Assessment Methodologies for Girth Weld Defects in Pipelines
Imperfections such as lack-of-fusion and undercut are inevitable in field welding of pipelines. Also, small defects can grow in service by corrosion or fatigue. Above a certain size, such defects must be removed or repaired. In the present state of the art, determination of allowable defect size is done by Engineering Critical Assessment (ECA). ECA methods used in current international pipeline standards are reviewed and compared.
KeywordsStress Intensity Factor Plastic Zone Linear Elastic Fracture Mechanics Limit Load Crack Mouth Opening Displacement
This paper provides background material that has been acquired by the authors over many years of experience in the field of fracture mechanics applied to pipelines. The authors are grateful to their employers (MTL/CANMET and TransCanada PipeLines Ltd., TCPL) for providing the opportunity to obtain this knowledge. The authors are grateful to TCPL for supporting the work on application of the Failure Assessment Diagram to pipeline girth welds.
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