Methods for Surface Treatment of Spiral Tubes

Release date:

2021-02-14

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Steel Pipe Knowledge

Surface treatment methods for spiral pipes: 1. Cleaning Solvents and emulsions are used to clean the steel surface, removing oil, grease, dust, lubricants, and similar organic substances. However, this method cannot eliminate rust, scale, welding flux, or other contaminants from the steel surface; therefore, it serves only as a supplementary step in corrosion‑prevention processes.

　　 Spiral tube Surface treatment method:

　　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 residues; therefore, in corrosion‑prevention processes, they serve only as auxiliary measures.

　　2. Rust removal using tools

　　First, use tools such as wire brushes to clean the steel surface, removing loose or flaking mill scale, rust, weld spatter, and other contaminants. Manual tool cleaning can achieve a Sa2 surface cleanliness rating, while power‑tool cleaning can reach Sa3. However, if the steel surface is covered with tightly adhering iron oxide scale, tool cleaning alone will yield unsatisfactory results and fail to attain the required anchor profile depth for corrosion‑protection applications.

　　3. Pickling

　　Conventional acid pickling is typically carried out by chemical or electrolytic methods; for pipeline corrosion protection, only chemical pickling is employed. This process can remove scale, rust, and old coatings, and it is sometimes used as a post‑treatment following sandblasting to remove rust. Although 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.

　　4. Blast (or shot) cleaning for rust removal

　　Blast (or shot) cleaning involves using a high‑power motor to spin blast wheels at high speed, generating centrifugal force that propels abrasive media—such as steel grit, steel shot, wire segments, and mineral abrasives—onto the pipe’s surface. 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. Following blast cleaning, the pipe’s surface exhibits enhanced physical adhesion, while the anti‑corrosion coating gains improved mechanical bonding. Consequently, blast (or shot) cleaning is an ideal method for pipeline corrosion protection. Generally, shot blasting is primarily used for treating both the inner and outer surfaces of pipes, whereas sandblasting is mainly applied to the external surface.

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