How to distinguish hot-dip galvanized and cold dip galvanized pipes
Hot dip galvanized pipes are widely applied in the field of curtain-walls, building and constructions, mechanical manufacture, solar energy bracket, steel structure, especially in curtain walls and constructions. While in the market, some of the sellers deceptively use cold galvanized instead to seek excessive profits. However the anticorrosion effect of the two types are far from each other. Then how to tell this two different pipes?
Below list a few methods telling you how to distinguish the two kind of galvanization pipes:
1. Tell from appearance. Cold dip galvanized pipes you can find that it’s surface is much more smooth and bright. But hot dip galvanized pipes are more tough from the appearance.
2. Tell from colors. When you are holding a cold dip galvanized pipe in the sunshine with a certain angle to the sun, this pipes will show kind of yellow greenish, bluish white or kind of colorful. On the contact, hot dip galvanized will only shows a silver white color.
3. zinc coating thickness. There is a big workmanship difference during galvanization. Cold galvanized pipes will easily get over-zinc on angle part where color is more gloom, zinc is much more thick. While in the internal corner area, due to electricity is not as adequate as balance parts, zinc thickness there is thinner. And inside wall of the cold dip galvanized pipes, there are no zinc coating. As a whole, cold dip galvanized pipes do not have zinc knot or lumps on the surface, but overall zinc coating thickness is thin, out-wall zinc coating is about 5um-10um. Hot dip galvanized pipes, there are zinc attached both inside and outside wall of the pipes. In the meantime there will have little zinc wave or knot, coating thickness is higher, both inside and outside zinc thickness is over 70um.
Above tips can be used to identify hot & cold dip galvanized angle steel, channel steel and other galvanized steel products.