FRP Grating Case Study | Cooling Tower & 110 kV Transformer Platform — ZeAllgrate
Power & Energy — Project Background
A 600 MW coal-fired power plant in East China required replacement access walkways inside its cooling tower (continuous high humidity, temperature cycling and water-treatment chemicals) and new non-conductive platforms around 110 kV transformers. Steel grating inside the cooling tower corroded within 3 years; around the transformers, steel created a step-and-touch voltage hazard during fault conditions, and plant electrical safety rules required a non-conductive walking surface with no metallic fasteners in the platform itself.
Two distinct material specifications were therefore needed: a cost-effective UV- and moisture-resistant isophthalic grade for the cooling tower, and a vinyl ester, fully FRP-fastened dielectric system for the transformer platforms. Client identity is kept confidential; the project is described as Confidential Client, a 600 MW coal-fired power producer.
Engineering Specification
Working values agreed with the client's engineering team during design review.
Cooling Tower Walkways
| Parameter | Selected Value | Standard / Reference |
|---|---|---|
| Pedestrian live load | 3.0 kN/m² | Plant design basis / EN 1991-1-1 |
| Clear span | 1.0 m | ZeAllgrate molded grating design guide |
| Deflection limit | L/150 | ZeAllgrate standard |
| Resin system | ZeAll ISO (isophthalic, UV-stabilized) | Humidity / water-treatment chemicals |
| Panel | 38 mm molded, concave surface | ZeAllgrate standard molded grating |
| Fixings | SS304 clips | ASTM A276 304 |
Transformer Platforms
| Parameter | Selected Value | Standard / Reference |
|---|---|---|
| Pedestrian live load | 3.5 kN/m² | Plant electrical safety basis |
| Clear span | 0.9 m | ZeAllgrate molded grating design guide |
| Deflection limit | L/150 | ZeAllgrate standard |
| Resin system | ZeAll VE (vinyl ester) | Dielectric + chemical resistance |
| Panel | 38 mm molded, grit-top | ZeAllgrate standard molded grating |
| Fixings | FRP (non-metallic) clips | Full electrical isolation |
| Dielectric strength | >10 kV/mm | ASTM D149 / plant spec |
What Was Supplied and How It Went In
ZeAllgrate supplied 380 m² of ZeAll ISO UV-stabilized molded grating for the cooling tower walkways, and 120 m² of ZeAll VE molded grating for the transformer platforms. The cooling-tower panels use SS304 hardware; the transformer platforms use all-FRP non-metallic fasteners so the walking surface remains fully dielectric — no metal clip bridges the insulation path.
The transformer platforms passed a dielectric proof test before energization at the plant's specified voltage, demonstrating dielectric strength above 10 kV/mm per ASTM D149. Because FRP does not conduct, the platforms require no grounding grid beneath them, simplifying design and reducing fault-current risk to maintenance staff.
FRP grating access walkway inside cooling tower
Non-conductive molded grating platform near high-voltage transformer
FRP structural profiles used for non-conductive support framing
Outcomes and Inspection Findings
At 4-year inspection, the cooling-tower walkways showed zero corrosion (steel walkways there previously lasted about 3 years). The transformer platforms have operated with no electrical incidents and no repair work. Plant maintenance reports that overall grating-related maintenance has fallen by roughly 80%.
- Cooling tower: zero corrosion at 4 years vs. ~3-year service life for the previous steel system.
- Transformer platforms: passed dielectric proof test; no step-and-touch incidents; no grounding grid required.
- Maintenance: ~80% reduction in walkway-related maintenance hours.
- Electrical safety: non-metallic fasteners preserve full isolation; grit-top surface provides safe footing for live-line adjacent work.
- Lifecycle: expected 25-year service life in both environments.
Engineering Notes
Cooling tower and transformer service is specified for the chlorinated water side, the UV exposure and the electrical duty: vinyl ester where panels sit in treated water, UV-stabilised resin for sun-exposed decks, and non-conductive construction on the transformer platforms where the grating carries no earthing burden. Grit-top handles the wet traffic; E84 class is confirmed for rated areas; and the lightweight panels install over existing steel with no hot work near live equipment.
What to Specify
- Vinyl ester for the treated-water side; UV-stabilised for exposed zones.
- Non-conductive grating on transformer and substation platforms.
- Grit-top on wet traffic surfaces.
- E84 class confirmed for rated areas.
- Vinyl ester for the treated-water side; UV-stabilised for exposed zones.
- Non-conductive grating on transformer and substation platforms.
- Grit-top on wet traffic surfaces.
- E84 class confirmed for rated areas.
Planning a Similar FRP Grating Project?
Send us your layout drawings, service chemicals and span requirements — ZeAllgrate will return a design proposal, load calculation and reference pricing within 48 hours.
- ZeAllgrate molded grating design guide, load and deflection tables.
- ASTM D149 — Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials.
- EN 1991-1-1 — Eurocode 1: actions on structures, imposed loads for walkways.
- IEEE / plant electrical safety guidance on step-and-touch voltage and non-conductive work platforms.
- Project inspection records supplied by Confidential Client; values quoted as-reported.