In a respone to a PHMSA NPRM, the Safety Board made the following comments: The National Transportation Safety Board has reviewed the Pipeline and Hazardous Materials Safety Administration's (PHMSA's) notice of proposed rulemaking (NPRM), "Pipeline Safety: Integrity Management Program for Gas Distribution Pipelines," that was published at 73 Federal Register 36015 on June 25, 2008. PHMSA is proposing to amend the Federal pipeline safety regulations, 49 Code of Federul Regulutions Part 192, to require
operators of gas distribution pipelines to develop and implement integrity management programs.
Proposed Regulatory Approach
The IVPRM proposes requiring operators of distribution pipeline systems to develop integrity management programs that would have the same objectives as the existing integrity management programs for hazardous liquid and gas transmission pipeline systems. Integrity management programs require operators to identify and invest in risk control measures, identify and manage factors that affect risks to the pipeline, and integrate the best available information about the pipeline in order to make informed risk management decisions.
The Safety Board notes that PHMSA is proposing a regulatory approach to integrity management programs for distribution lines that accounts for the design and operational differences between gas distribution systems and hazardous liquid or gas transmission pipelines. The Safety Board supports this approach and agrees that, overall, the NPRM provides a reasonable and logical approach that operators of distribution pipelines can use to develop and implement integrity management plans.
Integrity management programs for hazardous liquid or gas transmission pipelines generally require the operators to assess the condition of their pipelines primarily by using in-line inspection tools and pressure testing, which yield direct information on the condition of the pipelines. However, the pipe used in distribution pipelines has a smaller diameter than the pipe used in hazardous liquid or transmission pipelines. Distribution pipelines also tend to have many bends and service lines that branch off. Consequently, using in-line inspection tools for the typical distribution pipeline system is not feasible. PHMSA notes that because distribution pipelines operate at far lower pressures than hazardous liquid or gas transmission pipelines, the failure of a distribution pipeline is typically detected from reports of a gas leak rather than from a catastrophic rupture, which often occurs when hazardous liquid and gas transmission pipelines fail. Therefore, the implementation of an effective leak management program is, in the Board's view, an important element of an integrity management program for a distribution pipeline. An effective leak management program must
prescribe the use of equipment that prevents or mitigates leaks and establish criteria for monitoring and, if necessary, replacing aging components susceptible to failure. Consequently, the Board believes that the NPRM does not adequately address the use of excess flow valves (EFVs) and compression couplings.
PWMSA also notes in the NPRM that the leading causes of accidents on distribution pipelines include excavation damage and equipment failures. PHMSA does not address directional drilling, a major cause of excavation damage. Addressing these areas as discussed in the sections that follow can strengthen the NPRM.
The principal tools for detecting leaks in a distribution pipeline are leak surveys, corrosion control surveys, odorization surveys, and valve inspections; the use of all these tools is required under current safety regulations for distribution systems. Effective leak management depends on combining the data yielded by each of these tools, statistically analyzing the combined data to determine the problems within a system, and correcting the problems before they pose an unacceptable risk to public safety. However, an effective leak management program must also prescribe the use of equipment that prevents or mitigates leaks and must discourage the use of unreliable components. The Board believes that the NPRM is not sufficiently explicit about the use of EFVs to mitigate leaks or about the risks posed by compression couplings, as discussed in the
Excess Flow Valves
In 1974, the Safety Board investigated the explosion of a commercial building in New York city.' Over the next 34 years, the Safety Board investigated 17 accidents and issued 20 recommendations, as well as a recommendation to each governor of the 50 States, urging the use of EFVs for all distribution pipeline systems. The Pipeline Integrity, Protection, Enforcement, and Safety (PIPES) Act of 2006 mandated that PHMSA require operators of distribution pipeline systems to install EFVs after June 1, 2008, on all new and replacement service lines to singlefamily residences. Further, the PIPES Act mandated that the requirement be incorporated in the integrity management rulemaking for distribution pipeline systems. Because the rulemaking was
delayed, PHMSA issued an advisory bulletin (ADB-08-04) on May 30, 2008, which was published in the Federal Register on June 5, 2008. The bulletin advised operators that as of June 1, 2008, EFVs must be installed on new and replacement services for single-family homes that operate continuously at a pressure above 10 pounds per square inch, guage, and that are not connected to a gas stream with a history of contaminants. Although the NPRM and the advisory bulletin may satisfy the mandate of the PIPES Act,
they fail to require EFVs for apartment buildings, other multifamily dwellings, and commercial properties, which are susceptible to the same risks from damaged service lines as single-family residences. On June 22,2001, the Board recommended that PHMSA: Require that excess flow valves be installed in all new and renewed gas service lines, regardless of a customer's classification, when the operating conditions are compatible with readily available valves. (P-01-2) The recommendation was issued as the result of the Board's investigation of the July 7, 1998, natural gas explosion and fire that destroyed a newly constructed residence in South
Riding, a community in Loudoun County, Virginia. The accident caused one fatality and one serious injury. The Safety Board determined that the service line to a home had failed and that an uncontrolled release of gas had accumulated in the basement and subsequently ignited. The Board concluded from its investigation that had an EFV been installed in the service line, the EFV would have closed after the hole in the service line developed and the explosion likely would not have occurred.
The Board urges PHMSA to amend the NPRM to require EFVs on all new and renewed service lines for all gas service customers, regardless of customer classification, as specified in Safety Recommendation P-01-2, when the operator's conditions are compatible with readily available valves.
Between 1970 and 1990, the Safety Board investigated 20 accidents involving pipe in distribution systems that had pulled out of compression couplings. The Board issued 32 safety recommendations on the subject and attributed the causes of the pullouts to various factors and conditions, such as thermal contraction of the pipe and soil, overpressurization, and mechanical damage. Following the successful implementation of several of the Safety Board's recommendations, the number of accidents involving compression couplings decreased
significantly. From 1991 to 2004, the Board investigated only three such accidents, and it did not issue any safety recommendations to PHMSA about compression couplings. However, because of incidents involving compression couplings, four States since the 1990s have been increasingly demanding that the couplings be replaced, and, in a few instances, individual distribution