Expansion bolts should be treated with extreme caution

Expansion bolts should be treated with extreme caution

Climbers are being warned that bolts in north Wales quarries could be dangerous and likely to fail.

The British Mountaineering Council said a survey found expansion bolts pulled out of their positions on slate very easily.

It now says climbers should treat 10mm expansion bolts with great caution when using them for protection and particularly for lowering off.

Resin bolts are not affected by the problem.

Local instructor Mark Reeves checked a number of bolts after one failed on a lower off on a popular route in the Sidings near Llanberis.

He found that a number of 10mm expansion bolts pulled out at very low loads, with popular route lower offs badly affected. The BMC said any bolt which can be moved must be considered dangerous.

After rain expansion bolts which look good may be weakened dangerously, it added.

A BMC spokesperson said: “During original testing the results with both 10mm and 12mm expansion bolts were good on slate.

“Follow-up tests made more recently confirmed that when initially placed, expansion bolts appear to meet UIAA [the International Mountaineering and Climbing Federation] standards.

“With heavy use, the softness of slate appears to allow degradation of the rock leading to movement and weakening of the bolt because it no longer securely fits into the drilled hole.

“In addition, after wet conditions it appears that water can infiltrate the slate, weakening the rock and allowing otherwise good bolts to fail.

“Resin bolts do not stress the rock except when loaded and spread the load better, so in future will be the only bolts recommended for use on slate.”

The BMC said a local bolt fund has begun urgent remedial action, testing and replacing loose bolts on the most heavily used routes with resin bolts.

But it added the work is being done by volunteers with limited resources, so it may be some time before all potentially dangerous bolts are checked and replaced. In the meantime, it warned climbers using the slate quarries to treat expansion bolts with extreme caution.

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