All the insider knows that steel pipe surface treatment is one of the key factors determine the service life of the pipeline corrosion, it is a precondition for whether the anti-corrosion layer and steel tube can be combined. It is verified by the research institutions that the life of the coating depends on the quality of coating types, coating quality and environmental factors such as construction. The steel tube surface treatment effects on coating life accounted for about 50%, therefore, we should be strictly accordance with the specification on the coating on the surface of steel pipe requirements, continuously explore and summary, continuously improve steel pipe surface treatment.


1. Cleaning
Using solvent and emulsion to clean the steel surface, to remove oil, grease, dirt, lubricants, and similar organic matters, but it cannot remove rust, scale, such as welding flux on the surface of the steel, so only as auxiliary in the anti-corrosion production.


2. Rust cleaning by tools
Mainly by using the steel wire brush tool to clean the steel surfaces, and it can remove the loose or cock scale, rust, slag, etc. Hand tools can achieve de-rusting Sa2 level, power tool cleaning can reach grade Sa3. If solid iron oxide adhered on the surface of the steel, tool cleaning effect is not ideal, and it cannot reach the requirements of anti-corrosion construction requirements.


3. Acid pickling
Commonly used chemical and electrolytic pickling process, and pipeline anti-corrosion only chooses chemical pickling, it can remove scale, rust, old coating, sometimes can be used as sandblasting de-rusting after reprocessing. Chemical cleaning while can make the surface reaches a certain cleanness and roughness, but the anchor lines are shallow, and easy to damage the environment.


4. Spray shot derusting
Spray shot derusting is to have spray processing of steel pipe surface under the action of centrifugal which is driven by high-power motor (cast) shoot high-speed rotating blades. It can not only thoroughly remove rust, oxides and dirt, but also can achieve the required uniform roughness.
After shot derusting spray, not only the physical adsorption on the surface of the pipe can be enlarged, but also the anti-corrosion layer and mechanical adhesion on the surface of the pipe can enhanced. Therefore, shot derusting spray (cast) is an ideal cleaning pipeline corrosion protection method. In general, shot peening (sand) cleaning is mainly used for the pipe inner surface treatment and shot (sand) is mainly used for pipe derusting outside surface treatment.


Next time, the article will specially present the specific topic on “several problems should be pay attention on when using spray (cast) shot derusting”.