What is a gas pipeline?
Gas pipeline is the long – distance transport of liquid or vapor gas via a pipe network usually to a customer location. Pipeline testing is mainly done to enhance and ensure the safety of the gas pipeline system.
How to test a gas pipeline?
- Pipeline Pressure Testing: The pipeline is supplied with a 1.5 – fold working pressure of air / nitrogen gas and is maintained for one hour to three hours.
- Hydrostatic Tests: This includes pressurizing a pipe with water to detect possible vulnerabilities. Hydrostatic testing is an existing method of evaluating a gas pipeline’s capacity to work at a pressure. The following steps are involved in conducting a hydrostatic test:
- The pipeline to be tested is withdrawn from operations. All the gas inside it is removed and the interior is washed mechanically.
- The pipe is then closed on both ends and filled wholly with water. The water is pressurized to the test pressure. The pressure of the test is kept and tracked for a specified period of time, usually 8 hours.
- Once it is identified that there is no pressure loss then the pipeline portion is drained of water, completely cleaned and put back into operation.
- If a section fails to meet or maintain the pressure, it means that the hydrostatic test has either caused the pipe to leak or break. In that situation the leak is detected, fixed and the pipe is again checked. Pipes which don’t pass a hydrostatic examination are replaced.
- In – Line Testing: In-line inspection requires the use of sophisticated technical devices, also referred to as ‘smart pigs’ or in – line inspection methods that are deployed inside the pipeline. In – line inspection requires the use of sophisticated technical devices, also referred to as ‘smart pigs’ or in-line inspection methods that are deployed inside the pipeline. The ‘smart pigs’ travels at around five miles an hour and is usually used to inspect gas pipelines operating at higher pressures. The machine records data (such as the thickness of the wall, corrosion, dents, etc.) as it passes through the pipeline. The data is processed and adjustments are made after inspection.
- Camera Testing: Camera inspection involves drilling multiple holes along the transmission line length so that a tethered camera can be install to monitor the pipe’s internal conditions. The camera’s video footage will be transmitted to a surveillance and recording device. Trained professionals will then analyse the recording and decide if any actions are required.
When to test a gas pipeline?
- Pipeline in storage area: Every 12 months.
- Hydrostatic valve: These can be replaced every 10 years with new units operating at a pressure.
- Normal testing: Testing is typically performed three times a year, depending on the age and form of gas network and pipeline. We recommend that you go for testing twice a year.
Gas pipeline certification
Gas pipelines should be tested and certified yearly. Failure to comply not only increases risks of incidents but may result in penalties and shutdown of operations by authorities.
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