Steel pipe anti-corrosion methods generally use coating anti-corrosion. Coating anti-corrosion is to apply coating uniformly and densely on the surface of the rusted metal pipe to isolate it from various corrosive media.
1. Anti-corrosion coating on the outer wall of steel pipe
The anti-corrosion of the outer wall coating is to apply the paint evenly and densely on the surface of the rusted metal pipe to isolate it from various corrosive media. It is the most basic method of steel pipe anti-corrosion. Steel pipe anti-corrosion coatings are increasingly made of composite materials or composite structures. These materials and structures must have good dielectric properties, physical properties, stable chemical properties, and a wide temperature range.
2. Anti-corrosion coating on the inner wall of steel pipe
To prevent corrosion in the pipe, reduce frictional resistance, and increase throughput, the film is applied to the inner wall of the pipe. Commonly used coatings include amine-cured epoxy resin and polyamide epoxy resin, and the coating thickness is 0.038-0.2 mm. To ensure that the coating is firmly bonded to the pipe wall, surface treatment must be carried out on the inner wall of the pipe. Since the 1970s, the same material has been used for the coating of the inner and outer walls of the pipe, so that the coating of the inner and outer walls of the pipe can be carried out at the same time.
3. Anti-corrosion steel pipe insulation coating
On medium and small-diameter heat-transporting crude oil or fuel oil pipelines, to reduce heat dissipation from the pipeline to the soil, a composite layer of thermal insulation and anti-corrosion is added to the outside of the pipeline. The commonly used insulation material is rigid polyurethane foam, and the applicable temperature is -185～95℃. This kind of material is soft. To improve its strength, a layer of high-density polyethylene is applied outside the insulation layer to form a composite material structure to prevent groundwater from penetrating the insulation layer.
4. Other situations
If the outer protective pipe is a polyethylene pipe, there is no need to do anti-corrosion. Polyethylene is odorless, non-toxic, feels like wax, has excellent low-temperature resistance (use temperature can reach -70 ~ -100 ° C), good chemical stability, and can resist most acid and alkali erosion (not resistant to oxidizing properties) Acid), is insoluble in general solvents at room temperature, low water absorption, but because it is a linear molecule, it can slowly dissolve in some organic solvents without swelling and has excellent electrical insulation properties.