OPS Stresses Atmospheric Corrosion Prevention for Gas Pipes of All Vintages
As is already required of hazardous liquid pipelines, the Department of Transportation's Office of Pipeline Safety (OPS) has enacted revised safety standards that call on natural gas transmission and distribution pipelines to use the same level of protection against atmospheric corrosion on their facilities despite the vintage.
The new standard, which took effect Oct. 15, replaced a regulation that permitted gas pipelines to approach atmospheric corrosion differently in the past, depending on whether the pipe facilities were built before or after July 31, 1971. Aboveground pipelines or portions of pipelines built after the cut-off date were required by OPS to take steps to prevent corrosion caused by exposure to the atmosphere, while regulations for facilities built before the date focused more on remediation of existing atmospheric corrosion.
In an effort to promote greater uniformity, the OPS modifications now require operators to "clean and coat each pipeline or portion of pipeline that is exposed to the atmosphere" with a coating material that is suitable to prevent atmospheric corrosion. Operators generally need not protect from atmospheric corrosion if, after conducting a test, investigation or through experience, they find that corrosion will "only be a light surface oxide," or it "[will] not affect the safe operation of the pipeline before the next scheduled inspection."
The OPS concluded that light surface oxide was a "non-damaging form of corrosion that does not need remedial action," said the Washington, DC-based law firm of VanNess Feldman, which has illustrated the many changes to OPS gas safety standards in a chart. It is available on its web site at http://www.vnf.com.
The corrosion-control requirements mirror those that are already in place for liquid pipelines, according to the OPS.
The standard on atmospheric corrosion control was one of a number of revisions adopted by the OPS in a final rule addressing pipeline safety issues, which was based on recommendations made by the National Association of Pipeline Safety Representatives and a review of the recommendations by the State Industry Regulatory Review Committee (SIRRC).
Revised rules affecting primarily distribution lines included an expanded definition of "service line," design limitations for plastic pipeline, and modified installation requirements for plastic pipeline. Other revised OPS regulations focused on monitoring of external corrosion, leak test record keeping and valve maintenance. These applied to both gas distribution and transmission pipelines.
As for monitoring of atmospheric corrosion, the OPS said operators must inspect onshore pipelines at least once every three years, and offshore pipelines at least once each calendar year.
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