Summary

For more than 50 years the National Transportation Safety Board (NTSB) has been recommending that the U.S. Department of Transportation require the more widespread installation of automatic and remote-control shutoff valves on hazardous liquid and gas transmission pipelines. In investigating several major pipeline ruptures, NTSB concluded that the time required for personnel to access and close manual shutoff valves had delayed isolation of the ruptured pipe segment to prolong the release of hazardous material and cause more severe consequences and added risks to emergency responders. As directed by Congress, the Pipeline and Hazardous Materials Safety Administration (PHMSA) issued a new rule in April 2022 mandating the installation of these safety devices, now referred to in regulation as rupture mitigation valves (RMVs), on newly constructed and entirely replaced segments of hazardous liquid and gas transmission pipelines. For these pipelines, RMVs must be installed at specified spacings unless an operator can demonstrate that an alternative technology, including a manual valve, can meet a 30-minute rupture isolation performance standard and that an RMV installation would be cost-prohibitive or operationally or technically infeasible.

In commenting on the new rule as it was being proposed, NTSB raised concerns that the required installation of RMVs, or the demonstrated ability to meet a performance standard for timely rupture isolation, would not apply to existing pipelines, especially when segments pass through and near populated and environmentally sensitive areas, defined in regulation as “high consequence areas” (HCAs). While RMVs are not required for pipelines installed prior to the issuance of the new rule, PHMSA obligates

pipeline operators to evaluate the need for them as part of their integrity management (IM) programs required for pipelines that are located in or that could affect HCAs. Operators are required to implement IM programs that include risk analyses and evaluations of safety measures that can reduce the likelihood of ruptures and other failures and limit the severity of their consequences when they occur. The design of the IM regulations is intended to ensure that operators account for the risks specific to their pipelines and make deliberate and documented decisions about their risk management choices. The risk assessments should include evaluations of whether RMVs should be installed for added safety when considering a series of factors listed in the regulations, including the timeliness of a pipeline’s emergency shutdown capabilities. PHMSA and state inspectors are charged with reviewing each operator’s IM program documents to verify the completeness and quality of the risk analyses and the RMV evaluations.

In passing the Protecting Our Infrastructure of Pipelines and Enhancing Safety (PIPES) Act of 2020, Congress directed PHMSA to commission this study to assess regulatory standards and criteria for deciding when automatic and remote-control shutoff valves (i.e., RMVs) should be installed on existing hazardous liquid and gas transmission pipelines in HCAs.¹ To fulfill its charge, the study committee reviewed the recent history of pipeline incidents involving HCAs, including findings and recommendations by NTSB and PHMSA following investigations of major pipeline ruptures. The committee consulted and surveyed pipeline operators to estimate the prevalence of RMVs, obtain information on RMV installation costs, and understand how operators make choices about when to install RMVs in HCAs and other populated locations. The committee reviewed the regulatory rationale for IM programs and the direction and guidance provided to operators on their implementation, including efforts by PHMSA to strengthen implementation guidance in response to NTSB recommendations and the agency’s own findings of shortcomings in the quality and execution of some IM programs. The committee also reviewed the design of PHMSA’s new rule mandating the installation of RMVs on newly constructed and entirely replaced segments of pipelines. PHMSA has not taken a position on the installation of RMVs on existing pipelines. Existing statutory language, however, can be interpreted as precluding the establishment of new regulatory standards for their installation when applied to existing pipelines.²

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¹ While the study request in the PIPES Act does not refer to RMVs, the report uses this term when referring to automatic and remote-control shutoff valves. Such valves may serve functions in addition to rupture mitigation, including routine operational purposes.

² This report notes that Title 49 USC § 60104(b) states, “[A] design, installation, construction, initial inspection, or initial testing standard does not apply to a pipeline facility existing when the standard is adopted.”

Based on this review, the committee was asked to make recommendations, as appropriate, on regulatory or statutory changes that should be considered concerning decisions about when to install RMVs on existing hazardous liquid and gas transmission pipelines in HCAs and other populated areas. Key study conclusions and recommendations follow.

CONCLUSIONS

• The long-standing and widespread use of rupture mitigation valves (RMVs) by pipeline operators who have judged them to be beneficial for operations and safety demonstrates that their use is technically and operationally feasible under many circumstances and across a wide range of conditions. While RMVs can be installed on pipelines mainly by changing the actuators of existing manual valves, the varied conditions and circumstances that exist across pipeline systems mean that retroactive RMV installations can differ greatly in feasibility, complexity, and cost, as well as in the benefits they can confer.
• There is a strong rationale for the integrity management (IM) process and its obligations on operators for active risk management to make rupture mitigation valve installation choices because of the wide variability among pipelines in terms of where they are sited and their conditions and circumstances. However, the efficacy of the approach depends on operators being capable and diligent in their implementation of required IM processes with sufficient direction, guidance, and oversight from regulators.
• As currently written for both hazardous liquid and gas transmission pipelines, the integrity management regulations governing operator risk assessments are short on direction and guidance on how the need for a rupture mitigation valve should be evaluated and decided by operators, despite requiring operators to undertake such evaluations.
• The integrity management process depends on operators using sound risk modeling and analysis methods for informing their prevention and mitigation strategies in high consequence areas. These methods must account for the location-specific probabilities of different types of failures occurring, potential consequences ensuing, and alternative measures being effective in failure prevention and consequence mitigation. By using quantitative models that represent risk and uncertainty in a probabilistic manner, the operator will be in a better position to assess the risk reduction potentials of alternative safety measures at any given site. However, risk modeling capabilities vary among operators, who are not required

to use quantitative models that can provide such probability-based output for assessing the risk reduction potential of rupture mitigation valves and other safety measures.

• In deciding on the use of alternative safety measures with differing potentials for risk reduction, including rupture mitigation valves (RMVs) at specific locations, operators need to be able to determine the array of benefits and costs of each measure, including benefits to the public. However, standardized practices for estimating benefits and costs for pipeline risk management do not exist, raising questions about how operators are establishing the need for RMVs and, more generally, how they are prioritizing and making choices about all candidate safety measures with the public interest in mind.
• Because of the rigor, expertise, and data quality required, risk assessments using quantitative modeling and economic analyses of the benefits and costs of alternative safety measures can be challenging for operators to implement and for inspectors to assess for quality. Operators and inspectors lack guidance and support on the application of requisite analytic methods, including opportunities for training.

While all 10 committee members agreed with the conclusions above, 9 of the 10 members also agreed on the following conclusion. The reasoning of the one committee member who disagreed with the conclusion is provided in Appendix A.

• A broadly applicable requirement for the installation of rupture mitigation valves (RMVs), such as in the rule for newly constructed and entirely replaced segments of pipelines, would not be advisable for existing hazardous liquid and gas transmission pipelines in high consequence areas. While newly constructed and entirely replaced segments of pipelines can be designed for RMVs, a similar broad-based requirement that is retroactively applied to existing pipelines would not be advisable because the available evidence on costs and benefits attributed to the installation of RMVs varies widely as a function of factors such as site-specific pipeline characteristics, land use patterns, the built environment, ecological sensitivity, topography, and commodity.

RECOMMENDATIONS

In the view of the 9 of 10 committee members who continue to believe that operator decisions about when to install RMVs on existing pipelines in

HCAs should be made in IM programs, the following steps are warranted to strengthen the quality and execution of operator IM processes and their verification by safety inspectors.

Regarding this recommendation for PHMSA to establish evaluation criteria, metrics, and methods for operators to use when evaluating factors such as a pipeline’s shutdown speed, some committee members believe that PHMSA should require operators to evaluate on the basis of a prescribed metric, such as the 30-minute isolation time that must now be satisfied by newly constructed and entirely replaced segments of pipelines. The results from the operator’s evaluation using the prescribed metric would need to be documented and thus could be readily noted by federal and state inspectors when reviewing an operator’s IM program and the results from the RMV evaluations. While statutory restrictions may preclude PHMSA from compelling RMV installations on existing pipelines when the evaluation metric is not satisfied, the agency could compile the information gleaned from these inspector-reviewed RMV evaluations for insight into how much of the pipeline system could be at risk for slow or delayed rupture isolation. Some other committee members, however, do not favor such a prescribed evaluation metric out of concern that a single value would not be applicable

to many circumstances and could be used by operators to justify decisions not to install RMVs when public interests may warrant their use.

Regarding Recommendations 2 and 3, some committee members believe that PHMSA should advise operators on the specific methods they should use in making choices among alternative risk reduction measures. These committee members favor the use of benefit-cost analysis to establish the net benefits of alternatives coupled with requirements that operators document their analytic methods and results for inspectors to review. They believe operators are now making such net-benefit calculations, formally or informally, but that some may be construing safety and risk reduction benefits on a limited basis that does not fully account for the societal interests as one would expect from a sound and compliant IM program. Although all committee members share a concern that operators may not be considering societal benefits and interests fully when deciding on the use of RMVs and other risk reduction measures, some members do not endorse making a net-benefit calculus an explicit standard for decision making. Those members want to be sure that operators are not dissuaded from making decisions that favor RMVs when all potential benefits cannot be enumerated, such as when the choice advances equity or promises other public benefits sufficient to justify an installation.

In the committee’s view, it is fair and reasonable to expect all pipeline operators to use quantitative risk modeling for their IM programs. A large share of HCA mileage is managed by a relatively small number of major operators likely to have the resources and technical capacity to employ such methods, and smaller operators can seek outside assistance. The recommended technical guidance and training should help all operators, including smaller companies whose obligations to meet the requirement could be phased in.

CONCLUDING OBSERVATIONS

Nine of the committee’s 10 members believe the advice offered above, if followed, has the potential to strengthen operator IM decisions about

when to install RMVs and PHMSA’s ability to ensure sound decisions. Not similarly confident that improvements to IM processes will be made and result in operators making decisions about RMVs that align more closely with the public interest, one committee member proposes alternative approaches based on reasoning offered in Appendix A. All other committee members agree, however, that if PHMSA is not successful in furthering the recommended actions or if operators do not implement them effectively, then alternative approaches may be warranted, including the introduction of regulatory standards stipulating when RMVs should be installed.