How to treat galvanized steel pipe affected by white rust

White rust is a post-galvanizing phenomenon. How to treat galvanized steel pipe affected by white rust lies in the manner it is packed, handled and stored prior to the galvanized product’s installation and use. The presence of white rust is not a reflection on the galvanized coating’s performance, but rather the responsibility of all those involved in the supply chain to ensure that the causes of white rust are recognized and the risks of its occurrence minimized on newly galvanized steel.

Hot dipped galvanized pipe has been considered popular a lot among many users today. For one thing, the galvanization process protects the steel from rusting damage that can occur during transportation, installation and service. The zinc layer on the surface of pipe can form a barrier protection for steel products to extend the service life in applications. For the other thing, this layer is also resistant to wear and scratches, which makes the steel look more attractive. Like many metals, the good corrosion properties of zinc are due to a thin film of corrosion product that forms on the surface of the metal. This tightly-adherent corrosion film is called a passivation layer. The formation of the passivation layer is essential to achieving long life with galvanized steel pipes in use. With newly galvanized steelwork, the zinc’s surface has been subjected to little oxidation and is at its most vulnerable. For this reason, a chromate passivation should be used in conjunction galvanizing operations to provide protection to the galvanized coating during the ‘youth’ period of the coating. This passivation coating provides short term protection to the zinc to give the stable oxides time to form on the surface.

How to avoid white rust formation of galvanized steel pipe used for structural steel pipe used in construction? There are a number of simple steps that can greatly reduce or eliminate the formation of white rust. These are:
•Keep the packed work dry
•Pack the items to permit air circulation between the surfaces
•Stack the packed items to allow water to drain out
•Treat the surface with proprietary water repellent or barrier coatings to prevent moisture contacting with galvanized surface

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