MAOP Addressed At Mears Seminar

By Alan Eastman, Mears Group | January 2012, Vol. 67 No. 1

At its recent Integrity Educational Seminar, Mears Group Inc. personnel focused on the topic of establishing the maximum allowable operating pressure (MAOP) of a gas pipeline and the general concept of operating margin of safety.

It included a historic look at how MAOP has been determined and what future regulatory requirements and industry initiatives will be. Speakers included Alan Eastman, Chris Warner and Kevin Garrity of Mears, Doug Spencer from Microline Technology Corporation and Bob Travers of Spectra Energy.

Alan Eastman explained that the recent PHMSA advisory notice on MAOP instructed companies to use recorded evidence and integrity management risk identification, assessment, prevention and mitigation when determining MAOP. When determining MAOP, operators follow regulation 192.619, which states that a steel pipeline cannot be operated at a pressure that exceeds the lowest of the following conditions:

• Design pressure of the weakest component;
• Pressure test divided by factors associated with class locations;
• The highest actual operating pressure realized during the five years preceding Nov. 11, 1970; and
• The pressure determined by the operator to be the maximum safe pressure after considering the history of the segment, known corrosion and the actual operating pressure.

PHMSA is pushing operators to re-validate a minimum current operating margin of safety and to take actions to prevent future degradation of that margin. It’s notice asks operators if they are fully cognizant and have accurate records of factors such as location, pipe material and seam type, coating, cathodic protection history, repair history, previous pressure testing or operational pressure history, and other assessment information, incident data, soil type and environment, operational history or other key risk factors. If not, and the pipeline is operating at or above 30 percent specified minimum yield strength, then take the following steps:

• Institute an aggressive program to obtain this information;
• Assess the risks;
• Take proper mitigation measures based on the operators IM program; and
• Take an immediate or interim mitigation measure which could include pressure reduction to 80 percent of the operating pressure for the previous month, run a hydro test or create a remediation program to address risks.