In the process of anti-corrosion construction of oil and gas pipelines, the surface treatment of
seamless steel pipes is one of the key factors to determine the service life of pipeline anti-corrosion. According to research by professional research institutions, the life of the anti-corrosion layer depends on factors such as the type of coating, coating quality and construction environment. Whether it is a seamless pipe or a
welded pipe, the surface treatment method of the steel pipe must be continuously improved in strict accordance with the requirements of the specification for the anti-corrosion layer on the surface of the steel pipe. The main methods of removing embroidery from seamless steel pipes are as follows:
1. Cleaning
Use solvents and emulsions to clean the steel surface to remove oil, grease, dust, lubricants and similar organic substances, but it cannot remove rust, oxide scale, welding flux, etc. on the steel surface, so it is only used as an auxiliary means in anti-corrosion operations.
2. Pickling
Generally, two methods of chemical and electrolytic pickling are used for pickling, and only chemical pickling is used for pipeline anticorrosion, which can remove oxide scale, rust, and old coating. Although chemical cleaning can make the surface achieve a certain degree of cleanliness and roughness, its anchor pattern is shallow and it is easy to cause pollution to the surrounding environment.
3. Tool rust removal
Mainly use tools such as wire brushes to polish the surface of the steel, which can remove loose oxide scale, rust, welding slag, etc. The rust removal of manual tools can reach Sa2 level, and the rust removal of power tools can reach Sa3 level. If the steel surface is adhered to a firm scale of iron oxide, the rust removal effect of the tools is not ideal, and the anchor pattern depth required for anti-corrosion construction cannot be achieved.
4. Spray rust removal
Jet derusting is to drive the jet blades to rotate at a high speed through a high-power motor, so that abrasives such as steel shot, steel sand, iron wire segments, minerals, etc. are sprayed on the surface of the straight seam steel pipe under the powerful centrifugal force of the motor, which can not only completely remove oxides , rust and dirt, and the straight seam steel pipe can achieve the required uniform roughness under the action of the violent impact and friction of the abrasive.
After spraying and removing rust, it can not only expand the physical adsorption on the surface of the pipe, but also enhance the mechanical adhesion between the anti-corrosion layer and the surface of the pipe. Therefore, jet derusting is an ideal derusting method for pipeline anticorrosion. Generally speaking, shot blasting is mainly used for inner surface treatment of pipes, and shot blasting is mainly used for outer surface treatment of straight seam steel pipes.
In the production process, the relevant technical indicators of rust removal should be strictly required to prevent the damage to the straight seam steel pipe caused by operation errors. Embroidery is a frequently used technique in the steel pipe industry.
