During thermal processing (welding), due to the uneven heating temperature, compression plastic deformation occurs in the high temperature area. During cooling, the contraction of this part is prevented by other parts (low temperature region or first cooling part), resulting in residual stress and various deformations. However, the hot-processed steel pipes (welded pipes or thermally expanded seamless pipes) in the steel market mainly show bending deformation.

The seamless steel pipe is expressed as outer diameter, wall thickness, and thick-walled seamless steel pipe is mainly used for machining, coal mining, hydraulic steel and other purposes. How to solve the rust spots of thick-walled seamless steel pipes? There are two ways to solve it.

The horizontal contact surface between the hook and the end of the spiral steel pipe shall not be less than 40mm, otherwise it will easily deform the nozzle and affect the connection of the pipe.

Round steel refers to a solid strip of steel with a circular cross section. Its specifications are expressed in diameter, in millimeters (mm), such as "50mm" means a round steel with a diameter of 50 mm.

Plastic-coated composite steel pipe is also called plastic-coated steel pipe. Plastic-coated steel pipe is a steel-plastic composite product with steel pipe as the base pipe, plastic powder as the coating material, a plastic layer on the inner surface, and a plastic layer or other anti-corrosion layer on the outer surface. .

Spiral steel pipe (SSAW pipe) is a spiral seam steel pipe made of strip steel coil as raw material, extruded at regular temperature, and welded by automatic double-wire double-sided submerged arc welding process. The spiral steel pipe sends the strip steel into the welded pipe unit, and after rolling by multiple rollers, the strip steel is gradually rolled up to form a circular tube blank with an opening gap. Adjust the reduction amount of the squeeze roller to control the gap between the weld seams at 1~3mm, and make the two ends of the weld joints flush.