Galvanized steel pipe Partial hot dip galvanized and galvanized two kinds, hot-dip galvanized galvanized layer thick, has the coating evenly, the adhesion is strong, the service life long and so on merits. Zinc plating Cost is low, the surface is not very smooth, its own corrosion-resistant specific heat of galvanized pipe is a lot of difference. In order to improve the corrosion resistance of steel tubes, the general steel tubes are galvanized. Galvanized steel pipe in hot dip galvanized and galvanized two kinds, hot-dip galvanized coating thick, zinc plating cost is low, the surface is not very smooth. Most of the old houses are galvanized pipes, now gas, heating of the kind of iron pipe is also galvanized pipes, galvanized pipes as pipes, the use of a few years after the tube produces a lot of rust, the outflow of yellow water not only pollute the sanitary ware, but also mixed with the non-smooth wall breeding bacteria, corrosion caused by heavy metals in the water, serious harm to the human 670 the 1990s, the developed countries began to develop new types of tubing, and gradually banned galvanized pipes. China Ministry of Construction and other four ministries also issued a clear from 2000 to ban galvanized pipe, the current new residential area of the cold water pipe has been rarely used galvanized tubes, some quarters of the hot water pipes used is galvanized pipe.