Fire protection of steel structures works only when the coating is intact and has the required thickness over the entire surface. In practice the coating gets damaged far more often than it seems: installation work on site continues for months after painting. Here is how to tell whether a local repair is enough or the coating has to be removed completely.
Where the damage comes from
- Installation work after painting. Welding on brackets, cutting, drilling, fixing building services — around every such spot the coating burns off or chips away.
- Mechanical impacts. Machinery, lifts, moving equipment — the lower parts of columns and the edges of beams suffer most often.
- Moisture. Roof leaks and condensation are especially dangerous for products designed for dry interiors: the layer swells and loses adhesion.
- Conditions the coating is not designed for. An interior-grade product left exposed to sun and precipitation, or no topcoat where one is needed.
Where a repair starts: the survey
Before defining the scope of work, we find out three things:
- Which material was applied. We review the as-built documentation and product certificates. The repair compound must be compatible with the existing one — otherwise the new layer will not hold or the coating will lose its properties.
- How much thickness is left. We go over the whole area evenly with a thickness gauge, element by element — this shows where the layer has dropped below the design thickness.
- How well the coating adheres. We check adhesion to the substrate and look for rust under the layer at the edges of the damage.
When a local repair is enough
- the damage is localised: weld spots, chips, scratches;
- around the damage the coating holds firmly and there is no corrosion beneath it;
- it is known which product was applied, and a compatible material is available for the repair.
In this case we clean the damaged spot back to a sound edge, level the edge, restore the anti-corrosion primer and apply the fire protection compound to the design thickness, overlapping the old layer, followed by the topcoat if one is specified.
When the coating is stripped back to metal
- the layer is peeling off over large areas or has blistered from moisture;
- corrosion is developing under the coating;
- the material is unknown and there is no documentation — compatibility cannot be checked;
- the thickness is below the design value over large areas, and the product does not allow building up on top.
The surface is then cleaned back to bare metal, usually by abrasive blasting, and the fire protection is applied again following the full procedure.
How a repaired area is accepted
After the repair we measure the thickness at the restored spots, draw up a report and add the repaired areas to the as-built documentation. This matters during inspections: the restored coating must be backed by documents just like the original one.
Need the fire protection surveyed at an operating facility? DQS provides repair of fire protection coatings throughout Uzbekistan. Call +998 90 978 10 00 or write to contact@dqs.uz.
