Introduction of galvanized steel pipe

Galvanized steel pipe

Introduction of galvanized steel pipe

In order to improve the corrosion resistance of steel pipe, the general steel pipe is galvanized. Galvanized steel pipe is divided into hot dip galvanized and electric galvanized. The layer of hot dip galvanized is thick, the cost of electric galvanized is low, and the surface is not very smooth. Oxygen blowing welding pipe: used for steel blowing oxygen pipe, generally with small diameter welded steel pipe, specifications from 3/8-2 inches of eight. Made of 08, 10, 15, 20 or 195-Q235 steel strip, in order to prevent corrosion, have to be aluminized.

Classification and characteristics of galvanized steel pipe

Galvanized steel pipe is divided into cold plated tube and hot plated tube, the former has been banned, the latter is also advocated by the state for temporary use.

Hot-dip galvanized pipe

Hot dip galvanized pipe is made of molten metal and iron matrix reaction to produce alloy layer, so that the matrix and the coating of the two combination. Hot dip galvanizing is to first pickling the steel pipe. In order to remove the iron oxide on the surface of the steel pipe, after pickling, it is cleaned by ammonium chloride or zinc chloride aqueous solution or mixed aqueous solution of ammonium chloride and zinc chloride, and then sent into the hot dip plating tank. Hot dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. Complex physical and chemical reactions occur between the steel tube substrate and the molten bath to form a compact zinc-iron alloy layer with corrosion resistance. The alloy layer is integrated with the pure zinc layer and the steel tube matrix. Therefore, its corrosion resistance is strong.

1. Uniformity of galvanized layer: steel tube sample shall not turn red (copper plating color) after 5 consecutive impregnations in copper sulfate solution.

2, surface quality: the surface of galvanized steel pipe should be complete galvanized layer, there should be no black spots and bubbles on the plating, allowing a small rough surface and local zinc tumor.

3, galvanized layer weight: according to the requirements of the customer, galvanized steel pipe can be measured zinc layer weight, its average should not be less than 500g/ square meter, including any sample should not be less than 480g/ square meter.

Cold galvanized pipe

Cold galvanized is electric galvanized, galvanized amount is very small, only 10-50g/m2, its own corrosion resistance is much different than hot galvanized pipe. Regular galvanized pipe manufacturers, in order to ensure quality, most do not use galvanizing (cold plating). Only small businesses with obsolete equipment use galvanizing, and of course their prices are relatively cheap. At present, the Ministry of Construction has formally below, eliminate the backward technology of cold galvanized pipe, the future is not allowed to use cold galvanized pipe as water, gas pipe. The zinc layer is an electric coating, and the zinc layer is layered independently with the steel tube substrate. Zinc layer is thin, zinc layer is simply attached to the steel tube matrix, easy to fall off. So its corrosion resistance is poor. It is prohibited to use cold galvanized steel pipes as water supply pipes in newly built houses.

Application of galvanized steel pipe

Now the kind of iron pipe used in gas, greenhouses and heating is also galvanized pipe. Galvanized pipe as a water pipe produces a large number of rust scale in the pipe. The yellow water flowing out not only pollues sanitary ware, but also contains bacteria bred on the unclean inner wall, which causes excessive heavy metal content in the water and seriously harms human health. In the 1960s and 1970s, developed countries began to develop new types of pipes, and have banned galvanized pipes. China's Ministry of Construction and other four ministries and commissions also issued a document to prohibit galvanized pipes from 2000. At present, galvanized pipes are rarely used in cold water pipes of new residential areas, and galvanized pipes are used in hot water pipes of some residential areas.