One of the common methods for assessing pipeline integrity is the hydrostatic pressure test.
How it Works
Hydrostatic pressure testing is a process that uses water to exert pressure on a pipeline at levels much greater than its usual operating pressure. Here's how it works:
- The segment of pipeline that's being tested is temporarily removed from service and excavations are dug at both ends of the segment to expose the pipeline. Then, the natural gas inside is safely vented.
- Short sections of pipeline are removed from both ends of the segment to be tested and the ends are sealed with test caps.
- Next, the sealed test segment is filled with water using a pump. The water pressure is increased to a point higher than the pipeline will normally operate to see if it has any leaks. After holding the increased pressure for eight hours or more, the test is complete.
The water is then drained from the pipeline test segment in accordance with applicable regulations and local requirements, and the test caps are removed from the ends. The pipeline segment is then thoroughly dried and new replacement pipe is installed at both ends to reconnect the pipeline segment into the system. Natural gas is safely reintroduced into the pipeline and it is brought back into service.
Minimizing Impact to the Community
Whenever SoCalGas® conducts a hydrostatic pressure test project in a community, we make every effort to minimize and mitigate any impacts. If a pressure test 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.
You may also 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.
Safety always comes first when performing a test, and we have plans in place and repair teams standing by in the event a pipeline fails the test or needs to be repaired. If a pipeline ruptures during testing, a large amount of water will be released at the rupture site - but it should dissipate quickly.
If a hydrostatic pressure test of a pipeline section results in a leak or a rupture, the pipeline will be repaired or replaced. If repairs are needed, we'll make them and then perform a second pressure test to confirm the success of the repairs. If a segment needs to be replaced, we'll do it with a pipe that has already passed a pressure test.
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.
Hydrostatic Pressure Tests in Southern California
To view Pipeline Safety Enhancement Plan (PSEP) hydrostatic pressure tests that are currently active, visit our PSEP Activities by City page for more information.