Hot-dip galvanized steel pipe has the characteristics of surface gloss, uniform zinc layer, no leakage, no dripping, strong adhesion, and strong corrosion resistance. It has greatly increased in suburban environments. The standard hot-dip galvanized rust-proof thickness can be maintained There is no need for repairs for more than 50 years; in urban or offshore areas, the standard hot-dip galvanized anti-rust layer can last for 20 years without repairs.