Rating new rope

Hi Kevin,
The WLL (Work load Limit) Is the certified maximum that a given item can lift safely this already has the factor of safety included.IT does not account for specific configuration and may therefore be greater than the SWL.If you want to work out the factor of safety for yourself then you use the Tensile strength of the item and workout your SWL from that.

I always use 10:1 Factor of safety on Rigging and Climbing.

Didj


Didj
 
Didj;
I have been rating all my ropes at 10:1 but I'm not certain this is correct and judging by the many views and only one response I think this is something we should try and clear up.
What I think might be the standard is 4:1 on guys, 5:1 on loads and 10:1 on life lines.
 
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What I think might be the standard is 4:1 on guys, 5:1 on loads and 10:1 on life lines.

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This is consistent with everything I've ever heard. So why are you making up this 20:1 thing for lowering lines? Perhaps the reason no one has responded is that no one has ever heard of this mythical 5% WLL but were afraid to say it.
 
i think i saw what Kevin wrote, but understood what he meant 5:1 for loads; 10:1 for lifeleine. After all, having the load rating ("5%")more conservative than the lifeline factor("10%"), would be trolling a bit i guess anyway..... So i considered it consistent with standards and had not much to offer constructive more than that...... at the time...

Of course if we are calling 300# per leg of line as productive and safe loading; 400#,500# starting to push it; then we are kinda getting a 20:1 or 5% load rating on 6000#-8000# line strength ratings altogether actually always accruing almost accidentally anyways!

The more possibility of dynamic loading, should be given the widest SWL for loads i think. If you can slowly peel over a limb, self leveraged tightening the support line oat a leveraged position on the load as it does hinge down, then quit cutting and let the rope man lower on the hinge, still the line self tightening with leverage as s/he lowers ; then cut it off and it doesn't move, drop, or swing etc. Because the line is so tight at tearoff (set just right by the load itself); and in doing so move the hitch point on the load directly under the support point of the redirect to control man; Ya can puts lots on a line(and thereby supports), handling it baby soft; by handling the load only, and none of the multipliers of the load's force! IMLHO.
 
As Far as I know the rule of thumb is 5:1 on loads and 10:1 for protection of life
The problem is the factor of safety can vary a great deal
In Austrailia it is 8:1 lifelines
In the UK 10:1 Sometimes 15:1 depending on application
Depending on rope and application It can vary from 5:1 to 15:1
This is why now manufacturers have to put the WLL on the item Then the safety factor is already accounted for provided the equipment is used for the purpose it was tested for.Makes more sense really WLL says 1000kg thats all you can put on it even if it will take 10,000kgs to destroy it.

Didj
 
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So why are you making up this 20:1 thing for lowering lines?

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Brian, where did you get that?
 
5% of WLL equals 20-1. I got it from your first post in this thread. Perhaps you didn't mean to type that but I can only read what is typed. Did you mean to type 5-1 instead of 5%?
 
How are used ropes rated?

By their history?
very carefully?
sometimes as dragging/non critical application etc.; as to not use 'better'/known lines perhaps.


Orrrrrrrr something like that
-KC
 
Just happen to have gone through some of the Arbormaster/ISA/NAA training tapes today with the crew. I was presenting the 8 tape set, The Art and Science of Rigging. More than once, they made mention of the 10-1 rule. They never really mention (or I do not recall) where the rule was from.
Rick H...
 
The majority have it right. Or, at least, what I was taught. Jamie G here from Yale Cordage. Not trying to sell anything but only to pass the tid bit of info that Yale declares in their new Arb catalog the working loads of the ropes. 10:1 on climbing ( or life lines ) and 4:1 or 5:1 on the lowering lines. I say either/or, because of the R&amp;D done on the fibers we work with, nylon, polyester, spectra, vectran.....we find some can permit a 4:1 load rating....some need more. So, you are correct when you say the manufacturers but the standard committees can over ride that in a heartbeat if they wanted to

You can never be toooo safe so use your heads..

I have a link here to the catalog http://www.yalecordage.com/html/arborist.html
 
The use of safety factors is a standard practice for any system. The more time that we spend closer to the 1:1 safety factor the more likely the system is to fail.

By starting out with a high safety factor rope wear can be accepted. Since there are many variables in tree work that can't be measured its always good to use bigger ropes and smaller pieces.

Tom
 
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