Non-destructive testing of straight seam steel pipe surface

Straight seam steel pipe is a welded pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. Usually divided into ERW pipe, LSAW pipe, metric electric welded steel pipe, electric welded thin-walled pipe, transformer cooling oil pipe, octg casing and so on. The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid.

Principles for selection of non-destructive testing methods for the surface of straight seam steel pipes: for ferromagnetic steel pipes, magnetic particle testing should be used; for non-ferromagnetic steel pipes, penetrant testing should be used. For welded joints prone to delayed cracks, the surface non-destructive inspection should be carried out after a certain period of welding cooling; for welded joints prone to reheat cracks, the surface non-destructive inspection should be carried out once after welding and after heat treatment. The application of surface non-destructive testing is carried out in accordance with standard requirements, and its detection objects and application occasions are generally as follows:

(1) Quality inspection of the outer surface of the pipe material.

(2) Detection of surface defects of important butt welds.

(3) Detection of surface defects of important fillet welds.

(4) Detection of surface defects of welded joints of important socket welds and crossover tee branches.

(5) Surface defect detection after pipe bending.

(6) Groove detection of welded joints with large material quenching tendency.

(7) Detection of non-austenitic stainless steel pipe grooves whose design temperature is lower than or equal to minus 29 degrees Celsius.

(8) Inspection after rooting of weld seams specified for rooting on double-sided weldments

(9) When the oxyacetylene flame is used to cut the welding fixture on the alloy pipe with hardening tendency, the defect detection of the grinding part.

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