Appearance:
The appearance of hot-dip galvanized square tubes is slightly rougher than that of cold-dip galvanized square tubes; the appearance of cold-dip galvanized square tubes is relatively smooth and bright.

Zinc layer thickness:
There is a big difference between cold-dip galvanized square tubes and hot-dip galvanized square tubes in the galvanizing process; the corners of cold-dip galvanized square tubes are prone to "electrical burning". The color of this part is dark and the zinc layer is thicker. It is easy to form a current dead angle in the inner corner to produce an undercurrent area. The zinc layer in this area is thinner, and there is no zinc layer attached to the inner wall of the cold-dip galvanized square tube.
The cold-dip galvanized square tube has no zinc nodules, agglomerations, etc. as a whole, but the overall zinc layer is thinner, and the thickness of the outer wall zinc layer is 5μm-10μm.
The inner and outer walls of the hot-dip galvanized square tube are both attached with zinc layers, there will be water marks and a few zinc nodules, but the overall zinc layer is thicker, and the thickness of the zinc layer on the inner and outer walls of the square tube is more than 70μm.

Color:
Cold-dip galvanized square tubes are yellowish-green, bluish-white, or slightly colorful at a certain angle to the sun. Hot-dip galvanized square tubes are silvery white at a certain angle to the sun.

1. The dimensions of stainless steel pipes refer to the size of the pipe diameter, which is generally expressed in millimeters (mm) or inches. In the stainless steel pipe market, common specifications are 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 32mm, etc. There are also some non-standard sizes of pipes that can be customized according to needs.
2. The wall thickness of stainless steel pipes refers to the thickness of the pipe, which is generally expressed in millimeters or inches. In the production of stainless steel pipes, common specifications are 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, etc. There are also some non-standard thickness pipes.
3. The length of stainless steel pipes is generally expressed in meters (m), and common specifications are 3m, 6m, 9m, etc. The length can also be customized according to customer needs.

The standard range of zinc layer thickness of hot-dip galvanized steel grating varies depending on different countries, regions, specific application areas, and steel grating thickness. The following are some common standards:

International Standards: According to ISO 1461 of the International Organization for Standardization (ISO), the zinc layer thickness of hot-dip galvanized steel grating should be between 65μm and 85μm.

European Standards: The European EN ISO 1461 standard stipulates that the zinc layer thickness of hot-dip galvanized steel grating should be between 45μm and 85μm.

US Standards: The US ASTM A123/A123M standard requires that the zinc layer thickness of hot-dip galvanized steel grating should be between 3.9mil and 5.9mil, equivalent to about 100μm to 150μm.

Hot-dip galvanizing is a chemical treatment that melts zinc ingots at high temperatures, with good adhesion and high zinc content. The amount of zinc on the galvanized steel grating directly affects the service life of the steel grating.
1. When the thickness of the steel grating is between 1.5-3mm, the average zinc thickness on the hot-dip galvanized steel grating should be greater than 55μm, and the local thickness should be greater than 45μm.
2. When the thickness of the steel grating is between 3-6mm, the average zinc thickness on the hot-dip galvanized steel grating should be greater than 70μm, and the local thickness should be greater than 55μm.
3. When the thickness of the steel grating is equal to or greater than 6mm, the average zinc thickness on the hot-dip galvanized steel grating should be greater than 85μm, and the local thickness should be greater than 70μm.