Batch Galvanised Steel vs Pre-galvanised Steel

Batch Galvanised Steel vs Pre-galvanised Steel

Galvanising is a broad term that is generally used to describe any metal that has been coated in zinc. However, there are several different methods used to apply a zinc coating. In terms of Hot Dip Galvanising, where the galvanised h channel steel posts are dipped in molten zinc, there are two different variations known as Batch Galvanising and Pre-Galvanising.

Batch Hot Dip Galvanisation

Batch galvanised steel posts are created by dipping steel posts in molten zinc after they have already been fabricated. Prior to galvanisation, the posts must be rigorously cleaned in a painstaking procedure known as Surface Preparation.

This cleaning process involves 3 steps- degreasing, pickling and fluxing the posts. Degreasing removes impurities, pickling removes traces of iron oxide, and fluxing removes leftover oxides. If the post is not prepared properly, it will not be galvanised effectively because zinc does not react where impurities are present.

When the surface preparation has concluded, the steel post is dipped in a zinc bath, which coats the entirety of the post.

Advantages of Hot Dipped Galvanised H Channel Steel Posts

Hot dipped galvanised steel posts have a number of advantages. Because the entirety of the steel posts are coated in zinc, they have reinforced corrosion protection. This means that they are impervious to harsh weather conditions. Along with this, the zinc coating on galvanised steel posts is often thicker in the edges and welds, giving more durability to the weakest points of the posts.

Pre-galvanised Steel

Pre-galvanised metals are produced by galvanising the steel when it is still in sheet format. This is done by an automated process. The sheet is unrolled and then enters a reducing atmosphere before being dipped in a bath of molten zinc. On removal from the bath, a mechanical wiper removes any excess zinc.

After galvanisation, the sheet is cut to size and then recoiled. The sheet of steel will have an even, uniform thickness. Because of this, pre-galvanised steel is more aesthetically pleasing than hot-dipped steel.

Once the sheet has been galvanised, it is then manufactured into different products such as conduit and open channels. Pre-galvanised steel is not generally suitable to be fabricated into galvanised h channel steel posts, as it would not offer the same strength or reinforcement as hot dipped galvanised steel posts. This is because materials galvanised after fabrication have twice the coating thickness.

Factors That Weaken Galvanised H Channel Steel Posts

Placing galvanised h channel steel posts in direct contact with copper or brass in a humid environment will cause the zinc coating to corrode quickly due to a chemical reaction called bimetallic corrosion. In order to avoid this happening, the steel posts should be kept away from copper or brass.

Here at RW Steel, we stock a full range of galvanised h channel steel posts to suit every project and budget. Contact us here with any queries or click here for a free no-obligation quote.