Pipeline valves are one of the key safety components involved in the testing, maintenance and everyday operational activities of our natural gas pipeline. Natural gas valve replacement is one of the many ways that we maintain the safety and integrity of our natural gas pipeline system.
How Pipeline Valves Work
Valves are mechanical devices that control the flow of natural gas through our pipelines. An open valve allows the flow of natural gas to move freely. A closed valve shuts off the flow of natural gas to a pipeline segment to allow for maintenance, testing, repair or replacement of that segment.
Our transmission pipelines are equipped with valves that separate our pipelines into sections. These valves are called mainline valves and there are about 800 of them in our transmission pipeline system. Situated inside underground pipelines, a mainline valve usually has a stem extension that reaches through to the surface and connects to either a hand wheel or an actuator.
- Hand wheel: a device that must be turned by hand by qualified field personnel to open or close the valve.
- Actuator: a device that can open or close the valve manually by qualified field personnel, or be triggered automatically when equipped with power and specialized communication systems technology.
Types of Valves
Remote Control Valves (RCVs)
Remote control valves can be opened or closed remotely by system operators from a central control location.
Automatic Shut-off Valves (ASVs)
Automatic shut-off valves are equipped with a control device that automatically triggers the actuator and shuts off the flow of natural gas in the event of a large pressure drop.
These valves also provide routine pressure control to safeguard against exceeding the pipeline’s maximum pressure. Upgrading or retrofitting valves on the pipeline system with RCV and ASV technology provides natural gas control operators with greater flexibility and shorter response times if it's necessary to close a valve or valves quickly in the event of an emergency, such as an earthquake.
Replacement and Retrofitting
Safety always comes first when replacing or retrofitting a valve with RCV or ASV technology.
- Before work begins on the valve, the flow of natural gas into the pipeline segment is turned off at the nearest valve on each side, and the natural gas is safely removed by venting.
- The new valve or retrofitted equipment is installed and then tested to affirm it is functioning properly.
- Then natural gas is safely reintroduced into the pipeline segment and it is brought back into service.
Expanding the number of remote-controlled and automatic shut-off valves is one of the ways SoCalGas® maintains the safety and integrity of our natural gas pipeline system.
Minimizing Community Impact
Whenever we implement a valve replacement or retrofit project in a community, we make every effort to minimize and mitigate any impacts. If a pipeline valve replacement is happening in your community, you may see trucks and equipment on the streets, excavation sites, temporary “No Parking” signs on streets, possible lane reductions or closures, detours and temporary delays on surface streets.
Community members also may hear some work-related noise and notice an occasional natural gas odor. In some instances there may be temporary natural gas service interruptions, but we strive to provide continuous natural gas service for our customers while testing is being performed.
Construction time varies for each project, from a week or less for minor retrofits, to several weeks for more significant work such as valve replacements, relocation and retrofits. The timing ultimately depends on a number of factors such as the length of the process for obtaining necessary permits, permissible working hours as determined by the local jurisdiction, traffic control issues, location of the valve, ease of access to the valve, amount of excavation necessary to install the valve and even the weather.
We sincerely appreciate the cooperation and patience of our customers and the communities we serve as we work to enhance the safety of our natural gas pipeline system.
Natural Gas Valve Upgrades in Southern California
To view a list of valve upgrades that are currently active, visit our Pipeline Safety Enhacement Plan (PSEP) Activities by City page for more information.