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PRCI PR-003-9403
- Protocol to Prioritize Sites for High pH Stress-Corrosion Cracking in Gas Pipelines
- Report / Survey by Pipeline Research Council International, 09/01/1998
- Publisher: PRCI
$448.00$895.00
L51864e
Battelle Memorial Institute
Need: Stress Corrosion Cracking has been an ongoing concern for pipelines. The first documented SCC service incident occurred in 1965. This incident probably involved a carbonate/bicarbonate environment with a pH in the range of 9 to 11. Since 1985, the low pH environment has been identified as the cause of SCC on a number of Canadian pipelines as reported in the 1996 NEB Inquiry (MH-2-95). The development of an improved understanding of the mechanism, particularly for the high pH environment, has made it feasible to develop this protocol to identify locations on pipelines that may be likely to be susceptible to high pH SCC.
Result: This program developed a stress-corrosion cracking (SCC) protocol for use in assessing the likelihood of the conditions necessary for high pH SCC on individual pipeline segments and an SCC integrity management plan to assist operators in selecting appropriate remedial actions depending on whether SCC is located and the potential consequences. This protocol was developed as a conservative guideline based on existing knowledge at the time of development. This high pH SCC protocol was validated using data from 15 SCC service incidents collected during the conduct of this program and three test cases on pipelines without SCC available from another SCC protocol. An SCC Likelihood Index was developed that provides index values from 40 to 140.
Benefit: The SCC Likelihood Index value provides an indication of whether the conditions necessary for SCC are likely to be found in a given segment along a pipeline. It is expected that there will be regions identified as "high susceptibility regions" which upon field examination will not contain any SCC, because of a conservative approach adopted in arriving at the SCC Likelihood Index. An SCC Integrity Management Plan is included that describes recommended inspection types, inspection frequencies, and remedial actions as a function of the value of the SCC Likelihood Index and the potential consequences to the public.
Battelle Memorial Institute
Need: Stress Corrosion Cracking has been an ongoing concern for pipelines. The first documented SCC service incident occurred in 1965. This incident probably involved a carbonate/bicarbonate environment with a pH in the range of 9 to 11. Since 1985, the low pH environment has been identified as the cause of SCC on a number of Canadian pipelines as reported in the 1996 NEB Inquiry (MH-2-95). The development of an improved understanding of the mechanism, particularly for the high pH environment, has made it feasible to develop this protocol to identify locations on pipelines that may be likely to be susceptible to high pH SCC.
Result: This program developed a stress-corrosion cracking (SCC) protocol for use in assessing the likelihood of the conditions necessary for high pH SCC on individual pipeline segments and an SCC integrity management plan to assist operators in selecting appropriate remedial actions depending on whether SCC is located and the potential consequences. This protocol was developed as a conservative guideline based on existing knowledge at the time of development. This high pH SCC protocol was validated using data from 15 SCC service incidents collected during the conduct of this program and three test cases on pipelines without SCC available from another SCC protocol. An SCC Likelihood Index was developed that provides index values from 40 to 140.
Benefit: The SCC Likelihood Index value provides an indication of whether the conditions necessary for SCC are likely to be found in a given segment along a pipeline. It is expected that there will be regions identified as "high susceptibility regions" which upon field examination will not contain any SCC, because of a conservative approach adopted in arriving at the SCC Likelihood Index. An SCC Integrity Management Plan is included that describes recommended inspection types, inspection frequencies, and remedial actions as a function of the value of the SCC Likelihood Index and the potential consequences to the public.
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