11.Methods of derusting and anticorrosion of inner wall of steel pipe?
The anti-corrosion method of anti-corrosion steel pipe is generally to use coating for anti-corrosion. Let's learn about coating for anti-corrosion. Coating anticorrosion is one of the most basic methods for anticorrosion of steel pipes, which is to uniformly and compactly coat the surface of metal pipes after derusting to isolate them from various corrosive media. Composite materials or composite structures are more and more used as anticorrosion coatings for steel pipes. These materials and structures should have good dielectric properties, physical properties, stable chemical properties and wide temperature adaptation range. 1. Anticorrosive coating on outer wall: material types and service conditions of coating on outer wall of pipeline. ② Inner wall anticorrosion coating: a thin film coated on the inner wall of the pipe to prevent corrosion in the pipe, reduce friction resistance and improve transportation capacity. Commonly used coatings are amine cured epoxy resin and polyamide epoxy resin, and the coating thickness is 0.038 ~ 0.2 mm. In order to ensure the adhesion between the coating and the pipe wall, the inner wall of the pipe must be surface treated. Since 1970s, the coating of inner and outer walls of pipes tends to be made of the same material, so that the coating of inner and outer walls of pipes can be carried out at the same time. ③ Anti-corrosion and heat preservation coating: In order to reduce the heat dissipation from the pipeline to the soil, a composite layer of heat preservation and anti-corrosion is added to the outside of the pipeline. The commonly used thermal insulation material is rigid polyurethane foam plastic, and the applicable temperature is-185 ~ 95℃. This kind of material is soft in texture. In order to improve its strength, a high-density polyethylene layer is applied outside the insulation layer to form a composite structure to prevent groundwater from penetrating into the insulation layer. 2. If the outer protective pipe is polyethylene pipe, there is no need to do anticorrosion Polyethylene is odorless and nontoxic, feels like wax, and has excellent low temperature resistance (the lowest service temperature can reach-70 ~-100℃), good chemical stability, resistance to most acid and alkali (resistance to acid with oxidation property), insolubility in common solvents at normal temperature, and low water absorption. However, because it is a linear molecule, it can slowly dissolve in some organic solvents without swelling, and has excellent electrical insulation performance.
22.Advantages of anticorrosion steel pipe?
In addition to improving the service life of steel pipes through anticorrosion, it is also manifested in the following aspects: 1) Combine the mechanical strength of steel pipes with the corrosion resistance of plastics
2) The outer wall coating is more than 2.5mm, which is resistant to scratches and bumps
3)The friction coefficient of inner wall is small, 0.0081-0.091, which reduces energy consumption
4)The inner wall meets the national health standard
5)The inner wall is smooth and difficult to scale, with self-cleaning function.
33.How to check and accept anticorrosive steel pipes?
General construction acceptance mainly depends on appearance, without bubbles, falling, bright and smooth surface, followed by measuring film thickness, which is generally acceptable, and the most important thing is to remove rust at the grass-roots level before anticorrosion, without measuring adhesion.