Production and processing of 3PE anti-corrosion spiral pipes, buried water supply spiral steel pipes

　　A supplier engaged in the research and production of 325 spiral steel pipe, spiral seam submerged arc welded steel pipe, insulation spiral steel pipe, and spiral steel pipe, with excellent equipment and advanced technology spiral steel pipe

　　Spiral steel pipe is a spiral seam steel pipe made of strip steel coil as raw material, often formed by warm extrusion, and welded by automatic double wire double-sided submerged arc welding process.

　　production process

　　(1) The raw materials are strip steel coils, welding wire, and flux. Strict physical and chemical tests must be conducted before investment.

　　(2) The head and tail of the strip steel are connected by single or double wire submerged arc welding, and automatic submerged arc welding is used for repair welding after being rolled into a steel pipe.

　　(3) Before forming, the strip steel undergoes leveling, trimming, planing, surface cleaning, conveying, and pre bending treatment.

　　(4) The use of an electric contact pressure gauge to control the pressure of the oil cylinders on both sides of the conveyor ensures the smooth transportation of the strip steel.

　　(5) Adopting external or internal control roller molding.

　　(6) Adopting a weld seam gap control device to ensure that the weld seam gap meets the welding requirements, the pipe diameter, misalignment, and weld seam gap are strictly controlled.

　　(7) Both internal and external welding are carried out using American Lincoln welding machines for single or double wire submerged arc welding, in order to achieve stable welding quality.

　　(8) The welded seams are all inspected by an online continuous ultrasonic automatic damage tester, ensuring the coverage of non-destructive testing for spiral welds. If there is a defect, it will automatically sound an alarm and spray a mark, and production workers will adjust the process parameters accordingly to eliminate the defect in a timely manner.

　　(9) Use an air plasma cutting machine to cut steel pipes into individual pieces.

　　(10) After cutting into individual steel pipes, each batch of steel pipes must undergo a strict initial inspection system to check the mechanical properties, chemical composition, fusion condition, surface quality of the welded joints, and undergo non-destructive testing to ensure that the pipe manufacturing process is qualified before it can be officially put into production.

　　(11) The parts with continuous ultrasonic testing marks on the weld seam shall be manually inspected by ultrasonic and X-ray. If there are indeed defects, they shall be repaired and undergo non-destructive testing again until it is confirmed that the defects have been eliminated.

　　(12) The pipes where the welded joints of the strip steel and the T-shaped joints intersecting with the spiral welds are located are all inspected by X-ray television or film.

　　(13) Each steel pipe undergoes a hydrostatic pressure test, and the pressure is sealed radially. The test pressure and time are strictly controlled by the steel pipe water pressure microcomputer detection device. Automatic printing and recording of experimental parameters.

　　(14) Mechanical processing of pipe ends to accurately control the perpendicularity, slope angle, and blunt edge of the end face.

　　Folding weld seam treatment

　　Spiral steel pipes feed the strip steel into the welded pipe unit, where it is rolled by multiple rollers and gradually rolled up to form a circular billet with open gaps. The pressing amount of the extrusion roller is adjusted to control the weld seam gap between 1-3mm and ensure that both ends of the weld are level.

　　If the gap is too large, it will cause a reduction in proximity effect, insufficient eddy current heat, poor intergranular bonding in the weld seam, and result in incomplete fusion or cracking.

　　If the gap is too small, it will cause an increase in proximity effect, excessive welding heat, and result in weld burnout; Or the weld seam may form deep pits after being squeezed or rolled, affecting the surface quality of the weld seam.

　　After heating the two edges of the billet to the welding temperature, a common metal grain penetrates and crystallizes with each other under the extrusion of the extrusion roller, ultimately forming a solid weld seam. If the extrusion force of the spiral steel pipe is too small, the number of common crystals formed will be small, the strength of the weld metal will decrease, and cracking will occur after being subjected to force; If the extrusion force is too high, the molten metal will be squeezed out of the weld seam, which not only reduces the strength of the weld seam, but also produces a large number of internal and external burrs, and even causes defects such as welding overlap.