Steel by the sea: galvanising or is paint enough?

A railing facing the sea in Alanya and one a few kilometres inland in the same district do not last the same. The difference is not in the steel but in the salt in the air.

What a corrosivity category means

ISO 9223 sorts environments by how aggressively they attack steel. Rural and inland areas usually sit in C2–C3. Coastal settlements reach C4, and lines within reach of sea spray go as far as C5-M. The higher the category, the shorter the life of the same coating.

In practice: a treatment that gives ten trouble-free years inland can start showing rust within a few years on the shoreline.

Hot-dip galvanising

In hot-dip galvanising the steel is immersed in molten zinc and a metallurgically bonded zinc layer forms on the surface. The difference from paint is this: even at a scratch or a cut, zinc keeps protecting the exposed steel cathodically. Coating weight is typically around 400 g/m² on pipe and 275 g/m² on sheet and sections.

When paint is enough

In enclosed spaces, heated interiors and places where humidity is controlled, a properly prepared paint system is enough. What decides the outcome is surface preparation rather than the paint itself; the best paint over a greasy or rusted surface will not hold.

If paint alone is used outdoors, a maintenance schedule is part of the job. Where no maintenance is planned, galvanising is cheaper from the start.

On the coast the question is not "what does it cost now" but "which one is still standing in five years".

After welding and cutting

Cutting or welding galvanised material destroys the zinc layer at that spot. Those areas need a zinc-rich repair coating; skip it and corrosion starts exactly there. This is the most common mistake on site.

Practical choices on the coast

External railings, pergolas, canopies, greenhouses and perimeter fencing: galvanised section. Roof and wall cladding: galvanised or pre-painted galvanised sheet. Structural frames in enclosed spaces: black section with a suitable paint system.

Our Alanya warehouse stocks black and galvanised pipe and box section side by side. Tell us where the structure will stand and in what conditions, and we can work out which is right for that job.