Hot dipped galvanized steel pipe is in manufacturing process using steel pipes of removed rust dipped into zinc liquid of 500℃ temperatures, and making steel surface attached zinc layer so as to achieve the purpose of anti-corrosion.
Hot galvanizing is a kind of effective anti-corrosive treatment, used in kinds of steel structural products. Since 1836 France used hot galvanizing in industry the first time, it have been more than 180 years. However following by the development of cold rolled steel, it has greatly developed in recent decades. With the high-voltage transmission, transportation, communications, the protection products require higher standards, hot galvanizing demand is also increasing.
The processing of hot galvanizing:
Finished pickling – washing – plating – drying – hanging plating – cooling – medicine – cleaning – grinding – hot galvanized finish.
Zinc thickness for hot galvanized steel pipe
Hot galvanized steel pipe zinc layer thickness is 35μm, and the most thick is up 650μm. Instead cold zinc layer thickness is only 5-15μm. Zinc layer have the effects of anti air corrosion and electric chemical protection.
The theory of hot galvanized steel pipe’s zinc layer effect to anti corrosion
In the processing of hot galvanizing, it will formed a film of zinc-steel alloy layer first, above it is pure zinc layer. When the air corroded the zinc layer, it will form a layer of ZnO, Zn(OH)2 and basic zinc carbonate protection film. Which have the effect of anti air corrosion. When this film was destroyed, a new one will form. When the zinc layer destroyed heavily, zinc start up electric chemical protection. Zinc as the first element dissolved. It’s obviously that hot galvanized steel have better anti corrosive performances than cold galvanizing pipe.
How long of hot galvanized steel pipe lifetime?
Galvanized steel pipe have long lifetime. But in different conditions the lifetime of use are different. Generally speaking, 13 years in heavy industrial district, 50 years for ocean environment, 104 years in suburbs, 30 years in city. In fact galvanizing have played a role of anti- rusty, it is no need other rust treatment.
Hot galvanizing process specially suitable for kinds of strong-acid, alkali fog and other strong corrosive conditions. This kinds of fastener used a lot in outside of steel tower contribution.
