October 24, 2022
Hot dip galvanized pipe is to make molten metal and iron matrix reaction to produce an alloy layer, so that the matrix and coating are combined. Hot dip galvanized steel pipe is first pickling, in order to remove iron oxide on the surface of the steel pipe, after pickling, through ammonium chloride or zinc chloride aqueous solution or ammonium chloride and zinc chloride mixed aqueous solution tank for cleaning, and then into the hot dip plating tank. Hot dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. Hot dip galvanized steel tube matrix and molten bath have complex physical and chemical reactions, forming corrosion resistant structure of tight zinc-iron alloy layer. The alloy layer is integrated with pure zinc layer and steel tube matrix, so it has strong corrosion resistance.
Cold galvanized pipe is electric galvanized, galvanized amount is very little, 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 galvanized (cold plating). Only those small enterprises with obsolete equipment use electrogalvanizing, of course, their price is relatively cheaper. The Ministry of Construction has officially below, the elimination of cold galvanized pipe technology behind, not allowed to use cold galvanized pipe for water, gas pipe. The galvanized layer of cold galvanized steel pipe is an electric coating, and the zinc layer is independently layered with the steel pipe matrix. The zinc layer is thin, and the zinc layer is simply attached to the steel tube matrix and easy to fall off. Therefore, its corrosion resistance is poor. In new residential buildings, it is forbidden to use cold galvanized steel pipes as water supply pipes.
The weight coefficient of Nominal wall thickness (mm) : 2.0, 2.5, 2.8, 3.2, 3.5, 3.8, 4.0, 4.5.
Coefficient parameters (c) : 1.064, 1.051, 1.045, 1.040, 1.036, 1.034, 1.032, 1.028.
Note: THE MECHANICAL PROPERTY OF STEEL IS AN IMPORTANT INDEX TO ENSURE THE FINAL SERVICE PERFORMANCE (MECHANICAL PROPERTY) OF STEEL, which DEPENDS on the CHEMICAL composition and heat treatment system of steel. In the steel pipe standard, according to the different use requirements, stipulate the tensile properties (tensile strength, yield strength or yield point, elongation) and hardness, toughness index, as well as user requirements of high and low temperature performance.
Steel grade: Q215A; Q215B; Q235A; Q235B.
Test pressure /Mpa: D10.2-168.3mm is 3Mpa; D177.8-323.9 mm to 5 mpa
The current national standard
National standard and size standard for galvanized pipe
GB/T3091-2015 Welded steel tubes for low-pressure fluid delivery
Straight seam electric welded steel pipe
GB/T21835-2008 welded steel pipe dimensions and weight per unit length
