Inspection items for seamless carbon steel pipes

Inspection items for seamless carbon steel pipes

The inspection of seamless carbon steel pipes generally includes: inspection of geometric dimensions and surface quality; inspection of chemical composition, mechanical properties, process properties, high and low microstructures; non-destructive testing; some special performance inspections and length measurements.

(1) Geometric inspection of seamless steel pipes: The outer diameter, wall thickness, bending degree and length of seamless steel pipes can be inspected on the inspection table with external calipers, micrometers, bending gauges and length tapes.

For the outer diameter, wall thickness and length, automatic size detection devices (such as automatic diameter measuring, thickness measuring, and length measuring devices) can also be used for continuous detection. The seamless steel pipe production plants put into operation in the late 1980s generally have online automatic diameter and thickness measuring devices, and length measuring and weighing devices are installed in the finishing area. For OCTG seamless steel pipe, 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 visually. In addition to visual inspection, the inner surface can also be inspected by a reflective prism. Some special-purpose seamless steel pipes also require non-destructive testing to test the quality of the inner and outer surfaces of seamless steel pipes, including eddy current, magnetic flux leakage, ultrasonic, and magnetic particle inspection.

(3) Testing of mechanical properties and process performance: In order to verify whether the mechanical properties of seamless carbon steel pipes meet the standard requirements, it is necessary to test the mechanical properties of seamless steel pipes.

The mechanical properties 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 are selected according to the differences in standards and the use of seamless steel pipes.

(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 inspection, ultrasonic inspection, eddy current inspection and fluorescent magnetic particle inspection have been widely used in seamless steel pipe enterprises. In recent years, non-destructive testing methods have made great progress, and new technologies such as acoustic emission holography, ultrasonic spectral analysis and flaw detection, ultrasonic imaging testing, and ultrasonic high-temperature testing have recently appeared.

After the finished seamless steel pipe is completed, it is sent to the inspection department for product quality inspection, which is an important measure to ensure the quality of the seamless steel pipe. The inspection standards and content are stipulated by national standards and some standards or technical conditions.

Inspection of finished seamless steel pipes can be random and complete. Sampling inspection is generally to determine the mechanical properties, internal structure and chemical composition of seamless steel pipes. In addition to sampling inspection of a batch of seamless steel pipes, some important seamless steel pipes are sometimes fully inspected. In addition, hot-rolled seamless steel pipes are also subjected to process tests such as flattening, bending, hemming, and flaring, as well as hydraulic tests according to standard requirements.

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