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.

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.

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.

BS 7910: History and Future Developments

2009 ◽  
Author(s):  
Isabel Hadley
Keyword(s):  
Assessment Methods ◽  
Weld Strength ◽  
Assessment Procedure ◽  
Metallic Structures ◽  
History Of ◽  
Fracture Assessment ◽  
Offshore Industry ◽  
Crack Tip Constraint ◽  
The Uk ◽  
Assessment Procedures

BS 7910, the UK procedure for the assessment of flaws in metallic structures, was first published almost 30 years ago in the form of a fracture/fatigue assessment procedure, PD6493. It provided the basis for analysing fabrication flaws and the need for repair in a rational fashion, rather than relying on long-established (and essentially arbitrary) workmanship rules. The UK offshore industry in particular embraced this new approach to flaw assessment, which is now widely recognised by safety authorities and specifically referred to in certain design codes, including codes for pressure equipment. Since its first publication in 1980, PD6493/BS 7910 has been regularly maintained and expanded, taking in elements of other publications such as the UK power industry’s fracture assessment procedure R6 (in particular the Failure Assessment Diagram approach), the creep assessment procedure PD6539 and the gas transmission industry’s approach to assessment of locally thinned areas in pipelines. The FITNET European thematic network, run between 2002 and 2006, has further advanced the state of the art, bringing in assessment methods from SINTAP (an earlier European research project), R6, R5 and elsewhere. In particular, the FITNET fracture assessment methods represent considerable advances over the current BS 7910 methods; for example, weld strength mismatch can be explicitly analysed by using FITNET Option 2, and crack tip constraint through Option 5. Corrosion assessment methods in FITNET are also more versatile than those of BS 7910, and now include methods for vessels and elbows as well as for pipelines. In view of these recent advances, the BS 7910 committee has decided to incorporate many elements of the FITNET procedure into the next edition of BS 7910, to be published c2012. This paper summarises the history of the development of BS 7910, its relationship with other flaw assessment procedures (in particular FITNET and R6) and its future.

Fracture Assessment of Flaws in Weldments using FITNET FFS Procedure: An Overview

2007 ◽  
Vol 345-346 ◽  
pp. 401-409 ◽  
Author(s):  
Mustafa Koçak ◽  
Stephen Webster ◽  
Isabel Hadley
Keyword(s):  
European Community ◽  
Structural Integrity ◽  
Assessment Procedure ◽  
Metallic Structures ◽  
Fracture Assessment ◽  
Basic Equations ◽  
Network Project

Recently a European community funded thematic network project (participation of 17 countries) FITNET (www.eurofitnet.org) has completed a new and unified engineering assessment procedure (FITNET FFS Procedure) of flaws in metallic structures and welds. This newly developed procedure (under CEN Workshop Agreement WA22) provides assessment rules for flaws or damage due to fracture, fatigue, creep and corrosion to demonstrate the structural integrity of the component. This paper gives an overview of the FITNET Fitness-for-Service (FFS) Procedure and specifically presents the features and basic equations of the Fracture Module. It also presents two brief examples for the validation of the procedure using laser welded specimens.

Fitness-for-Service Assessment for Pressure Equipment in Japan

2003 ◽  
Author(s):  
Takayasu Tahara
Keyword(s):  
High Pressure ◽  
Pressure Vessel ◽  
Working Group ◽  
Pressure Vessels ◽  
The Other ◽  
Task Group ◽  
Assessment Procedure ◽  
Storage Tanks ◽  
Task Groups ◽  
Petrochemical Industries

Pressure equipment in refinery and petrochemical industries in Japan has been getting old, mostly more than 30 years in operation. Currently, the Japanese regulations for pressure equipment in service are the same as those in existence during the fabrication of the pressure equipment. Accordingly, there is an immediate need for an up to date more advanced “Fitness For Service” (FFS) evaluation requirements for pressure equipment. In order to introduce the latest FFS methodologies to Japanese industries, the High Pressure Institute of Japan (HPI) has organized two task groups. One is a working group for development of a maintenance standard for non-nuclear industries. Its prescribed code “Assessment procedure for crack-like flaws in pressure equipment” is for conducting quantitative safety evaluations of flaws detected in common pressure equipment such as pressure vessels, piping, storage tanks. The other is a special task group to study of API RP579 from its drafting stage as a member of TG579. The FFS Handbook, especially for refinery and petrochemical industries, has been developed based on API RP579 with several modifications to meet Japanese pressure vessel regulations on April 2001. [1] It is expected that both the Standard and FFS handbook will be used as an exemplified standard with Japanese regulations for practical maintenance. This paper presents concepts of “Assessment procedure for crack-like flaws in pressure equipment” HPIS Z101, 2001 [2].

New Needs of Fracture Mechanic Analysis at Design and Operation Level: Status of French Nuclear Mechanical Codes

2018 ◽  
Author(s):  
Claude Faidy
Keyword(s):  
Fracture Mechanic ◽  
Pressure Vessels ◽  
Regulatory Requirements ◽  
Mechanic Analysis ◽  
Term Operation ◽  
Fracture Mechanic Analysis ◽  
Class 1 ◽  
Leak Before Break ◽  
Service Inspection

Based on ASME Boilers and Pressure Vessels Code the major fracture mechanic analysis is limited to protection of class 1 components to brittle fracture. All the Operators of future plants have to enlarge the scope of these analyses to different concepts, at design or operation stage: - brittle and ductile analysis of hypothetical large flaw - leak before break approach - break exclusion concept - incredibility of failure of high integrity components - end of fabrication acceptable defect - in-service inspection performance - acceptable standards in operation - Long Term Operation (LTO) All these requirements needs a procedure, an analysis method with material properties and criteria. After a short overview of each topic, the paper will present how RCC-M, RSE-M French Codes and ASME III and XI take care of all these new modern regulatory requirements.

scholarly journals Innovative Study on Microstructural Change in Duplex Stainless Steel in Corrosive Media

2021 ◽  
Vol 9 (12) ◽  
pp. 1428-1435
Author(s):  
Sumit Banerjee
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Unit Area ◽  
High Strength ◽  
Pressure Vessels ◽  
High Alloy ◽  
Corrosive Media ◽  
Corrosion Rates ◽  
Process Plants ◽  
Resistance To Stress

Abstract: Duplex Stainless Steel was developed long back in 1930 and gradually finds its wide application because of its high strength, good weldability, good toughness and resistance to stress corrosion cracking. This alloy finds its application in pressure vessels, bridges, process plants and also in typically down to minus 50 degree centigrade applications. However, because of its high alloy content thermal conductivities of duplex stainless steel are low. Casting this alloy is difficult and can be industrially used after proper heat treatment. In this present study corrosion rates were measured for CD4MCu in terms of weight loss/unit area/hour and microstructures were observed in different corrosive medium with time as variable.

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.

Sign in / Sign up

Export Citation Format

Share Document