Hydrogen pipeline construction
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Our company is currently constructing two hydrogen pipelines at a thermal power plant, and we would like to inquire about the inspection requirements for the welds of these pipelines, as well as the requirements regarding pressure testing.
Hydrogen has a large explosion range, so special attention is required!
1.5 times hydrostatic test; note: the water quality requires a chloride content of less than 25 mg/L； 100% flaw detection inspection. Hydrogen pipelines are very special; one must be extremely careful!
Hydrogen pipelines – it’s not necessarily a very great hazard. Our company has many H2 pipelines, and as long as the temperature is not too high and the pressure is not too high, it is sufficient to conduct pressure testing using water. If the temperature of the medium (H2) is high, the issue of hydrogen embrittlement in the pipes must be taken into consideration. When calculating the flow rate of H2, it is important to ensure that the flow rate is not too high; generally, the design requirement for the flow rate of flammable and explosive gases is less than 8 m/s.
Hydrogen pipelines are preferably made of stainless steel; if carbon steel is used, hydrogen embrittlement is likely to occur, and hydrogen cracking can happen at high temperatures. The occurrence of these two situations is both quite dangerous. It is very important to check for leaks in hydrogen pipelines after they are completed
Weld inspection: 10% for fixed joints, 5% for rotating joints. A pneumatic pressure test is conducted, with the test pressure being 1.15 times the design pressure. These are the requirements for weld inspection of hydrogen pipelines in the project I am working on.
Generally, in accordance with the provisions of the \"Code for Construction and Acceptance of Industrial Metal Piping Projects\" (GB50235-97) and the \"Code for Construction and Acceptance of Welding Works of Field Equipment and Industrial Piping\" (GB50236-98), design institutes require that pipelines transporting hydrogen be subjected to 10% radiographic inspection, with the quality level having to be no lower than Grade II.