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What is the process flow of Mengcun large-diameter spiral steel pipe?

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.

Introduction to the standard of 3PE anti-corrosion spiral steel pipe

If anti-corrosion steel pipes are classified according to their types, they can be mainly divided into several forms: anti-corrosion spiral steel pipes, anti-corrosion straight seam steel pipes, and anti-corrosion seamless steel pipes. The common form of anti-corrosion steel pipes on the market now is 3pe anti-corrosion. The SY/T0413-2002 standard has been implemented domestically since August 1, 2002. The standard mainly specifies polyethylene and high-density polyethylene, with a Vicat softening point set at not less than 110 ℃; The thickness of the external anti-corrosion layer is determined according to the German standard DIN30670-1991, which mainly uses low and medium density polyethylene. Improved the impact resistance of the 3PE anti-corrosion coating. SY/T0413-2002 significantly improves the peel strength and impact resistance indicators of the 3PE anti-corrosion layer, and specifies that based on the carbon black content of some special materials, the mechanical strength and weather resistance of the 3PE anti-corrosion layer have been improved, and the sampling frequency of the joint peeling strength (i.e. the peeling strength of the heat shrink sleeve and heat shrink tape to the primer steel) has been increased. The anti-corrosion spiral steel pipe 3PE structure anti-corrosion coating combines the advantages of high-density polyethylene coating and fusion bonded epoxy powder. The epoxy powder of this system is firmly bonded to the surface of the steel pipe, utilizing high-density polyethylene to resist mechanical damage. The special adhesive layer between the two layers forms a composite structure of molecular bonds, thereby achieving a good combination of anti-corrosion and mechanical properties.

Research on Spiral Pipe Fracture in Hebei Spiral Steel Pipe Factory

In the current steel pipe industry, there is a lot of further research on the fracture of straight seam pipes, but there is very little research on spiral welded steel pipes, which will take several years. Foreign countries are also starting to do this work, but it has not been introduced to China. The steel pipe factory mainly produces spiral steel pipes. The buried steel pipes nowadays are all spiral steel pipes, so the problem of spiral steel pipe rupture is very serious. So there is very little research on the rupture of spiral steel pipes abroad, mainly due to two reasons: one is that the application of spiral pipes and straight seam pipes is very limited, especially in the study of rupture of important tracheal lines; Another issue is that the study of steel pipe rupture is very rare, so the results of straight seam pipe research are often applied to spiral steel pipes. The research on the rupture of spiral steel pipes is still in its infancy. The characteristics of spiral steel pipe rupture: Samples are taken from different directions of the steel pipe, and then subjected to tensile and Charpy impact tests; For pipelines, the maximum principal stress is the circumferential stress, and the direction of maximum driving cracking is generally along the axial direction. But for straight seam pipes, the direction of maximum driving cracking and the minimum resistance to fracture are consistent; Defects in welded pipes are difficult to detect in raw materials, usually in the weld seam or heat affected zone, but their two defects are consistent with the weld seam. The defect direction of straight seam pipes is axial, while the defect direction in spiral pipes is oblique. In general, although the tensile test results of spiral steel pipes are basically independent of the sampling direction, if it is a Charpy impact test, it is closely related to the sampling direction; The difference between the rupture of a spiral tube and a straight seam tube is that for a straight seam tube, the driving direction of rupture or expansion must be along the axis and must be mutual. However, for spiral tubes, the direction of maximum driving force and minimum resistance for rupture and expansion is not consistent.