Seeking help with issues regarding seamless steel pipes
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I would like to ask everyone: For general industrial pipelines, are cold-rolled seamless steel pipes used or hot-rolled ones? When purchasing seamless steel pipes, do we need to specify whether they are to be cold-rolled or hot-rolled, as well as their condition at the time of delivery? If not specified, is the default supply cold-rolled or hot-rolled?
A contract for ordering steel pipes should generally include the following contents: (1) Standard number. For example, GB/T 8163-2008 \"Seamless steel tubes for transporting fluids\". (2) Product name. For example, seamless steel pipes. (3) The grade of the steel; if there is a quality grade, it should be specified. For example, 20 steel, or Q345-B, etc. (4) Dimensions and specifications. (5) Order quantity (total weight or total length). (6) Manufacturing method: When the buyer specifies a particular method (hot rolling or cold rolling) for manufacturing the steel pipe, it shall be indicated in the contract. (7) Delivery status. Hot-rolled (extruded, expanded) steel pipes shall be delivered in their hot-rolled state or after heat treatment. When delivery in the heat-treated condition is required, it must be specified in the contract ； Cold-drawn (rolled) steel pipes shall be delivered in the heat-treated condition. At the request of the buyer, and after consultation between the supplier and the buyer, with it specified in the contract, delivery in cold-drawn (rolled) condition is also possible. (8) Special requirements.
Cold rolling and hot rolling are two different steel rolling techniques. As the name implies, cold rolling involves rolling steel at room temperature, while hot rolling involves rolling steel at high temperatures. Differences between hot-rolled seamless steel pipes and cold-rolled seamless steel pipes: 1) Cold-rolled seamless steel pipes are usually of small diameter, while hot-rolled seamless steel pipes are generally of large diameter. 2) The precision of cold-rolled seamless steel pipes is higher than that of hot-rolled seamless steel pipes, and their price is also higher. 3) Hot-rolled seamless pipes are classified into ordinary steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes, and other types of steel pipes. 4) Cold-rolled (drawn) seamless steel pipes include, in addition to ordinary steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other types of steel pipes, carbon thin-walled steel pipes, alloy thin-walled steel pipes, stainless thin-walled steel pipes, and shaped steel pipes as well. 5) Cold-rolled (drawn) seamless steel pipes include, in addition to ordinary steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other types of steel pipes, carbon thin-walled steel pipes, alloy thin-walled steel pipes, stainless thin-walled steel pipes, and shaped steel pipes as well. Process flow: Hot rolling (extrusion of seamless steel tubes): Round tube billet → Heating → Piercing → Three-roller skew rolling, continuous rolling or extrusion → Tube removal → Dimensioning (or reduction in diameter) → Cooling → Billet tube → Straightening → Hydrostatic testing (or flaw detection) → Marking → Storage. Cold-drawn (rolled) seamless steel tubes: round tube billet → heating → piercing → end forming → annealing → acid washing → oiling (copper plating) → multiple passes of cold drawing (cold rolling) → semi-finished tube → heat treatment → straightening → hydraulic testing (flaw detection) → marking → storage.