1. Understanding the Corrosion Environment
Chlorine reacts with humidity in the pool hall to form chlorides that attack steel surfaces continuously, especially in the condensation zone above the water. The corrosion rate is highest where the metal is wet, hot and poorly ventilated, such as in roof cavities and behind cladding. The designer must assume that the steel will be exposed to aggressive moisture for the life of the building.
2. Coating Systems and Surface Preparation
H-beams in pool halls require a high-performance coating system: blast cleaning to Sa 2.5, a zinc-rich primer, and a topcoat that resists chlorides and UV. Edges, bolt heads and weld toes receive extra coats because corrosion starts at these points. The coating specification should be written for pool-hall service, not ordinary building paint.
3. Detailing to Avoid Traps
Design details that trap water, such as horizontal flanges facing up, flat pockets and unsealed laps, are avoided or detailed with drainage. Stiffeners and gussets are shaped so water runs off, and box sections are sealed or ventilated to prevent internal condensation. Connections are kept accessible so that coating can be inspected and repaired without dismantling the structure.
4. Steel Grade and Thickness
Structural H-beams are normally specified in S275JR or S355JR, and the section thickness is chosen with a corrosion allowance where full recoating is not practical. Thicker flanges and webs extend the time before section loss becomes critical. For critical members, galvanizing plus a topcoat provides a second line of defence under the coating.
5. Ventilation, Inspection and Maintenance
Mechanical ventilation that removes humid air and limits condensation is part of the design, because dry steel corrodes far more slowly. Walkways and access platforms give inspectors a safe route to examine the roof steel every year. The maintenance plan should schedule washing, spot repairs and full recoating before the corrosion reaches the steel surface.