Methods for rust removal from SMLS steel pipe surfaces:
Causes of Rust on the Surface of Seamless (SMLS) Steel Pipes:
The causes of rust on the surface of SMLS steel pipes can be multifaceted, with common causes including:
1. Improper surface treatment of the seamless steel pipe leads to an uneven oxide film, which cannot prevent rusting.
2. The steel pipe is affected by oxidation and corrosion during transportation, storage, and use, resulting in surface rust.
3. Environmental factors also affect the surface of SMLS steel pipes, such as humidity, high temperature, and strong acids.
Assessing the Degree of Rust:
Slight rust: Surface has loose rust or a few reddish-brown spots, without pitting or rust holes.
Moderate rust: Thick rust layer, with slight localized peeling or pitting.
Severe rust: Thick rust layer, peeling off in large patches, with obvious rust pits or damage on the surface.
Physical Treatment Methods:
1. Manual Rust Removal
Use sandpaper, steel wool, or similar tools to manually remove rust, thoroughly cleaning the surface oxide film and rust. Then wipe dry with a clean cloth. This method is suitable for light rust, small areas, or localized on-site treatment.
2. Mechanical Rust Removal
Use power tools, angle grinders with steel wire wheels/grinding wheels, or similar mechanical tools to remove rust from the surface. This method is highly efficient and suitable for moderate rust. Care must be taken to avoid damaging the substrate when grinding.
3. Sandblasting and Shot Blasting
a. Sandblasting: Uses high-pressure gas to propel sand onto the steel pipe surface, removing the oxide film and rust.
Dry Sandblasting: Uses abrasives such as quartz sand and steel shot. It thoroughly removes rust and creates a rough surface, which is beneficial for coating adhesion.
Wet Sandblasting: Adds water or rust inhibitors to reduce dust. Suitable for environments with high environmental protection requirements.
b. Shot blasting: This method uses a high-speed rotating impeller to propel metal abrasive particles, suitable for batch processing of prefabricated parts, offering high efficiency and uniform quality.
Chemical Treatment Methods:
1. Acid pickling: Diluted hydrochloric acid, phosphoric acid, or a specialized acidic solution is used to chemically remove the oxide film and rust from the steel pipe surface, followed by rinsing with water. Suitable for complex shapes or batch processing, but caution is advised when environmental requirements are high.
2. Chemical conversion: Chemical agents are used to convert the oxide film on the steel pipe surface into a protective compound film, preventing the steel pipe surface from rusting again.
Surface Cleaning and Pretreatment:
Residue removal: After rust removal, use compressed air or a clean cloth to remove surface dust and abrasive particles.
Degreasing: If there is oil on the surface, clean with a solvent (such as acetone or a specialized cleaning agent).
Drying: Ensure the steel pipe is completely dry, avoiding any residual moisture.
Precautions:
1. When performing physical or chemical treatments, take care to protect your skin and respiratory tract, avoiding inhalation or contact with harmful substances.
2. During the treatment process, appropriate tools and materials should be used to avoid secondary damage to the steel pipe surface.
3. After treatment, the treatment agent and tools should be cleaned promptly to avoid environmental pollution.
Regular Maintenance:
Regularly check the pipeline coating condition; promptly grind and touch up any localized rust.
Avoid prolonged exposure of the steel pipe to humid, acidic, alkaline, or salt spray environments.
Read more: SMLS Steel Pipe Internal Corrosion Treatment
