Galvanized square pipes are divided into hot-dip galvanized square pipes and cold-dip galvanized square pipes from the production process. It is precisely because the processing of these two galvanized square tubes is different that they have many different physical and chemical properties. In general, they have many differences in strength, toughness and mechanical properties.
Hot-dip galvanized square tube: It is a square tube made of steel plate or steel strip crimped and welded. On the basis of this kind of square tube, the square tube is placed in a hot-dip galvanizing bath after a series of chemical reactions. A square tube formed. The production process of hot-dip galvanized square tube is relatively simple, and the production efficiency is very high, and there are many varieties and specifications. This kind of square tube requires very little equipment and funds, and is suitable for the production of small galvanized square tube manufacturers. But in terms of strength, the strength of this steel pipe is much lower than that of seamless square pipes.
The cold galvanized square tube uses the principle of cold galvanizing on the square tube used to make the square tube have anti-corrosion performance. Different from hot-dip galvanizing, cold-dip galvanizing paint mainly uses electrochemical principles to prevent corrosion. Therefore, it is necessary to ensure that the zinc powder and the steel are in full contact to produce electrode potential differences, so the surface treatment of the steel is very important.
The difference between hot and cold galvanizing
Galvanized square pipes are divided into two categories: hot-dip galvanized square pipes and electro-galvanized square pipes. Hot-dip galvanized square pipes include wet method, dry method, lead-zinc method, redox method and so on. The main difference between different hot-dip galvanizing methods is what method is used to activate the surface of the pipe body to improve the quality of galvanizing after the acid immersion cleaning of the steel pipe. Dry method and oxidation-reduction method are mainly used in production, and their characteristics are shown in the table. The surface of the electro-galvanized zinc layer is very smooth and compact, with uniform structure; it has good mechanical properties and corrosion resistance; the zinc consumption is 60% to 75% lower than that of hot-dip galvanizing. Electro-galvanizing has certain technical complexity, but this method must be used for single-sided plating, double-sided plating with different inner and outer surface plating thicknesses, and thin-walled pipe galvanizing.
Calculation of theoretical weight per meter of galvanized square pipe
4 * Thickness * (side length-thickness) * 0.00785
Among them, the side length and wall thickness are in millimeters (mm), and the values are directly substituted into the above formula, and the result is the weight of the square tube per meter, in kilograms.
For a square tube of 30 x 30 x 2.5 mm, the weight per meter can be calculated according to the above formula: 4 x 2.5 x (30-2.5) x 7.85=275 x 7.85=2158.75 grams, which is about 2.16 kg.
When the wall thickness and side length are both in millimeters, 4x wall thickness x (side length-wall thickness) is calculated as the volume of a square tube per meter length, in cubic centimeters (cm3), multiplied by the specific gravity of iron 7.85 grams per cubic centimeter, which is the weight of each square tube per meter in kilograms