How is rust removed from straight-seam pipes?

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2022-01-12

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In the anti-corrosion construction of oil and gas pipelines, surface treatment of longitudinal‑seam pipes is one of the key factors determining the service life of the pipeline’s corrosion protection; it is also a prerequisite for ensuring strong adhesion between the protective coating and the pipe. According to research by specialized institutions, the service life of an anti-corrosion coating depends on such factors as coating type, coating quality, and the construction environment. Surface treatment of longitudinal‑seam pipes accounts for approximately 50% of the influence on the coating’s service life; therefore, surface‑treatment methods must be continuously refined in strict accordance with the requirements specified in the anti-corrosion coating standards.

　　In the anti-corrosion construction of oil and gas pipelines, Straight-seam pipe Surface treatment is one of the key factors determining the service life of pipeline corrosion protection and serves as the prerequisite for ensuring a strong bond between the protective coating and the straight‑seam pipe. According to research by specialized institutions, the service life of a corrosion‑protective coating depends on such factors as coating type, coating quality, and the construction environment. Surface treatment of straight‑seam pipes accounts for approximately 50% of the influence on the protective coating’s service life; therefore, surface‑treatment methods for these pipes should be continuously refined in strict accordance with the requirements specified in the relevant coating standards.

　　The main methods for removing rust from straight-seam pipes include the following:

　　1. Clean the steel surface with solvents and emulsions to remove oil, grease, dust, lubricants, and similar organic contaminants; however, this method cannot eliminate rust, scale, flux residues, or other such substances from the steel surface, and thus serves only as a supplementary measure in anti‑corrosion operations.

　　2. Pickling is typically carried out using chemical and electrolytic methods. Chemical pickling is used solely for pipeline corrosion protection; it can remove scale, rust, and old coatings, and is sometimes employed as a post‑treatment following sandblasting for rust removal. Although chemical cleaning can achieve a certain level of surface cleanliness and roughness, the resulting anchor profile is relatively shallow, making it prone to contaminating the surrounding environment.

　　3. Manual tool-based rust removal primarily involves using wire brushes and similar tools to abrade the steel surface, effectively eliminating loose scale, rust, weld spatter, and other contaminants. Manual tool cleaning can achieve a Sa2 surface cleanliness grade, while power‑tool cleaning can reach Sa3. However, if iron filings are firmly adhered to the steel surface, tool‑based methods may yield unsatisfactory results, failing to attain the required anchor profile depth for anti‑corrosion coating applications.

　　4. Abrasive blasting: Abrasive blasting involves a high‑power motor driving blast wheels at high speed, which propel abrasive media—such as steel shot, steel grit, wire segments, and mineral abrasives—onto the surface of the straight‑seam pipe under the powerful centrifugal force of the motor. This process not only thoroughly removes oxides, rust, and contaminants but also achieves the required uniform surface roughness through the intense impact and friction of the abrasive particles.

　　After blast‑cleaning to remove rust, not only is the physical adsorption capacity of the pipe surface enhanced, but the mechanical adhesion between the anti‑corrosion coating and the pipe surface is also improved. Consequently, blast cleaning is an ideal method for rust removal in pipeline corrosion protection. In general, shot blasting is the primary technique used for treating the internal surfaces of pipes, while it is also the main method for external surface treatment of straight‑seam pipes. During production, strict adherence to the relevant technical specifications for rust removal is essential to prevent operational errors that could damage the pipe’s exterior. Following blast cleaning, the product’s surface appearance becomes noticeably smoother than before; this process is a widely adopted practice in the steel pipe industry.

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