Cycles to Failure

H

hernv031

Stable braid 9/16 Bull rope 13,300 tensile strength. I am going to keep track of cycles to failure. The question I have was butt-tying or tip-tying have the same results or one or the other take more strength out of the rope? When do I have to retire my Bull rope before it fails? I am trying to avoid shock-loading.
 
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When do I have to retire my Bull rope before it fails? I am trying to avoid shock-loading.

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many, many, many cycles

The type of usage ( work history, heavy, light, always, occasionally) will determine its life span. It becomes a judgement call on your part. I'm amazed at some of the ropes i've seen still in use. Heartwood tree company has a beautiful retired rope collection, thanks to the good judgement of Altreeist.
 
every repetition is a cycle.It does not matter so much tip, or butt, but how the rope is loaded/used ,and how close to its max tensile strength are you using? Ex: if your swl is 1000lbs and you are consistently roping 1000lbs you will have fewer available cycles! does this make sense or am I telling you stuff you already know?
 
Frequency is also a huge factor.-If you load a rope with 90% of the tensile strength and then relax and load it a gain it may break on the second(or third, fourth, fifth) loading. Give the rope some recovery time and do the same thing with days between loads and it will endure more cycles. Using ropes within their safe working load range they will visibly "wear out" before they cycle out.
 
Two models that I use to understand what happens inside a rope during use make use cycles a bit easier to visualize.

Think of grabbing Silly Putty or bubble gum. Gently pulling the fiber/gum/putty [fgp] won't break the fiber but it will damage it. Snap the fgp and it breaks...one cycle to failure.

When the rope is loaded the fibers rub across each other and the get a small rug burn. This weakens or breaks the fibers. How many/much damage can a rope take before failure?

Replace rigging ropes every year...or sooner.
 
If you are worried about any rope failing, (do to time, excessive weight, wear and tear, you let a friend use it, whatever) RETIRE IT. Do not take chances. Roger is right, we have a beautiful collection of retired rope. I like to weave mats with them and put my dirty boots on them at the end of the day. Know your rope's history and care, use it with confidence and retire it with confidence.
 
Its amazing to me the thought process sometimes. Where I used to work many moons ago we would retire our climbing lines in to rigging lines.
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I retire climbing lines to rigging lines. I dont see a problem with it unless your riding the climbing line to final cycle. My climb lines are retired in good condition with alot of useful life left in them. Ive always done this and have NEVER broken a rigging line, even one that used to be climbed on. Of course designing and implementing appropriate rigging systems is key.
 
My point was if you dont feel it is safe to climb on it might not be safe to rig what would be heavier than a person. It depends on the reason it was retired I guess.
 
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It depends on the reason it was retired I guess.

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Supposed to replace the climbing one every year no? I don't think it's possible to cycle through a rope with just one years climbing is it? I move any ropes that aint been nicked to rigging lines also. ?????
 
I'll agree with that. If I feel it unsafe to climb on, I wont downgrade it to rigging. It will be cut, and downgraded to brush tie downs or some other non critical application.

Am I retiring my climbing lines too early? I average 8 -12 months. They are comfortably retired and taken very good care of (not stepped on! :) ).
 
Another thought I had is that rigging lines should be rope made for rigging. Climbing lines are made for climbing. Based on the personell you work with there might be confusion between the two if the ropes had the same appearance.
What is the difference in the construction of rigging lines vs. climbing lines.....elongation...etc.

Just more food for thought.
 
Climbing lines to rigging lines is a slippery slope. If the crew/company is larger or transient, I think it's an absolute no-no. If you are the ONLY one in charge of these transitions, well, then, in theory and practice, there's no harm in using a retired climbing line for some light rigging, especially as a tag line or the like. But if some yahoo comes into your secret locker early in the morning and grabs XTC retired thinking it's a life line, that's trouble.
 
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...Check out the chart for nylon and polyester fibers.

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Fascinating and useful chart, Norm. Where does it come from?
 
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