Issues with the Clove Hitch Biner Block Method > Shape

— In Yahoo Canyons Group, “tom” wrote: > The recent accident in Heaps drew attention to the awareness that > you cannot create a viable block, of any sort, against a ring > which will allow the block to pass through it.

> No testing required, just education and situational awareness.

I thought people were stating that part of the rope/knot could be used in the block and the testing I was thinking of was determining what the actual loads were to pull a “rope constrained” block through different anchor points.

>> In reality, using two oval metal loops to create a block is a bad >> design prone to error.
I disagree that using two metal loops is a “bad design”.

The problem is the shape, not that they are loops. Oval isn’t the right word either, more like a rounded rectangle with a high aspect ratio for quick links (rapides). Because each loop has a short and long axis, it isn’t that hard for the inexperienced or uninformed to make the mistake that the long axis of the carabiner is sufficient to block the short axis of the anchor point.

The post that listed the results of various caribiners against
quicklink sizes fails to meet basic safety standards. It did
nothing to determine the actual loads/forces at which the
combination would pull through.

> I don’t think that was Brian’s intent. I think he was attempting to > determine the largest Rapide which would not pass a Petzl > Attache…

Although I don’t have the equipment to repeat his tests I believe he was including the rope/knot in his determination of whether it could pass or not. If this is not the case, I apologize for writing statements stating he did.

>> The gate, and compressive loading of it >> (which it was not designed for), also needs to be accounted for

> rapide? This would be a bending load, not compression.

You are right, the gate itself would be under a bending moment. I was using compression to refer to the load applied across both sides of the carabiner.

The rated load across the short axis of a carabiner refers to a tensile load, or pulling apart the two sides. It does not apply to the forces a carabiner would experience if it fit half way into the anchor point such that a squeezing force would be pressing the two sides together. That strength is much lower due to the design of the gate (it opens inwared).

If people feel that a half way stuck carabiner fulfills the requirement that it does not pass, then tests should be done to confirm the actual failure loads are higher than the WLL, as well as to understand what happens under shock loads. From my perspective, this is an inappropriate use of the hardware and this situation should just be ruled out as unsafe.

Steve Newcomb Tucson, AZ