Mechanical and electrical installation materials galvanized

What are the national standards for galvanizing in mechanical and electrical installation materials?

Galvanized metal surface as an important surface protection and anti-rust, anti-corrosion measures, is the most widely used and economic, effective means, we often meet in the construction of mechanical and electrical engineering materials and equipment. General thin steel plate, steel pipe (including water and gas steel pipe, seamless pipe, spiral pipe, JDG wire pipe, etc.), bridge materials usually need galvanized protection, galvanized requirements we make a simple comparison according to the provisions of national standards.

The main materials used in mechanical and electrical engineering are generally hot-dip galvanized.

Hot plating Process in which a zinc and zinc-iron alloy coating is formed on the surface of surface treated steel or cast iron by immersing it in a molten zinc solution at high temperature.

Cold plating, also known as electroplating, is the use of chemical displacement reaction, through chemical reaction will metal elements on the surface of the metal into zinc, the formation of coating, zinc layer thickness is generally not more than 10μm.

What is the difference between hot galvanizing and cold galvanizing?

Hot-dip galvanizing

Hot-dip galvanizing is generally thicker, more resistant to corrosion, and of better quality.

Second hot dip galvanized surface is dark, gray color, no luster

Cold galvanizing

Electrogalvanizing zinc layer is thin, adhesion is relatively poor, and rust prevention ability is not strong as hot dip galvanizing.

The surface of galvanizing is bright and the color is better than that of hot-dip galvanizing.

For galvanized steel plate (commonly used between 0.5 and 1.5mm thickness), mechanical and electrical engineering is mainly used to make ventilation and smoke prevention and exhaust air pipes, which are in great demand on site. They are all hot dip galvanized process. Galvanized has flowers and no flowers, this is only the difference in the process caused by the coating on the surface of the crystallization image is different, does not affect its performance.

In the GB/T2518-2008 galvanized steel plate national standard, there are clear provisions for galvanized layer, the minimum is not less than 80g/m2, marked as Z80 in the design drawings, some projects have higher requirements for corrosion resistance, will require 120g/m2, 275g/m2 or even 500g/m2.

In the specific field detection, we generally choose the coating thickness tester (iron based probe) to measure the thickness of the galvanized layer, the 80g refers to the sum of the zinc layer on both sides of the plate to 80g.

Galvanized thickness measurement, is generally each specification of plate pumping 3 pieces, in the galvanized steel plate area is not greater than 1cm2 on the front and back of each do 3 times galvanized thickness measurement, the average value of the measurement is local galvanized thickness, measured on the steel plate 5 times the average value of local galvanized thickness is its average galvanized thickness. The thickness measured by the coating thickness tester is µm, galvanized layer weight = thickness ×7.14. The thickness is measured in µm, and the resulting weight is measured in grams. In fact, 7.14 is the density of zinc.