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Large caliber spiral steel pipe is a spiral seam steel pipe made of strip steel or rolled plate as raw material, often formed by warm extrusion, and welded by automatic double wire double-sided submerged arc welding process 
Below is a brief introduction to the manufacturing process of large-diameter spiral steel pipes: 
The raw materials are strip steel coils, welding wire, and flux. Strict physical and chemical tests must be conducted before investment. 
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. 
Before forming, the strip steel undergoes leveling, trimming, planing, surface cleaning, conveying, and pre bending treatment. 
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. 
Adopting external or internal control roller molding. 
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. 
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. 
The welded seams are all inspected by an online continuous ultrasonic automatic damage tester, ensuring 100% non-destructive testing coverage of 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. 
Use an air plasma cutting machine to cut steel pipes into individual pieces. 
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. 
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. 
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. 
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. 
Mechanical processing of pipe ends to accurately control the perpendicularity, slope angle, and blunt edge of the end face. 
Although affected by the economic crisis, the large-diameter spiral steel pipe company is recovering and developing, welcoming a better tomorrow. Large diameter spiral steel pipes have played a significant role in the transportation of gas.