In 2010, a massive gas explosion in San Bruno, California, that killed eight people, injured numerous others and leveled more than 30 homes, spurred industrywide change.

After 10 years in the making and many rounds of operator feedback, the Pipeline and Hazardous Materials Safety Administration (PHMSA) released significant regulation updates — collectively referred to as the Mega Rule — to improve federal pipeline safety laws as well as the U.S. energy infrastructure.

PHMSA, which is a branch of the Department of Transportation, split its packed Mega Rule into three major rules, the first of which focuses on increasing the level of safety associated with onshore gas transmission pipelines as well as improvements to documentation and data collection for added safety and efficiency. These recently published changes debuted in October 2019.

Here’s the breakdown of Phase 1 and its three key updates:

Verify material properties. Operators must know the material strength properties for all transmission pipe and associated fittings, including wall thickness of pipe, the diameter of pipe and the material grade, among others. If operators do not have adequate material records on their pipe and components, they must develop and implement procedures for conducting destructive and nondestructive tests for verification.

Reconfirm the Maximum Allowable Operating Pressure (MAOP). PHMSA outlines six approved methods for reconfirming MAOP: pressure test, pressure reduction, engineering critical assessment, pipeline replacement, pressure reduction for pipeline segments with a potential impact radius less than or equal to 150 feet, or alternative technology. If operators don’t have the necessary information or records to confirm MAOP, they must use one of these methods to do so.

Confirming MAOP and material properties might not sound too complex, but when there are miles of pipe in ground, it can be an immense undertaking and might require a vast records review and large sampling programs.

Limitations to the grandfather clause. Perhaps the most significant change, however, is the now limited applicability of Part 192.619, commonly referred to as the “grandfather clause,” for confirming MAOP. This clause allowed operators to confirm MAOP using the highest pressure recorded within a five‑year period that predated July 1, 1970. No test records were required nor knowledge of what exactly was in the ground. That’s a lot of unknown information on numerous pipelines in the U.S., many of which are still around and in service today.

Under the new ruling, the grandfather clause can only be used to establish the MAOP of pipelines that operate under 30% specified minimum yield strength (SMYS) or pipelines that operate in a Class 1 or Class 2 area.

To fully comply with the new Mega Rule, operators are going to have to look at all records, thoroughly assess their systems and address any gaps. If there are gaps in test records but operators know pipe specs, they might just need to retest. However, if they have a valid pressure test but no records of their material specs, they’ll be unable to verify MAOP. If that’s the case, this new rule prescribes a sampling program, requiring operators to dig up pipe and test at different intervals for verification. This time-consuming step could require significant changes to operational work.

Additionally, this ruling requires that records confirming MAOP and material properties be traceable, verifiable and complete, leaving operators to interpret what that means for them.

These significant improvements to quality and safety can, in the long term, reduce costs and minimize risk, but they don’t offer a one-size-fits-all solution. Many of the rule updates can be interpreted differently and will affect companies differently, a potentially lengthy process that might require assistance from a knowledgeable industry partner who can execute activities on MAOP reestablishment projects and help improve safety and compliance for the owner’s system.

The deadline for operators to document their plan and procedures for identifying and addressing assets that do not meet the verification requirements for MAOP and material specifications is July 1, 2021.


This final rule improves the processes for documentation and data collection necessary to enhance safety and meet the emerging needs of today’s natural gas pipeline infrastructure. Get specifics on the changing rules and regulations of pipeline integrity as well as the operational impacts of the finalized plan.

Read the White Paper

Amanda Palm, PE, is a project engineer and section manager at Burns & McDonnell, providing design and project management services for transmission and distribution pipelines and facilities.