Main Inspection Items and Methods of Seamless Steel Pipes

The inspection of seamless steel pipe usually includes: the inspection of geometric dimension and surface quality; the inspection of chemical composition, mechanical properties, process performance, high and low microstructure; non-destructive test; some special performance inspection and length measurement.


(1) geometric dimension inspection of seamless steel pipe: the external diameter, wall thickness, bending degree and length of seamless steel pipe can be inspected on the inspection table through the external diameter caliper, micrometer, bending ruler and length tape.
For outer diameter, wall thickness and length, automatic dimension detection equipment (such as automatic diameter measurement, thickness measurement, length measurement equipment) can also be used for continuous detection. In the late 1980's, the seamless steel pipe plants which were put into operation generally had online automatic diameter measurement and thickness measurement devices, and length measurement and weighing devices were set in the finishing area. For OCTG seamless steel pipe, the thread parameters need to be checked.


(2) internal and external surface inspection of seamless steel pipe: the internal and external surfaces are usually inspected by visual inspection. In addition to visual inspection, reflection prism can also be used to inspect the internal surface. Some special-purpose seamless steel pipes also require non-destructive testing to check the quality of internal and external surfaces of seamless steel pipes, including eddy current, flux leakage, ultrasonic and magnetic particle inspection.


(3) mechanical properties and process performance test: in order to verify whether the mechanical properties of seamless steel pipe meet the standard requirements, it is necessary to test the mechanical properties of seamless steel pipe.
Mechanical property test mainly includes tensile strength, yield strength, elongation, impact energy, etc. Process performance inspection mainly includes flattening test, flaring test, hydraulic test, crimping test, cold bending test, perforation test, etc. These inspection items shall be selected according to the standard differences and the use of seamless steel pipes.


(4) nondestructive testing refers to the method of directly checking internal and surface defects without damaging seamless steel pipes. At present, seamless steel tube enterprises have widely used flux leakage testing, ultrasonic testing, eddy current testing and fluorescent magnetic particle testing. In recent years, nondestructive testing methods have made great progress. Recently, new technologies, such as acoustic emission hologram, ultrasonic spectrum analysis and flaw detection, ultrasonic imaging inspection and ultrasonic high temperature inspection, have been developed.