The inspection of steel pipe generally includes the inspection of geometric dimension and surface quality; Chemical composition, mechanical properties, technological properties, high and low power structure inspection; Non destructive testing; Inspection of some special properties, length measurement and weighing, etc.
(1) Geometric dimension inspection of steel pipe
The outer diameter, wall thickness, bending and length of steel pipe can be checked on the inspection table with external caliper, micrometer, bending ruler and length tape.
The outer diameter, wall thickness and length can also be continuously detected by automatic size detection devices (such as automatic diameter, thickness and length measurement devices). The steel pipe plants put into operation in the late 1980s generally have on-line automatic diameter and thickness measuring devices, with length measuring and weighing equipment in the finishing area. For OCTG steel pipe, the thread parameters also need to be checked.
(2) Inspection of inner and outer surface of steel pipe
Generally, visual inspection is used for internal and external surface inspection, and in addition to visual inspection, the internal surface can also be inspected by using reflection prism. Some special purpose steel pipes also require nondestructive testing, including eddy current testing, magnetic flux leakage testing, ultrasonic testing, magnetic particle testing, etc.
(3) Inspection of mechanical and technological properties
In order to verify that the mechanical properties of the steel pipe meet the requirements of the standard, it is necessary to inspect the mechanical properties of the steel pipe by sampling.
Mechanical property inspection mainly includes tensile strength, yield strength, elongation, impact energy, etc. Process performance inspection mainly includes flattening test, expanding test, hydraulic test, curling test, cold bending test, perforation test, etc. These inspection items are selected according to different standards and different uses of steel pipes.
(4) Nondestructive testing
Nondestructive testing refers to the inspection of internal and surface defects of steel pipe without damage. At present, magnetic flux leakage testing, ultrasonic testing, eddy current and fluorescent magnetic particle testing have been widely used in steel pipe enterprises. In recent years, nondestructive testing has made great progress. Recently, new technologies such as acoustic emission holography, ultrasonic spectrum analysis, ultrasonic imaging and high temperature ultrasonic testing have emerged.
(5) Chemical composition test
According to the requirements of the standard, the main components of the steel pipe are retested according to the furnace batch number.
(6) High and low power test
It includes the inspection and determination of macrostructure, non-metallic inclusion, actual grain size, metallographic microstructure, decarburized layer, etc. It should be carried out according to the requirements of the standard.
(7) Weight test
For the steel pipe with single weight requirement, it is necessary to check whether the weight meets the contract or standard requirements through the weighing device.
