Surface treatment methods for steel pipes
2013-07-03
In order to extend the lifespan of oil and gas pipelines, surface treatment is usually required to facilitate a strong bond between the steel pipe and the anti-corrosion layer. Common treatment methods include: cleaning, tool rust removal, acid pickling, and shot blasting rust removal.
1. Cleaning
The grease, dust, lubricants, and organic matter adhered to the surface of the steel pipe are usually cleaned using solvents or emulsions. However, rust, oxide scale, and welding slag on the surface of the steel pipe cannot be removed and require further assistance from other treatment methods.
2. Tool Rust Removal
Oxide scale, rust, and welding slag on the surface of the steel pipe can be cleaned and polished using a wire brush. Tool rust removal is divided into manual and powered types; manual tool rust removal can achieve Sa2 level while powered tool rust removal can reach Sa3 level. If there is particularly stubborn oxide scale attached to the surface of the steel pipe that cannot be cleaned with tool rust removal, other methods need to be sought.
3. Acid Pickling
Common acid pickling includes chemical and electrolytic methods. However, only chemical acid pickling is used for pipeline anti-corrosion. Chemical acid pickling can achieve a certain level of cleanliness and roughness on the surface of the steel pipe, facilitating subsequent anchor pattern lines. It is usually used as a re-treatment after shot blasting (sand).
4. Shot Blasting Rust Removal
A high-power motor drives blades to rotate at high speed, causing abrasives such as steel sand, steel balls, wire segments, and minerals to be ejected against the surface of the steel pipe under centrifugal force. This process thoroughly removes rust, oxides, and dirt while achieving the desired uniform roughness due to intense impact and friction from abrasives.
Among these four treatment methods, shot blasting rust removal is considered the most ideal method for pipeline rust removal; generally speaking, shot blasting is mainly used for treating the inner surface of steel pipes while shot peening is primarily used for treating their outer surfaces.
Shenyang Tengfei Iron Corporation
Shenyang Tengfei Steel Pipe Co., Ltd.
Address: No.6 A 3, No.13 Road, Economic and Technological Development Zone, Shenyang City, Liaoning Province
E-mail:tfwelcome@163.com
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