Assessment Procedure for Multiple Crack-Like Flaws in Fracture Assessment Diagram (FAD)

2008 ◽  
Author(s):  
Shinji Konosu
Keyword(s):  
Body Force ◽  
Pressure Vessels ◽  
The Body ◽  
Assessment Procedure ◽  
Multiple Crack ◽  
Reference Stress ◽  
Discrete Crack ◽  
Fracture Assessment ◽  
Common Problems ◽  
Shielding Effects

Assessment of multiple discrete crack-like flaws is one of the most common problems relating to pressure vessels and piping components. Under the current Fitness for Service (FFS) rules, such as ASME, BS and so on, multiple crack-like flaws are usually recharacterized as an enveloping crack (defined as a single larger crack), following their assessment rules. The procedure, however, varies significantly in these FFS codes. In this paper, the interaction between non-aligned multiple unequal cracks is clarified by applying the body force method. Based on the interaction which indicates the magnification and shielding effects and the reference stress solutions, a newly developed assessment procedure for multiple discrete crack-like flaws in the Fracture Assessment Diagram (FAD) is proposed.

Assessment Procedure for Multiple Volumetric Flaws (LTAs) in p-M Diagram

2008 ◽  
Author(s):  
Shinji Konosu
Keyword(s):  
Body Force ◽  
Pressure Vessels ◽  
The Body ◽  
Assessment Procedure ◽  
Multiple Crack ◽  
Force Method ◽  
Reference Stress ◽  
Body Force Method ◽  
Common Problems ◽  
Shielding Effects

Assessment of multiple volumetric flaws (LTAs) is one of the most common problems relating to pressure vessels and piping components. Under the current Fitness for Service (FFS) rules, such as ASME, BS and so on, multiple volumetric flaws are usually recharacterized as an enveloping volumetric flaw (defined as a single larger volumetric flaw) as well as multiple crack-like flaws, following their assessment rules. However, the rules proposed in their codes will not often agree and their justification is unknown. Furthermore, they can provide unrealistic assessment in some cases. In this paper, the interaction between two different sized non-aligned volumetric flaws such as local thin areas (LTAs) is clarified by applying the body force method. Unlike multiple crack-like flaws, the effect of biaxial stresses on the interaction is evident. Based on the interaction which indicates the magnification and shielding effects and reference stress solutions, a new procedure for multiple volumetric flaws is proposed for assessing the flaws in the p-M (pressure-moment) Diagram, which is a simple assessment procedure for vessels with LTAs.

Assessment Procedure for Multiple Volumetric Flaws in p-M Diagram

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Shinji Konosu
Keyword(s):  
Body Force ◽  
Pressure Vessels ◽  
The Body ◽  
Assessment Procedure ◽  
Force Method ◽  
Reference Stress ◽  
Body Force Method ◽  
Common Problems ◽  
Shielding Effects

Assessment of multiple volumetric flaws is one of the most common problems relating to pressure vessels and piping components. Under the current fitness for service rules, such as ASME, BS, and so on, multiple volumetric flaws are usually recharacterized as an enveloping volumetric flaw (defined as a single larger volumetric flaw) as well as multiple cracklike flaws, following their assessment rules. However, the rules proposed in their codes will not often agree and their justification is unknown. Furthermore, they can provide unrealistic assessment in some cases. In this paper, the interaction between two differently sized nonaligned volumetric flaws such as local thin areas is clarified by applying the body force method. Unlike multiple cracklike flaws, the effect of biaxial stresses on the interaction is evident. Based on the interaction that indicates the magnification and shielding effects and reference stress solutions, a new procedure for multiple volumetric flaws is proposed for assessing the flaws in the p-M (pressure-moment) diagram, which is a simple assessment procedure for vessels with volumetric flaws.

Assessment Procedure for Multiple Cracklike Flaws in Failure Assessment Diagram (FAD)

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Shinji Konosu
Keyword(s):  
Body Force ◽  
Pressure Vessels ◽  
The Body ◽  
Assessment Procedure ◽  
Failure Assessment Diagram ◽  
Reference Stress ◽  
Body Force Method ◽  
Failure Assessment ◽  
Common Problems ◽  
Shielding Effects

Assessment of multiple discrete cracklike flaws is one of the most common problems relating to pressure vessels and piping components. Under the current fitness for service (FFS) rules, such as ASME, BS, and so on, multiple cracklike flaws are usually recharacterized as an enveloping crack (defined as a single larger crack), following their assessment rules. The procedure, however, varies significantly in these FFS codes. In this paper, the interaction between nonaligned multiple unequal cracks is clarified by applying the body force method. Based on the interaction that indicates the magnification and shielding effects and the reference stress solutions, a newly developed assessment procedure for multiple discrete cracklike flaws in the failure assessment diagram is proposed.

Fracture Assessment of Through-Wall and Surface Cracked Pipes by BS 7910 and API 579 Assessment Procedures: A Comparative Study

2004 ◽  
Author(s):  
Afshin K. Motarjemi
Keyword(s):  
Experimental Data ◽  
Comparative Study ◽  
Pressure Vessels ◽  
Plastic Collapse ◽  
Four Point Bending ◽  
Reference Stress ◽  
Fracture Assessment ◽  
Pipe Geometry ◽  
Assessment Procedures ◽  
The Comparative Study

Fracture assessment procedures such as BS 7910 and API 579 are formulated based on the Fracture Mechanics concept for assessing integrity of structures such as pipelines, pressure vessels, etc. In the current study those procedures are applied to through-wall and surface cracked pipe geometry under four-point bending. The predicted maximum tolerable applied loads are then compared with pipe full-scale fracture testing results published by Miura et al (2002). Other assessment schemes namely, GE/EPRI, Net-section plastic collapse, LBB.NRC and finally LBB.ENG2, as reported in the same publication are also included in the current paper for sake of comparison. The comparative study showed that BS 7910 and API 579 predict similar maximum tolerable load for through-wall pipes but different value for surface-cracked pipes. Difference in predictions for the latter geometry is owing to the use of different stress intensity factor/reference stress solution by BS 7910 than API 579. However, both procedures provided conservative results compared with the experimental data as well as other engineering routes mentioned in Miura et al (2002).

Development and validation of a leak before break criterion for cylindrical pressure vessels

2015 ◽  
Vol 231 (3) ◽  
pp. 285-296 ◽  
Author(s):  
P Kannan ◽  
KS Amirthagadeswaran ◽  
T Christopher
Keyword(s):  
Pressure Vessels ◽  
Assessment Procedure ◽  
Operating Pressure ◽  
Plant Operator ◽  
Process Plants ◽  
Fracture Assessment ◽  
Fail Safe ◽  
Development And Validation ◽  
Leak Before Break ◽  
Two Parameter

Leak before break is a fail–safe design concept for application in pressure vessels and piping of power and process plants. A quantitative maximum allowable flaw size is required to establish to set acceptance/rejection limit to predict whether the specific cracked pipe will leak or break. A new modification and its boundary based on Modified Two Parameter Fracture Criterion is capable of separating the leak and break cases distinctly in order to predict the behavior of cracked cylinders, pipelines and pressure vessels in advance for taking necessary precautions by the plant operator and also very much handy for the designers. For the given operating pressure under the observed crack dimensions, whether the crack will leak or break can be assessed from the boundary generated for the material concerned using Modified Two Parameter fracture assessment procedure.

The Future of the BS 7910 Flaw Assessment Procedures

2010 ◽  
Author(s):  
Isabel Hadley ◽  
Bob Ainsworth ◽  
Peter Budden ◽  
John Sharples
Keyword(s):  
Weld Strength ◽  
Assessment Procedure ◽  
Metallic Structures ◽  
Damage And Failure ◽  
Reference Stress ◽  
Fracture Assessment ◽  
Crack Tip Constraint ◽  
The Uk ◽  
Assessment Procedures ◽  
Industry Sectors

BS 7910, the UK procedure for the assessment of flaws in metallic structures, was first published some 30 years ago in the form of a fracture/fatigue assessment procedure, PD6493. Since then it has been regularly maintained and expanded, taking in elements of other publications such as the UK power industry’s ‘R6’ procedure (in particular the Failure Assessment Diagram or FAD approach), the creep assessment procedure PD6539 and the UK gas transmission industry’s approach to corrosion assessment of locally thinned areas in pipelines. Work is currently underway to prepare another major revision, this time incorporating many elements of the European flaw assessment procedure FITNET. Like its predecessor, the new BS 7910 is intended for use by a range of industry sectors for virtually any type of metallic structure or component. The procedures will cover damage and failure by fatigue crack growth, fracture, creep and corrosion, including Environmentally Assisted Corrosion. The objective in revising the procedures is to support the use of more advanced assessment methods, whilst preserving compatibility with previous editions of BS 7910 and retaining methods for preliminary analyses based on simple, conservative inputs. Features of the new BS 7910 will include adoption of new advanced fracture assessment procedures (taking account of crack tip constraint and weld strength mismatch where appropriate), revision of the residual stress annex, preparation of a new annex covering guidance on NDE, an enhanced library of K-solutions and reference stress solutions and greater compatibility with procedures such as R6 and FITNET.

Assessment of Overlapped Internal and External Volumetric Flaws in p-M Method

2009 ◽  
Author(s):  
Shinji Konosu ◽  
Hikaru Miyata
Keyword(s):  
Pressure Vessels ◽  
Assessment Procedure ◽  
Diagram Method ◽  
Common Problems ◽  
Good Agreement

Assessment of overlapped internal and external volumetric flaws is one of the most common problems relating to pressure vessels and piping components. Under the current Fitness for Service (FFS) rules, such as ASME, BS and so on, the procedures have not yet defined how to assess these flaws. In this paper, a new procedure for these volumetric flaws is proposed for assessing the flaws by the p-M (pressure-moment) diagram method, which is a simple assessment procedure. Numerous FEAs for a cylinder with overlapped internal and external flaws were conducted to verify the proposed procedure. There is good agreement among them.

Study on Sufficiency of Reference Stress Solutions for Crack-Like Flaws for Fitness-for-Service Evaluation

2019 ◽  
Vol 795 ◽  
pp. 424-431
Author(s):  
Naoki Miura ◽  
Kenji Oyamada
Keyword(s):  
Service Evaluation ◽  
Pressure Vessels ◽  
Assessment Procedure ◽  
Storage Tanks ◽  
Structural Components ◽  
Reference Stress ◽  
Surface Flaws ◽  
Additional Reference ◽  
Level 2 ◽  
Service Inspection

High Pressure Institute of Japan (HPI) has instituted the industrial standard HPIS Z101-2, “Assessment Procedure for Crack-Like Flaws in Pressure Equipment ‒ Level 2,” which addresses the methodology for the evaluation of fitness-for-service for detected flaws in industrial structural components such as pressure vessels, pipes, storage tanks, etc. during in-service inspection. In the standard, reference stress solutions for fundamental structures with surface flaws are prepared for the assessment of the acceptability of the detected flaws. From the viewpoint of the comprehensiveness of available solutions for excessive conditions, additional reference stress solutions for long surface flaw in plate, axially through-wall flaw in cylinder, circumferentially through-wall flaw in cylinder, and through-wall flaw in sphere were required. In this paper, the appropriate reference stress solutions to be adopted for the above structures were investigated by comparing the existing solutions in referable codes/standards.

Stress-Intensity Factors for an Internal Semi-Elliptical Surface Crack in Cylindrical Pressure Vessels

1995 ◽  
Vol 117 (3) ◽  
pp. 213-221 ◽  
Author(s):  
D.-H. Chen ◽  
H. Nisitani ◽  
K. Mori
Keyword(s):  
Surface Crack ◽  
Body Force ◽  
Crack Problem ◽  
Pressure Vessels ◽  
The Body ◽  
Intensity Factors ◽  
Infinite Body ◽  
Force Method ◽  
Body Force Method ◽  
Point Forces

In this paper, the surface crack problem in a cylinder subjected to internal pressure is solved. The analysis is based on the body force method, but it is different from the conventional body force method in the following point. That is, the body forces to be distributed continuously on the assumed boundaries in an infinite body are approximated by some discrete point forces acting on the outside of the assumed boundaries. By using this method combined with the resultant force boundary conditions, solutions with high accuracy are obtained.

Effect of Cladding-Induced Stresses on Crack Driving Force in the Fracture Analysis of Pressure Vessels

2020 ◽  
Author(s):  
Julian Emslie ◽  
Josh White ◽  
Ben Pellereau ◽  
Andrew Wood
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Base Material ◽  
Ductile Failure ◽  
Fracture Analysis ◽  
Pressure Vessels ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Fracture Assessment ◽  
Induced Stresses

Abstract The inner surfaces of ferritic steel pressure vessels are often coated with a weld-deposited layer of austenitic cladding for the purpose of corrosion resistance. UK practice of assessing the defect tolerance by postulating defects in components leads to the requirement for a fracture assessment that includes cladding. Section XI requires that the cladding be considered in the fracture analysis, including cladding-induced stresses in the KI evaluation; these stresses largely arise due to the different coefficients of thermal expansion of the cladding and base material, and can also be known as cladding residual stresses. It is thought that in some assessments of clad pressure vessels, the cladding residual stress is either not included, or assumed to be of a significantly reduced magnitude — due to it decreasing at typical operating temperatures and/or being relaxed by prior overloads such as a hydrostatic test. This paper describes finite element analysis to determine the effect of cladding residual stress, comparing J values for loading with and without cladding stresses. Comparisons are also made with J-estimations using the R6 fracture assessment procedure. It is argued that cladding-induced stresses would not contribute to ductile failure as they would be reduced by prior loading, with remaining residual stresses being overcome under large plasticity before failure, due to their secondary nature. Further, it may be misleading to include them in an R6 assessment when using simplified approaches, as their contribution can be exaggerated through pessimistic calculations of the V factor.

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