The Steel Journey: Galvanisation

Economical, Sustainable, Maintenance-Free:

Rank Engineering recommend galvanisation on metal fabrication if rusting is deemed to be potentially problematic on exterior installations. Hot dip galvanizing is economical, environmentally sustainable and is an integral part of the steel manufacturing process.  It gives a bright, shiny, ‘spangled’ (crystallised pattern), metallic effect.  It is formed from the metallurgical reaction between iron and zinc, creating a series of zinc-iron alloy layers.  Galvanisation is a robust, maintenance-free, surface application with good impact and abrasion resistance.

Rust Prevention on Exterior Metal Fabrication:

Galvanisation is used predominantly on exterior, metal fabrication installations to prevent rusting.  The process involves covering iron or steel with a protective layer of zinc. This serves as a sacrificial anode; a self-repairing barrier.  It also prevents corrosive substances from reaching the underlying base metal when the surface is damaged.  Metal fabrications can then be powder coated in any colour, post galvanisation.  

Galvanisation Requirement Specification:

The thickness of galvanizing required can be specified at either 85 or 140 microns by the engineer.  This can be adapted to the longevity needed for different projects, in different environments. Coastal environments, for example, have a higher atmospheric corrosion rate.  Part numbers are also often identified on steel fabrications if required.  This is achieved by welding the number directly onto the steels, making them easier to identify, post galvanisation, for installation purposes.

Galvanisation Method:

Metal fabrications, identified as requiring galvanisation, are picked up by one of our specialist subcontractors, from our workshop and transported to the galvanizing yard. 

They are then dipped in a large bath of acid, in a process called pickling. This subsequently cleans off any contaminants from the surface of the metal.  

The metal components are then submerged in a large bath of molten zinc for a set period of time, to allow their temperature to optimally increase as required. 

In order to achieve the optimum zinc coating and to ensure that, the liquid zinc can flow freely over all of the external and internal surfaces, venting and drainage holes, where there are sealed hollow sections or cavities, are essential! 

The iron or steel fabrications are then removed from the bath, allowed to cool down, loaded back onto the lorry and transported back to us. 

Rapid Process on Metal Fabrications:

This whole process sometimes only takes 24 hours.  Therefore, at Rank Engineering we do recommend not to avoid galvanizing due to time constraints, if rusting is deemed as potentially problematic, due to the location of the installation.  It doesn’t take as long as you think it does and the benefits in the long run can prevent from atmospheric, sulphur dioxide corrosion for over 85 years!