Applying a hot dip galvanizing process to steelwork provides fabrications with a robust, durable and corrosion protective finish that lasts for many years without maintenance.
Galvanizing is the process of applying a protective zinc coating to prevent rusting. The most common method is hot-dip galvanizing, where the steel parts are submerged in a bath of molten zinc. Hot dip galvanization is a highly-specialized job therefore at Novelty Steel, unlike painting works, galvanization works are subcontracted to the specialized subcontractors.
Figure 1 : Steel Hot Dip Galvanization
Although it is a more expensive type of coating compared to 2 layer organic paint coating, hot dip galvanization offers the below great advantages;
A galvanized coating is one of the most durable forms of corrosion protection on the market. An average coating thickness of 85 microns, the same thickness as a sheet of A4 paper, can protect steel structures for more than 50 years.
The long-term durability provided by galvanizing is achieved at relatively low environmental burden in terms of energy and other globally relevant impacts.
Galvanizing is a relatively straightforward and closely controlled process. The coating formed is consistent, predictable and simply specified. Hot dip galvanizing is defined by a single standard – EN ISO 1461.
Unlike painting, the metallurgical bond that is formed through galvanizing becomes part of the steel itself and is not merely a chemical or mechanical bond.
Due to the metallurgical bond that is formed when steel is dipped into molten zinc, a galvanized coating offers straightforward, secure protection from the get-go. Hot dip galvanizing requires rust-free, uncontaminated steel for the process to occur. Once the coating is present, it is impossible for it to fail from underneath. Other coatings can adhere to residual contaminants, this can undermine performance, lead to flaking and cause premature failure.
A galvanized coating offers predictable corrosion protection that weathers in a linear fashion. Coating thicknesses are measurable and offer lifespans that can be easily forecast and relied upon.
Batch hot dip galvanizing is a standardized process which produces a quantifiable coating thickness. The coating is simply specified through European and international standards.
The coating thickness depends upon the gauge of the steel that is galvanized and is produced consistently across the component, both inside and out. This can be measured easily throughout its lifetime, using non-destructive methods.
Figure 2 : Galvanization Coating Thicknesses
There are multiple reasons why hot dip galvanizing outperforms other organic coatings. A crucial factor is the way the process achieves complete coverage of a component, both inside and out.
The dipping of steel into a tank of molten zinc via the hot dip galvanizing process means the zinc can access even the trickiest areas.
A further benefit of hot dip galvanizing is that hollow components are coated on internal surfaces too, meaning that a structure will not corrode from the inside out. In addition, the coating will also build up at vital corners and edges, unlike brushed or sprayed coatings, which traditionally thin out in these areas.
7. Abrasion Resistance
Galvanizing has an abrasion resistance up to ten times better than organic paint coatings. The hot dip process is unique, producing a coating which is bonded chemically to the steel. As a result, galvanized steel has superior resistance to mechanical damage during handling, storage, transport and erection.
Along with paint coatings, Novelty Steel offers hot dip galvanization finish to its metal fabrications. It is essential to know whether products are going to be galvanised right in the beginning of the design phase in order to customise the part design for the hot dip galvanization.