropriate parameters were determined by correlation coefficients obtained by comparison of maximum loads of fracture tests and collapse loads of evaluation with various parameters. We found that the appropriate parameters to apply the alignment rule with equations to evaluate collapse load for non-aligned flaws were the ratio of the vertical or direct distance between flaws to the maximum or average flaw length.

Allowable Axial Flaw Sizes for Stainless Steel Pipes Derived From Limit Load Criteria and Failure Assessment Diagram Procedure

2003 ◽  
Author(s):  
Kunio Hasegawa ◽  
Katsumasa Miyazaki ◽  
Gery M. Wilkowski ◽  
Douglas A. Scarth
Keyword(s):  
Stainless Steel ◽  
Limit Load ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Steel Pipes ◽  
Failure Assessment Diagram ◽  
Axial Part ◽  
Wide Range ◽  
Failure Assessment ◽  
Asme Code

Piping containing flaws that exceed the Acceptance Standards of Section XI of the ASME Code is evaluated using analytical procedures described in Section XI to determine plant operability for the evaluated time period. Subarticle IWB-3640 of Section XI provides allowable axial and circumferential part-through-wall flaws determined from limit load criteria. ASME Section XI Code Case N-494-3 also provides evaluation procedures based on use of a failure assessment diagram to determine allowable flaw sizes. To understand the allowable flaw sizes determined by the limit load criteria and the failure assessment diagram procedure, anstenitic stainless steel pipes with axial part-through-wall flaws with a wide range of pipe diameters were analyzed. The allowable flaw depth based on limit load from Code Case N-494-3 was determined to be very close to that determined from IWB-3640 of Section XI, when the predicted failure mode is elastic-plastic fracture. It was found that the allowable flaw depths derived from the failure assessment diagram procedure of Code Case N-494-3, are lower, but are not significantly different, from those determined from the limit load criteria of IWB-3640. This is due to the relatively high fracture toughness that was used for the austenitic stainless steel.

Evaluation of Alignment Rules Using Stainless Steel Pipes With Non-Aligned Flaws

2009 ◽  
Author(s):  
Kunio Hasegawa ◽  
Katsumasa Miyazaki ◽  
Koichi Saito ◽  
Bostjan Bezensek
Keyword(s):  
Stainless Steel ◽  
Limit Load ◽  
Plastic Collapse ◽  
Paper Briefly ◽  
Limit Loads ◽  
Bending Tests ◽  
Steel Pipes ◽  
Four Point Bending ◽  
Close Proximity ◽  
As Stress

Multiple flaws such as stress corrosion cracks are frequently detected in the same welded lines in pipes. If multiple discrete flaws are in close proximity to one another, alignment rules are used to determine whether the flaws should be treated as non-aligned or as coplanar. Alignment rules are provided in fitness-for-service codes, such as ASME, JSME, API 579, BS 7910, etc. However, the criteria of the alignment rules are different among these codes. This paper briefly introduces these flaw alignment rules, and four-point bending tests performed on stainless steel pipes with two non-aligned flaws. The experimental plastic collapse stresses are determined from the collapse loads and compared with collapse stresses calculated from the limit load criteria. The limit loads are obtained for single non-aligned or aligned coplanar flaws in accordance with the alignment rules. On this basis, the conservatism of the alignment rules in the above codes is assessed.

CASS Fracture Tests Using Flat Plate Specimens With a Surface Flaw

2015 ◽  
Author(s):  
Kiminobu Hojo ◽  
Wataru Nishi ◽  
Shotaro Hayashi
Keyword(s):  
Stainless Steel ◽  
Flat Plate ◽  
Thermal Aging ◽  
Limit Load ◽  
Surface Flaw ◽  
Tensile Fracture ◽  
Ferrite Number ◽  
Fracture Tests ◽  
Depth Curve ◽  
Two Parameter

JSME rules for fitness for service have flaw acceptance rules for cast austenitic stainless steel (CASS) pipes. They allow applying two-parameter and elastic-plastic fracture mechanics methods using Z-factor. However they do not clearly describe whether limit load method is applicable for the case of no or low thermal aging condition. The authors performed tensile fracture tests using flat plate specimens with a surface flaw and confirmed that limit load method is applicable in the conditions of no thermal aging and even fully saturated thermal aging with high ferrite number. Also the plate with a shallow flaw ruptured at the critical stress defined by nominal stress at rupture-flaw depth curve in the code case which was determined by the similar flat plate tests of stainless steel or nickel alloy specimens. These results will be reflected to the revision of the code.

Study on Incorporation of New Design Fatigue Curves and a New Environmental Fatigue Correction Factor for PWR Environment Into the JSME Environmental Fatigue Evaluation Method

2020 ◽  
Author(s):  
Seiji Asada ◽  
Shengde Zhang ◽  
Masahiro Takanashi ◽  
Yuichiro Nomura
Keyword(s):  
Stainless Steel ◽  
Base Metal ◽  
Stainless Steels ◽  
Evaluation Method ◽  
Austenitic Stainless Steels ◽  
Steel Base ◽  
Improved Design ◽  
Fatigue Evaluation ◽  
Cast Stainless Steel ◽  
Metal Weld

Abstract Improved design fatigue curves were developed in the Subcommittee on Design Fatigue Curve in the Atomic Energy Research Committee in the Japan Welding Engineering Society (JWES). Working Group on Design Fatigue Curves (WG DFC) in the JSME has studied the validity and the applicability of the improved design fatigue curves developed in the JWES to incorporate into the JSME Environmental Fatigue Evaluation Method. The authors propose a fatigue analysis method using the design fatigue curves developed in the JWES that are applied revised factors to optimize the environmental fatigue analysis. Also, the Japanese pressurized water reactor (PWR) utility group developed equations of environmental fatigue factors (Fen) for austenitic stainless steel base metal, weld metal and cast stainless steel in PWR environment. The WG DFC has investigated the Fen equations and concluded that the Fen equation of austenitic stainless steel base metal is the most conservative among the three equations and close to NUREG/CR-6909 Rev.1 [24]. The authors propose to use the Fen equation for base metal for austenitic stainless steels for all of the base metal, weld metal and cast stainless steel. In addition, the authors have confirmed that the employment of the proposed Fen equation to the proposed design fatigue curves of austenitic stainless steels accurately predicts the existing environmental fatigue test data of austenitic stainless steels, which were used in the development of the current Fen equation of austenitic stainless steels in PWR environments in the JSME Environmental Fatigue Evaluation Method. Therefore, the proposed Fen equation can be applied to environmental fatigue evaluation for austenitic stainless steels.

Failure Stresses for Pipes With Multiple Circumferential Flaws

2004 ◽  
Author(s):  
Kunio Hasegawa ◽  
Hideo Kobayashi
Keyword(s):  
Stainless Steel ◽  
Limit Load ◽  
Combination Rules ◽  
Steel Pipes ◽  
Ductile Materials ◽  
Asme Code ◽  
As Stress ◽  
Simple Equations ◽  
Service Inspection ◽  
Single Flaw

Flaw evaluation for fully-plastic fracture uses the limit load criterion. As stainless steels are high toughness ductile materials, limit load criterion is applicable to stainless steel pipes. When a single circumferential flaw is detected in a stainless steel pipe during in-service inspection, the single flaw is evaluated in accordance with Article EB-4000 in the JSME Code or Appendix C in the ASME Code, Section XI. However, multiple flaws such as stress corrosion cracking are sometimes detected in the same circumferential cress-section in a pipe. If the distance between adjacent flaws is short, the multiple flaws are considered as a single flaw in compliance with combination rules. Failure stress is easily calculated by the equations given by Article EB-4000 or Appendix C. If the two flaws are separated by a large distance, it is not required to combine the two flaws. Each flaw is treated as independent. However, there are no equations for evaluating collapse stress for a pipe containing multiple independent flaws in Article EB-4000 and Appendix C. The present paper focus on a proposal of simple equations for evaluating collapse stresses for pipes containing multiple circumferential part-through wall flaws.

Experimental Estimation of Fully Plastic Collapse Stresses for Pipes With Three Circumferential Flaws

2009 ◽  
Author(s):  
Fuminori Iwamatsu ◽  
Katsumasa Miyazaki ◽  
Koichi Saito ◽  
Kunio Hasegawa
Keyword(s):  
Stainless Steel ◽  
Limit Load ◽  
Theoretical Method ◽  
Failure Stress ◽  
Experimental Results ◽  
Past Study ◽  
Bending Tests ◽  
Steel Pipes ◽  
Four Point Bending ◽  
As Stress

Fully plastic failure stress for a single circumferential flaw on a pipe is evaluated by the limit load criteria in accordance with Appendix E-8 in the JSME S NA-1-2004 and Appendix C in the ASME Code Section XI. However, multiple flaws such as stress corrosion cracking are frequently detected in the same circumferential cross section in a pipe. Hasegawa had proposed failure stress for pipes with two and three circumferential flaws based on net-stress approach. Authors performed four-point bending tests on stainless steel pipes with two symmetrical circumferential flaws in a past study. It was concluded that the experimental results were in good agreement with the theoretical results. In this study, we performed quasi-static four-point bending tests on stainless steel pipes with three symmetrical circumferential flaws. Each experiment resulted in different fracture behavior. We compared the experimental results with the proposed theoretical method.

Prediction of Fully Plastic Collapse Stresses for Pipes With Two Circumferential Flaws

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Kunio Hasegawa ◽  
Koichi Saito ◽  
Fuminori Iwamatsu ◽  
Katsumasa Miyazaki
Keyword(s):  
Evaluation Method ◽  
Limit Load ◽  
304 Stainless Steel ◽  
Plastic Collapse ◽  
Combination Rules ◽  
Steel Pipes ◽  
Asme Code ◽  
As Stress ◽  
Type 304 ◽  
Type 304 Stainless Steel

Fully plastic collapse stress for a single circumferential flaw on a pipe is evaluated by the limit load criteria in accordance with the JSME Code S NA-1-2004 and the ASME Code Section XI. However, multiple flaws such as stress corrosion cracking are frequently detected in the same circumferential cross section in a pipe. If the distance between adjacent flaws is short, the two flaws are combined as a single flaw in compliance with combination rules. If the two flaws separated by a large distance, it is not required to combine two flaws. However, there is no evaluation method for two separated flaws in a pipe in the JSME and ASME Codes. Plastic collapse stresses for pipes with two symmetrical circumferential flaws based on net-stress approach had been proposed by one of the authors. Bending tests were performed on Type 304 stainless steel pipes with two symmetrical circumferential flaws. Consequently, it was shown that the proposed method can predict well the plastic collapse stresses for pipes with two flaws. In addition, it is also shown that this method is appropriate to use in fitness-for-service procedures, and higher plastic collapse stresses are expected, compared with current prediction methods for pipes with two flaws.

A limit load criterion to predict crack growth in stainless steel pipes

1992 ◽  
Vol 43 (5) ◽  
pp. 807-813 ◽  
Author(s):  
M.K. Kassir ◽  
C.H. Hofmayer ◽  
K.K. Bandyopadhyay
Keyword(s):  
Stainless Steel ◽  
Crack Growth ◽  
Limit Load ◽  
Steel Pipes

Development of EPFM Procedure for Axially Flawed Pipe Using Z Factor Based on CVN

2006 ◽  
Author(s):  
Kunio Hasegawa ◽  
Katsumasa Miyazaki ◽  
Naoki Miura ◽  
Koich Kashima ◽  
Douglas A. Scarth
Keyword(s):  
Fracture Mechanics ◽  
Ductile Fracture ◽  
Working Group ◽  
Limit Load ◽  
Evaluation Procedure ◽  
Empirical Equations ◽  
Shelf Energy ◽  
Evaluation Procedures ◽  
Asme Code ◽  
Semi Empirical

Evaluation procedures on an allowable axial flaw in a pipe for fully plastic fracture is provided by limit load criteria in Appendix C-5000 of the ASME Code Section XI. However, flaw evaluation for ductile fracture using EPFM (Elastic Plastic Fracture Mechanics) criteria is not provided for axial flaw in the Appendix. Methodology of the flaw evaluation for ductile fracture using EPFM criteria is discussing at the Working Group on Pipe Flaw Evaluation of ASME Code Section XI. Many failure experiments on axially flawed pressurized pipes made of moderate toughness materials had been performed at Battelle Columbus Laboratories. Semi-empirical equations for predicting failure stresses were developed from these experiments. This paper describes a derivation of load multiplier, Z factor, based on Charpy V notch upper shelf energy (CVN) from failure stresses for moderate toughness materials based on the experiments, and proposes a flaw evaluation procedure to determine allowable axial flaw for a ductile fractured pipe using the EPFM criteria.

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