How are seamless pipes produced?

Seamless pipes have hollow sections and are widely used as pipelines for transporting fluids, such as pipelines (octg pipes) for transporting oil, natural gas, coal gas, water and certain solid materials. According to different production methods, it can be divided into hot-rolled tubes, cold-rolled tubes, cold drawn seamless tubing, extruded tubes, etc.

1. Hot-rolled seamless pipes are generally produced on automatic pipe rolling units. The solid tube blank is inspected and surface defects are removed, cut into the required length, centered on the perforated end of the tube blank, and then sent to the heating furnace for heating and piercing on the punching machine. It continues to rotate and advance during piercing holes. Under the influence of the rollers and the end, the tube blank is hollow gradually, which is called gross pipe. Then it is sent to the automatic pipe rolling machine to continue rolling. Finally, the wall thickness is evened by the leveling machine, and the diameter is determined by the sizing machine to meet the specification requirements. The use of continuous pipe rolling units to produce hot-rolled seamless steel pipes is a more advanced method.

2. If you want to obtain seamless pipes with smaller size and better quality, cold rolling, cold drawing or a combination of the two must be used. Cold rolling is usually carried out on a two-roll mill, and the steel pipe is rolled in an annular pass composed of a variable cross-section circular groove and a fixed conical head. Cold drawing is usually performed on a 0.5 to 100T single-chain or double-chain cold drawing machine.

3. The extrusion method is to place the heated tube blank in a closed extrusion cylinder, and the perforation rod and the extrusion rod move together to make the extrusion part extruded from the smaller die hole. This method can produce steel pipes with smaller diameters.

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