New MAOP Leeway Pretty Narrow

By Stephen Barlas, Washington Editor | December 2008 Vol. 63 No. 12

The U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA) finalized new rules allowing transmission companies to operate pipeline segments in Class 1 locations at 80 percent of specified minimum yield strength (SMYS) of the steel.

But what PHMSA calls “rigorous” requirements will kill the attractiveness of the new leeway for almost all of the 320,000 miles of interstate pipeline in the U.S. Terry Boss, senior vice president at INGAA, says the association will file a “petition for reconsideration” protesting two specific areas in the final rule.

PHMSA’s own estimate forecasts that only 3,500 miles of existing pipeline will be uprated to 80 percent from the current cap of 72 percent of SMYS. The operating pressures in more populated Class 2 and Class 3 locations are limited to 60 and 50 percent of SMYS, respectively. They, too, can be increased to 67 and 56 percent of SMYS, respectively. Since 1990, the American Society of Mechanical Engineers has had in its B31.8 Code that pipelines could operate safely at stress levels up to 80 percent of SMYS.

In the final rule published on Oct. 17, PHMSA said, “Many pipeline operators are expected to find the cost of using the alternative maximum allowable operating pressure (MAOP) to be too high. For instance, fitting and pressure vessel replacement costs may prevent some pipeline operators from converting to a higher MAOP. Additionally, the costs associated with converting nonpiggable lines are expected to be prohibitive.” PHMSA estimates total costs will be between $239 billion and $165 billion over 20 years, depending on the rate of inflation. Benefits from lower fuel and capital costs would be between $1.5 trillion and $1.1 trillion.

PHMSA has already given a number of major pipelines approval to operate at 80 percent of SMYS under special permits. Now any pipeline can self certify that it meets the PHMSA safety requirements and uprate its segments on its own, subject to post uprating certification either by PHMSA or the state agency.