As part of the fabrication process followed by heavy steel fabrication companies, applying a correct finish to the end product is a necessary step. Finishing ensures that products like structural steel I-beams, columns or channels have a visually aesthetic appearance while improving the durability and weather resistance of the metal by reducing the risk of rust developing on the surface. The two most common steel finishes are powder coating and galvanizing. Multiple factors are involved in the decision to have steel sections galvanized or powder coated, including the intended use of the steel fabrication product. This blog will outline the advantages and disadvantages of these two finishing techniques.
Definitions of Powder Coating and Galvanizing
Powder coating is a dry process which requires an electrostatic charge in the metal to allow the powder to bind to the surface of the metal. The metal then undergoes a heat induction process; the heat enables the powder to complete the binding process, forming a protective layer to shield the steel from the elements. Galvanizing is a process in which the steel is submerged in a bath of molten zinc. The zinc creates a thick layer around the steel, preventing corrosion such as rust from damaging the product’s structural integrity.
Benefits and Drawbacks
Galvanizing and powder coating are two very distinct processes. However, both are great at protecting the structural steel beams and columns from succumbing to corrosion. A key difference between these two is that while galvanizing alone can only provide a metallic silver finish, powder coatings come in a variety of stock colours. Differences based on a few other metrics are detailed as follows: –
- Initial Cost – The upfront price of galvanizing steel is, on average, higher than that of powder coating. However, the cost of galvanizing has been steadily decreasing, as technological improvements have made the galvanizing process easier and more cost-effective.
- Ongoing Maintenance Cost – Whilst the initial cost of powder coating may be lower, it is unlikely to match the 80+ years that galvanized steel regularly lasts, lasting only 20 years on average. The shorter lifespan of a powder coated structural steel section means it’s going to need more frequent and thorough maintenance, which can significantly increase the ongoing costs compared to galvanized steel.
Both of these processes create an extremely durable steel beam that can take a heavy amount of use and wear in all settings, including large-scale industrial use. However, a powder finish is prone to chipping and cracking if not given due care and attention during the steel fabrication process, leaving the underlying steel exposed to the moisture in the environment, eventually leading to rust. Galvanization, however, creates a thick zinc coating around the steel, protecting it through some of the toughest wear you can throw at it. You won’t have to worry about chips or cracks damaging the protective layer with galvanized steel.
The environmental impact of powder coating on a steel product is low because a dry powder is used, containing no solvents. Dry powder coating emits zero or negligible amounts of volatile organic compounds (VOCs). VOCs are harmful to both the environment and human health and are against the current trend of sustainability in steel manufacturing. There is little to no environmental impact when it comes to galvanization; this is because the zinc used in the coating is a reusable material. Additionally, because there is very little waste involved, any solution that falls off the steel remains in the bath to coat the next product.
It can be observed that powder coating and galvanizing have their pros and cons. While galvanization is more resistant to corrosion over time, powder coating provides a superior texture and finish. It is also possible to powder coat on top of already galvanized steel, providing exceptional protection against both the environment and wear. Thus, while a steel fabrication job can be expertly performed, the finishing touch is important – and these approaches help in finishing up in style!