Commonly used
steel pipeline corrosion coatings include traditional petroleum asphalt or asphalt enamel, coal tar and coal tar enamel, polyethylene, and polypropylene tapes. From a technical point of view, these anti-corrosion materials can be used for the prefabrication of the anti-corrosion layer in the workshop, the jointing, and the renewal of the anti-corrosion layer. There is the focus. In addition, there are other coatings, such as paraffin wax and amorphous petroleum jelly, which are commonly used for the anticorrosion of special-shaped pipe fittings and equipment in stations. Asphalt-based coatings include petroleum asphalt and coal tar asphalt, as well as asphalt enamel or coal tar enamel made of asphalt mixed with stone 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; poor resistance to soil stress; the joint structure and quality can be the same as the pipe anti-corrosion layer.
Petroleum asphalt and its enamel paint: Petroleum asphalt is a thermoplastic coating, which is a by-product obtained by fractionating gasoline, kerosene, diesel oil, and lubricating oil from crude oil. The main substance is aliphatic linear alkanes. Mineral oil, resin, and asphaltene are the three major components of petroleum asphalt. Oil and resin give asphalt fluidity and plasticity, and 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 softening point reflects the hardness of the asphalt and determines the service temperature of the anti-corrosion layer. The way to increase the softening point is to blow air into the asphalt at high temperatures to oxidize the asphalt and remove light components. The petroleum asphalt anti-corrosion layer has good electrical insulation, water resistance, chemical resistance, and anti-corrosion properties, but has a high water absorption rate, low cohesive force, and is easily damaged by mechanical force. Some bacteria in the soil are fond of asphalt, and plant roots can Penetrate the asphalt layer, in addition, it is susceptible to soil stress damage in clayey soils with changes in dryness and humidity. Under the action of temperature and gravity, the anti-corrosion layer may produce creep or cold flow.
