Our quality management system is strictly implemented in accordance with ISO9001 to ensure that every step of products from raw materials to finished products is strictly controlled and effectively managed. Our production and inspection process of seamless steel pipe:

Production Technology of Seamless Steel Pipe

The production methods of seamless steel pipe are roughly divided into skew rolling method (Mennesmann method) and extrusion method. Cross rolling (Mennesmann method) is the process of piercing a tube with a cross roll and then extending it with a rolling mill. This method has a fast production speed, but requires a high machinability of the billet. It is mainly suitable for the production of carbon steel and low alloy steel pipes.

The extrusion method is to use a piercing machine to pierce the billet or ingot and then extrude it into steel pipe. This method is less efficient than the skew rolling method and is suitable for the production of high strength alloy steel pipe.

Both cross rolling and extrusion methods must first heat the billet or ingot, and the produced steel pipe is called hot-rolled pipe. Steel pipes produced by hot-working method can sometimes be cold-processed as needed. There are two methods for cold working: one is cold drawing, which is to draw steel pipe through drawing die, so that the steel pipe will gradually become thinner and elongated; the other is cold rolling, which is the method of applying the hot rolling mill invented by Mennesmann Brothers to cold working. Cold processing of seamless steel tubes can improve the dimensional accuracy and processing smoothness of steel tubes, and improve the mechanical properties of materials.

Production Technology of Seamless Steel Pipe (Hot Rolled Steel Pipe)

The seamlessness of steel tube is mainly accomplished by tension reduction, which is a continuous rolling process of hollow base metal without mandrel. Under the condition of guaranteeing the welding quality of the main pipe, the tension reducing process of the welded pipe is to heat the whole welded pipe to above 950 degrees Celsius, and then to roll the finished pipe with various external diameters and wall thickness through the tension reducing machine (24 passes in total). The hot-rolled steel pipe produced by this process is essentially different from the ordinary high frequency welded pipe. After heating in the heating furnace, the weld seam and the matrix metallograph of the welded pipe are essentially different. In addition, the dimension accuracy (especially the roundness and wall thickness accuracy) of steel tube is better than that of seamless tube by multi-pass rolling and automatic control of stretch reducing mill. Welded pipe seamless technology has been widely used in fluid pipes and boiler pipes produced in developed countries. With the development of society, the situation that hot-rolled welded pipes gradually replace seamless pipes has been formed in China.