Docket No. PHMSA-2011-0009
The National Transportation Safety Board (NTSB) has made a safety
recommendation to PHMSA 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. In response
to that recommendation, PHMSA is seeking public comment on several issues
relating to the expanded use of excess flow valves (EFVs) in gas distribution
systems. PHMSA is also interested in seeking comment from gas distribution
system operators on their experiences using EFVs, particularly from a
cost-benefit perspective. PHMSA seeks public comment regarding the technical
challenges, and the potential costs and the potential benefits of any expanded
requirement to use EFVs in applications other than service lines serving single
family residences. PHMSA additionally seeks comment as to whether to establish
and/or adopt technical standards or guidance for the performance,
specification, manufacturing, testing, installation, identification, and
operation of EFVs.
Specifically, PHMSA is asking for comment on the following issues:
- Technical Challenges – Operators have identified technical challenges to installing EFVs on services other than single family residences. These challenges include:
- the effect of changing gas usage patterns
- snap loads
- business-critical gas supply applications
- system configuration
- pressure ratings; and
- size of commercially available EFVs.
- Economic Analysis Considerations (Potential Costs and Benefits).
- Technical Standards and Guidance for EFVs.
PHMSA has identified several potential areas in which enhanced or expanded technical standards and guidance for the performance, operation, installation, identification, and testing of EFVs could be valuable regardless of whether PHMSA decides to expand the classes of services requiring an EFV. The current DOT regulation applicable to excess flow valve standards is 49 CFR 192.381 which requires excess flow valves to be manufactured and tested by the manufacturer according to an industry specification or to the manufacturer’s written specification but does not prescribe a specification. While not incorporated by reference into the pipeline safety regulations, there are three technical standards that address the specification, manufacturing, and testing of EFVs. These standards may not be applicable to all sizes and pressure ratings of EFVs that would be needed if they were mandated for use in applications other than single family residences and would likely need to be expanded to cover other sizes and pressure ratings.
A number of factors affect the performance and reliability of EFVs such as: installation location, configuration, selection, sizing, identification, installation method, and operation. ASTM International (ASTM) F2138 “Standard Specification for Excess Flow Valves for Natural Gas Service” addresses some of these factors at a high level, but not in depth. These standards may need to be expanded to better address the selection, installation, and performance testing of EFVs for a variety of design considerations and service line configurations. Operating conditions and system configurations under which EFVs are not compatible or potentially not advisable may need to be identified and integrated into the guidelines. If these standards and guidance are enhanced or developed, PHMSA may consider if they are adequate to be incorporated by reference into the Pipeline Safety Regulations.
- Factors affecting the performance and reliability of EFVs such as installation location, configuration, selection, sizing, or installation method.
PHMSA has identified several situations where the installation of an EFV may not be technically practicable. In these situations, the installation of a readily-accessible curb valve and box might serve a similar safety function to an EFV. Although not instantaneous, a curb valve could facilitate the manual shut-off of natural gas service in an emergency and provide an alternative solution to an EFV.
PHMSA has identified several issues related to the costs and benefits associated with mandatory EFV or curb valve installation that should be considered when performing the economic analysis. Since the subset of incidents whose consequences potentially could have been mitigated if an EFV was installed versus those that potentially could have been mitigated by a curb valve is different, the magnitude of the expected benefits will also be different.
Persons interested in submitting written comments on this ANPRM must do so by February 18, 2012, to docket number PHMSA-2011-0009. For further information contact: Mike Israni, by telephone at (202) 366-4571, or by mail at DOT, PHMSA, 1200 New Jersey Avenue SE., PHP-1, Washington, DC 20590-0001.