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Dyneema sling break-test revisited

Richard Tregoweth - Wednesday, November 24, 2010




About a year ago tree climbers began debating the suitability of Dyneema webbing slings for use in tree work.

The Dyneema material used to construct the webbing presented possible issues regarding UV degradation in the New Zealand environment. Other questions revolved around the strength of the sling (even though most webbing slings are rated at 22kN or above).

At the time, DB Tree used an Aspiring webbing sling (rated at 22kN) as part of a soft-eye rope saver sold into the local market. During the development of the product Drew Bristow wanted to see how the sling would stand up to abuse in the work environment. Not satisfied with a simple 'break test' Drew opted for a simulated fall, using 80kg and then 100kg weights.

Climb Every Thing, Johno Smith had been using an Aspiring webbing sling for about nine months as part of his everyday climbing kit. This particular sling was configured into a climbing system. A load of 100kg was dropped with a fall factor of 1, then 2 then 3 and then 5 on the same sling (the DB Tree team was determined to break something!)

During all the DB Tree drop tests, Johno's nine-month-old Aspiring sling did not break. Rather, the Yale Blaze rope melted at the point-of-contact with the prussic (formed by the sling).

Since those drop tests conducted in November 2009, the Aspiring sling has been resident in the Treetools showroom - as living testimony to what an Aspiring webbing sling can withstand. Large sections of the sling were completely glazed and at a couple of points the edges of the webbing were fraying from the force - in other words the sling was obviously knackered.

Today (24 November 2010), just over one year later we broke the (knackered) test sling to see what force could be applied before it finally broke.

The break test result for the Aspiring sling was 16kN - download test results here . See video below for one of the original drop tests by DB Tree back in November 2009.

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