After Todd Skinner’s death due to a broken belay loop, Black Diamond tested belay loops and slings that were 75-percent cut and they were still 90 percent of full strength. But I can’t find information on (intact) fixed gear. How strong are dogbones and biners that have hung in a cave for several years?
—Keith Hengen, via rockandice.com
I’d rather trim my toenails with communal clippers than use some of the nasty tat I’ve seen dangling in caves of sicky sickness.
Slings and harnesses were sawed three-quarters of the way through and still held 90 percent of their rated strength? Not so fast! This is all about data mining, and since we’re talking about lives rather than gold nuggets, let’s at least try and get things flowing in the right direction.
Kolin Powick, the quality-assurance guy for Black Diamond, did the testing. According to his results, the belay loop you are thinking of held 2,918 pounds, which is 87 percent of the rated strength, but the rated strength is well below the loop’s ultimate strength, which is around 6,000 pounds. In short, the belay loop actually saw a decrease in strength of roughly 50 percent.
At face value, it’s fair to say that webbing can sustain a lot of damage and remain remarkably strong. The problem is, unless you take the slings, dogbones, belay loop or whatever, and test them, you have no idea how strong they are. This is where, again, Powick comes in handy. Over the years he has tested fixed quickdraws, slings and carabiners he snagged from sport climbs. Powick found that carabiners, even badly worked, crusty ones that you’d think would be weak, retain most of their strength and that the true danger is the rope-fraying grooves worn in them.
The sling test results were less black and white. Some tattered quickdraws broke around 8 kN while others held up to 23 kN (22 kN gets you passing marks on the CE test). Since the spread in strength is all over the map, you really can’t deduce much of anything. About all you can know is that slings do weaken over time from wear (abrasion) and UV exposure. If those mankey old draws and slings spook you, do the public-service thing and replace them. The karma you’ll accrue could come in handy next time you tie your bowline backwards or you’re benighted without a headlamp.
One good option for replacing fixed draws is the ClimbTech PermaDraw. For $15.99 you get a stainless steel quickdraw with a steel quicklink for the bolt hanger, and a hearty steel, bent-gate carabiner.
This article appeared in Rock and Ice issue 187 (July 2010).
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Feature Image: Keith Hengen on Whip Tide (5.12c), Rumney, New Hampshire.