The Pipeline and Hazardous Materials Safety Administration (PHMSA) is authorised to consider environmental factors, including hazardous and non-hazardous methane leakages, when designing safety standards.
Leak repair requirements
PHMSA requires operators of all regulated pipelines, including gathering lines, transmission lines, and distribution lines, to repair all “hazardous” leaks promptly and ensure pipeline safety. Operators of Type A gathering lines and pipelines located in high consequence areas (HCAs), areas where pipeline releases may have larger consequences, must take “prompt” actions to address pipeline irregularities that may jeopardise pipeline integrity. Generally, leaks that are dangerous to human health or property are given precedence and must be repaired “immediately”. Less “hazardous” leaks may be repaired on a longer timescale. The regulation does not require the repair of non-hazardous leaks.
Requirements for Transmission Pipelines
PHMSA requires quarterly patrols and leakage surveys for transmission pipelines located closest to populated areas and annually for pipelines located furthest from populated areas. Operators of transmission lines carrying odorless gas, such as methane, must utilize leak detection equipment when conducting leak surveys. Operators of transmission pipelines located in High Consequence Areas (HCAs) must develop an integrity management plan (IMP), designed to inform operators on key information about pipeline conditions, such as age, material, and leak history, which is then used to develop a strategy for ensuring pipeline safety and integrity. One of the main objectives of an IMP is to detect and mitigate issues, such as leaks, before they become dangerous.
Operators of transmission pipelines are required to make “immediate” temporary measures in the event of damage that impairs serviceability, followed by permanent repairs to pipelines “as soon as feasible” for non-integrity management repairs and requires operators to follow specific procedures for integrity management repairs. Operators must also annually inspect critical valves that may be needed in an emergency and promptly resolve any inoperable valves.
Requirements for Distribution Pipelines
Operators of distribution systems must conduct patrols and leakage surveys using “leak detection equipment”. The frequency of distribution systems’ patrolling is based on an assessment of the conditions which could cause failure or leakage and the consequent hazards to public safety, with specific requirements for business districts. PHMSA requires patrols at least four times a year and leakage surveys annually in business districts.
Operators of distribution pipelines must also develop IMPs, similar to transmission lines. One important difference between transmission and distribution line IMPs is that transmission IMPs are only needed for pipelines located within HCAs, while distribution IMPs must be implemented by all local distribution companies (LDCs).
Hazardous leaks along distribution pipelines must be repaired “promptly,” but specific repair timelines are not specified. As part of the IMP, the number of hazardous leaks repaired must be reported.
Requirements for Other Pipeline Facilities
PHMSA issued limited leak inspection requirements for compressors and pressure-limiting and regulating stations, which may help to reduce fugitive emissions of methane—particularly for “hazardous” leaks. Each compressor station in a compressor building is required to have a fixed gas detection and alarm system. Operators are required to replace or repair defective compressor equipment and monitor for leaks that could cause explosions, including methane.
PHMSA requires operators at pressure-limiting and regulating stations to perform annual inspections to ensure all equipment remain in good mechanical condition. Distribution systems must also have telemetering or recording pressure gauges installed in order to monitor gas pressure.