Full body load on slaice? YES!

Recently there has been some on-line discussion regarding Teufelberger’s [slaice] rope termination and whether it is suited to support a full body load, e.g. when base-anchoring a stationary rope to a base anchor.

In order to pass, EN1891, the European standard for low stretch kernmantle rope (AKA semi-static lines) requires a MBS (minimum breaking strength) of 15kN for three minutes in a static pull for type A lines.

EN1891 is a stationary rope standard, so the 15kN termination strength requirement for Type A has proven suitable and sufficient since at least 1998. [slaice] fulfils all requirements demanded by this standard.

But what about the 5’000 tensile strength requirement which the Z133 ANSI standard demands of all climbing equipment, you ask?

Apart from there being a degree of ambiguity regarding this requirement – it seems it is more of a perceived than a clearly stated one – , it certainly does not apply to terminations. In fact, there is no defined termination strength requirement for climbing lines in Z133. Further, I would suggest that we need to consider configured strength vs. component strength. Let’s assume you take a climbing line with a MBS of 25kN (≈5’000 lbs) and tie a figure of eight knot to attach it to your base anchor. The exact amount the tight bend radii in a knot reduce the breaking strength by is a matter of some contention, yet depending on where you look, you will find reference to a reduction from anywhere around 60 all the way up to 80% (and if we are talking high-tech fibre, this figure will be even higher!). Taking this into account, your configured, knotted line ends up well below 15kN right away!

Interestingly, all the Z133 standard has to say on the matter of terminations is that ’Splicing shall be done in accordance with manufacturer’s specifications’ (this would be a pass for [slaice] in that case), making no further requirements regarding knotted or configured strength of cordage.

Add to that the fact that the European standards for harnesses require an MBS of 15kN and the whole concept of requiring a 25kN MBS for terminations becomes a bit nonsensical. And the US? Similar picture to Europe: as from 1 January 2018, the fall protection attachment elements of arborist saddles in the US will also be required to withstand a load of 15kN for 3 mins (ASTM F887-2016).

To put all of these numbers in perspective, it is worth bearing in mind that your body cannot survive these kinds of loads, so I would suggest that you can be perfectly at ease using the [slaice] to attach to your base anchor.

But there was that safety warning a while back, you say?

Yes, Teufelberger issued a warning due to a couple of [slaice] turning up with inconsistent diameters behind the stitching. Mind you, despite that, the termination still passed the 15kN test – just not for the required three minutes. So this was less of a safety critical issue and more of a cosmetic matter. I believe Teufelberger were right to admitting to the fault and communicating in a pro-active, transparent fashion.

One strong point of the [slaice] construction is that it offers a tiered resistance to wear and tear: part of its strength stems from a Dyneema tape which passes through the eye of the termination and is included in the stitching.  So any abrasion or damage which occurs to the mantle of the line will have no adverse effect on the Dyneema, which is almost like a second line of defence. This makes for a highly robust, resilient rope termination. This technique is applied to all Teufelberger/ NER lines with a thin cover, e.g. Fly and Tachyon. The classic 16-strand construction lines, Arbor Elite and Braided Safety Blue, have a sufficient volume of material and hence strength in the cover for this not to be necessary.

I love climbing on lines with [slaice] terminations. They are low bulk, easy to pass through pulleys, thimbles and rings and do not get caught in tight forks. I also like the fact that the length which is stiffened due to the termination is very short, which lends itself to techniques like climbing in a loop. I find when I go back to a line with a standard splice on it, this seems very clunky and bulky in comparison.

But hey, à chaqun son plaisir, this is simply a further tool to add to the toolbox. If it suits your style and you like it, use it – if not, don’t.

So let’s be clear: [slaice] is absolutely safe to be used as a termination on arborist climbing lines in a PPE context for both stationary and doubled configurations.