Introduction
With Part 1 of the Pipeline and Hazardous Materials Safety Administration’s (PHMSA) “Mega Rule” in effect since July 2020, operators of onshore gas transmission pipelines in the U.S. are currently working through the technical challenges associated with the prescriptive requirements of the new regulations. The amendments in the revised regulations include prescriptive guidance on when and how the maximum allowable operating pressure (MAOP) must be reconfirmed.
Where original pressure test records are lost for certain class locations of pipe, the rule requires operators to reconfirm MAOP using one of several methods, including pressure testing, pipe replacement, and pressure reduction, as appropriate. Alternatively, operators may reconfirm MAOP by conducting an Engineering Critical Assessment (ECA), which is based on a comprehensive in-line inspection (ILI) program, gathering data as input to the analysis.
The ECA method can minimize service disruption and offer significant cost advantages over these other options. Additionally, this method provides a more complete “picture” of pipeline integrity, including identifying sub-critical defects not reflected by hydrotest, and providing a better understanding of the material properties, attributes, and threats in order to help reduce uncertainty and support integrity management for the remainder of the pipeline’s life.
A crucial aspect of the new regulations is the use of traceable, verifiable, and complete (TVC) material properties in the ECA. The regulation stipulates specific requirements for how the material properties and attributes (e.g., diameter, wall thickness, seam type, grade, and toughness) of above- and below-ground pipelines and components must be verified or established, including a prescriptive number of digs.
In essence, the Mega Rule compels operators to reestablish or verify the material properties within their line and to carry out integrity assessments, such as fitness-for-service (FFS) assessments, using accurate, representative material properties.
Though prescriptive regulation is not in place in all countries, we are now seeing other regions across the globe start to follow the lead of the U.S. industry and recognize the importance of a robust knowledge of pipeline material properties in ensuring the safety of their pipelines.
Whether the outcome is for input into FFS assessments in an effort to reconfirm MAOP or input into hydrogen feasibility studies as we slowly transition to cleaner fuel sources, the fundamental basis of knowing your material properties is the same. Only when the fundamental basis is as accurate and reliable as required can we begin to make informed integrity management decisions.
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