In practice, we can use welded pipes to transport various low-pressure fluids. The products are generally made of Q195, Q215A, Q235A steel and Q235B carbon. It can also manufacture 0317 standard model 6012 and steel 755 mild steel that are easy to weld. After the production of welded pipes is completed, tests such as water pressure, bending, and flattening shall be carried out. At the same time, its surface quality also has certain requirements.

At the same time, the length and diameter of the welded pipe should also meet the actual application requirements. According to the different wall thickness, it can be divided into ordinary steel pipe and thick steel pipe. According to the shape of the pipe end, the steel pipe has two kinds of threads, one with threads and the other without threads. Among them, submerged arc welding of straight seam steel pipes generally uses submerged arc welding technology, and fill welding and submerged arc welding of particle protectants are used. The diameter of submerged arc welded straight seam steel pipes can reach 1500 mm. Submerged arc welding straight seam steel pipe production technology includes JCOE forming technology and continuous submerged arc welding technology.

Welded pipe

That is to say, with the continuous improvement of production level, the production quality and process level of various welded pipes have also been improved. So what are the acceptance criteria for welded pipes?

1. Straight seam steel pipes shall be submitted for inspection in batches, and the group approval rules shall comply with relevant product standards.

Second, the welded pipe inspection should be carried out according to the relevant product standards, inspection items, sampling quantity, sampling position and test method. With the consent of the purchaser, hot-rolled seamless straight seam steel tubes can be sampled in batches according to the rolling root array. In the analysis of the test results, if there is one that does not meet the requirements of the product standard, the unqualified personnel should be selected, and double samples from the same batch of straight seam steel pipes should be selected for re-inspection of the unqualified items. If the re-inspection result (including any index required by the project test) fails, the batch of straight seam steel pipes shall not be shipped from the factory.

If the re-inspection result is still unqualified, the welded pipe should be inspected and accepted one by one, or re-heat treated (the number of re-heat treatments should not exceed two times), and the acceptance shall be submitted according to the new batch. When the product standard has no special provisions, the chemical composition of the welded pipe shall be inspected and accepted according to the melting composition.