Crews build a temporary bypass around the damaged section so customers keep gas service, then cut out and replace the damaged pipe.
- Gas service
- Stays on
- Damaged section isolated
- After the bypass is built and the segment is blown down
- Permanent repair
- Two weeks
- Worker hazard
- Welding into a mix of gas and air
- Also
- Continuous, 24-hour excavation; traffic re-routed (Class 3 location)
Step 1 of 7
Where things stand
Gas is still escaping from the damaged main, and the fire department remains on scene.
Step 2 of 7
Dig on both sides of the damage
Crews begin continuous, 24-hour excavation upstream and downstream of the damaged area.
Step 3 of 7
Install hot taps on the live line
Leak-proof taps are installed into the pipeline at either end of the damaged area while gas keeps flowing.
Worker hazardWelding into a mix of gas and air can lead to sparks and ignition, since the line isn’t shut down. Pressure is reduced as low as possible, workers wear flame-retardant fire suits and self-contained breathing apparatus, and the fire department stands by with hoses charged.Step 4 of 7
Build the bypass
A bypass is constructed between the two taps to divert flow from the damaged segment. Customers keep gas service.
Step 5 of 7
Blow down the damaged segment
Gas is blown down to vacate the impacted segment before it is cut out.
Step 6 of 7
Cut out and replace
With the bypass providing gas service, repair crews work within normal business hours to cut out the damaged pipe and install a new segment.
Step 7 of 7
Return to normal flow
The bypass is disabled and gas flows normally through the new pipe. The permanent repair takes two weeks, and traffic must be re-routed because this is a densely populated Class 3 location.