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PRCI PR-003-9407
- Failure Criterion for Stress-Corrosion Cracking in Pipelines
- Report / Survey by Pipeline Research Council International, 09/01/1995
- Publisher: PRCI
$298.00$595.00
L51803e
Battelle Memorial Institute
Need: Failures due to stress-corrosion cracking (SCC) generally involve several adjacent, parallel, deep cracks that because of their proximity coalesce to form long flaws, which can cause ruptures.Recent studies indicate that such multiple flaws cause a local increase in compliance as compared to a single crack that represents the largest of the cracks involved.This means that the failure pressure for such a group of cracks can be poorly represented by a single flaw failure criterion, such as the Pipe Axial Flaw Failure Criterion (PAFFC) developed for the Pipeline Research Council International, Inc.
Benefit: The objective of this project was to develop a failure criterion for the multiple flaw situations typical of SCC based on available literature data for a repeating pattern of cracks (a regular array of cracks). This report begins with a discussion of predicted failure pressures for several typical field failures due to SCC. This discussion clearly demonstrates significant errors in predicted failure pressure for the multiple cracking typical of SCC when the failure pressure is predicted in terms of available single-flaw failure criteria for part-through-wall flaws in pipelines. This is followed by an analysis based on available literature data. It is shown that the literature data fail to represent the essential features of typical patches of cracks that control SCC failures. Analysis representing realistic cracking patterns is then introduced and used in conjunction with PAFFC to show that very accurate predictions can be made if the typical nature of the SCC patch is embedded in the failure criterion.
Result: The most significant conclusions from this study are: (1) the failure pressure of deep, adjacent cracks is significantly different than predicted by single-flaw models; (2) accurate failure predictions and failure criteria are possible for SCC; and (3) a failure criterion more general than that based on literature results is needed to address SCC.
Battelle Memorial Institute
Need: Failures due to stress-corrosion cracking (SCC) generally involve several adjacent, parallel, deep cracks that because of their proximity coalesce to form long flaws, which can cause ruptures.Recent studies indicate that such multiple flaws cause a local increase in compliance as compared to a single crack that represents the largest of the cracks involved.This means that the failure pressure for such a group of cracks can be poorly represented by a single flaw failure criterion, such as the Pipe Axial Flaw Failure Criterion (PAFFC) developed for the Pipeline Research Council International, Inc.
Benefit: The objective of this project was to develop a failure criterion for the multiple flaw situations typical of SCC based on available literature data for a repeating pattern of cracks (a regular array of cracks). This report begins with a discussion of predicted failure pressures for several typical field failures due to SCC. This discussion clearly demonstrates significant errors in predicted failure pressure for the multiple cracking typical of SCC when the failure pressure is predicted in terms of available single-flaw failure criteria for part-through-wall flaws in pipelines. This is followed by an analysis based on available literature data. It is shown that the literature data fail to represent the essential features of typical patches of cracks that control SCC failures. Analysis representing realistic cracking patterns is then introduced and used in conjunction with PAFFC to show that very accurate predictions can be made if the typical nature of the SCC patch is embedded in the failure criterion.
Result: The most significant conclusions from this study are: (1) the failure pressure of deep, adjacent cracks is significantly different than predicted by single-flaw models; (2) accurate failure predictions and failure criteria are possible for SCC; and (3) a failure criterion more general than that based on literature results is needed to address SCC.
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