In most cases, small-diameter seamless steel pipes are also used as pipelines for conveying fluids. Compared with solid steels such as round steel, they have the same bending and torsion strength and are lighter. They are economical cross-section steels and are widely used Manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile drive shafts, bicycle frames, steel scaffolding used in construction, etc.
The general specification of small-diameter seamless steel pipes is between 6-89mm in outer diameter, and its diameter is relatively small. The wall thickness of 1-12mm can also be divided into small-diameter thick-walled seamless pipes and small-diameter thin-walled seamless pipes. Its weight calculation formula: [(outer diameter-wall thickness)*wall thickness]*0.02466 = kg/m (weight per meter)
To produce seamless pipes with smaller dimensions and better quality, cold rolling, cold drawing or a combination of both must be used. Cold rolling is usually carried out on a two-high rolling mill. The steel pipe is rolled in an annular pass formed by a variable cross-section circular hole groove and a stationary tapered plug. Cold drawing is usually performed on a single-chain or double-chain cold drawing machine. The hot tube is placed in a closed extrusion cylinder. The perforated rod and the extrusion rod move together to make the extruded part smaller Extrusion into the die hole, so that small diameter seamless steel pipe can be produced.
Note: cold drawn seamless tubing (CDS) is a cold drawn 1018/1026 steel tube which offers uniform tolerances, enhanced machinability and increased strength and tolerances compared to hot-rolled products.