The production process of large-diameter thick-walled steel pipe generally includes hot rolling, hot coiling, casting and other production methods. Large-diameter thick-walled steel pipes are mostly produced in double-sided submerged arc welding (SSAW pipe). After bending, jointing, internal welding, external welding, straightening, and flattening, the products meet the standards of the American Petroleum Institute.

At present, there are three types of steel piles commonly used in engineering construction, namely steel pipe piles, section steel piles, and steel sheet piles. Compared with other steel piles, steel pipe piles have their unique advantages in many aspects. Such as bending stiffness, single pile bearing capacity and many other aspects.

High-frequency welded pipe is a steel pipe that uses the skin effect and adjacent effect generated by high-frequency current to connect steel plates. The emergence and maturity of high-frequency welding technology is a key process in the production of ERW pipe. The quality of high-frequency welding directly affects the overall strength, quality level and production speed of welded pipe products.

Submerged arc welding (including submerged arc surfacing and electroslag surfacing, etc.) is a method in which the arc burns under the flux layer for welding. Its inherent advantages such as stable welding quality, high welding productivity, no arc light and little smoke make it the main welding method in the manufacture of important steel structures such as pressure vessels, pipe section manufacturing (mainly SSAW pipes and LSAW pipes), and box-shaped beams and columns.

The flaring test is a method to test the deformation performance of the steel pipe end flaring process. When performing the flaring test, press the top core with a certain taper into one end of the metal tube sample to make it evenly expand to the flaring rate (%) specified in the relevant technical conditions, and then check whether there are cracks and other defects at the flaring , to determine whether it is qualified or not.

During the processing of steel pipes (seamless pipes or welded steel pipes), residual stress is generated, and the higher ones are near the yield limit. Most of the residual stress in the steel pipe shows a great harmful effect. For example, the strength of the steel pipe is reduced, the fatigue limit of the workpiece is reduced, stress corrosion and brittle fracture are caused, and the component is deformed due to the relaxation of the residual stress, which affects the dimensional accuracy of the component. Therefore, it is very necessary to reduce and eliminate the residual stress of components.