The production methods of seamless steel pipe are roughly divided into skew rolling method (Mennesmann method) and extrusion method. Skew rolling (Mennesmann method) is to pierce the tube embryo with a skew roll and then extend 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.
ASTM A106 API 5L seamless 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.
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 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 by tension reducing machine (24 passes of tension reducing machine). The hot-rolled steel pipe produced by this process is essentially different from the ordinary high frequency welded pipe. The metallographic structure and mechanical properties of the weld seam and the matrix can be completely consistent after the overheating furnace is heated.
In addition, the dimensional accuracy of the steel pipe (especially the roundness and thickness accuracy of the pipe body) is superior to that of the same kind of seamless pipe by rolling and automatic control of multi-pass stretch reducing mill.Welded pipe seamless technology has been widely used in fluid pipes and boiler pipes produced in developed countries.
Haihao Group manufacture seamless steel pipes in different standards such as ASTM A106,ASTM A53,ASTM A312,ASTM A333,ASTM A335,API 5L,API 5CT,etc.The materials can be carbon steel,stainless steel and alloy steel.If you want to know more about our products,please email us:sales@haihaogroup.com
