Stevedoring and cargo handling company P&O Ports has been fined AUD40,000 for failing to provide a safe workplace after an incident at Port Hedland in which a worker's legs were seriously and permanently injured.

The company pleaded guilty in the Perth Magistrates Court last week to failing to provide and maintain a safe workplace and, by that failure, causing serious injury to a worker.

The incident occurred in 2004 when P&O Ports was conducting stevedoring operations at the Port Hedland Wharf and three employees were given the task of dismantling a large bar that had been left on the wharf after a ship had been unloaded.

The bar, which was 13m long, weighed more than 2 tonnes and was used to unload lengths of railway, had removable plates affixed at each end with shelves to hold the lengths of railway and wire rope slings attached along its length.

The workers elevated the bar on two stacks of wooden gluts and removed the plates from the ends, and while one of the men moved the plates to a storage area, the other two tied up the rope slings so they would not hang loose during transportation.

While the rope slings were being secured, the bar toppled and fell onto a worker's legs. Another worker who was nearby used a forklift to lift the bar from the man's legs.

He suffered serious fracture and crush injuries to both legs and has been left with a substantial permanent disability.