The composition and weight ratio of the centrifugally cast tubular coating are: 100 parts of base material, 100 to 120 parts of water, 5 to 8 parts of bentonite, 0.15 to 0.3 parts of Na2CO3, and 0.1 to 0.3 may be added. An anionic surfactant, wherein the base material is diatomaceous earth and quartz powder, the base material is calculated weight, the remaining components are actually weighted, and the relationship between the calculated weight of the base material and its actual weight is: W (count) silicon Algae = 3W (real) diatomaceous earth, W (count) quartz powder = W (real) quartz powder, the coating has good suspension, low gas permeability, good mold release and anti-iron wash Performance and insulation properties.