First, the difference between galvanized pipe and Steel Pipe
Hot-dip galvanized steel pipe: the molten metal and iron matrix reaction to produce alloy layer, so that the combination of the substrate and the coating. Hot-dip galvanizing is the first pickling of steel pipe, in order to remove iron oxide on the surface of the steel pipe, pickled, through ammonium chloride or zinc chloride aqueous solution or ammonium chloride and zinc chloride mixed water tank cleaning, and then sent Hot dip bath. Hot galvanized with uniform coating, strong adhesion, long life and other advantages. Hot galvanized steel pipe matrix and the molten bath of the complex physical and chemical galvanized steel pipe should be formed to corrosion-resistant structure of a close zinc-iron alloy layer. Alloy layer and pure zinc layer, steel pipe body integration. So its strong corrosion resistance.
Hot-dip galvanized Steel Pipe: very little galvanized, only 10-50g / m2, its own corrosion resistance than hot galvanized pipe a lot worse. Formal galvanized pipe manufacturers, quasi-cold galvanized pipe for water, gas pipe. Galvanized galvanized steel galvanized layer is the electroplating layer, zinc layer and steel pipe matrix independent layer. Zinc layer is thin, zinc layer simply attached to the steel pipe matrix, easy to fall off. So its poor corrosion resistance. In the new residential, the use of cold galvanized steel pipe as a water supply pipe.
Galvanized pipe and Steel Pipe how to choose galvanized pipe selection
1, efficient and environmentally friendly, non-toxic non-polluting, non-corrosive, not only to acid corrosion inhibition fog function, but also with rust and efficient degreasing effect. In the course of the use of non-toxic, harmful substances, reduce air pollution, is conducive to the health of the operator to improve the work environment of the workshop. The existing pickling process, hydrochloric acid consumption, acid mist is also large, the waste acid discharge cycle is short, and the product in the course of the use of a small amount of added can be recycled after use in the course of acid Of the vast majority of ferrous chloride into iron oxide and precipitation, thus greatly extending the waste discharge cycle.
2, rust process does not produce "over erosion" rust "hydrogen embrittlement." Iron and steel material for a long time soaking no "weight loss" phenomenon.
3, rust ability, the effect is good, fast (rust speed can be adjusted according to the need to self) General floating rust can be removed in about 5 minutes, significantly better than the current pickling process.
4, the use of this product after rusting the workpiece, galvanized zinc layer evenly rust strong adhesion. Good finish, significantly better than pure hydrochloric acid wash out the workpiece.
5, the cost of rust is lower than the existing pickling costs (acid added to the product can be extended after the use of more than four times).
6, rust speed can be adjusted in the range of 1min-60min. General floating rust can be removed within 3min, the rust within 30min can be removed in addition to clean. According to the size of the steel surface, the degree of corrosion and the different grades of steel, each ton of rust can remove 20-100 tons of material surface corrosion.
Second, the classification of galvanized steel pipe
There are two ways of galvanizing, one is the electroplating contrast, the other is to be plated into a liquid filled with a pool, similar to electrophoresis, strong and poor, the advantages of low cost, speed, also There is what is broken can be plated, usually the use of galvanized steel construction site is the lack of diameter of the broken steel bar plating, a few thousand dollars difference.
1, the pipe contains a seam pipe and seamless pipe, indicating that the method for the Φ diameter × δ wall thickness.
2, there are many kinds of sewn tube. But there is a very common tube, that is, the national standard tube, also known as water gas pipe, usually with the diameter of the project that the way DN nominal diameter. For example, DN20, indicating that the outer diameter of 26.8 mm, wall thickness of 2.75 mm, with inches that 3 / 4in, we usually called 6 tube. This tube, we usually called the national standard tube, water and gas pipe. They are divided into black tubes and hot galvanized pipes. We usually say that the galvanized water gas pipe that is hot galvanized GB tube, it was also called "hot galvanized steel pipe" is a return operation.
3, seamless pipe is usually not galvanized.
4, galvanized into hot and cold plating two. Hot-dip galvanized layer thick, bright color white shiny, the national standard hot galvanized pipe (ie galvanized water gas pipe) is usually 6 meters long, both ends of the brush has a blue circle, no matter how long the wind and rain, galvanized layer is not Will fall off, the color will not change. Cold galvanized galvanized layer of thin, gray color, put a long time, will rust, it is usually used for engineering on the electrical dark laying lighting tube, wall thickness is thinner than the national standard tube, used in concrete, Do not need rust. (Assuming used in concrete, you can also use non-galvanized black tube, but the need for rust inside the black tube operations, compared to trouble, the external does not need. With hot galvanized pipe as a dark lay, waste).
Third, how to choose galvanized pipe
1, galvanized steel pipe grades and chemical composition, in the production process, galvanized steel used in steel grades and chemical composition should be consistent with GB-3092 in the black tube steel grades and chemical composition requirements.
2, galvanized steel pipe manufacturing method selection, the manufacturer choose to manufacture black tube manufacturing methods, galvanized should be hot dip galvanized method.
3, galvanized steel pipe thread and pipe connection
(1) with the delivery of galvanized steel pipe, the thread should be in the galvanized car system. The thread must meet the requirements of YB822.
(2) steel pipe joints must meet the requirements of YB238, cast iron pipe joints must meet the provisions of YB230.
4, galvanized steel pipe mechanical properties and galvanized layer weight, galvanized steel pipe before the mechanical properties should be consistent with the provisions of GB3092. Galvanized layer weight should not be less than 500g / ㎡.
5, galvanized layer uniformity and cold bending test, steel pipe sample in the copper sulfate solution for 5 times can not be red. Galvanized steel pipes with diameters not more than 50mm should be tested for cold bending. The bending angle is 90 degrees.
6, galvanized steel pipe hydraulic pressure test and surface quality, test pressure and eddy current testing Contrast sample size should be consistent with the provisions of national standard GB3092. Galvanized steel pipe surface should have a complete layer, there must be no zinc coated with black spots and bubbles exist. Allows the presence of small rough surfaces and localized zinc tumors.