Pipeline Plugging is the method of safely isolating and bypassing a section of pipeline enabling modification to a pressurized system without the need to shutdown the line under operating conditions.
Why Plug a Pipeline?
Isolation may be required for several reasons:
- Replace or install a new line valve
- Repair a damaged section of pipe due to external damage or corrosion
- Repair a ruptured line
- Isolate a compressor station or plant unit
- Line requiring modification due to:
- Line re-route
- Plant alteration
- Tie-in new section of pipeline
Pipeline Plugging Techniques:
Isolation of a pipe is obtained by inserting a plugging head into the pipe through a hot tapped fitting and temporary valve assembly while under pressure.
After the plugging head has been set, the pressure is relieved in the isolated section through an equalization fitting on the isolated section of pipe.
After the modification to the pipeline or plant has been made, the equipment needs to be removed.
The line is equalized, and the plugging head is retracted.
In order to remove the temporary valve a completion plug is installed and secured into the fitting. The pressure is relieved above the plug and the equipment is removed.
A blind flange is then installed over the plug and the job is completed. If necessary the fitting can be re-entered in the future by removing the blind flange, re-installing the temporary valve and removing the completion plug.