Technical Basis for Flaw Acceptance Criteria for Cast Austenitic Stainless Steel Piping

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Do Jun Shim ◽  
Nathanial Cofie ◽  
Dilipkumar Dedhia ◽  
Tim Griesbach ◽  
Kyle Amberge
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Evaluation Procedure ◽  
Correction Factors ◽  
Acceptance Criteria ◽  
Regulatory Guidance ◽  
Asme Code ◽  
Tensile Data ◽  
Equivalent Factor ◽  
Technical Basis

Abstract According to the current ASME Code Section XI, IWB-3640 and Appendix C flaw evaluation procedure, cast austenitic stainless steel (CASS) piping with ferrite content (FC) less than 20% is treated as wrought stainless steel. For CASS piping with FC equal or greater than 20%, there was no flaw evaluation procedure in the ASME Code prior to the 2019 Edition. In this paper, the technical basis for the recently approved Code change containing flaw acceptance criteria for CASS piping is presented. The procedure utilizes the current rules in ASME Code Section XI, IWB 3640/Appendix C and the existing elastic-plastic correction factors (i.e., Z-factors) for other materials in the Code. The appropriate Z-factor to use for the CASS piping is determined based on the FC (using Hull's equivalent factor). Experimentally measured fully saturated fracture toughness and tensile data of the three most common grades of CASS material in the U.S. (CF3, CF8, and CF8M) were used to determine the flaw acceptance criteria in the Appendix C Code method. As described here, the method is conservative since it utilizes the fully saturated condition of CASS materials. In addition, it is simple and consistent with the current regulatory guidance on aging management of CASS piping.

Technical Basis for Flaw Acceptance Criteria for Cast Austenitic Stainless Steel Piping

2017 ◽  
Author(s):  
D. J. Shim ◽  
N. G. Cofie ◽  
D. Dedhia ◽  
D. O. Harris ◽  
T. J. Griesbach ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ferrite Content ◽  
Evaluation Procedure ◽  
Acceptance Criteria ◽  
Regulatory Guidance ◽  
The Us ◽  
Asme Code ◽  
Tensile Data ◽  
Technical Basis

According to the current ASME Code Section XI, IWB-3640 and Appendix C flaw evaluation procedure, cast austenitic stainless steel (CASS) piping with ferrite content less than 20% is treated as wrought stainless steel. For CASS piping with ferrite content equal or greater than 20%, there is currently no flaw evaluation procedure in the ASME Code. In this paper, the technical basis for a proposed flaw acceptance criteria for CASS piping is presented. The procedure utilizes the current rules in ASME Code Section XI, IWB 3640/Appendix C and the existing elastic-plastic correction factors (i.e., Z-factors) for other materials in the Code. The appropriate Z-factor to use for the CASS piping is determined based on the ferrite content (using Hull’s equivalent factor). Experimentally measured fully saturated fracture toughness and tensile data of the three most common grades of CASS material in the US (CF3, CF8 and CF8M) were used to determine the flaw acceptance criteria in the proposed method. The proposed method is conservative since it utilizes the fully saturated condition of CASS materials. In addition, it is simple and consistent with current regulatory guidance on aging management of CASS piping.

Development of Analytical Evaluation Procedures and Acceptance Criteria for Pipe Wall Thinning in ASME Code Section XI

2004 ◽  
Author(s):  
Kunio Hasegawa ◽  
Gery M. Wilkowski ◽  
Lee F. Goyette ◽  
Douglas A. Scarth
Keyword(s):  
Pipe Wall ◽  
Evaluation Methodology ◽  
Current Status ◽  
Evaluation Procedure ◽  
Analytical Evaluation ◽  
Acceptance Criteria ◽  
New Class ◽  
Wall Thinning ◽  
Class 1 ◽  
Asme Code

As the worldwide fleet of nuclear power plants ages, the need to address wall thinning in pressure boundary materials becomes more acute. The 2001 ASME Code Case N-597-1, “Requirements for Analytical Evaluation of Pipe Wall Thinning,” provides procedures and criteria for the evaluation of wall thinning that are based on Construction Code design concepts. These procedures and criteria have proven useful for Code Class 2 and 3 piping; but, they provide relatively little flexibility for Class 1 applications. Recent full-scale experiments conducted in Japan and Korea on thinned piping have supported the development of a more contemporary failure strength evaluation methodology applicable to Class 1 piping. The ASME B&PV Code Section XI Working Group on Pipe Flaw Evaluation has undertaken the codification of new Class 1 evaluation methodology, together with the existing Code Case N-597-1 rules for Class 2 and 3 piping, as a non-mandatory Appendix to Section XI. This paper describes the current status of the development of the proposed new Class 1 piping acceptance criteria, along with a brief review of the current Code Case N-597-1 evaluation procedure in general.

Technical Basis for Proposed Fifth Revision to ASME Code Case N-513

2018 ◽  
Author(s):  
Dylan Cimock ◽  
Eric J. Houston ◽  
Russell C. Cipolla ◽  
Robert O. McGill
Keyword(s):  
Gate Valve ◽  
Evaluation Procedure ◽  
Straight Pipe ◽  
System Operation ◽  
Short Term ◽  
Valve Body ◽  
Safety Issues ◽  
Asme Code ◽  
Moderate Energy ◽  
Technical Basis

Code Case N-513 provides evaluation rules and criteria for temporary acceptance of flaws, including through-wall flaws, in moderate energy piping. The application of the Code Case is restricted to moderate energy, Class 2 and 3 systems, so that safety issues regarding short-term, degraded system operation are minimized. The first version of the Code Case was published in 1997. Since then, there have been four revisions to augment and clarify the evaluation requirements and acceptance criteria of the Code Case that have been published by ASME. The technical bases for the original version of the Code Case and the four revisions have been previously published [1, 2, and 3]. There is currently work underway to incorporate additional changes to the Code Case and this paper provides the technical basis for the changes proposed in a fifth revision. These changes include clarification for buried piping, investigation of various radii used in the Code Case, removal of the 0.1 limit on the flexibility characteristic for elbow flaw evaluation, and an update of the stress intensity factor parameters for circumferential through-wall flaws. In addition, a new flaw evaluation procedure is given for through-wall flaws in gate valve body ends. This procedure evaluates flaws in the end of the valve body as if in straight pipe. These changes and their technical bases are described in this paper. Clarifications and changes deemed editorial are not documented in this paper.

Capabilities of Ultrasonic Phased Arrays for Far-Side Examinations of Austenitic Stainless Steel Piping Welds

2006 ◽  
Author(s):  
Michael T. Anderson ◽  
Stephen E. Cumblidge ◽  
Steven R. Doctor
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Phased Array ◽  
Fatigue Cracks ◽  
Welding Parameters ◽  
Circumferential Welds ◽  
Array Technology ◽  
Asme Code ◽  
Ultrasonic Techniques ◽  
Performance Demonstration

A study was conducted to assess the ability of advanced ultrasonic techniques to detect and accurately determine the size of flaws from the far-side of wrought austenitic piping welds. Far-side inspections of nuclear system austenitic piping welds are currently performed on a “best effort” basis and do not conform to ASME Code Section XI Appendix VIII performance demonstration requirements for near side inspection. For this study, four circumferential welds in 610mm (24inch) diameter, 36mm (1.42inch) thick ASTM A-358, Grade 304 vintage austenitic stainless steel pipe were examined. The welds were fabricated with varied welding parameters; both horizontal and vertical pipe orientations were used, with air and water backing, to simulate field welding conditions. A series of saw cuts, electro-discharge machined (EDM) notches, and implanted fatigue cracks were placed into the heat affected zones of the welds. The saw cuts and notches ranged in depth from 7.5% to 28.4% through-wall. The implanted cracks ranged in depth from 5% through-wall to 64% through-wall. The welds were examined with phased array technology at 2.0 MHz, and compared to conventional ultrasonic techniques as a baseline. The examinations showed that phased-array methods were able to detect and accurately length-size, but not depth size, the notches and flaws through the welds. The ultrasonic results were insensitive to the different welding techniques used in each weld.

Study on Hydrogen Compatibility of S31603 Weld Joints in 98MPa Gaseous Hydrogen

2018 ◽  
Author(s):  
Qi He ◽  
Zhengli Hua ◽  
Jinyang Zheng
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Gaseous Hydrogen ◽  
Weld Joints ◽  
Secondary Cracks ◽  
Fracture Behaviors ◽  
Tensile Data ◽  
Fracture Features ◽  
Pressure Hydrogen

Austenitic stainless steel of the 300 series and their welds are widely employed in the production, storage and distribution infrastructures of gaseous and liquid hydrogen. However, hydrogen compatibility of their welds has not been completely understood, especially in high-pressure hydrogen environment. In this study, the influence of 98MPa high pressure gaseous hydrogen on the tensile properties and fracture behaviors of three kinds of S31603 weld joints were investigated, including SMAW, SAW and TIG welds. The tensile data indicated that hydrogen caused the ductility loss of the SAW and TIG weld joints, particularly for the TIG welds. For the SMAW weld joints, hydrogen had little impact on its ductility. Fractographic analysis revealed that hydrogen scarcely induced a change in the fracture mode of the SMAW welds. Different from this, the SAW and TIG welds were found to exhibit an obvious susceptibility to hydrogen embrittlement in this study, particularly for the TIG welds, based on the change of fracture features from dimples to facets, striations and secondary cracks. Additionally, both fracture surfaces of the SMAW and SAW welds contained some inclusions where the secondary cracks were promoted.

The Background to Light Water Reactor Environment Fatigue Evaluation Methods for Austenitic Stainless Steel and Their Application to Sample Pressurised Water Reactor Components

2011 ◽  
Author(s):  
C. T. Watson
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Test Data ◽  
Cylindrical Specimen ◽  
Fatigue Curve ◽  
Light Water Reactor ◽  
Light Water ◽  
Water Reactor ◽  
Specimen Test ◽  
Asme Code

There is now a large amount of small cylindrical specimen test data, which indicates that in a Light Water Reactor (LWR) environment, compared to that in air, the fatigue life of stainless steel is significantly reduced. The current ASME III design fatigue curve does not explicitly include factors to account for a LWR environment. Using the available cylindrical specimen test data, methods for accounting for a LWR environment in fatigue assessments have been proposed in NuReg/CR-6909 and in two American Society of Mechanical Engineers (ASME) code cases. One of the code cases (N-792) uses a penalty factor (Fen) approach, similar to that in NuReg/CR-6909, another (N-761) utilizes a set of environmentally corrected fatigue curves. A third code case, which is still under development, uses a flaw tolerance approach. In this paper the background to the methods for correcting for a LWR environment in fatigue calculations is presented. The safety margin present in the ASME fatigue design methodology is discussed and a short review of civil nuclear plant operating and geometrical features testing experience provided. The NuReg/CR-6909 and ASME code case N-761 methods are applied to a number of ASME III Class 1 austenitic stainless steel components, and the cumulative usage factors calculated compared with those obtained using the ASME 2007 design fatigue curve. An objective of the paper is to highlight some of the issues arising out of applying the newly proposed methods to reactor plant components.

Introduction of JSME Rules on Fitness for Service for CASS Piping and Proposal for Improvements

2013 ◽  
Author(s):  
Kiminobu Hojo ◽  
Masayuki Kamaya
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Brittle Fracture ◽  
Nuclear Power ◽  
Power Plants ◽  
Failure Modes ◽  
Limit Load ◽  
Evaluation Procedure ◽  
Japan Society ◽  
Two Parameter

The Japan Society of Mechanical Engineers (JSME) Code Rules on Fitness for Service (FFS) for Nuclear Power Plants describe a flaw evaluation procedure for stainless steel piping including cast austenitic stainless steel (CASS) piping. It consists of three methods; limit load, elastic plastic fracture mechanics (EPFM) and two-parameter (covering failure modes from brittle fracture to limit load) methods. This paper describes a brief introduction of the flaw evaluation procedure for CASS piping in the JSME rules. Some improvements for the current rules are also proposed.

Environmental Fatigue Factors (NUREG/CR-6909) and Strain Controlled Data for Stabilized Austenitic Stainless Steel

2013 ◽  
Author(s):  
Jussi Solin ◽  
Sven Reese ◽  
H. Ertugrul Karabaki ◽  
Wolfgang Mayinger
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Slow Rate ◽  
Laboratory Data ◽  
Fatigue Tests ◽  
Hot Water ◽  
Fatigue Performance ◽  
Evaluation Procedure ◽  
Long Life ◽  
First Time

Experimental research on fatigue performance of niobium stabilized stainless steel (1.4550, X6CrNiNb1810 mod) relevant for German NPP primary piping has previously demonstrated good long life performance. Slow rate fatigue tests in 325 °C PWR water are first time presented and discussed in this paper. Good fatigue performance was measured also in hot water. Our experiments give consistently about doubled lives or 50% smaller Fen factors in compared to predictions by NUREG 6909. Transferability of the laboratory data, reference and design curves together with the proposed Fen evaluation procedure to component evaluation will be discussed.

Ultrasonic Phased Array Evaluations of Implanted and In-Situ Grown Flaws in Cast Austenitic Stainless Steel Pressurizer Surge Line Piping

2011 ◽  
Author(s):  
Susan L. Crawford ◽  
Anthony D. Cinson ◽  
Traci L. Moran ◽  
Matthew S. Prowant ◽  
Aaron A. Diaz ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Phased Array ◽  
Fatigue Cracks ◽  
Base Material ◽  
Pacific Northwest National Laboratory ◽  
Asme Code ◽  
Ultrasonic Phased Array ◽  
Surge Line

A set of circumferentially oriented thermal fatigue cracks (TFCs) were implanted into three cast austenitic stainless steel (CASS) pressurizer (PZR) surge-line specimen welds (pipe-to-elbow configuration) that were salvaged from a U.S. commercial nuclear power plant that had not been operated. Thus, these welds were fabricated using vintage CASS materials that were formed in the 1970s. Additionally, in-situ grown TFCs were placed in the adjacent CASS base material of one of these specimens. Ultrasonic phased-array responses from both types of flaws (implanted and in-situ grown) were analyzed for detection and characterization based on sizing and signal-to-noise determination. Multiple probes were employed covering the 0.8 to 2.0 MHz frequency range. To further validate the Pacific Northwest National Laboratory (PNNL) findings, an independent in-service inspection (ISI) supplier evaluated the flaws with their American Society of Mechanical Engineers (ASME) Code, Section XI, Appendix VIII-qualified procedure. The results obtained by PNNL personnel compared favorably to the ISI supplier results. All examined flaws were detected and sized within the ASME Code-allowable limits.

Some aspects of the defect structure in an austenitic stainless steel

1978 ◽  
Vol 36 (1) ◽  
pp. 314-315
Author(s):  
R. Gonzalez ◽  
L. Bru
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cellular Structures ◽  
Total Strain Amplitude ◽  
Total Deformation ◽  
Density Of Dislocations ◽  
Planar Arrays ◽  
Stacking Fault Tetrahedra ◽  
Distribution Of Dislocations ◽  
Very High

The analysis of stacking fault tetrahedra (SFT) in fatigued metals (1,2) is somewhat complicated, due partly to their relatively low density, but principally to the presence of a very high density of dislocations which hides them. In order to overcome this second difficulty, we have used in this work an austenitic stainless steel that deforms in a planar mode and, as expected, examination of the substructure revealed planar arrays of dislocation dipoles rather than the cellular structures which appear both in single and polycrystals of cyclically deformed copper and silver. This more uniform distribution of dislocations allows a better identification of the SFT.The samples were fatigue deformed at the constant total strain amplitude Δε = 0.025 for 5 cycles at three temperatures: 85, 293 and 773 K. One of the samples was tensile strained with a total deformation of 3.5%.

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