Cooling Tower FRP Grating — Maintenance & Replacement

Inside a cooling tower, FRP pultruded grating is the internal walkway and support deck — and one of the few materials that survives constant warm moisture, drift, UV at the air intakes and biocides. Galvanized steel in the same service corrodes within a season. But "corrosion-proof" is not "no maintenance": drift deposition, biological growth and thermal cycling still need a planned inspection and replacement programme. This article sets out that programme.

1. Why Cooling-Tower Service Is Harsh

Cooling towers combine warm humid air, water drift, chlorine or bromine biocide, ozone in some systems, and UV at exposed intakes. The FRP deck sees all of it, plus periodic shutdown cleaning. Isophthalic (ZeAll ISO) with UV stabilizer and SS316 hardware is the standard grade; the grating itself lasts decades, but the hardware and surface finish are the wear items.

2. Inspection Programme (indicative)

3. Cleaning and Biocide Compatibility

During a scheduled outage, wash the deck with water and mild detergent at ≤100 bar (see cleaning and disinfection). Routine chlorine/bromine drift is compatible with ZeAll ISO and VE; avoid strong solvents and concentrated biocides left in contact. Remove slime and algae before it builds into a slippery layer — a grit-top deck still skids when coated in biofilm.

4. When to Replace a Panel

Replace a panel when any of the following appears:

• Audible delamination on tap-test (hollow, drummy note) at a load-carrying bar.
• Through-thickness cracking or a severed bearing bar.
• Surface veil loss that exposes glass over a walking area.
• Chloride-pitted or broken SS316 hardware that can no longer locate the panel.

Because cooling-tower access is difficult and outages are short, keep spare panels of each configuration on site — a panel ordered during an outage is a schedule risk. See cooling-tower service context.

5. Hardware: The Most Common Failure

The grating outlasts the clips. SS316 is specified precisely because SS304 and galvanized hardware pit in chloride-laden drift; if a previous maintenance crew installed galvanized clips, they will fail within a season and look like a "FRP problem" when they are a hardware problem. Re-torque at 6 months then annually (per fastener torque standards), and always upgrade to SS316 on replacement.

6. Replacement Plan

Order spare panels at installation, cut to the same mesh and resin, banded identically. At the next outage, swap panels one support bay at a time, keep the deck walkable, and record the new clip torque. ZeAllgrate supplies cooling-tower-grade ZeAll ISO pultruded grating with SS316 clips and an inspection checklist; send tower dimensions, biocide regime and outage window for a spares and replacement plan.

7. Drift, Biofilm and the Hidden Wear Item

Cooling-tower grating wears in ways that never appear on a steel inspection sheet. Drift — the fine water droplets carried out with the exhaust — deposits a film across the walking surface that, combined with warm air and nutrients, grows biofilm even on grit-top. A grittened deck coated in slime has the wet COF of a wet oily plate, regardless of how good the grit is. So the maintenance programme is not only structural: during each scheduled outage, scrub or pressure-wash the walking surface to remove the film, and check that the drift-eliminators above are actually doing their job — a tower with poor drift removal keeps wetting the deck and accelerates every other failure. The second hidden wear item is the hardware: SS316 clips survive, but galvanized or SS304 clips installed by an earlier maintenance crew pit within a season and look like a "FRP problem" until the clip is examined. Upgrade every replaced clip to SS316, re-torque at six months, and keep a spares set sized to the tower so a half-day outage does not become a three-week part wait.

Bottom line: cooling-tower FRP is corrosion-proof but not maintenance-free. Schedule a drift-and-biofilm wash each outage, upgrade every clip to SS316, re-torque at six months, and keep a spares set sized to the tower. The panel outlasts the hardware and the biofilm programme — plan for both.

Related reading: the structural detail behind a cooling-tower deck is in connection design details, and the broader power-plant context in the cooling-tower industry page.