Seamless steel pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances that can flow — liquids and gases (fluids), slurries, powders and masses of small solids.
Seamless Pipe (and tubing) is made by extruding a steel block or by drilling a solid steel bar. Next, the extrusion or the drilled steel bar is cold drawn through a dye to achieve the diameter and thickness needed. Because this process can cause mechanical hardening, sometimes the material is annealed and straightened as a final process. Seamless Pipe & Tubing is subdivided as:
Cold Drawn Seamless, or CDS, exhibits precise tolerances and a good surface finish.
Hot Finished Seamless or HFS has less critical tolerances and a somewhat scaly finish and is not as strong as CDS.
For Drawn over Mandrel, or DOM tubing, the first stages of manufacturing are identical to the ones used to make electric resistance welded tubing, but in the finishing stages the entire flash weld is taken out and the tube is cold drawn over a mandrel. A mandrel is a round object against which material can be forged or shaped. The cold-drawn process provides the tube with better dimensional tolerances, improved surface finish and the strongest weld strength achievable.
DIN 2391 and DIN 1629 are both standards for seamless precision steel tubes used in various applications such as hydraulic and pneumatic systems, the automotive industry, and mechanical engineering.
DIN 2391 specifies the technical delivery conditions for seamless precision steel tubes with specified tolerances on dimensions and specified maximum carbon content. These tubes are characterized by high dimensional accuracy, excellent surface quality, and good machinability. DIN 2391 standardizes the sizes of tubes with outside diameters ranging from 4mm to 120mm and wall thicknesses from 0.5mm to 10mm.
DIN 1629, on the other hand, covers seamless circular tubes of non-alloy steel with special quality requirements. It specifies the dimensions, tolerances, and technical conditions for the delivery of tubes with outside diameters from 21.3mm to 660mm and wall thicknesses from 2.3mm to 100mm. These tubes are used for conveying fluids at elevated temperatures and high-pressure levels.
DIN 2391 & 1629: German standard
Precision cold-drawn seamless steel tube & Seamless Circular Tubes of Non-Alloys Steels With Special Quality Requirements;
Application: Oil, Gas and water delivery; Refinery, Boiler and Mechanical equipment manufacturer; structure construction; drilling, ship building and etc.
DIN2391 Chemical Composition
DIN2391 Mechanical Property
Chemical Composition & Mechanical property (DIN1629)
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