What are the rust removal and forming technologies for straight seam steel pipes

First, what are some rust removal technologies for straight seam steel pipes?

In the anti-corrosion construction of oil and gas pipelines, the surface treatment of straight seam steel pipes is one of the key factors determining the service life of the pipeline's anti-corrosion coating. It is a prerequisite for a firm bond between the anti-corrosion layer and the straight seam steel pipe. Research institutions have shown that, in addition to factors such as coating type, application, and construction environment, the surface treatment of the straight seam steel pipe accounts for approximately 50% of the anti-corrosion coating's lifespan. Therefore, the surface requirements for straight seam steel pipes should be strictly followed according to the anti-corrosion coating specifications, and surface treatment methods should be continuously improved. The main rust removal methods for straight seam steel pipes are as follows:

1. Cleaning: Using solvents and emulsions to clean the surface of the straight seam steel pipe to remove oil, grease, dust, lubricants, and similar organic matter. However, it cannot remove rust, scale, welding flux, etc., from the surface of the straight seam steel pipe; therefore, it is only used as an auxiliary means in anti-corrosion operations.

2. Pickling: Pickling is generally performed using both chemical and electrolytic methods. For straight seam steel pipe corrosion protection, only chemical pickling is used. This removes oxide scale, rust, and old coatings, and can sometimes be used as a post-treatment after sandblasting. While chemical cleaning can achieve a certain level of cleanliness and roughness on the surface of straight seam steel pipes, it results in shallow anchor patterns and can easily pollute the surrounding environment.

3. Tool Rust Removal: This mainly uses tools such as wire brushes to grind the surface of straight seam steel pipes, removing loose oxide scale, rust, welding slag, etc. Manual tool rust removal can achieve Sa2 grade, while power tool rust removal can achieve Sa3 grade. If the surface of the straight seam steel pipe has firmly attached iron oxide scale, tool rust removal is not ideal, and cannot achieve the anchor pattern depth required for the anti-corrosion construction of straight seam steel pipes.

4. Blasting: Blasting removes rust by using a high-powered motor to drive the blasting blades at high speed. Steel shot, steel grit, wire segments, and minerals are then blasted onto the surface of the straight seam steel pipe under the powerful centrifugal force of the motor. This process not only removes oxides, rust, and dirt, but also achieves the desired uniform roughness of the straight seam steel pipe through the intense impact and friction of the abrasive.

After blasting, the physical adsorption capacity of the straight seam steel pipe surface is increased, and the mechanical adhesion between the anti-corrosion layer and the pipe surface is enhanced. Therefore, blasting is an ideal rust removal method for straight seam steel pipe corrosion protection. Generally, shot blasting is mainly used for the internal surface treatment of straight seam steel pipes, while shot blasting is mainly used for the external surface treatment.

Second, what is the forming technology of straight seam steel pipes?

Straight seam steel pipe is a building material whose performance is widely recognized. So, how is it formed?

1. Pre-bending: The plate edges are pre-bent using a pre-bending machine to achieve the required curvature.

2. Forming: On a JCO forming machine, one half of the pre-bent steel plate is first pressed into a "J" shape through multiple step-by-step stamping processes. The other half is then similarly bent and pressed into a "C" shape, ultimately forming an open "O" shape.

3. Pre-welding: The formed straight seam steel pipe is joined together and continuously welded using gas shielded welding (MAG).

4. Inner welding: Welding is performed on the inner side of the straight seam steel pipe using longitudinal multi-wire submerged arc welding (usually four wires).

5. Outer welding: Welding is performed on the outer side of the straight seam steel pipe using longitudinal multi-wire submerged arc welding.

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

7. X-ray inspection I: 100% X-ray industrial television inspection of the inner and outer welds of the straight seam steel pipe is performed, using an image processing system to ensure the sensitivity of the flaw detection.

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

9. Hydrostatic Testing: Each expanded straight seam steel pipe is inspected on a hydrostatic testing machine to ensure that it meets the standard test pressure requirements. This machine has automatic recording and storage functions.