The high quality anticorrosion treatment adopted in the manufacturing process of the expansion joint can effectively prevent the occurrence of various corrosion phenomena, prolong the service life of the product, reduce the maintenance cost of the pipeline, and ensure the safe and effective operation of the pipeline. The concrete operation steps are as follows: Coating uniformly and compactly on the surface of the rusted metal pipeline. It is one of the most basic methods for pipeline corrosion protection to isolate it from various corrosive media.
Since the 1970s, pipelines have been laid in harsh polar and ocean environments, and pipelines have been heated and transported by oil products, which have raised the temperature of pipelines. More requirements have been put forward for coating performance. Therefore, more and more composite coatings or composite structures are used for pipeline anticorrosive coatings. These materials and structures should have good dielectric properties, physical properties, stable chemical properties and a wide temperature range.
Anticorrosive coating: a film applied to the inner wall of a pipe in order to prevent corrosion, reduce friction resistance and increase transportation. The commonly used coatings are amine cured epoxy resin and polyamide epoxy resin, the thickness of the coating is 0.038-0.2 mm. To ensure the bonding between the coating and the tube wall is firm, the inner surface of the tube must be treated. Since the 1970s there has been a tendency to use the same materials for both inner and outer wall coatings so that the coating can be carried out simultaneously.
Anti-corrosion and thermal insulation coatings: In order to reduce the heat dissipation from the pipeline to the soil, heat preservation and anti-corrosion composite coatings are added to the outside of the pipeline on medium and small diameter heat-transfer crude oil or fuel oil pipelines. The commonly used thermal insulation material is rigid polyurethane foam, and the temperature is between 18 and 95 degrees. The material is soft in texture. In order to improve its strength, a layer of high density polyethylene (HDPE) is added to the insulation layer to form a composite structure to prevent groundwater from infiltrating into the insulation layer.