Last weekend we went and visited a friend who is a wine maker (and a climber).
On the back of his forklift I found two 'busted' quickdraws. I asked about them and it wasn't exactly clear what they were using the draws for, but sure enough the lifting weight would have been in
excess of 2500kg because one of the biners broke

and the rest are stretched and busted.
I confiscated his quickdraws sighting a very nasty accident (he was still keen on using them

) and replaced them with a steel triangular Mailon (4500kg load limit).
What I find interesting is that the nylon material appears to be a lot stronger than the carabiners! The quickdraws are from 1993 and 1994 - that makes the material and biners 18 years old - the DMM biners take a load of 2500KN (more than most quickdraw biners)!
*Note: These quickdraws were abused in a non climbing environment