The inspection of black steel pipe generally includes: inspection of geometric dimensions and surface quality; chemical composition, mechanical properties, process performance, non-destructive testing and metallographic testing, etc.
(1) Geometric dimension inspection of black steel pipe
The outer diameter, wall thickness, curvature, and length of black steel pipe can be checked on the inspection table using external snap gauges, dry rulers, curvature rulers, and length tapes. The outer diameter, wall thickness and length can also be continuously detected using automatic dimensional detection devices (such as automatic diameter measuring, thickness measuring and length measuring devices). Steel pipe production plants put into operation in the late 1980s generally have online automatic diameter and thickness measurement devices, and length measurement and weighing equipment in the finishing area. For OCTG steel pipes, the thread parameters also need to be checked.
(2)Inner and outer surface inspection of black steel pipe
Generally, visual inspection is used to inspect the internal and external surfaces. In addition to visual inspection, the inner surface can also be inspected using a reflective prism. Some special-purpose steel pipes also require non-destructive testing, including eddy current, magnetic flux leakage, ultrasonic, magnetic particle testing, etc. to inspect the quality of the inner and outer surfaces of the steel pipe.
(3) Mechanical properties and process performance inspection
In order to verify that the mechanical properties of black steel pipe meet the requirements of the standard, it is necessary to conduct mechanical property inspection on steel pipe samples. Mechanical property testing mainly includes tensile strength, yield strength, elongation, impact energy, etc. Process performance inspection mainly includes flattening test, expansion 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) Non-destructive testing
Non-destructive testing refers to a testing method to inspect the surface and internal quality of the inspected components without damaging the working condition of the black steel pipe. This is a testing method to check the surface and internal quality of components without affecting the performance and service life of the workpiece or raw materials.
The principle of non-destructive testing is to detect these defects by utilizing various physical and chemical properties of substances and the existence of defects. Commonly used non-destructive testing methods include X-ray testing, ultrasonic testing, eddy current testing, magnetic particle testing, etc. These methods can detect defects on the surface and inside the workpiece with good reliability.
(5) Metallographic examination
Metallurgical inspection is a very important metal material inspection method, which is generally carried out by microscopic observation, microhardness measurement, fracture analysis and other methods.
Metallographic structure is the macroscopic expression of the internal structure of metal materials, and it is also the way to determine the internal structure of metal materials.and the main method of defects. In the manufacturing process of black steel pipe, metallographic inspection is an important process. Its purpose is to check whether the metallographic structure of the workpiece is uniform and complete, whether there are any abnormal phenomena, and whether there are metallurgical defects, etc. At the same time, the workpiece can also be heat treated or other processes based on the observation results of the metallographic structure.
(1) Geometric dimension inspection of black steel pipe
The outer diameter, wall thickness, curvature, and length of black steel pipe can be checked on the inspection table using external snap gauges, dry rulers, curvature rulers, and length tapes. The outer diameter, wall thickness and length can also be continuously detected using automatic dimensional detection devices (such as automatic diameter measuring, thickness measuring and length measuring devices). Steel pipe production plants put into operation in the late 1980s generally have online automatic diameter and thickness measurement devices, and length measurement and weighing equipment in the finishing area. For OCTG steel pipes, the thread parameters also need to be checked.
(2)Inner and outer surface inspection of black steel pipe
Generally, visual inspection is used to inspect the internal and external surfaces. In addition to visual inspection, the inner surface can also be inspected using a reflective prism. Some special-purpose steel pipes also require non-destructive testing, including eddy current, magnetic flux leakage, ultrasonic, magnetic particle testing, etc. to inspect the quality of the inner and outer surfaces of the steel pipe.
(3) Mechanical properties and process performance inspection
In order to verify that the mechanical properties of black steel pipe meet the requirements of the standard, it is necessary to conduct mechanical property inspection on steel pipe samples. Mechanical property testing mainly includes tensile strength, yield strength, elongation, impact energy, etc. Process performance inspection mainly includes flattening test, expansion 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) Non-destructive testing
Non-destructive testing refers to a testing method to inspect the surface and internal quality of the inspected components without damaging the working condition of the black steel pipe. This is a testing method to check the surface and internal quality of components without affecting the performance and service life of the workpiece or raw materials.
The principle of non-destructive testing is to detect these defects by utilizing various physical and chemical properties of substances and the existence of defects. Commonly used non-destructive testing methods include X-ray testing, ultrasonic testing, eddy current testing, magnetic particle testing, etc. These methods can detect defects on the surface and inside the workpiece with good reliability.
(5) Metallographic examination
Metallurgical inspection is a very important metal material inspection method, which is generally carried out by microscopic observation, microhardness measurement, fracture analysis and other methods.
Metallographic structure is the macroscopic expression of the internal structure of metal materials, and it is also the way to determine the internal structure of metal materials.and the main method of defects. In the manufacturing process of black steel pipe, metallographic inspection is an important process. Its purpose is to check whether the metallographic structure of the workpiece is uniform and complete, whether there are any abnormal phenomena, and whether there are metallurgical defects, etc. At the same time, the workpiece can also be heat treated or other processes based on the observation results of the metallographic structure.
