What are the commonly used external anti-corrosion coating materials for steel pipe

commonly used anti-corrosion steel pipes material include traditional petroleum asphalt or asphalt enamels, coal tar and coal tar enamels, polyethylene, and polypropylene tapes. from a technical point of view, these anti-corrosion materials can be used for the prefabrication of anti-corrosion layers in workshops, patching, and renewal of anti-corrosion layers. however, due to the limitations of anti-corrosion layer construction performance, equipment, and environmental factors, the application fields of these materials are also different. there is the focus. in addition, there are other coatings, such as paraffin, amorphous petroleum plaster, etc., which are commonly used for the anti-corrosion of special-shaped pipe fittings and equipment in the station. asphalt-based paint coatings include petroleum asphalt and coal tar asphalt, as well as asphalt enamels or coal tar enamels made of asphalt mixed with slate powder, shale powder, or coal powder at high temperatures. this type of coating has the following common characteristics: low requirements for rust removal; high-temperature flow, low temperature hard and brittle; poor resistance to mechanical damage;

petroleum bitumen and its enamel: petroleum bitumen is a thermoplastic coating, which is a by-product obtained from the fractional distillation of gasoline, kerosene, diesel oil, and lubricating oil from crude oil. the main substance is aliphatic straight-chain alkanes. mineral oil, resin, and asphaltene are the three major components of petroleum asphalt. oil and resin impart fluidity and plasticity to asphalt, while asphaltene determines the hardness and brittleness of asphalt. steel pipe anti-corrosion asphalt must have a certain hardness and plasticity. the main indicators for evaluating the quality of anti-corrosion petroleum asphalt are softening point and penetration. the level of softening point reflects the hardness of the asphalt and determines the service temperature of the anti-corrosion layer. the method to increase the softening point is to blow air into the asphalt at high temperatures to oxidatively polymerize the asphalt and remove light components. the petroleum asphalt anti-corrosion layer has good electrical insulation, water resistance, chemical resistance, and anti-corrosion, but it has high water absorption, low cohesion, and is easily damaged by mechanical force. some bacteria in the soil are addicted to asphalt, and plant roots can penetrates the asphalt layer, and is susceptible to soil stress damage in cohesive soils with dry and wet changes. under the action of temperature and gravity, the anti-corrosion layer may produce creep or cold flow.