UKC

Hi All,

I was wondering if there was anyway of establishing the strength rating of expansion anchor type bolts. I understand the holding strength will be variable due to the strength/integrity/type of rock, but is there anyway of ascertaining a max load capable of being held?

Only ask as I have been given some bolts, and I am curious as to their strength, not planning on bolting owt!

Cheers, Matt

In reply to Nordie_matt:

You put them on a tester and break them. It´s extremely variable depending on exactly how you test them (how the load comes on the bolt) and how the bolt was made, for a 10mm stainless wedge bolt the values can vary between 8kN and 38kN.

In reply to jimtitt:

Thanks, so there is no minimum rating over all then?

I was just curious obviously bolt hangers etc are all rated.

Cheers, Matt

In reply to Nordie_matt:



Not really, for use the construction industry bolts have an ETA (European Technical Approval) but the loads are imposed differently to climbing. You can have two different bolts both with ETA and an ultimate breaking strength higher than the requirements for EN959 (theclimbing bolt standard) but one will fail certification for EN959 and the other one pass.
I´ve dealt with a German manufacturer over this very problem and we´ve done the two certification tests side by side and the results are very different, even bolts from reputable manufacturers sometimes don´t make it which is why coincidentally my job this morning was breaking bolts as we recieved a new batch on Friday (one of the pleasures of running a business is going to work on Sunday, not climbing)
Bolt hangers for sale in Europe for climbing use must be certified to EN959, same as the bolts.

In reply to jimtitt:

Thanks a lot for this post, really interesting, and definitely food for thought where bolts are the primary protection.

On a side note, do you break test glue in bolts such as Petzl Collinox? as I see the tech specs refer to Pull Tests etc and resisitance to cutting (is this just shearing?) on concrete with agiven rating in KN.

Cheers, Matt

In reply to Nordie_matt:

The standard doesn´t differentiate between glue-ins and mechanical bolts strength wise, they are all just anchors. They are tested in a standardised concrete block and have to withstand 15kN straight out and 25kN at right angles but mostly they hold considerably more in a decent bit of rock, the test blocks aren´t particularly strong so tend to disentigrate at higher loads. The Collinox holds about 45kN before it breaks and there are plenty out there that get much more than that, I´ve seen over 100kN from some. The 10mm wedge bolts I tested yesterday got over 35kN straight out.
Loads of info on my wierd website if you´re interested, go to this page:-http://www.bolt-products.com/Glue-inBoltDesign.htm

In reply to jimtitt:

Cheers stuck in work today, so will have a good look at the link.

Thanks for all the info, some really interesting stuff here.

Matt