Sat in Abu Dhabi a while ago when someone tried to checkin a jerry can container full of water, probably about 50 or 60 litres which equates to 50 - 60kg. Couldn't even carry/drag it to the desk, no way he was going to be able to put it on the conveyor. Was rapidly directed to the queue to pay for excess baggage. Not sure if he managed to drag it that far down the terminal...