Method of Removing Rust for ERW Welded Pipe

In the anti-corrosion construction process of oil and gas pipelines, the surface treatment of ERW welded pipes is one of the key factors that determine the pipeline's anti-corrosion service life. It is the premise of whether the anti-corrosion layer and ERW welded pipe can be firmly combined. According to the research of professional research institutions, the life of the anti-corrosion layer depends on the type of coating, coating quality and construction environment. The surface treatment of ERW welded pipe has an impact on the life of the anti-corrosion layer. Therefore, it should be strictly in accordance with the anti-corrosion layer. Standardize the requirements for the surface of ERW straight seam steel pipes, and continuously improve the surface treatment methods of ERW welded pipes.

There are mainly the following methods for removing rust from ERW welded pipes:

1. Cleaning
Solvents and emulsions are used to clean the steel surface to remove oil, grease, dust, lubricants and similar organic matter, but it cannot remove rust, oxide scale, welding flux, etc. on the steel surface, so it is only used as an auxiliary means in the defense operations.

2. Pickling
Generally, two methods of chemical and electrolysis are used for pickling. Pipeline anticorrosion only uses chemical pickling, which can remove oxide scale, rust, and old coatings. Sometimes it can be used as a reprocessing after sandblasting and rust removal. Although chemical cleaning can achieve a certain degree of cleanliness and roughness on the surface, its anchor lines are shallow and easily pollute the surrounding environment.

3. Derusting tools
Mainly use tools such as wire brushes to polish the steel surface, which can remove loose oxide scale, rust, welding slag, etc. The rust removal of hand tools can reach the Sa2 level, and the rust removal of power tools can reach the Sa3 level. If the steel surface is attached with solid oxide scale, the tool rust removal effect is not ideal, and the anchor pattern depth required for anti-corrosion construction cannot be reached.

4. Spray rust removal
Jet rust removal is driven by a high-power motor to drive the jet blades to rotate at a high speed, so that steel shot, steel grit, iron wire, minerals and other abrasives are sprayed on the surface of the ERW welded pipe under the strong centrifugal force of the motor, which can not only completely remove oxides, but also Rust and dirt, and the ERW welded pipe can achieve the required uniform roughness under the action of the violent impact and friction of the abrasive.

After spraying to remove rust, not only can the physical adsorption of the pipe surface be expanded, but also the mechanical adhesion of the anti-corrosion layer and the pipe surface can be enhanced. Therefore, spray rust removal is an ideal rust removal method for pipeline anticorrosion. Generally speaking, shot blasting is mainly used for the inner surface treatment of pipes, and shot blasting is mainly used for the outer surface treatment of ERW welded pipes.

In the production process, the relevant technical indicators for rust removal must be strictly required to prevent secondary damage to the ERW welded pipe due to operating errors. After the ERW welded pipe is derusted, the appearance of the product will be smoother than before the rust removal. The derusting of the ERW welded pipe is on the steel pipe. It is a frequently used technology in the industry.