Gain a thorough understanding of the practical techniques for surface galvanizing treatment of ductile iron pipe fittings

As the main connecting pipe fittings in waterway pipelines, malleable iron pipe fittings are frequently in contact with water and air during use, and thus have very high

requirements for corrosion resistance. To enhance the anti-rust ability of the product, the surface of ductile iron pipe fittings is usually galvanized. At present, the common

galvanizing methods are divided into hot-dip galvanizing and cold galvanizing. The following will provide a brief summary of these two methods.

From the appearance, the galvanized layer of cold galvanizing is uniform, and the surface is close to the blank, with the unique surface concavity and convexity of blank

products, looking smooth and bright. Due to the electrical shielding phenomenon, the cold-galvanized parts generally do not have a galvanized layer (except for special

galvanizing processes). However, the hot-dip galvanized coating is applied later, and the fluidity of the zinc liquid is poor. The zinc layer on the surface of the hot-dip

galvanized pipe is relatively thick. Moreover, the surface of the hot-dip galvanized coating will oxidize to form a white protective layer, which is generally darker in color

and has a much lower surface finish than cold-galvanized products.

Some manufacturers spray a layer of silver powder paint on the surface of ungalvanized black parts and then sell them as galvanized McKema steel pipe fittings.

The method of identification is also very simple. When two pipe fittings collide with each other, the silver powder paint on the surface of the pipe fittings will peel off. In

addition, in terms of color, if the silver powder paint pipe fittings do not peel off, the paint layer is very bright, while cold galvanized pipe fittings are both dark and bright,

and generally have no galvanized layer inside, while hot-dip galvanized pipe fittings will turn dark gray after a period of time from the factory.

The galvanizing process of ductile iron pipe fittings is a method of immersing the pipe fittings in molten zinc liquid, also known as hot-dip galvanizing. This process needs to follow some principles, including good coverage, dense coating and no organic inclusions.