If the non-destructive testing of all welds in the pipeline is satisfactory, can the pressure test and airtightness test be omitted?

It is absolutely not allowed according to the standards, especially for gas pipelines! Passing the flaw detection test does not mean that the strength of the component is also satisfactory. Valves, flanges, and drain pipes used in industrial applications must be leak-proof; therefore, it is necessary to conduct airtightness tests, especially for materials that are flammable or explosive!

It is absolutely not allowed according to the standards, as non-destructive testing also requires a certain proportion of weld inspections; 100% inspection is not permissible either. The explanation given above is already very clear! Gaskets are also a potential source of leaks!

Since the non-destructive testing of all welds in the pipeline has passed, pressure tests and airtightness tests are still required. In fact, these tests are carried out on the premise that the non-destructive testing has been successful

Voltage resistance can test strength; it cannot be replaced； The applicability of the airtightness testing conditions is also irreplaceable ； Especially in some areas, it is difficult to perform flaw detection, such as at fillet welds. Therefore, design specifications must be followed; this is all based on experience.

It is absolutely not allowed; this is a **mandatory requirement**. After all, welds are just welds, and they do not represent all potential locations of leaks. Things such as the bolts on flanges and the threads themselves are also potential sources of leaks. Even if the welds are of satisfactory quality, problems can still occur.

The Code for Construction and Acceptance of Industrial Metal Piping Projects GB50235-97 specifies as follows: **Pressure test**.1 After the piping has been installed and heat treatment as well as non-destructive testing have been completed successfully, a pressure test shall be carried out. Pressure tests shall comply with the following provisions: **.1.1 Pressure tests shall use liquid as the testing medium. When the design pressure of the pipeline is less than or equal to 0.6 MPa, gas can also be used as the testing medium, but effective safety measures must be taken. Gas pressure testing is strictly prohibited for brittle materials. **.1.2 When site conditions do not permit the use of liquids or gases for pressure testing, with the consent of the project owner, the following methods may be used as alternatives: (1) All welds (including those on attachments) shall be inspected using the liquid penetrant method or the magnetic particle method. (2) Butt welds shall be inspected by 100% radiography. **.5 Pipelines transporting highly toxic fluids, toxic fluids, and flammable fluids must undergo leak testing. The leak test shall be carried out in accordance with the following provisions: **.5.1 The leak test shall be conducted after the pressure test is successful. Air is preferably used as the testing medium. **.5.2 The leakage test pressure shall be the design pressure. **.5.3 The leakage test can be carried out simultaneously with the commissioning work. **.5.4 The leakage test should focus on inspecting the valve stuffing boxes, flange or threaded connections, relief valves, exhaust valves, drain valves, etc. It is considered qualified if no leakage is detected using a foaming agent. **.5.5 Pipes that have passed the pressure test and have not been disassembled after the test may be exempted from the leak test. **.6 After passing the pressure test, the vacuum system shall also undergo a 24-hour vacuum level test in accordance with the specifications in the design documents, with the pressure increase rate not exceeding 5%. **.7 When the design documents specify that leakage tests be carried out using halogens, helium, ammonia, or other methods, such tests shall be conducted in accordance with the relevant technical specifications.

It is not allowed according to the standards; GB 50235 and GB/T 20801 have relevant provisions.

They should be two different things, but both should be carried out