Galvanized pipe classification and process description
Galvanized pipe classification and process description 1. Classification of galvanized pipes: galvanized steel pipes are divided into cold-plated pipes and hot-plated pipes. 1, hot-dip galvanized pipe The hot-dip galvanized pipe is obtained by reacting molten metal with an iron matrix to produce an alloy layer, thereby combining the substrate and the plating layer. The hot-dip galvanizing is to pickle the steel pipe first, 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 solution of ammonium chloride and zinc chloride solution, and then sent to hot dip plating tank. Hot-dip galvanizing has the advantages of uniform plating, strong adhesion and long service life. 2, cold galvanized pipe Cold galvanizing is electroplating zinc, galvanizing is very small, only 10-50g/m2, its corrosion resistance is much worse than hot-dip galvanized pipe. Regular galvanized pipe manufacturers, in order to ensure quality, most do not use electroplating Zinc (cold plating). Only small enterprises with small scale and outdated equipment use electro-galvanized steel. Of course, their prices are relatively cheaper. At present, the Ministry of Construction has officially laid out the cold-galvanized pipes with backward technology and will not be allowed to use cold in the future. Galvanized pipe for water, gas pipe. 3. Hot-dip galvanized steel pipe The steel pipe matrix and the molten plating solution undergo complex physical and chemical reactions to form a corrosion-resistant structure of zinc-iron alloy layer. The alloy layer is integrated with the pure zinc layer and the steel pipe matrix. Therefore, its corrosion resistance is strong. 4, cold galvanized steel pipe The zinc layer is an electroplated layer, and the zinc layer and the steel pipe base are separately layered. The zinc layer is thin, the zinc layer is simply attached to the steel pipe base, and is easy to fall off. Therefore, the corrosion resistance is poor. In the newly built house, the use of cold-galvanized steel pipe is prohibited. As a water supply pipe. Second, the steel pipe should be pre-plated before galvanizing: That is, pickling, washing, rinsing, dip coating solvent, and drying. The welded pipe is washed by the crane to the pickling tank for pickling (about 2 tons per hoist). About 26% hydrochloric acid solution is pickled. In order to prevent excessive pickling and acid mist evaporation, 0.5~1.0g/L of corrosion inhibitor and anti-fogging agent are added to the pickling solution, and pickling is performed at normal temperature. The pickling time is generally For 30~60 minutes, in order to make the steel pipe evenly pickled, the steel pipe is lifted 2~3 times in the pickling process to improve the pickling effect. When the acid concentration drops to 100g/L, it should be added or replaced, and the iron content reaches 220~260g/L as waste acid. The pickled steel pipe is washed by the crane to the cleaning tank to remove the residual acid and iron salt accumulated on the surface of the steel pipe after pickling, and then hanged to the washing station and rinsed with 0.7~0.8Mpa of water. The steel pipe is immersed in a solvent bath, and the dipping time is about one minute. The solvent is 600-650 g/L zinc chloride and 80-100 g/L ammonium chloride and 1~2 g/L OP-10 surfactant. In order to improve the pre-plating effect in the solvent of the steel pipe, the solvent is always weakly alkaline, and then it is driven by the crane to the drying oven stand to be dried in the drying furnace, and the drying temperature is 100-130 degrees, and the time is generally 6-10 minutes. The most advantageous advantages of sulphate galvanizing sulphate galvanizing pipes are current efficiency up to 100% and fast deposition rate, which is unmatched by other galvanizing processes. Third, the optimization of sulphate galvanized pipe: Because the plating crystal is not detailed enough, the dispersing ability and the deep plating ability are poor, so it is only suitable for electroplating of pipes and wires with simple geometric shapes. The sulphate electroplating zinc-iron alloy process optimizes the traditional sulphate galvanizing process, leaving only the main salt zinc sulphate, and the remaining components are discarded. In the composition of the new process, an appropriate amount of iron salt is added to form a zinc-iron alloy coating on the original single metal coating. The reorganization of the process not only carries forward the advantages of high current efficiency and fast deposition rate of the original process, but also greatly improves the dispersing ability and deep plating ability. In the past, complicated parts could not be plated, and now simple and complicated parts can be plated, and the protective performance It is 3 to 5 times higher than single metal. The production practice proves that for continuous plating of wire and pipe, the plated grain is more refined and brighter than the original, and the deposition rate is fast. The thickness of the coating reached the requirement within 2 to 3 minutes. Fourth, the scope of use of galvanized pipe: The galvanized steel pipe is divided into two types: hot-dip galvanizing and electro-galvanizing. The hot-dip galvanizing layer is thick, with uniform plating, strong adhesion and long service life. The cost of electroplating is low, the surface is not very smooth, and its corrosion resistance is much worse than that of hot-dip galvanized pipes. In order to improve the corrosion resistance of the steel pipe, the general steel pipe is galvanized. The galvanized steel pipe is divided into two types: 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. Most of the old houses are made of galvanized pipes. Now the iron pipes for gas and heating are also galvanized pipes. The galvanized pipes are used as water pipes. After a few years of use, a large amount of rust is generated in the pipes, and the yellow water flowing out is not only polluted. Sanitary ware, and mixed with bacteria that grow on the inner wall of the slick, the rust causes the heavy metal content in the water to be too high, which seriously endangers the health of the human body. In the 1960s and 1970s, developed countries in the world began to develop new types of pipes and banned galvanized pipes. The Ministry of Construction and other four ministries and commissions also issued a document clarifying that galvanized pipes will be banned from 2000. At present, cold-water pipes in newly built communities have rarely used galvanized pipes, and some districts use galvanized pipes for hot water pipes. Pressure Measurenment,Air Pressure Gauge,Pressure Meter,Hydraulic Pressure Gauge Wuxi Winsun Automation Instrument Co., Ltd , https://www.jswxwinsun.com