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.

Flaw Evaluation Procedures and Acceptance Criteria for Nuclear Piping in ASME Code Section XI

2003 ◽  
Author(s):  
Douglas A. Scarth ◽  
Gery M. Wilkowski ◽  
Russell C. Cipolla ◽  
Sushil K. Daftuar ◽  
Koichi K. Kashima
Keyword(s):  
Fracture Mechanics ◽  
Nuclear Power ◽  
Limit Load ◽  
Acceptance Criteria ◽  
Linear Elastic ◽  
Evaluation Procedures ◽  
Piping Systems ◽  
Asme Code ◽  
American Society ◽  
Plant Evaluation

Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code provides rules and requirements for maintaining pressure boundary integrity of components, piping, and equipment during the life of a nuclear power plant. Evaluation procedures and acceptance criteria for the evaluation of flaws in nuclear piping in Section XI of the ASME Code were first published in 1983 and have been under revision for the past several years. This paper provides an overview of the procedures and acceptance criteria for pipe flaw evaluation in Section XI. Both planar and nonplanar flaws are addressed by Section XI. The evaluation procedures and acceptance criteria cover: failure by plastic collapse as characterized by limit load analysis; fracture due to ductile tearing prior to attainment of limit load, as characterized by elastic-plastic fracture mechanics (EPFM) analysis; and brittle fracture as characterized by linear elastic fracture mechanics (LEFM) analysis. A major revision to the evaluation procedures and acceptance criteria was published in the 2002 Addenda to Section XI. Evaluation procedures and acceptance criteria in the 2001 Edition, as well as the revisions in the 2002 Addenda, are described in this paper. Code Cases that address evaluation of wall thinning in piping systems, as well as temporary acceptance of flaws in moderate energy piping systems, are also described.

Validation of Pipe Flaw Evaluation Procedures in Section XI of the ASME Code Against Pipe Fracture Experiments

2004 ◽  
Author(s):  
Phuong H. Hoang ◽  
Gery M. Wilkowski
Keyword(s):  
Fracture Mechanics ◽  
Nuclear Power ◽  
Limit Load ◽  
Acceptance Criteria ◽  
Linear Elastic ◽  
Evaluation Procedures ◽  
Asme Code ◽  
Elastic Fracture ◽  
American Society ◽  
Plant Evaluation

Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code provides rules and requirements for maintaining pressure boundary integrity of piping during the life of a nuclear power plant. Evaluation procedures and acceptance criteria for the evaluation of flaws in nuclear piping in Section XI of the ASME Code were first published in 1983 and have been under revision for the past several years. The evaluation procedures and acceptance criteria cover: failure by plastic collapse as characterized by limit load analysis; fracture due to ductile tearing prior to attainment of limit load, as characterized by elastic-plastic fracture mechanics (EPFM) analysis; and brittle fracture as characterized by linear elastic fracture mechanics (LEFM) analysis. A major revision to the evaluation procedures and acceptance criteria was published in the 2002 Addenda to Section XI. A brief overview of the pipe flaw evaluation procedures published in the 2002 Addenda are provided in the paper. The evaluation procedures that were published in the 2002 Addenda have been validated against the results of a large number of pipe fracture experiments. The results of this validation exercise are summarized in this paper.

Technical Basis of Proposed New Acceptance Standards for Class 1, 2 and 3 Piping

2007 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Kunio Hasegawa ◽  
Naoki Miura ◽  
Koichi Kashima ◽  
Douglas A. Scarth
Keyword(s):  
Fracture Mechanics ◽  
Ultrasonic Inspection ◽  
Limit Load ◽  
Flaw Size ◽  
High Fracture Toughness ◽  
Evaluation Procedure ◽  
High Fracture ◽  
Development Methodology ◽  
Class 1 ◽  
Technical Basis

Acceptance Standards in Section XI of the ASME Boiler and Pressure Vessel Code have an important role as the first step in the flaw evaluation procedure. When a flaw size is within the allowable flaw size in the Acceptance Standard, the flaw is acceptable and analytical evaluation is not required. Although ASME Section XI has Acceptance Standards for Class 1 piping in IWB-3500, there are no Acceptance Standards for Class 2 and 3 piping. Furthermore, the development of the current Acceptance Standards for Class 1 piping was based on flaw detectability by ultrasonic inspection and consideration of fracture mechanics. In this paper, the development of proposed new Acceptance Standards for Class 2 and 3 piping, as well as for Class 1 piping, is described. The development methodology is based on a fracture mechanics approach. For Class 1 piping with high fracture toughness, the allowable flaw sizes were determined by limit load solution. For Class 1 piping, the intent was to maintain overall consistency with the current Acceptance Standards. Proposed Acceptance Standards for Class 2 and 3 austenitic piping were also developed by the methodology used to develop the proposed new Acceptance Standards for Class 1 piping. Allowable flaw sizes for both surface flaws and subsurface flaws for preservice and inservice examinations were developed.

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.

An Improvement in the Code Evaluation of Flawed Pipes

2007 ◽  
Author(s):  
Amy J. Smith ◽  
Keshab K. Dwivedy
Keyword(s):  
Stainless Steel ◽  
Fracture Mechanics ◽  
Base Material ◽  
Limit Load ◽  
Evaluation Methodology ◽  
Linear Elastic ◽  
Weld Material ◽  
Steel Base ◽  
Asme Code ◽  
Elastic Fracture

ASME Code Section XI Nonmandatory Appendix C [1] formalized evaluation of flaws in piping for justification of continued service of piping components with an identified crack-like flaw. The revision of this appendix in 2004 was a significant improvement in the evaluation methodology for both flawed austenitic stainless steel and ferritic steel pipe depending upon the failure mode governed by limit load (fully plastic), elastic-plastic fracture mechanics, or linear elastic fracture mechanics. The appendix also provides a screening procedure to determine failure mechanism and a procedure for flaw modeling based on the estimated flaw size at the end of a specified evaluation period. The purpose of this paper is to propose an improvement to the limit load method applicable to screened-in carbon steel, wrought stainless steel base material, stainless steel weld material with nonflux weld, and cast products in which the ferrite content is less than twenty percent. In addition, changes in the formulation are proposed to extend the methodology to non-crack-like flaws. Both crack-like and non-crack-like circumferential flaws in the piping are analyzed to simplify formulation for flaw evaluation. The paper concludes that the proposed formulation improves efficiency of the application of Appendix C methodology for crack-like flaw and non-crack-like flaw evaluations.

Flaw Proximity Rules for Parallel Planar Flaws Under Limit Load Conditions

2005 ◽  
Author(s):  
Sam Ranganath ◽  
Bob Carter ◽  
Francis Ku ◽  
Marcos Herrera
Keyword(s):  
Fracture Mechanics ◽  
Test Data ◽  
Limit Load ◽  
Linear Elastic ◽  
Parallel Cracks ◽  
Asme Code ◽  
Elastic Fracture ◽  
Load Analysis ◽  
Load Conditions ◽  
Reactor Internals

This paper describes the evaluation of adjacent cracks (including parallel cracks in different planes) from a limit load perspective. The proposed approach complements the current ASME Code rules that are largely based on linear elastic fracture mechanics considerations. The evaluation considers limit load analysis and is validated by comparison with test data. In particular the paper provides criteria to determine load capability of structures with offset cracks in parallel planes. The objective of the work was to provide criteria for the evaluation of reactor internals, but the results can be applied to evaluate cracking in ductile pressure boundary piping also.

Determination of the Elastic-Plastic Fracture Mechanics Z-Factor for Alloy 182 Weld Metal Flaws for Use in the ASME Section XI Appendix C Flaw Evaluation Procedures

2007 ◽  
Author(s):  
G. Wilkowski ◽  
H. Xu ◽  
D.-J. Shim ◽  
D. Rudland
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Weld Metal ◽  
Alloy Steel ◽  
Limit Load ◽  
Full Scale ◽  
Low Alloy Steel ◽  
Evaluation Procedures ◽  
Estimation Scheme ◽  
J Estimation

One of the ways that the ASME Section XI code incorporates elastic-plastic fracture mechanics (EPFM) in the Section XI Appendix C flaw evaluation procedures for circumferential cracks is through a parameter called Z-factor. This parameter allows the simpler limit-load (or net-section-collapse) solutions to be used with a multiplier from EPFM analyses. Traditionally the EPFM solution was determined by using the GE-EPRI J-estimation scheme to determine the maximum load by EPFM, and Z = limit load / EPFM solution. The Z-factor is a function of the material toughness as well as the pipe diameter. With the advent of primary water stress-corrosion cracks (PWSCC) in pressurized water reactor (PWR) dissimilar metal welds (DMW), there is a need to develop Z-factors for Alloy 82/182 nickel-based alloy welds that are susceptible to such cracks. Although there have been Z-factor solutions for cracks in stainless and ferritic pipe butt welds, the DMW are somewhat different in that there is a much lower yield strength material on one side of the weld (typically forged or wrought 304 stainless steel) and on the other side of the weld the low alloy steel has a much higher strength than even the weld metal. This paper shows how 3D finite element analyses were used for a particular pipe size to determine the sensitivity of the crack location in the Alloy 182 weldment (crack in the center of weld, or closer to the stainless or low alloy steel sides), and how an appropriate stress-strain curve was determined for use in the J-estimation schemes. A Z-factor as a function of the pipe diameter was then calculated using the LBB.ENG2 J estimation scheme using the appropriate stress-strain curves from the finite element analysis. The LBB.ENG2 analysis was used rather than the GE-EPRI estimation scheme since it has been found that the LBB.ENG2 analysis is more accurate when compared with full-scale pipe tests. From past work, the GE-EPRI method was found to be the most conservative of the J-estimation schemes in predicting the maximum loads for circumferential flaws when compared to full-scale circumferentially cracked-pipe tests. The proposed Z-factor relationship should be restricted to normal operating temperatures (above 200C) with low H2 concentrations, where the Alloy 182 weld metal exhibits high toughness.

Sensitivity Analysis of Crack Shape on Screening Parameter in JSME FFS Rules for Nuclear Power Plants

2017 ◽  
Author(s):  
Naoki Miura ◽  
Kiminobu Hojo
Keyword(s):  
Sensitivity Analysis ◽  
Fracture Mechanics ◽  
Surface Crack ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Limit Load ◽  
Evaluation Procedure ◽  
Crack Shape ◽  
Screening Parameter

In the 2012 version of the JSME Fitness-for-Service Rules for Nuclear Power Plants, the procedure to calculate screening parameter, SC, which is used for selecting the analysis method (limit load controlled by plastic collapse, elastic-plastic fracture mechanics, or linear elastic fracture mechanics), has been revised to reflect a semi-elliptical surface crack. Both limit load solution and stress intensity factor solution are needed to calculate SC, and the solutions for a semi-elliptical surface crack are different from those for a fan-shape surface crack. In this study, the effect of the difference in crack shape on SC is investigated. Through the results on the sensitivity analysis, the adequacy of the evaluation procedure of SC is ascertained.

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.

Ultrasonic Evaluation of "Silent Regions" in the Thyroid Scintiscan

1978 ◽  
Vol 17 (01) ◽  
pp. 16-23 ◽  
Author(s):  
Ch. L. Zollikofer ◽  
J. Wewerka ◽  
Th. Frank
Keyword(s):  
Needle Biopsy ◽  
Clinical Course ◽  
Stimulation Test ◽  
Evaluation Procedure ◽  
Sonographic Diagnosis ◽  
Non Invasive ◽  
Evaluation Procedures ◽  
Ultrasonic Evaluation ◽  
Invasive Evaluation ◽  
Autonomous Adenoma

35 patients with scintigraphically silent thyroid regions without palpable cold nodules were further evaluated by ultrasonography. In 33 cases the sonographic diagnosis was confirmed by other examinations or the clinical course. 2 cases were misinterpreted right at the beginning of our series.The use of ultrasonography in evaluating silent thyroid regions in the totally decompensated autonomous adenoma, in unilateral thyroid aplasia, thyroiditis and hyperthyroidism is shown to be a reliable and valuable supplement to the clinical and radioisotopic evaluation procedures. When differentiating the totally decompensated autonomous adenoma from unilateral thyroid aplasia a stimulation test need not be performed in most cases. Suspected thyroiditis can be confirmed in a simple way. Being a non-invasive evaluation procedure, ultrasonography should be used before performing a needle biopsy.

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