Small diameter seamless steel pipe

　　In general, seamless steel pipes used in daily life are of normal caliber, and small caliber seamless steel pipes are used in some special places. Today, I'd like to introduce the relevant knowledge of small-diameter seamless steel pipe, which will help you better use this kind of pipe in the future. Generally speaking, seamless steel pipes with small outer diameter are collectively referred to as small-diameter seamless steel pipes, but there is still a specific range. Generally, those with steel diameter less than 89mm and more than 4mm can be called small-diameter seamless steel pipes.

　　In most cases, small-diameter seamless steel pipe is also used as a pipe for conveying fluid. Compared with solid steel such as round steel, it is light in weight when its bending and torsional strength is the same. It is a kind of economic section steel, which is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, bicycle frames, steel scaffolds used in construction, etc.

　　The general specification of small-diameter seamless steel pipe is that its outer diameter is between 6-89mm, and its diameter is relatively small. The wall thickness of 1-12mm can also be divided into small-diameter thick wall seamless pipe and small-diameter thin-wall seamless pipe. Its weight calculation formula: [(outer diameter - wall thickness) * wall thickness] *0.02466 = kg/ meter (weight per meter)

　　In order to produce seamless pipes with smaller size and better quality, cold rolling, cold drawing or a combination of the two methods must be used. Cold rolling is usually carried out on a two high mill. Steel pipes are rolled in an annular pass consisting of a variable cross-section circular groove and a fixed conical plug. Cold drawing is usually carried out on a single chain or double chain cold drawing machine, that is, the hot tube blank is placed in a closed extrusion cylinder, and the perforated rod moves together with the extrusion rod to extrude the extruded part from the smaller die hole, so that small-diameter seamless steel pipe can be produced.