1. Cleaning
Solvents and emulsions are used to clean the steel surface, removing oil, grease, dust, lubricants, and similar organic contaminants; however, they cannot eliminate rust, scale, welding flux, or other surface imperfections. Therefore, in corrosion protection, they serve only as auxiliary methods.
2. Blast (or shot) cleaning for rust removal
Blast (or shot) cleaning involves using a high‑power motor to drive blast wheels at high speed, which propel abrasive materials such as steel grit, steel shot, wire segments, and mineral abrasives onto the pipe surface under centrifugal force. This process not only thoroughly removes rust, oxides, and contaminants but also achieves the desired surface roughness through the intense impact and friction of the abrasive media.
After blast (or shot) cleaning, not only is the physical adsorption on the pipe’s surface enhanced, but the mechanical adhesion between the anti-corrosion coating and the pipe surface is also improved. Therefore, blast (or shot) cleaning is an ideal method for rust removal in pipeline corrosion protection. Generally speaking, shot (or sand) blasting is primarily used for treating both the inner and outer surfaces of pipes, while shot (or sand) blasting is mainly employed for surface treatment.
3. Rust removal using tools
First, use tools such as wire brushes to grind the steel surface, removing loose or lifted mill scale, rust, weld spatter, and other contaminants. Manual tool cleaning can achieve a Sa2 grade, while power‑tool cleaning can reach Sa3. However, if the steel surface is covered with tightly adherent iron oxide scale, tool cleaning will yield unsatisfactory results and fail to attain the required anchor profile depth for corrosion‑protection work.
4. Pickling
Conventional acid pickling is typically carried out by chemical or electrolytic methods; for pipeline corrosion protection, only chemical pickling is employed. It can remove scale, rust, and old coatings, and is sometimes used as a post‑treatment following sandblasting to remove rust. While chemical cleaning can achieve a certain level of surface cleanliness and roughness, the resulting anchor profile is shallow, and it is prone to causing environmental pollution.
