Why is it necessary to sandblast steel pipes before anti-corrosion?

Why is it necessary to sandblast steel pipes before anti-corrosion?

Sandblasting, also known as sandblasting, is a surface treatment method that uses high-speed jets of sand to polish metal surfaces to remove rust, scale and dirt while improving the roughness of the metal surface. Why do steel pipes (such as seamless pipes or welded pipes) need sandblasting before corrosion protection?

1. Improve the surface roughness of steel pipes
Sandblasting can effectively improve the surface roughness of steel pipes and create good conditions for coating adhesion. The adhesion of the coating to the steel pipe surface mainly depends on the mechanical anchoring. The surface of the steel pipe after sandblasting and external treatment forms many tiny unevennesses, which increases the contact area between the coating and the steel pipe surface, thus improving the adhesion of the coating.

2. Remove surface dirt and scale
During the production, transportation and storage process of steel pipes, various dirt, such as rust, oxide scale, oil stains, etc., will adhere to the surface. These impurities will affect the adhesion between the coating and the steel pipe surface and reduce the anti-corrosion effect. Sandblasting can effectively remove surface dirt and ensure that the coating is closely combined with the surface of the steel pipe.

3. Improve the stress state of the steel pipe surface
Sandblasting can effectively improve the stress state on the surface of steel pipes. During sandblasting, the sand particles produce uniform impact on the surface of the steel pipe, causing slight periodic deformation on the surface of the steel pipe, thereby reducing surface residual stress and extending the service life of the steel pipe.

4. Improve coating quality
The surface roughness of the steel pipe after sandblasting increases, and the adhesion between the coating and the steel pipe surface increases, making the coating stronger. At the same time, sandblasting can make the coating more closely combined with the surface of the steel pipe, reduce the air gaps and gaps under the coating, and improve the sealing and corrosion resistance of the coating. The steel pipe coating after sandblasting is more uniform and smooth, which not only improves the anti-corrosion performance of the coating, but also improves the overall aesthetics of the steel pipe.

5. Enhance the wear resistance of the coating
Sandblasting can make the surface of the steel pipe more uniform and smooth, which is beneficial to the even distribution of the dry coating. The coating after sandblasting is denser and has significantly improved wear resistance, thereby extending the service life of the steel pipe.

6. Improve production efficiency
Sandblasting is a fast and efficient surface treatment method that can greatly improve production efficiency. Compared with traditional manual rust removal and grinding, sandblasting is faster and more efficient, saving labor and time costs.

In summary, sandblasting before anti-corrosion of steel pipes is of great significance to improving the quality and effect of anti-corrosion coatings. Sandblasting can not only remove surface dirt and improve coating adhesion, but also improve the stress state on the surface of the steel pipe and improve the wear resistance of the coating, thereby extending the service life of the steel pipe. Therefore, sandblasting is an indispensable key link in steel pipe anti-corrosion engineering.