Because of “dramatic improvements in pipeline technology and risk controls” over the past 25 years, the Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) is proposing to amend pipeline safety regulations to allow certain gas transmission pipelines to operate at pressures based on higher stress levels, thus expanding operating capacity.

The agency has issued a notice of proposed rulemaking (NOPR) that would increase the maximum allowable operating pressure (MAOP) for certain pipelines, making standards and conditions it has used to issue special permits for higher operating pressure available for general use.

The NOPR would update regulatory standards to reflect improvements in pipeline materials, assessment tools and maintenance practices, which together have significantly reduced the risk of failure in steel pipe fabricated and installed over the last 25 years, the NOPR says. It would allow use of an established industry standard for the calculation of MAOP, but limit application of the standard to pipelines posing a low safety risk based on location, materials and construction.

The federal pipeline safety agency said the proposed rule would boost the potential capacity and efficiency of pipeline infrastructure, while promoting investment in improved pipe technology and rigorous life-cycle maintenance. Almost all risk controls on gas transmission pipelines have been strengthened since 1970, when the current rules were put in place, due to improved manufacturing, metallurgy, testing, and assessment tools and standards. Pipe manufactured and tested to modern standards is far less likely to contain defects that can grow to failure over time than pipe manufactured and installed a generation ago.

Likewise, modern maintenance practices, if consistently followed, significantly reduce the risk that corrosion, or other defects affecting pipeline integrity, will develop. Integrity management programs followed by pipeline operators also have increased understanding about the condition of pipelines and of how to reduce pipeline risks. “In view of these developments, PHMSA believes that certain gas transmission pipelines can be safely and reliably operated at pressures above current federal pipeline safety design limits,” the agency said.

The deadline for written comments is May 12. Comments should reference Docket ID PHMSA-2005-23447 and may be submitted on the E-Gov website at, or by fax at (202) 493-2251, or mail to Docket Management System, U.S. Department of Transportation, 1200 New Jersey Avenue, SE, Room W12-140, Washington, DC 20590. Hand delivery can be made to the DOT Docket Management System in Room W12-140 on the ground floor of the West Building, 1200 New Jersey Avenue, SE, Washington, DC. For information about this rulemaking, contact Barbara Betsock by phone at (202) 366-4361, by fax at (202) 366-4566, or by e-mail at For technical information, contact Alan Mayberry by phone at (202) 366-5124, or by e-mail at

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