First, rust removal technology of straight seam steel pipes: In the process of anti-corrosion construction of oil and gas pipelines, the surface treatment of straight seam steel pipes is one of the key factors that determine the service life of pipeline anti-corrosion. It is the premise for the firm combination of the anti-corrosion layer and the straight seam steel pipe. According to research institutions, the life of the anti-corrosion layer depends on factors such as the type of coating, coating, and construction environment. The surface treatment of the straight seam steel pipe accounts for about 50% of the influence on the life of the anti-corrosion layer. Therefore, the requirements of the anti-corrosion layer specification for the surface of the straight seam steel pipe should be strictly followed, and the surface treatment method of the straight seam steel pipe should be continuously improved. There are mainly the following methods for rust removal of straight seam steel pipes:

1. Cleaning: Use solvents and emulsions to clean the surface of the steel to remove oil, grease, dust, lubricants, and similar organic matter, but it cannot remove rust, scale, welding flux, etc. on the surface of the steel, so it is only used as an auxiliary means in anti-corrosion operations.
2. Pickling: Generally, chemical and electrolytic methods are used for pickling. Pipeline anti-corrosion only uses chemical pickling, which can remove oxide scale, rust, and old coating. Sometimes it can be used as a re-treatment after sandblasting. Although chemical cleaning can achieve the best cleanliness and roughness of the surface, its anchor pattern is shallow and it is easy to pollute the surrounding environment.
3. Tool rust removal: Mainly use tools such as wire brushes to grind the steel surface to remove loose oxide scale, rust, welding slag, etc. Manual tool rust removal can reach the Sa2 level, and power tool rust removal can reach the Sa3 level. If the steel surface is firmly attached to the oxide scale, the tool rust removal effect is not ideal and the anchor pattern depth required for anti-corrosion construction cannot be achieved.
4. Spraying rust removal: Spraying rust removal is using a high-power motor to drive the spray blade to rotate at high speed, so that steel shot, steel sand, wire segments, minerals, and other abrasives are sprayed on the surface of the straight seam steel pipe under the strong centrifugal force of the motor, which can not only remove oxides, rust and dirt, but also achieve the required uniform roughness under the violent impact and friction of the abrasive.
After spraying rust removal, can not only expand the physical adsorption effect on the surface of the steel pipe but also enhance the mechanical adhesion between the anti-corrosion layer and the surface of the steel pipe. Therefore, spraying rust removal is an ideal rust removal method for pipeline anti-corrosion. Generally speaking, shot peening rust removal is mainly used for the inner surface treatment of steel pipes, and shot blasting rust removal is mainly used for the outer surface treatment of straight seam steel pipes.

Second, the forming technology of straight seam welded pipes: straight seam welded pipes are a kind of building material that is loved by users, and its performance has been recognized by everyone, so how is it formed?
1. Pre-bending: Use a pre-bending machine to pre-bend the plate edge so that the plate edge has the required curvature;
2. Forming: First, on the JCO forming machine, half of the pre-bent steel plate is pressed into a "J" shape by multiple-step punching, and then the other half of the steel plate is bent in the same way to form a "C" shape, and then an open "O" shape is formed.
3. Pre-welding: The formed straight seam welded steel pipe is joined and continuously welded by gas-shielded welding (MAG).
4. Internal welding: Use longitudinal multi-wire submerged arc welding (four wires at most) to weld on the inside of the straight seam steel pipe.
5. External welding: Use longitudinal multi-wire submerged arc welding to weld on the outside of the straight seam submerged arc welded steel pipe.
6. Wave inspection I: 100% inspection of the internal and external welds of the straight seam welded steel pipe and the parent materials on both sides of the weld.
7. X-ray inspection I: 100% X-ray industrial television inspection of the internal and external welds, using an image processing system to ensure the sensitivity of flaw detection.
8. Diameter expansion: The diameter of the submerged arc welded straight seam steel pipe is expanded over the entire length to improve the dimensional accuracy of the steel pipe and the distribution of stress in the steel pipe.
9. Water pressure test: The expanded steel pipes are inspected one by one on a water pressure test machine to ensure that the steel pipes meet the test pressure required by the standard. The machine has automatic recording and storage functions.