Common problem
Steel rusts in sea air and humidity; concrete is eaten by acids, sulfates and the gases in wastewater. What protects it is chosen by the chemical it touches — so we start by finding what is attacking it.
| What you see / where | Why it happens | How to tell |
|---|---|---|
| Rust on steel (outdoors, by the sea) | Salt and moisture speed up rusting; hot, humid and coastal sites are among the harshest environments. | Red rust, worn coating |
| Blistered or peeling coating, rust under the film | Salt, dust or rust left on the steel before painting draws in water and lifts the film; rust spreads from where it breaks. | Blisters, flaking, rust beneath the coating |
| Tank bottoms | They corrode from both sides: inside, where bottom water and sludge sit, and underneath, where it cannot be seen. | Deep pits and rust nodules, found when the tank is emptied, cleaned and inspected |
| Splash zones and wet-dry areas | Areas that are wetted and dried again and again are among the most severe. | Steel thins locally; concrete cracks and spalls |
| Concrete attacked by acids and sulfates | Acids dissolve the cement; sulfates form minerals that swell and crack the concrete. | A soft surface, exposed aggregate, cracks and spalls |
| Wastewater tanks and manholes above the water line | Hydrogen sulfide from the wastewater turns into sulfuric acid on the damp walls and eats the concrete; heat speeds it up. | Walls and soffits above the water are soft, with aggregate showing |
| Chemical spills on floors and in bunds | Concrete is porous and lets chemicals in; once the protective layer breaks, damage starts there. | Softening, peeling, cracked protective layer |
Rust, blisters, peeling and soft concrete are mapped by amount and location.
Which chemical, at what concentration and temperature — the protective system is chosen from this.
Coating thickness, adhesion, pinholes, salt on the steel and the soundness of the concrete surface. Salt on steel cannot be seen; it is found only by measuring.
These are examples of how leaks are traced. We choose the checks to suit the site.
These are the possible repairs. Which one fits is decided after we see the roof.
| Repair | When it fits | Keep in mind |
|---|---|---|
| Spot repair | The damage is limited to a few places. | If the surface is not prepared properly, damage starts again around the repair. |
| Blast and recoat the steelProtective lining Details → | Rust and coating breakdown have spread across the steel. | Left-over salt, condensation or a poor blast profile make the new coating fail early. |
| Rebuild damaged concrete, then protect itConcrete patching Details → | Chemicals have softened or eaten into the concrete. | Damaged layers left in place make the coating above come away. |
| Chemical-resistant coating (epoxy, novolac, polyurea)Protective lining Details →Polyurea Details → | Tanks, bunds and floors exposed to chemicals, chosen for the chemical it touches. | No single coating suits every chemical; it is chosen by the chemical, concentration and temperature. Aromatic polyurea fades in the sun, so exposed areas get a UV-resistant top coat. |
| FRP lining (resin + glass fibre)Protective lining Details → | The most severe service, mainly strong acids. Resin and glass are chosen from the maker's chemical-resistance chart. | It needs a dry, sound substrate and time with the tank or area out of service. |
This is one example. We decide the actual work after seeing the roof.
The area, the surface preparation (blasting, concrete repair), the chemical and its temperature, the system and number of coats, how long it can be out of service, and the safety measures for confined spaces. Send the chemical, drawings and photos on LINE.
By the chemical it touches, its concentration and temperature; no single coating suits every chemical. Many cases are covered by coatings without fibre, and the most severe service takes an FRP lining, often with vinylester resin. The resin is chosen from the maker's chemical-resistance chart.
The surface must stay well above the dew point, and coating stops when the humidity is too high. Blasted steel can also be kept dry so it does not flash-rust before coating.
Send the chemical and its temperature, photos of the damage and where it is. We check the site and propose the protection that fits.
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