Method of removing embroideries from steel pipes

　　During the anti-corrosion construction of oil and gas transmission pipelines, the surface treatment of steel pipes is one of the key factors that determine the service life of pipeline anti-corrosion, and it is the premise that whether the anti-corrosion coating can be firmly combined with straight seam steel pipes. According to the research of professional institutions, the service life of the anti-corrosion coating depends on factors such as coating type, coating quality and construction environment. The influence of steel pipe surface treatment on the service life of the anti-corrosion coating accounts for about 50%. Therefore, the steel pipe surface treatment method should be improved continuously in strict accordance with the requirements of the anti-corrosion coating specification on the steel pipe surface. The steel pipe embroidering methods mainly include the following:

　　1. Cleaning

　　Solvents and emulsions are used to clean the steel surface to remove oil, grease, dust, lubricant and similar organic substances. However, it cannot remove rust, oxide skin, welding flux, etc. on the steel surface, so it is only used as an auxiliary means in government prevention operations.

　　2. Pickling

　　Generally, chemical and electrolytic methods are used for pickling. Only chemical pickling is used for pipeline corrosion prevention, which can remove oxide scale, rust and old coating. Sometimes, it can be used as the re treatment after sand blasting. Although chemical cleaning can make the surface reach a certain degree of cleanliness and roughness, its anchor lines are shallow and easy to pollute the surrounding environment.

　　3. Tool derusting

　　Steel wire brush and other tools are mainly used to polish the steel surface to remove loose oxide skin, rust, welding slag, etc. Rust removal with manual tools can reach Sa2 level, and that with power tools can reach Sa3 level. If the steel surface is firmly attached with iron oxide scale, the rust removal effect of tools is not ideal, and the anchor pattern depth required for anti-corrosion construction cannot be reached.

　　4. Spray derusting

　　Spray derusting is to drive the jet blade to rotate at a high speed by a high-power motor, so that the steel shot, steel sand, iron wire segment, minerals and other abrasives can spray the surface of straight seam steel pipe under the strong centrifugal force of the motor. It can not only completely remove oxides, rust and dirt, but also achieve the required uniform roughness of straight seam steel pipe under the effect of violent impact and friction of the abrasives.

　　After rust removal by spraying, not only the physical adsorption of the pipe surface can be expanded, but also the mechanical adhesion between the anti-corrosion coating and the pipe surface can be enhanced. Therefore, spray derusting is an ideal derusting method for pipeline anti-corrosion. 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.

　　During the production process, the relevant technical indicators of rust removal shall be strictly required to prevent the secondary damage to the straight seam steel pipe caused by operation errors. After the straight seam steel pipe is de embroidered, the product appearance will be smoother than before. The de embroidery of straight seam steel pipe is a frequently used technology in the steel pipe industry.