In fact, for the cast iron pipe buried in the ground, working in the general soil environment, the outer wall can only meet the requirements of anti-corrosion by applying𝓰 asphalt. However, for corrosive soils, such as swamp soil, loa💙ch soil, sulphate-containing soil, garbage soil and soil contaminated by drainage, it is difficult to apply asphalt-based anti-corrosion effect.
France Musongqiao Company began to carry out tube simulation and comparison experiments from 1949. The results shoꦓw that the corrosion protection effect of the composite coating after the tube is annealed and then spr🌃ayed with zinc and then coated with asphalt is the best. Spraying a zinc coating with a zinc spray machine has two effects:
1. Since the electrochemical point of zinc is lower than that of iron, the iron pipe is protected from c🌄orrosion by the reaction of zinc;
2. When the zinc layer is corroded by the salt solution, it will produce 🍨insoluble compounds (zinc phosphate, zinc chloride, zinc sulfate) covering the surface of the pipe, thereby slowing the intrusion of corrosive media.
The above is th🥃e anti-corrosion principle of the zinc spray machine, I hope to be able to help everyone know it.