Non Destructive Testing of DSAW Pipe

1. Weld appearance of the basic requirements of dsaw pipe
DSAW pipe before the non-destructive testing, weld appearance inspection should meet the requirements. The general requirements for the appearance of the seam and the surface quality of the welded joint are as follows:
The welding appearance should be well shaped and the width is covered by 2mm on each side of the groove. Fillet weld feet height should meet the design requirements, shape should be a smooth transition.

Welded joint surface (1) does not allow cracks, not fused, stomata, slag, splash exists. (2) design of the temperature below -29 degrees of the pipeline, stainless steel and hardening tend to larger alloy steel pipe weld surface, no biting phenomenon. Other material pipe weld seam depth should be greater than 0.5mm, continuous undercut length should not be greater than 100mm, and the weld on both sides of the total undercut is not greater than 10% of the full length of the weld. (3) the surface of the weld shall not be lower than the surface of the pipe. Weld height, and not more than 3mm, (for the welding joint group on the rear slope of the maximum width). (4) Weld joints should not be greater than 10% of the wall thickness, and not more than 2mm.

2. Non-destructive testing on surface
DSAW pipe surface non-destructive testing method selection principle: the ferromagnetic material steel pipe, should use the magnetic powder detection; non-ferromagnetic material steel pipe, should use the penetration test.

For non-destructive testing of weld joints with delayed crack tendency, the surface non-destructive testing shall be carried out after welding for a certain period of time. For weld joints with reheating cracks, the surface non-destructive testing shall be carried out once after welding and after heat treatment.

The application of surface non-destructive testing in accordance with the standard requirements, the detection of objects and applications are generally as follows:
(1) Inspection of outer surface of pipe material.
(2) Important butt weld surface defects detection.
(3) Detection of important fillet weld surface defects.
(4) Important socket welding and cross-type three-way pipe fittings welded joint surface defect detection.
(5) Surface defects after pipe bending test.
(6) The material quenching to the larger welding joints of the groove detection.
(7) The design temperature is less than or equal to minus 29 degrees celsius non-austenitic stainless steel pipe groove detection.
(8) Double-sided weldment of the provisions of the clear root of the weld after the detection of the root.
(9) When the use of oxygen acetylene flame cutting hardened alloy pipe on the welding fixture, grinding parts of the defect detection.

3. Ray detection and ultrasonic testing
The main object of ray detection and ultrasonic testing is the butt joint of the straight seam steel pipe and the butt joint of the welded pipe.Non-destructive testing methods are selected according to the design documents. For titanium, aluminum and aluminum alloy, copper and copper alloy, nickel and nickel alloy welded joint testing, should use the ray detection method.For welds with a tendency to delay the crack, ray detection and ultrasonic testing should be performed after a certain period of time after welding.When the jacket inside the tube with a weld, the weld should be 100% radiation testing, after passing the test before the covert operation.Pipes on the reinforcement ring or support plate covered welding joints, should be 100% ray detection, qualified before re-coverage.