Relief valves, engineered to prevent system over‑pressurization, are a critical part of the natural gas pipeline system. They actively regulate pressure within the system by opening at a preset pressure to vent excess gas and vapors and then by closing once the pressure is back within a safe range. These mechanical safety devices, though small, play a large role in protecting not only the system but also the community.

If the system does not vent properly, the resulting pressure buildup could lead to system failure. The consequences of a system failure could be as minor as a temporary gas outage or as catastrophic as an explosion. This is why first responders should NEVER attempt to operate these valves or restrict the associated vents in any way.

Be proactive. A natural gas event should not be your introduction to relief valves in the communities you serve. Partner with National Grid preemptively to learn the location of valves within their facilities.

Ask questions. Obviously, a natural gas emergency may not be the optimal time to ask dispatched National Grid personnel for valve safety education and training. Communication between you and utility personnel prior to an event is essential to valve safety. Ensure that you understand the basics of relief valve function and behaviors, but most importantly, NEVER operate or restrict pressure relief valves in any situation. Query utility personnel about any concerns and uncertainties you may have so that you are well informed and prepared.

Train. Knowing how to respond to normal and abnormal pressure release events helps protect not only you and your crew but also your community and the environment. The more informed and trained you are, the more effective you can be at managing a release event.

Contact and work with the utility. When dispatched to investigate, notify the utility and request the response of a subject matter expert (SME) to work in partnership with first responders as a member of the command team. Work with the onsite SME to:

Engage with the community. Even a small release of natural gas through a relief valve, which may be a normal operating condition, will often result in community concern – or even panic – stemming from the sulfur-like or rotten‑egg smell of mercaptan. During any pressure release event, you should work with the utility to distinguish between normal and abnormal (emergency) situations.

The discharge sounds, odorants and vapor clouds produced from the valves can be alarming to the public – and rightfully so. Once the utility has confirmed that the event is nonthreatening: