Straight seam steel pipe derusting technology and forming technology introduction

Straight seam steel pipe derusting technology:

In the process of anti-corrosion construction of oil and gas pipelines, the surface treatment of straight seam steel pipes is the key factor determining the service life of pipeline anticorrosion, and it is the premise of whether the anticorrosion layer can be firmly combined with straight seam steel pipes. According to research by research institutions, the life of the anti-corrosion layer depends on factors such as the type of coating, coating, and construction environment, and the surface treatment of straight seam steel pipes has an impact on the life of the anti-corrosion layer. For the requirements on the surface of straight seam steel pipes, the surface treatment methods of straight seam steel pipes are continuously improved, and the methods of removing embroidery from straight seam steel pipes mainly include the following types:

1. Cleaning: Use solvents and emulsions to clean the steel surface to remove oil, grease, dust, lubricants, and similar organic matter, but it cannot remove rust, scale, welding flux, etc. on the steel surface, so it is only used in defense operations as an aid.

2. Pickling: Generally, two methods of chemical and electrolytic pickling are used for pickling treatment. Only chemical pickling is used for pipeline anticorrosion, which can remove scale, rust, and old coatings. Sometimes it can be used for reprocessing after sandblasting and rust removal. Although chemical cleaning can achieve the 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 polish the steel surface, which can remove loose scale, rust, welding slag, etc. Hand tool derusting can reach the Sa2 level, and power tool derusting can reach the Sa3 level. If the iron oxide scale is firmly attached to the surface of the steel, the derusting effect of the tool is not ideal, and the anchor pattern depth required for anti-corrosion construction cannot be reached.

4. Spray rust removal: Spray rust removal is driven by a high-power motor to rotate the spray blades at high speed, so that steel shots, steel sand, iron wire segments, minerals, and other abrasives are sprayed on the surface of straight seam steel pipes under the powerful centrifugal force of the motor. It can not only remove oxides, rust, and dirt but also achieve the required uniform roughness under the action of abrasive impact and friction.

After spray derusting, not only the physical adsorption on the surface of the pipe can be expanded, but also the mechanical adhesion between the anti-corrosion layer and the surface of the pipe can be enhanced. Therefore, spray rust removal is an ideal rust removal method for pipeline corrosion. Generally speaking, shot blasting is mainly used for the inner surface treatment of pipes, and shot blasting is mainly used for the outer surface treatment of straight seam steel pipes.

Introduction to the forming technology of straight seam welded pipe:

Longitudinal welded pipe is a kind of building material that is very popular among users. Its performance has been recognized by everyone, so how is it formed?

1. Pre-bending: Use a pre-bending machine to pre-bend the edge of the plate so that the edge of the plate has a curvature that meets the requirements;

2. Forming: On the JCO forming machine, the first half of the pre-bent steel plate is stamped into a "J" shape by multiple steps, and then the other half of the steel plate is also bent into a "C" shape, and finally the opening is formed. The "O" shape.

3. Pre-welding: Make the formed straight seam welded steel pipe seam together and use gas-shielded welding (MAG) for continuous welding.

4. Internal welding: use tandem multi-wire submerged arc welding (mostly four wires) to weld on the inner side of the straight seam steel pipe.

5. External welding: Tandem multi-wire submerged arc welding is used to weld the outer side of the straight seam submerged arc welded steel pipe.

6. Wave inspection Ⅰ: 100% inspection of the inner and outer welds of the straight seam welded steel pipe and the base metal on both sides of the weld.

7. X-ray inspection Ⅰ: 100% X-ray industrial TV inspection is carried out on the internal and external welds, and the image processing system is used to ensure the sensitivity of flaw detection.

8. Diameter expansion: The diameter of the full length of the submerged arc welded straight seam steel pipe is expanded to improve the dimensional accuracy of the steel pipe and the distribution state of the internal stress of the steel pipe.

9. Hydrostatic test: On the hydrostatic testing machine, inspect the expanded steel pipes one by one to ensure that the steel pipes meet the test pressure required by the standard. The machine has automatic recording and storage functions.