Loose cover sheets blown off by heavy winds

What happened?

An area operator was doing routine surveillance of cooling towers.
They discovered broken polyvinyl chloride (PVC)/fibre-reinforced plastic (FRP) cable tray cover sheets had become detached from the top of the cooling towers.
The cover sheets had fallen 30m (98ft) to the ground.
The 1m x 2.7m (3ft x 9ft) sheets, weighing 20kg (44lbs) each, were found broken on the ground and on top of a cooling tower.
Luckily, no one was hurt.
Why did it happen?
Heavy winds caused vibration, allowing the loose cover sheets to become detached.
Clamps were found to be loose in most of the locations.
Clamps and fixing arrangements were not robustly designed and performed badly during high winds.
- Clamps were fixed every 2.5m (8ft) at the edges of the cable tray cover sheets.
- Each clamp had only one bolt.
Workers decided the type of clamps according to manufacturer’s preference.
What did they learn?
Friction hold clamps should not be used with PVC/FRP cover sheets.
- The clamp bolt is a friction hold clamp which does not penetrate the PVC/FRP cover sheet.
Replace hold clamps with double stainless-steel straps (minimum 3 per cover sheet) to minimise the risk of dropped objects.
Update specifications to include avoiding the use of friction hold clamps for PVC/FRP cable tray cover sheets.
Be alert to objects being unexpectedly detached and falling to the ground during high winds.
Ask yourself or your crew

What method do we use for securing cover sheets at height?
How often are DROPS risks assessed on your site?
Is there any equipment on your site that isn’t suitable for bad weather? Could it be replaced?
What measures do we have in place to prevent this from happening here? How can we improve?

Published on 24/11/20 1675 Views

An area operator discovered broken cable tray cover sheets had become detached from the top of the cooling towers. They had fallen 30m (98ft) and were found on the ground floor, in a U-ditch and on top of a cooling tower. Luckily no one was hurt.

Original material courtesy of IOGP