High-frequency welding originated in the 1950s. It is a new welding process that uses the skin effect and adjacent effect generated by high-frequency current to connect steel plates and other metal materials. The emergence and maturity of high-frequency welding technology has directly promoted the huge development of the straight seam welded pipe industry, which is a key process in the production of ERW steel pipes. The quality of high-frequency welding directly affects the overall strength, quality level and production speed of welded pipe products

Alloy tubes are divided into structural seamless tubes and high-pressure heat-resistant alloy tubes. Mainly different from the production standard of alloy pipe and its industry, annealing and tempering of alloy pipe changes its mechanical properties and achieves the required processing conditions.

Passivation of seamless tubes refers to the process of metal oxidation by strong oxidants or electrochemical methods to make the surface into an inactive state, that is, passivation.It is a method of converting the surface of the steel pipe into a state that is not easily oxidized and delaying the corrosion rate of the metal.

The hot-expanded steel pipe is a steel pipe produced by a waste pipe finishing process that expands the diameter of the pipe—the hot-expanding process. The heat-expanded steel pipes usually mentioned are seamless steel pipes.

API is an acronym for American Petroleum Institute. API is responsible for standardizing equipment used in the oil and gas industry to ensure the safety, reliability and interchangeability of equipment used in the industry. API oil casing is mainly used for the drilling of oil and gas wells and the transportation of oil and gas. It is a large-diameter seamless pipe, which plays the role of fixing the wall or hole of oil and gas oil wells.

JCOE pipe forming method is the main forming method of straight seam submerged arc welded pipe (LSAW). Sequential forming of O type, each step of stamping is based on three-point bending as the basic principle