The inspection of seamless steel pipes
generally includes: inspection of geometrical dimensions and surface quality; chemical composition, mechanical properties, process performance, inspection of high and low microstructures; non-destructive testing; some special performance inspections and length measurement.
(1) Geometrical dimension inspection of seamless steel pipe: the outer diameter, wall thickness and bending degree and length of seamless steel pipe can be inspected on the inspection table by external caliper, micrometer and bending degree ruler and length tape measure.
For the outer diameter, wall thickness and length, automatic size detection devices (such as automatic diameter measurement, thickness measurement, length measuring device) can also be used for continuous detection. The seamless steel pipe production plant put into operation in the late 1980s generally has an online automatic diameter measuring and thickness measuring device, and a length measuring and weighing device is arranged in the finishing area. For OCTG seamless steel tubes, the thread parameters need to be checked.
(2) Inspection of the inner and outer surfaces of seamless steel pipes: The inner and outer surfaces are generally inspected by visual inspection, and the inner surface can be inspected by using a reflective prism in addition to visual inspection. Some special-purpose seamless steel tubes also require inspection of the quality of the inner and outer surfaces of seamless steel tubes through non-destructive testing, including eddy currents, magnetic flux leakage, ultrasonic waves, and magnetic particle inspection.
(3) Mechanical properties and process performance test: In order to verify that the mechanical properties of the seamless steel pipe meet the requirements of the standard, it is necessary to test the mechanical properties of the seamless steel pipe.
Mechanical properties test mainly includes tensile strength, yield strength, elongation, impact work and so on. Process performance inspection mainly includes flattening test, flare test, hydraulic test, crimp test, cold bend test, perforation test and so on. These inspection items are selected according to the differences in standards and the use of seamless steel tubes.
(4) Non-destructive testing Non-destructive testing refers to the direct inspection of internal and surface defects without damaging the seamless steel pipe. At present, magnetic flux leakage testing, ultrasonic testing, eddy current and fluorescent magnetic particle testing have been widely used in seamless steel pipe enterprises. In recent years, the non-destructive testing method has developed greatly, and recently new technologies such as acoustic emission holography, ultrasonic spectrum analysis and flaw detection, ultrasonic imaging inspection and ultrasonic high temperature detection are now available.