Seamless steel pipes are rolled from solid tube blanks after perforation.
Manufacturing method 0f seamless steel pipe
According to different production methods, it can be divided into hot-rolled pipe, cold-rolled pipe, cold-drawn pipe, extruded pipe, etc.
1.1. Hot-rolled seamless pipes are generally produced on automatic rolling mills. After inspection and removal of surface defects, the solid tube blank is cut into required lengths, centered on the end face of the perforated end of the tube blank, then sent to a heating furnace for heating, and perforated on a punching machine. During the continuous rotation and advancement of the perforation at the same time, under the action of the roll and the plug, a cavity is gradually formed inside the tube blank, which is called a capillary tube. And then sent to the automatic rolling mill to continue rolling. Finally, the wall thickness of the whole machine is averaged, and the diameter is sizing by a sizing machine to meet the specification requirements. It is a relatively advanced method to produce hot-rolled seamless steel pipes with continuous pipe rolling mills.
1.2. In order to obtain seamless pipes with smaller size and better quality, cold rolling, cold drawing or a combination of the two methods 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-section circular hole groove and a stationary conical head. Cold drawing is usually carried out on a single-chain or double-chain cold drawing machine of 0.5 to 100T.
1.3. The extrusion method is to place the heated tube blank in a closed extrusion cylinder, and the perforated rod and the extrusion rod move together to extrude the extrusion part from the smaller die hole. This method can produce steel pipes with smaller diameters.
Application of seamless steel pipe
2.1. Seamless pipes are widely used. General-purpose seamless pipes are rolled from ordinary carbon structural steel, low-alloy structural steel or alloy structural steel, with the largest output, and are mainly used as pipelines or structural parts for conveying fluids.
2.2. According to different uses, it is divided into three types of supply: a. According to chemical composition and mechanical properties; b. According to mechanical properties; c. According to hydraulic test. Steel pipes supplied according to categories a and b, if they are used to withstand liquid pressure, should also undergo a hydrostatic test.
2.3. There are many kinds of seamless pipes for special purposes, such as seamless pipes for boilers, seamless pipes for geological use and seamless pipes for petroleum.
Type of seamless steel pipe
3.1. Seamless steel pipes can be divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, and extruded pipes according to different production methods.
3.2. According to the shape, there are round tubes and special-shaped tubes. In addition to square tubes and rectangular tubes, special-shaped tubes also include oval tubes, semicircular tubes, triangular tubes, hexagonal tubes, convex-shaped tubes, plum-shaped tubes, etc.
3.3. According to different materials, it is divided into ordinary carbon structure pipe, low alloy structure pipe, high-quality carbon structure pipe, alloy structure pipe, stainless steel pipe, etc.
3.4. According to the special purpose, there are boiler tubes, geological tubes, oil tubes, etc.