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Pipeline Safety: Reconsideration of Natural Gas Pipeline Maximum Allowable Operating Pressure for Class Locations

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Pipeline and Hazardous Materials Safety Administration, DOT.


Notice of meeting; call for papers.


On March 21, 2006, the Pipeline and Hazardous Materials Safety Administration (PHMSA) will hold a public meeting to discuss raising the allowable operating pressure on certain natural gas transmission pipelines. Pipelines are the energy highways of the Nation that provide the most efficient means to transport vast volumes of natural gas on which we depend. Raising the maximum allowable operating pressures (MAOP) for natural gas pipelines would allow more gas to flow through these pipelines. This notice is designed to announce a public meeting and to invite papers on relevant technical subjects.

Over the past 20 years, there has been a drastic improvement in technology pertaining to materials, metallurgy, controls, operations, and maintenance of the pipeline network. Based on these and other advances, PHMSA believes that certain pipelines in certain locations could be safely and reliably operated above the operating pressure established in current Federal pipeline safety regulation.

There are three categories of pipelines that could realize an immediate benefit from such an increase in the MAOP: the proposed Alaska Natural Gas Transmission System; new natural gas pipelines that are being certificated by the Federal Energy Regulatory Commission; and pipelines constructed since 1980 with line pipe of known metallurgical and mechanical properties.

This meeting provides the pipeline industry, Federal and State regulators, and interested members of the public an opportunity to share their knowledge and experience about the impact of increasing the MAOP to increase pipeline efficiency. Individuals that would like to make presentations should notify the individual listed under FOR FURTHER INFORMATION CONTACT by February 7, 2006, and submit papers at this meeting.


The March 21, 2006, meeting will be held at the Hyatt Regency Reston Hotel, 1800 Presidents Street, Reston, VA 20190. The telephone number for reservations at the Hyatt Regency Reston Hotel is (703) 709-1234. The hotel will post the particular meeting room the day of the meeting.

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Mr. Joy Kadnar, Director, Engineering and Emergency Support at (202) 366-4595 or about the subject matter in this notice.

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Pipeline operators continually explore ways to reduce the cost of new pipelines, or increase the efficiency of existing pipelines, without affecting reliability and safety. One way to achieve cost reductions is to use high-grade line pipe and employ new welding methods. Another method to increase cost-effectiveness and to make the pipeline more efficient is to operate pipelines at higher stress levels.

International pipeline regulations generally limit design stresses to 72% specified minimum yield strength (SMYS). Under highly selective conditions, some pipelines in the United States and Canada operate at hoop stresses up to 80% SMYS. Notwithstanding, the current United States Code of Federal Pipeline Safety Regulations (CFR) (49 CFR part 192) limits the stress to 72% SMYS for Class 1 locations, while Canada limits it to 80%. There are a lot of other countries considering operating at higher levels. Therefore, PHMSA believes it is appropriate to explore the reliability and integrity implications of operating pipelines at stress levels above 72% Start Printed Page 978SMYS, but not to exceed 80% SMYS for Class 1 locations.

The benefits of an increase in MAOP for natural gas pipelines are tremendous, mainly because of the increase in capacity and fuel efficiency. For new pipelines operated at a higher MAOP, operators might realize an initial cost savings, primarily in materials. A capacity increase in existing pipelines will have an auxiliary benefit by avoiding the construction of new pipelines or costly modifications that have the potential to damage the environment. Historical problems associated with seam failures are non-existent with new materials. Most new pipelines have been configured to accept inline inspection tools to monitor the pipeline's condition. Pipeline operators have improved their ability to manage internal corrosion. By allowing pipeline companies to safely increase the MAOP of existing pipelines that meet certain criteria, they could avoid new construction that can impact the environment.

Research by the Pipeline Research Council International concluded that pipeline operations can be safe and reliable at stress levels of up to 80% SMYS if the pipeline has well-established metallurgical properties and can be managed to protect it against known threats, such as corrosion and mechanical damage. Additionally, independent studies demonstrate the benefits of risk and reliability-based principles that strengthen safety.


The class location regulations require that pipelines routed through areas with higher local population density operate at lower pressures. This is intended to provide an extra safety margin in those areas.

The gas transmission integrity management program addresses protections in high consequence areas. The cost-benefit analysis included in the final rule noted that a significant benefit to implementing integrity management is reduced cost to the pipeline industry for ensuring safety in populated areas along pipelines. Improved knowledge of pipeline integrity provides a technical basis for considering alternatives to regulation, for example whether to replace pipe or to reduce operating stresses in pipelines when population near them increases, (i.e., when the class location increases to either Class 2 from Class 1 or to Class 3 from Class 2). A class location change results from new construction near a pipeline segment and unless a waiver is granted triggers a requirement that the MAOP be confirmed or revised.

On June 24, 2004, PHMSA issued criteria for granting class location waivers based on integrity management principles. The criteria provide information and guidance to pipeline operators concerning the specific pipe design and operating parameters within which PHMSA is likely to consider a class location waiver application to be consistent with pipeline safety. Class location waivers that are granted allow a pipeline operator to perform alternative risk control activities based on the principles and requirements of the integrity management program in lieu of pipe replacement or pressure reduction. These waivers allow operators to continue to operate pipelines at existing hoop stresses although the MAOP is no longer commensurate with the class location requirements.

Specified Minimum Yield Strength

In the early 1950s, the American Standards Association's (ASA) pipeline committee developed ASA Standard B31.8 and the concept of basing design stress on a percentage of the specified minimum yield strength (SMYS). The committee determined that 72% SMYS was an acceptable design factor. Thereafter, PHMSA incorporated this standard by reference into its pipeline regulations. In the late 1980s, ASME International (ASME) revisited the SMYS issue and determined that pipelines could operate safely at up to 80% SMYS. The committee then modified ASME B31.8 to include that provision.

The United States Federal pipeline safety regulations allow a maximum operating pressure of 72% SMYS. The Canadian regulations allow a maximum operating pressure of 80% SMYS. Currently, there are pipelines in the United States that have been “grandfathered” to operate at an MAOP above 72% SMYS. PHMSA statistics show that these pipelines have an equivalent safety record when compared with pipelines that operate according to the design factors in the pipeline safety regulations. Further, the pipeline safety regulations already allow pipelines to continue to operate at the original design factor when the class location increases by one Class, providing certain criteria are met. For example, a pipeline in a Class 2 location is allowed to continue operating at 60% of SMYS when it changes to a Class 3.

Preliminary Meeting Agenda

The public meeting will examine policies and technical issues that are central to understanding and improving pipeline safety. While providing opportunities for improved efficiency, the meeting will highlight contributed papers and studies and will provide opportunities to discuss and exchange views.

The agenda for this meeting will include discussion on:

  • Existing pipelines operating above 72% SMYS.
  • Evolution of the 72% SMYS ceiling.
  • Class Location.
  • Regulatory Requirements in the United States, Canada, and the United Kingdom.
  • Engineering and Technical Considerations for 80% SMYS Operation.
  • Waiver requests submitted to PHMSA. See DOT Docket Numbers: PHMSA-05-23448, and PHMSA-05-23387.

During the meeting, PHMSA would like participants to discuss their views on the MAOP and any experience they have had operating pipelines beyond 72% SMYS. PHMSA also would like participants to provide information on reliability and how moving beyond 72% SMYS would impact pipeline safety.

Call for Papers

We invite papers to address reasons why PHMSA should or should not provide relief from the class location requirements to pipelines that meet certain stringent operating criteria. PHMSA is interested in engineering and technical considerations. Papers may discuss the impact on public safety, the environment, the economy, and the State pipeline programs. All papers, whether presented at the public meeting or not, will be included in the public docket. PHMSA solicits papers on relevant policy and technical topics in the following areas:

  • The impact of operating pipelines at pressures greater than 72% SMYS.
  • The impact on pipeline threats at 80% SMYS operation.
  • The role of ongoing integrity assessment in managing the safety of pipelines designed to operate at pressures up to 80% SMYS.
  • The benefits of 80% SMYS operation on natural gas commodity movements and energy flows.
  • A qualitative assessment of the pipeline capacity increase across the grid that could result from such pressure uprating.
  • A comparison of failure histories, national and international, of pipelines operating up to 72% SMYS versus those operating above 72% SMYS.
  • Regulatory harmonization between the United States and Canada.
  • Role of initial hydrostatic testing for initial design integrity validation. Start Printed Page 979
  • Review of pipe robustness and resistance to excavation damage.
  • Impact on fatigue life of pipelines operating up to 80% SMYS.
  • Fracture control design parameters for 80% SMYS operation.
  • Evaluation of integrity re-assessment intervals for 80% SMYS operation.
  • Optimization of conditioning, monitoring, and mitigation programs for 80% SMYS operation.
  • Review of existing compressor station equipment relative to 80% SMYS operation.
  • Review of operations and controls for 80% SMYS.
  • Emerging approaches for reliability analysis, integrity management, and risk analysis in high stress pipelines.
  • Line pipe characteristics and flaws that preclude pipelines from higher operating stresses.

Authors must submit abstracts of their papers in 250 words or less to the docket by February 7, 2006. PHMSA will notify authors by February 14, 2006, whether their papers were accepted for presentation at the meeting. Each author of an accepted paper will have the choice of providing either a short paper (6-10 pages) or an extended abstract (3-5 pages) that will be due before the public meeting.

You may submit papers or comments by mail or deliver them to the Dockets Facility, U.S. Department of Transportation, Room PL-401, 400 Seventh Street, SW., Washington, DC 20590-0001. The Dockets Facility is open from 9 a.m. to 5 p.m., Monday through Friday, except Federal holidays. You also may submit papers or comments to the docket electronically by logging onto the following Internet Web address: Click on “Help & Information” for instructions on how to file a document electronically. All papers or comments should reference docket number PHMSA-05-23447. Anyone who would like confirmation of mailed papers or comments must include a self-addressed stamped postcard.

Privacy Act Statement: Anyone may search the electronic form of all comments received for any of our dockets. You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477) or you may visit

Information on Services for Individuals With Disabilities: For information on facilities or services for individuals with disabilities, or to request special assistance at the meeting, please contact Cheryl Whetsel at (202) 366-4431 by March 6, 2006.

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Authority: 49 U.S.C. 60102 and 60133.

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Issued in Washington, DC, on December 30, 2005.

Stacey L. Gerard,

Associate Administrator for Pipeline Safety.

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[FR Doc. 06-110 Filed 1-5-06; 8:45 am]