In order to protect the quality of the ERW welding pipe we manufacture, we carry out a quality test on every welding pipe we produce. What are the inspection methods for welded pipe? Today we are going to follow the editor of Welding Pipe Manufacturer Permanent Steel Manufacturing Co., Ltd to understand a little.
1. Basic requirements for the appearance of ERW steel pipe welds with straight seams
Before the non-destructive testing of steel pipes with a straight seam (ERW pipe), the examination of the appearance of welds should meet the requirements. The general requirements for the appearance of steel pipe welds with a straight seam and the surface quality of welded joints are as follows:
The appearance of the weld should be well shaped and the width should be 2mm above the edge of the groove on each side. The height of the weld feet of fillet welds should meet the design requirements, and the shape should blend in gently.
Weld area:
(1) Cracks, unmelted, air holes, slag inclusions and splashes are not permitted.
(2) For pipes with a design temperature of less than -29 degrees, there must be no undercut on the welding surface of pipes made of stainless steel and alloy steel, which have a greater tendency to harden. The undercut depth of the weld seam made from other materials must be greater than 0.5 mm, the length of the continuous undercut must not be greater than 100 mm and the total length of the undercut on both sides of the weld seam must not be greater than 10% of the total length of the weld seam .
(3) The surface of the weld seam must not be lower than the surface of the pipeline. The remaining height of the weld seam is no more than 3 mm (the maximum width of the weld joint group to the rear groove).
(4) The false edge of the weld joint should not be larger than 10% of the wall thickness and not larger than 2 mm.
2. Non-destructive surface testing
The selection principle of the non-destructive surface test method for steel pipes with a straight seam: For steel pipes made of ferromagnetic material, the test of magnetic particles should be used. Penetration tests should be selected for steel pipes made of non-ferromagnetic material.
For welds that tend to delay cracking, the non-destructive surface inspection should be performed after the weld has been allowed to cool for a period of time. For welded joints that tend to rewarm cracks, the non-destructive surface inspection should be performed once after welding and after heat treatment.
The application of the non-destructive surface testing takes place according to the requirements of the standard. The detection objects and applications are generally as follows:
(1) The quality inspection of the outer surface of the pipe material.
(2) Detection of surface defects in important butt welds.
(3) Detection of surface defects of important fillet welds.
(4) Detection of surface imperfections in socket weld ends of important socket weld and bridging three-way branch pipes.
(5) Detection of surface defects after pipe bending.
(6) Bevel detection of welds with a greater tendency to quench the material.
(7) Detection of non-austenitic pipe grooves made of stainless steel, the design temperature of which is below or equal to minus 29 degrees Celsius.
(8) Weld of the double-sided weld specified root inspection after rooting
(9) When an oxyacetylene flame is used to cut welders on alloy pipes that tend to be hardened, the defects of the repaired parts are detected.
3. Beam detection and ultrasonic detection
The main objects of X-ray and ultrasonic testing are butt joints of steel pipes with a straight seam and butt joints of butt-welded pipe fittings.
The selection of the non-destructive test methods must correspond to the design documents. The radiation detection method should be selected for the detection of welded joints made of titanium, aluminum and aluminum alloys, copper and copper alloys, nickel and nickel alloys.
For welds with a tendency to delay cracks, the x-ray and ultrasound tests should be performed after the weld has cooled for a period of time.
If the main pipe in the jacket has a circumferential weld, then the weld must be 100% checked radiologically, and the covert operation can be carried out after passing the pressure test.
The welded connections that are covered by the reinforcement ring or the support cushion on the pipeline must be 100% checked radiologically and covered after the test has been passed.
For the welds that are required for the intermediate welding test, a non-destructive test should be carried out after the qualified examination of the appearance. X-ray and ultrasonic testing should be performed after the surface has been non-destructively tested, and the welds tested can continue to be welded after they are qualified.
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