In This Issue

Proposed Rule: Increasing MAOP for Gas Transmission Pipelines

Docket ID PHMSA-2005-23447

The Department of Transportation / Pipeline Hazardous Materials Safety Administration (DOT/PHMSA) proposed to amend the pipeline safety regulations to prescribe safety requirements for the operation of certain gas transmission pipelines at pressures based on higher stress levels. The result would be an increase of maximum allowable operating pressure (MAOP) over that currently allowed in the regulations. This action 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 pipeline fabricated and installed over the last twenty-five years. The proposed rule would apply to both new and existing pipelines, and 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.

PHMSA has previously granted special permits on a case-by-case basis to allow operation of particular pipeline segments at a higher MAOP than currently allowed under the design requirements. These special permits have been limited to operation in Class 1, 2, and 3 locations and conditioned on demonstrated rigor in the pipeline’s design and construction and the operator’s performance of additional safety measures. Building on the record developed in the special permit proceedings, PHMSA has proposed to codify the conditions and limitations of the special permits into standards of general applicability. Under the proposed rule, several types of segments will not qualify for the higher MAOP:

  • Segments in densely populated Class 4 locations
  • Segments of grandfathered pipeline already operating at a higher stress level but not constructed in accordance with modern standards.
  • Bare pipe.
  • Non-steel pipe
  • Pipe with wrinkle bends or mechanical couplings in lieu of welding
  • Pipe experiencing failures indicative of a systemic problem, such as seam flaws, during the initial hydrostatic testing.
  • Pipe manufactured by certain processes, such as low frequency electric welding process.
  • Segments which cannot accommodate internal inspection devices.
  • Segments within compressor or meter stations or segments underlying certain crossings.
  • Segments not monitored by supervisory data control and acquisition systems.

The proposed rulemaking imposes new and additional design, construction, and operation standards to pipe operating at the higher MAOP, including:

  • Incorporating by reference ASTM Designation: A 578/A578M—96 (Reapproved 2001) “Standard Specification for Straight-Beam Ultrasonic Examination of Plain and Clad Steel Plates for Special Applications”.
  • Prescribing additional design standards in §192.112.
  • Prescribing additional construction requirements, including rigorous quality control and inspections, in §192.328.
  • Specifying additional operations, maintenance, testing, and notification requirements.

Comments may be submitted by May 12, 2008 to the E-Gov Web Site: For a complete copy of the proposed rulemaking, contact Jessica Roger.