Failed expansion bolt hangers, bolts and chain submitted for analysis
The development of sport climbing areas outside of Europe and in locations with aggressive environments has brought the need for greater understanding of corrosion mechanisms by material type.
In a 2013 report entitled “Material Classification for Climbing Anchors 2013” the UIAA determined that “the fundamental issues of environmental degradation (stress corrosion cracking (SCC) and corrosion) to climbing anchors” was deemed serious and “should be addressed as a matter of priority.”
The UIAA formed a working group to gather global information concerning bolt failures, together with environmental data and testing of failed samples, with the objective of revising the UIAA 123 Standard to class a material type with a suitable range of environmental conditions. Regions would then be defined by Anchor Class which in turn reflects known or potential degree of corrosion and an appropriate material and type of bolt for use. For example coastal Thailand is known to have highly aggressive SCC and would be Class 1 and only titanium resin bolts combined with pure epoxies recommended.
Hong Kong is within a region predicted to have high corrosion issues and this is supported by personal experience gained from the extensive re-bolting work conducted in Hong Kong in recent years.
My collaboration with the Working Group will include the provision of failed samples recovered from re-bolting work in Hong Kong and data describing bolt types and dates of installation. Looking ahead, a long term bolt installation program may happen in which test bolts are installed and their condition monitored over years then tens of years. This would also include periodic axial load testing, a process already conducted in the locality.
An initial sample of failed expansion bolts, hangers and chain was sent to Europe for materials testing and failure analysis this week as part of samples being received from climbing areas all over the world.