It is used to transport gas and heating.
The iron pipes used in gas, greenhouses and heating are also galvanized pipes. Galvanized pipes are used as water pipes. A large amount of rust is generated in the pipes. The yellow water that flows out not only pollutes sanitary ware, but also contains bacteria that breed on the uneven inner wall, causing water to be rusted. The high content of heavy metals seriously endangers human health. In the 1960s and 1970s, developed countries in the world began to develop new types of pipes and gradually banned galvanized pipes. Four ministries and commissions including the Ministry of Construction of China have also issued a document clarifying that galvanized pipes have been banned from 2000. At present, cold water pipes in newly built communities have rarely used galvanized pipes, and hot water pipes in some communities are galvanized pipes.
Hot-dip galvanized pipe: In order to improve the corrosion resistance of the steel pipe, the general steel pipe is galvanized. There are two types of galvanized steel pipes: hot-dip galvanizing and electro-galvanizing. The hot-dip galvanizing layer is thick, the cost of electro-galvanizing is low, and the surface is not very smooth.
The hot-dip galvanized pipe is to make the molten metal and the iron matrix react to produce an alloy layer, so that the matrix and the coating are combined. Hot-dip galvanizing is to first pickle the steel pipe. In order to remove the iron oxide on the surface of the steel pipe, after pickling, it is cleaned in a tank with ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to In the hot dip plating tank. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. Complicated physical and chemical reactions occur between the steel pipe matrix and the molten plating solution to form a corrosion-resistant zinc-iron alloy layer with a compact structure. The alloy layer is integrated with the pure zinc layer and the steel pipe matrix. Therefore, its corrosion resistance is strong.
1. The uniformity of the galvanized layer: the steel pipe sample shall not turn red (copper-plated color) after being immersed in copper sulfate solution for 5 consecutive times
2. Surface quality: The surface of the galvanized steel pipe should have a complete galvanized layer, and there must be no unplated black spots and bubbles, and small rough surfaces and local zinc tumors are allowed.
3. Galvanized layer weight: According to the requirements of the buyer, the galvanized steel pipe can be used to determine the weight of the zinc layer.