Warning issued over slate bolts

Posted by Daniel Middleton on 25/03/2014
Problems with expansion bolts on slate

Climbers are warned about potential bolt failures in the slate quarries of North Wales. The BMC advise climbers to use caution with any loose expansion bolts used for protection and in particular for lower off's on popular routes. Resin bolts are not affected.

After a 10mm expansion bolt was reported to have failed on a popular route lower off on the Sidings, locally based instructor and coach Mark Reeves started checking bolts and lower offs on the most popular routes in the quarries. Mark used a hydraulic bolt testing rig to pull test a number of bolts. Several things became apparent:

  • A small number of 10mm expansion bolts pulled out at very low loads.
  • Heavily used lower off's appear to be affected.
  • Any bolt which can be moved must be considered dangerous.

The local bolt fund (NWBF) has been supporting volunteers undertaking this testing and remedial action replacing loose bolts on the most heavily used routes with resin bolts.

This work is being done by volunteers with limited resources, so it may be some considerable time before all loose bolts are checked and replaced.

TREAT LOOSE EXPANSION BOLTS ON SLATE WITH CAUTION

You may be asking how has this happened? 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 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.

Resin bolts do not stress the rock except when loaded and spread the load more evenly so are a good choice for heavy usage situations and soft rock.

Mark Reeves replacing slate bolts

Photo: Mark Reeves replacing slate bolts

Big thanks are due to Mark Reeves for a huge amount of testing and bolt replacement. Check out his website: http://lifeinthevertical.co.uk

Contact the NWBF and donate by clicking here.

Article edited 26/03/2014



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1) Anonymous User
25/03/2014
I climbed a 4a ish route at bus stop a few weeks ago and found one bolt hammered in too far, and two put in at the wrong angle on a climb no higher than 10m. meaning the climb may as well have been a solo with a single bolt lower off. not to mention that the whole place is falling appart at an alarming rate. people seem to be putting bolts in low grade north wales slate without any practise, i think slate is a great rock to climb on, but sport climbing some of the low grade routes at dinorwic is like playing russian roulette. many of the routes there are bolted very well and its a shame that a few peoples bad bolting skills are giving the area a bad name.
2) Anonymous
25/03/2014
This comment broke the house rules and has been removed
3) Anonymous User
25/03/2014
The NWBF does not undertake any bolting or remedial actions itself. It supports individuals who volunteer to carry out installations and replacements by facilitating the provision of technical advice and training together with the loan of drills and other equipment and sourcing of bolting materials which it provides free to re-equippers and to fund donating new routers.
4) Anonymous User
25/03/2014
Great that this is being highlighted as the slate undergoes another resurgence in popularity or another generation start exploring; but has this not been the same story for the last 20 /25 years?! We didn't trust expansion bolts on slate in the 90's - treated them with caution, tied them off or hooked a wire over them if proud of the rock, but still cursed them if spinning at full stretch to clip and there was nothing else available for protection!! Yes - beware, and thank god for activists as mentioned who are replacing with resin bolts - said with a touch of that insane 'reminiscence' of the way it used to be! Hear hear to the rebolting, just don't change the traditional run outs ... Be thankful if you climbed the Illinois Enema Bandit eh! - gone into posterity/ scree now!
5) Daniel Middleton(author comment)
26/03/2014
In reply to 1)

This issue isn't about bad bolting, rather about a few bolts placed with the best of intentions failing after heavy usage. We all have to make our own risk assessment especially with the variable rock quality found in quarries- just because a route is bolted doesn't mean that we will climb it.

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