Steel remains the backbone of South Africa’s national infrastructure, including HVAC&R, yet its susceptibility to corrosion poses a severe threat to longevity and safety.
Critical electrical infrastructure on the coast must have zinc-galvanised parts to last for 30 years. Supplied by IZA
HVAC systems, especially those installed in industrial or coastal environments, face similar risks. Zinc-coated components in HVAC units – such as ducting, condenser housings and support structures – help prevent premature corrosion caused by moisture, salt-laden air and chemical pollutants.
According to Simon Norton, director of the International Zinc Association (IZA) Africa, zinc is the most effective and reliable solution. “Steel’s vulnerability to corrosion is a significant challenge, especially in environments with high humidity, sea salt, and variable air temperatures. Zinc provides an exceptional and indispensable form of protection, ensuring the durability and safety of infrastructure for decades.”
Zinc’s unique effectiveness lies in its dual protective action. Applied as a coating, it provides a physical barrier between steel and corrosive environments. More importantly, as a more electrochemically active metal, zinc acts as a sacrificial anode, corroding in preference to the steel substrate.
“Even when a zinc coating is scratched or damaged, the exposed steel remains protected by zinc’s sacrificial behaviour. This property sets zinc apart from all other corrosion protection methods,” explains Norton.
The most widely used process is hot-dip galvanising, where steel is immersed in molten zinc. This produces a metallurgical bond that forms multiple alloy layers, harder than the base steel itself. The result is outstanding durability, abrasion resistance, and decades-long performance even under severe conditions.
South Africa’s coastal rail networks are among the most vulnerable assets due to constant exposure to salt-laden air. Chloride ions accelerate rusting of steel tracks, fasteners, signalling equipment and bridges.
“Failure of these components can result in derailments, service disruptions, and prohibitive maintenance costs. “Hot-dip galvanised coatings on rail fasteners, signalling poles, overhead line structures, and bridge elements ensure that these critical assets withstand the relentless marine environment,” notes Norton.
Additional protective measures include inorganic zinc-rich paints and zinc thermal spray coatings, depending on design requirements. Power pylons, which form the backbone of the electrical grid, are continuously exposed to harsh weather and industrial pollutants. In coastal and industrial regions, corrosion risk is especially acute.
“Galvanised coatings are the first line of defence for pylons. The self-sacrificing galvanic protection of zinc ensures that even minor abrasions or surface cuts do not compromise structural integrity. This protection is essential in preventing failures that could trigger widespread power outages,” says Norton.
Exposed steel in buildings, pedestrian bridges, and transport hubs faces equally serious challenges. Without adequate protection, corrosion reduces load-bearing capacity and compromises entire structures.
“Hot-dip galvanising of beams, columns and fasteners provides exceptional durability in all environments, from the fog-bound West Coast of South Africa to humid coastal cities like Durban. “It minimises the need for repainting or maintenance and provides substantial whole-life cost savings,” says Norton.
This includes HVAC systems in public, commercial and industrial buildings – where galvanised components contribute to long-term performance, lower operating costs and safer indoor environments. “By extending the service life of steel, zinc reduces maintenance, improves safety, and ensures reliability across critical infrastructure systems. For South Africa’s coastal cities and towns, the adoption of hot-dip galvanised steel and galvanised rebar is essential to building infrastructure that endures for generations,” concludes Norton.
Source: Supplied by IZA, edited by Eamonn Ryan
