Two production processes of straight seam steel pipes

Straight seam steel pipe is a common steel pipe in daily life, and it is widely used. The production process of straight seam steel pipes can be divided into two categories, high-frequency straight seam steel pipes and submerged arc welded straight seam steel pipes. These two production processes are different. Next, let’s take a look at the production processes of these two types of straight seam steel pipes.

1. Submerged arc welding
After the steel plate for manufacturing large-diameter submerged arc welded straight seam steel pipes is put into the production line. First, the entire plate is ultrasonically inspected, and then the two edge faces of the steel plate are milled on both sides with a milling machine. Make the two edge surfaces of the steel plate reach the required plate width, edge parallelism and groove shape, and then use the pre-supplier's equipment to perform the pre-supplier's edge operation to make the edge of the plate have the required curvature. Then, using a JCO forming machine, half of the pre-bent steel plate is punched into a J shape multiple times. In addition, the other half of the stepped punching operation is punched into a C shape, which becomes an O shape with the last opening.

Align the formed longitudinally welded steel pipes and use gas shielded arc welding for continuous welding, and longitudinal multi-wire submerged arc welding is used for internal welding of longitudinally welded steel pipes. Longitudinal multi-wire submerged arc welding is used to weld the outside of longitudinal submerged arc welded steel pipes. After the welding is completed, the first ultrasonic inspection, the first X-ray inspection, diameter expansion and hydraulic test are carried out in sequence.

Then, the qualified steel pipe is processed into the required size, followed by the second ultrasonic inspection, the second X-ray inspection, the tube end magnetic particle inspection, anti-corrosion and coating, and the entire processing procedure is completed.

2. High frequency welding
The high-frequency welding technology is based on the principle of electromagnetic induction, which has the eddy current effect, skin effect and proximity effect of the AC charge in the conductor, and heats the welded edge steel to a molten state. In the rolling process, the butt welding particles can be combined together to achieve the purpose of welding. High-frequency welding is induction welding, also known as pressure welding. High-frequency welding does not require welding fillers, and there is no welding spatter during welding. The welding area affected by the welding heat is narrow, the shape after welding is very beautiful, and the mechanical properties of the welding are very good. It is precisely because of these advantages that high-frequency welding is widely used in steel pipe production.

The high-frequency welding of steel pipes uses alternating current power to roll the steel to form a circular tube blank with a divided cross section. Rotate one or a group of resistors near the center of the induction coil in the tube blank, and an electromagnetic induction circuit is formed at the opening of the resistor and the tube blank. A strong concentrated heat effect is generated at the edge of the tube blank opening, and the welding edge is quickly heated to the point of welding. The desired temperature.

The above are the two production processes of straight seam steel pipes. I hope that these contents can help you better understand the use of straight seam steel pipes.

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