1, inner wall anticorrosive coating
Firstly, the surface of the inner wall of the pipeline is treated to ensure that the pipe wall can be firmly combined with the coating. After cleaning, paint is evenly spread on the surface. Since 1970s, the outer wall of the pipeline tends to be coated with the same material as the inner wall of the pipeline, so that the outer coating and inner coating of the pipeline can be carried out at the same time.
Before the pipeline is subjected to anti-corrosion treatment, the surface of the pipeline should be cleaned to remove scale, rust, pollutants, dirt, oil pollution and moisture. There are many methods to clean the surface, among which chemical derusting, manual sandblasting and manual derusting are widely used. The coating shall be applied within four hours after surface treatment.
2, exterior wall anticorrosive coating
It is one of the most commonly used methods to coat the surface of derusted metal pipeline with dense and uniform coating to isolate it from various corrosive media. Since 1970s, when pipelines were installed in harsh environments such as ocean and polar regions, we transported relatively high-temperature oil, which made the temperature of pipelines rise gradually, which also put forward high requirements for the performance of coatings.
Therefore, more and more people will choose composite structures or composite materials as anti-corrosion coatings for pipelines. These materials have good wide temperature adaptability and stable chemical, physical and dielectric properties.
Precautions for pipeline anticorrosion
Before painting, the oil stain, dust, welding slag, floating rust and other attachments on the metal surface must be removed, and the surface of the anticorrosion part should be kept dry and waterless. In anti-corrosion construction, the next paint can only be carried out after the previous paint is completely dried. In order to ensure the thickness of paint film at the weld, the weld should be brushed twice first, and then fully brushed with antirust paint.
After painting, the surface should be smooth, without sagging, wrinkles, brush marks, exposure or cracking, and the coating should be uniform. Leave 100mm on both sides of the weld installed on site without painting, and paint as required after installation.
During transportation and hoisting, the pipeline should avoid hard friction with foreign objects to prevent damage. If it is damaged, it should be repaired to be qualified. Open construction is not allowed in rainy and foggy days. Artificial ventilation facilities should be used in the construction of parts with poor ventilation conditions.