Before natural gas is transported through a new pipeline, the entire length of the pipeline is pressure tested using water. This hydrostatic testing is the final construction quality assurance test before the pipeline is put into operation.
Requirements for this test are also prescribed in DOT’s federal regulations. Depending on the varying elevation of the terrain along the pipeline and the location of available water sources, the pipeline may be divided into sections to facilitate the test. Each section is filled with water and pressured up to a level higher than the maximum pressure at which the pipeline will operate when carrying natural gas.
The test pressure is held for a specific period of time to determine if the pipeline meets the design strength requirements and if any leaks are present. Once a section successfully passes the hydrostatic test, water is emptied from the pipeline and the pipeline is dried to ensure that no water is present when natural gas begins to flow.
Other steps in the constructions process:
- Clearing and grading
- Pipe bending and Welding
- Depositing the pipeline and Backfilling