Do seamless steel pipes need derusting?

Posted by zora li on March 23rd, 2023

As we all know, seamless steel pipe has good corrosion resistance and is a kind of pipeline resistant to weak acid substances such as steam, which is widely used in our daily life. However, if the seamless steel pipe is placed directly in a strong alkali or strong acid environment, corrosion will also occur. Therefore, in order to avoid affecting the later use, it is necessary to do anti-corrosion work and maintenance in advance, so that it can be used reasonably in production and life.

What are the common rust removal processes for seamless steel pipes?

1. Clean

Solvents and emulsions are used to clean steel surfaces to remove oil, grease, dirt, lubricants and similar organic matter. However, it cannot remove rust, rust, flux, etc. on the surface of steel. Therefore, it is only used as an aid in defensive operations.

2. Pickling

Typically, chemical cleaning and electrolysis are used for pickling treatment. Pipeline anticorrosion is simply chemical pickling to remove scale, rust and old coatings, and sometimes it can also be used as a post-treatment after sandblasting and rust removal. Although chemical cleaning can achieve a certain degree of cleanliness and roughness, its anchor pattern is shallow and it is easy to pollute the surrounding environment.

3. Tool derusting

Mainly use tools such as wire brushes to polish the steel surface to remove loose or raised scale, rust, welding slag, etc. The derusting of hand tools can reach Sa2 level, and the derusting of electric tools can reach Sa3 level. If the iron oxide scale is firmly attached to the surface of the steel, the derusting effect of the tool is not satisfactory, and the depth of the anchor pattern required by the anti-corrosion construction cannot be reached.

4. Spraying rust removal

Jet derusting is a high-speed motor that drives the jet blades to rotate at high speed. Under the action of strong centrifugal force, the motor that sprays abrasives such as steel balls, steel sand, steel wire fragments, and minerals onto the surface of seamless steel pipes can not only completely remove oxidation. Matter, rust and dirt, as well as seamless steel pipes, can achieve ideal uniform roughness under the action of abrasive impact and friction.

After spraying and derusting, it can not only expand the physical adsorption on the surface of the seamless steel pipe, but also enhance the mechanical adhesion between the anti-corrosion layer and the surface of the pipe. Therefore, spray descaling is an ideal method for eliminating corrosion of pipelines. Generally, shot peening is mainly used for the inner surface treatment of pipes, and shot peening is mainly used for the outer surface treatment of seamless steel pipes.