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Basic requirements for the appearance of welds of straight seam steel pipes
Date:2020-09-04      Views:257Time      Label:Basic requirements for the appearance of welds of straight seam steel pipes

1. The surface of the welding joint:

 

A. Cracks, lack of fusion, pores, slag inclusion, and splashes are not allowed.

B. The weld surface of pipes whose design temperature is lower than -29 degrees, stainless steel and alloy steel pipes with a greater tendency to hardening shall not have undercut. The undercut depth of the weld of other materials should be greater than 0.5mm, the continuous undercut length should not be greater than 100mm, and the total undercut length on both sides of the weld should not be greater than 10% of the full length of the weld.

C. The weld surface must not be less than the pipe surface. The remaining height of the weld is not more than 3mm (the large width of the posterior groove of the welded joint assembly).

D. The wrong side of the welded joint should not be more than 10% of the wall thickness and not more than 2mm.

 

2. Surface non-destructive testing: seam steel pipes: magnetic particle testing should be used for ferromagnetic steel pipes; penetrant testing should be used for non-ferromagnetic steel pipes. For welded joints with delayed cracking tendency, the surface non-destructive inspection shall be carried out after the welding cooling time; for welded joints with the trend of reheat cracking, the surface non-destructive inspection shall be carried out after welding and after heat treatment.

 

3. Radiographic inspection and inspection: The main objects of radiographic inspection and inspection are butt joints of straight seam steel pipes and butt welded pipe fittings. The selection of non-destructive testing methods is consistent with the design documents. For welding joints of titanium, aluminum and aluminum alloys, copper and copper alloys, nickel and nickel alloys, radiographic testing methods should be utilized. For welds with delayed cracking tendency, radiographic inspection and inspection shall be performed after the welding cooling time. When the main pipe in the jacketed tube has a girth weld, the weld shall be subjected to 100% radiographic inspection, and the concealed operation can be out in carried out after the pressure test is qualified. The welded joints on the pipeline covered by the reinforcement ring or the support pad shall be subject to 100% radiographic inspection and can be covered again after being qualified. For welds that are required to undergo intermediate welding inspections, non-destructive testing should be carried out after the visual inspection is qualified, radiography and wave testing should be carried out after surface non-destructive testing, and the inspected welds can be welded only after they are qualified.