Use high-quality rolled plate, and after re-inspection, use longitudinal shear or automatic forming and welding of rolled plate. At the same time, the optimum melting temperature is controlled by computer to remove the internal and external burrs of steel pipe. The steel pipes qualified by nondestructive testing are heated to 965,438+00℃-950℃ and discharged. The descaling is carried out by tension reducing mill for multiple passes, so that the metallographic structure, grain state, geometric size and mechanical properties of the steel pipe are uniform. The products meet the standards of API SPEC 5L, API SPEC 5CT and EN 102 17. This product is widely used in flammable and nonflammable fluid pipelines, boilers and steel structures. Seamless steel pipe is also called hot rolled seamless steel pipe or hot rolled steel pipe. The production technology of seamless steel pipe seamless steel pipe is very important. The expanding process is a continuous rolling process of hollow base material without mandrel. The expanding and shrinking process of welded pipe is to heat the whole pipe to above 950 degrees Celsius under the condition of ensuring the welding quality of the mother pipe, and then roll it into finished pipes with various external diameters and wall thicknesses by expanding and shrinking machine (expanding and shrinking machine * * *, a total of 24 passes). The hot-rolled steel pipe produced by this process is essentially different from ordinary high-frequency welded pipe, and the metallographic structure and mechanical properties of the weld after heating in the heating furnace can be completely consistent with that of the mother pipe. In addition, through multi-pass expanding, seamless welded pipe technology has been widely used in fluid pipes and boiler tubes produced in developed countries in the world. With the development of society, the situation that domestic hot-rolled welded pipes gradually replace seamless pipes has been formed.