Rappel Racks
Posted: Dec 2, 2007 8:58 pmIs there a strength difference between a rack with a coiled eye vs a welded one?
Here it is: (Quote from bill Storage's website http://www.bstorage.com/speleo/OnTech/ontech.htm ) Note: he was making a point about something else...
For example, a recent issue suggested that stainless rappel racks with coiled eyes should be welded at the eye to increase strength. These racks can uncoil under loads as small as 800 pounds. The author showed details of the weld procedure.
A good engineer might want to debate the likelihood of such welding, if done under less than ideal circumstances, resulting in an embrittled and corrosion-prone area about an inch from the weld. Or an engineer might make a point that while a 150 pound human hanging from a rack might survive a deceleration of 5.3 g (needed to begin uncoiling the eye) if its duration were short, it is inconceivable that a human would survive a load high enough to uncoil the rack for the length of time needed to uncoil the ten inch long coiled region. A practical caver might note that anyone subject to an 800 pound load on a rack has both locked off his rack and done some extremely poor rigging. Yeah sure, the rack article was concerned with rescue situations as opposed to standard caving; but if I were a victim I'd feel much better if my rescuers used wimpy racks and good rigging rather than the other way around.
All these intellectual arguments aside, let's say we agree that welded racks are essential. They cost twenty five dollars. Where on earth could you find a quality welder, one capable of doing a good job with austenitic stainless, for $25? Get serious. Revised advice: support your local equipment vendor. Buy a new rack. Learn proper rigging-for-rescue. Get a life.
