Seamless pipe is a long piece of steel with a hollow cross-section and no peripheral seams. In total, more than 5,100 plants under more than 1,850 companies in more than 110 countries produce seamless pipes worldwide, including more than 260 plants under more than 170 companies in 44 countries that produce oil pipes. The next seamless pipe supplier will introduce the common national standards and manufacturing process of seamless pipe.
Commonly used national standards
1. Seamless pipe for structure (GB/T8162-2008) is a seamless pipe used for general structure and mechanical structure.
2. Seamless pipe for fluid transportation (GB/T8163-2008) is a general seamless pipe used for the transportation of water, oil, gas and other fluids.
3. Seamless tubes for low and medium pressure boilers (GB3087-2008) are hot-rolled and cold-drawn (rolled) seamless tubes of high-quality carbon structural steel used for the manufacture of superheated steam tubes, boiling water tubes and superheated steam tubes for locomotive boilers, large smoke tubes, small smoke tubes and arch brick tubes for various structures of low and medium pressure boilers.
4. Seamless tubes for high-pressure boilers (GB5310-2008) are seamless tubes of high-quality carbon steel, alloy steel and stainless heat-resistant steel used for manufacturing the heating surface of water tube boilers with high pressure and above.
5. High-pressure seamless tubes for chemical fertilizer equipment (GB6479-2000) are seamless tubes of high-quality carbon structural steel and alloy steel for chemical equipment and pipelines with working temperatures of -40~400℃ and working pressures of 10~30Ma.
6. Seamless pipe for petroleum cracking (GB9948-2006) is a seamless pipe for furnace tubes, heat exchangers and pipelines in petroleum refineries.
7. Steel pipes for geological drilling (YB235-70) are steel pipes for core drilling in geological departments, which can be divided into drill pipes, drill collars, core pipes, casing and sediment pipes according to their uses.
8.Seamless pipe for diamond core drilling (GB3423-82) is a seamless pipe for drill pipe, core rod and casing used in diamond core drilling.
9. Oil drilling pipe (YB528-65) is seamless pipe used for oil drilling with thickened inside or thickened outside at both ends.
Hot-rolled, cold-drawn, hot-expanded.
According to different production methods, it can be divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, etc.
1. Hot-rolled seamless pipes are generally produced on automatic pipe rolling units. Solid billets are inspected and cleared of surface defects, cut to the required length, centered on the perforated end of the billet, then sent to a heating furnace for heating and perforated on a perforating machine. In the perforation while continuously rotating and advancing, under the action of the rollers and the top, the internal cavity of the billet is gradually formed, called the hairpin. Then sent to the automatic tube rolling machine to continue rolling. Finally, the wall thickness is equalized by the equalizing machine, and the diameter is fixed by the sizing machine to meet the specifications. The use of continuous rolling mill to produce hot rolled seamless steel pipe is a more advanced method.
2. To obtain smaller size and better quality seamless tubes, cold rolling, cold drawing or a combination of both methods must be used. Cold rolling is usually carried out on a two-roller mill, steel pipe in a circular hole pattern consisting of a circular groove with a variable section and an immovable conical head. Cold drawing is usually carried out on a single-chain or double-chain cold drawing machine of 0.5 to 100T.