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Pipeline weld inspection process

Pressure pipe weld appearance basic requirements

Tubing and Casing, Line Pipes



Before pressure pipeline do the nondestructive testing, visual inspection of weld inspection ruler should meet the requirements. General requirements for pressure pipe weld appearance and surface quality of welded joints are as follows:

welding should look good shape, width of each side edge bevel overshadowed 2mm appropriate. Fillet weld leg length should meet the design requirements, the level of regulation of small form factor should be smooth transition.

Welded joint surface does not allow cracks, lack of fusion, porosity, slag, spatter exist.

Pipeline design temperature is below -29 degrees, fan ruler of hardened stainless steel and alloy steel pipes tend to be larger weld surface, without undercut. Pipe weld undercut other materials should be greater than the depth of 0.5mm, continuous undercut length should not exceed 100mm, and both sides of the weld undercut grow at 10 percent of the total weld length. Weld surface not less than the pipe surface. Weld reinforcement, And no more than 3mm, (to a maximum width of weld joints on the groove). Welded joints wrong side wall thickness should not exceed 10% and not more than 2mm.

On the surface of nondestructive testing
Surface pressure pipeline NDT method selection principle: magnetic iron pipe should be used in magnetic particle testing; non-ferromagnetic steel should be used in penetration testing. There is a tendency to delayed cracking of welded joints, the surface should be non-destructive testing of cooling after welding certain time; reheat cracking tendency of welded joints, the surface should be in non-destructive testing and post-weld heat treatment once each.

Ray inspection and ultrasonic testing
Ray inspection and ultrasonic testing is the main target of the butt joint pressure pipe and pipe fittings for butt joints. NDT methods chosen by the design documents. Titanium, aluminum and aluminum alloy, copper and copper alloys, welded joints to detect nickel and nickel alloys, and should be used in radiation detection methods. There is a tendency to delay weld cracks, its ray inspection and ultrasonic testing should be at a certain time of cooling after welding.

When the head of a folder inside the casing has a girth weld, the weld should be operating 100% ray detection, covert operations can be carried out after passing through the pressure test. Reinforcement rings or bearing plate is covered with welded joints shall be 100% of the pipe-ray inspection, after passing then covered.

Examination of the provisions of the middle seam welding, non-destructive testing should be carried out after passing visual inspection, radiography and ultrasonic testing should be performed after the surface of the non-destructive testing, the test weld seam may continue after assessing eligibility.




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