Chockstone Forum

      Sponsored By
      ROCK
   HARDWARE

Chockstone Photography

Australian Landscape Prints

Chockstone Forum - General Discussion

General Climbing Discussion

Topic Date User

Proof loading bolts 28-Jul-2009 At 7:08:39 PM Jim Titt

Message

Hi Mikl

Some interesting points being raised, and as usual a few different viewpoints!

First, once you start pulling (destruction) a bolt you really need to rip it completely out in case it became weakened or damaged, from our experience you need to be looking at around 50kN capacity to be sure, though this is about the minimum. We´ve seen 100mm Salewa glue-ins over 60kN and our larger bolts are over 70kN (best is 102kN) as well which is why we are running a 100(+20%overload)kN puller. Buying a lower rated puller is a bit of a mistake as the BMC have discovered, they are doing a long-term glue/bolt deterioration test but as they can´t pull any of the bolts anyway it´s not very meaningful.
A puller system that can also do radial is useful, particularly in very soft rock, unfortunately most commercial fastener testers only do axial so normally you have to build your own, it´s cheaper as well!

The failure mode generally isn´t either simple tension or shear, despite the views of many.

The real question climbers have to face is when a standard for rock anchors is imposed what will it be? That a standard will be imposed at some time is almost inevitable, whether as the result of a spate of accidents, pressure from landowners or as part of a free trade bargaining round (it is often overlooked that the EN/CE standards are there to provide a level playing field for manufacturers and importers to the EU, not as a safety standard as such). If climbers in Australia adopt a proof testing system and legislators take this on board then you will have massive problems in the future. The only way climbing could survive is to establish the principle of design-based equipment standards, the only effective one at the moment being EN959 which has the added attraction for beaurocrats and legislators in that it is a well established international standard and will involve fact-finding trips to Europe!

Safe climbing and have fun.

Jim