There are many kinds of anti-corrosion outside the steel sleeve steel steam insulation pipe. The most common is epoxy coal tar (two cloths and three oils). The specific operation is to blast the steel pipe first and then rust and then paint a layer of epoxy zinc-rich primer gray. Then brush the epoxy coal tar pitch paint at the same time and wrap a layer of glass cloth, then brush the epoxy coal tar pitch paint again and then wrap the cloth, and finally paint it again. There is also a 3pe which is relatively expensive, but has a very high cost. Strong anti-corrosion effect, it will not rot when buried in the ground for 30 years.