The oil casing coupling can adapt to the temperature range of -185-95 degrees Celsius. The texture of the insulation material is relatively soft. In order to improve the hardness, a layer of anti-corrosion coating is usually applied on the outside of the insulation layer. It can be called a oil casing coupling. In the small and medium-sized oil pipelines, in order to reduce the heat dissipation of the pipeline to the soil, a composite layer of heat preservation and anti-corrosion is added to the outside of the pipeline, which is also beneficial to prevent groundwater from penetrating into the insulation layer, resulting in no economic loss, and anti-corrosion of the oil casing coupling. The layer is generally made of a polyethylene material, and the anticorrosive material is odorless and feels like wax. It has good low temperature resistance, low temperature can reach -70-100 degrees Celsius, can resist most acid and alkali corrosion, is not soluble in common solvent at room temperature, and has relatively low water absorption, but because it is a linear molecule, It can be slowly dissolved in some organic solvents, and it is not easy to swell, and the electrical insulation properties are also excellent.