Introduction to large diameter thick wall seamless steel pipe

Large-diameter thick-walled seamless pipes are made of round steel perforated into capillary tubes, and then hot-rolled, cold-rolled or cold-drawn. Large-diameter thick-walled steel pipes are mostly used in large-scale steel structure construction. Do the main support part, such as bridge piling, seabed piling, and high-rise building piling.

The raw material for the large-diameter thick-walled pipe is round tube blanks. The round tube blanks are cut by a cutting machine into billets with a length of about 1 meter and sent to the furnace for heating via a conveyor belt. The billet is fed into the furnace and heated to a temperature of approximately 1,200 degrees Celsius. The fuel is hydrogen or acetylene. Temperature control in the furnace is a key issue. After the round tube comes out of the furnace, it must be pierced through a pressure punching machine. Generally, the more common piercing machine is the tapered roller piercing machine. This type of piercing machine has high production efficiency, good product quality, large perforation diameter expansion, and can penetrate a variety of steel types. After perforation, the round tube blank is successively cross-rolled, continuous rolled or extruded by three rollers. After extrusion, the pipe should be removed and calibrated. The sizing machine rotates a tapered drill bit at high speed into the steel blank to drill holes to form a steel pipe. The inner diameter of the steel pipe is determined by the outer diameter length of the drill bit of the sizing machine. After the steel pipe is sized, it enters the cooling tower and is cooled by spraying water. After the steel pipe is cooled, it will be straightened. After straightening, the steel pipe is sent to the metal flaw detector (or hydraulic test) by a conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. After quality inspection, steel pipes must undergo strict manual selection. After the quality inspection of the steel pipe, spray the serial number, specification, production batch number, etc. with paint. And it is hoisted into the warehouse by a crane.

Large-diameter thick-walled steel pipes have super strong load-bearing performance and can withstand large impact forces. Currently widely used in frameworks. When the vehicle turns at high speed or brakes or stops suddenly, the high-strength steel pipe can easily absorb the strong impact. The impact force ensures the safety and maneuverability of the vehicle in emergency driving situations, and protects the body well.

Why do large-diameter thick-walled seamless steel pipes have such good load-bearing capacity? Practice has proven that there is an approximate correspondence between hardness values and strength values among various hardness values of metal materials, ensuring that large-diameter thick-walled seamless steel pipes have such good load-bearing capacity. Bearing capacity of steel pipe. Because the hardness value is determined by the initial plastic deformation resistance and the sustained plastic deformation resistance, the higher the strength of the material, the higher the plastic deformation resistance, and the higher the hardness value.

After the large-diameter thick-walled seamless steel pipe yields to a certain extent, the deformation resistance of the large-diameter thick-walled steel pipe increases again due to the rearrangement of the internal grains. At this time, although the deformation develops rapidly, it can only increase with the increase of stress. It increases with increasing stress until the stress reaches a maximum value. After that, the ability of the steel to resist deformation is significantly reduced, and large plastic deformation occurs at the weakest point. At this time, the cross-section of the sample shrinks rapidly and necking occurs until fracture failure. The maximum stress value before tensile fracture of large-diameter thick-walled steel pipes is called the strength limit or tensile strength.

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