New Gear and ANSI Standards

[treeclimber165]

Recently I have started diving into a lot of new methods and gear after many years of refusing to use anything other than a rope, saddle and locking clip. Many arbos here and on other boards discuss using ascenders, straps and friction hitch cord which are NOT rated for 5000 lbs. They might be close, but I am wondering why so much stuff is being used with smaller and smaller safety margins. For obvious reasons this gear could only be used by an independant climber, and not issued to employees by an employer.

Used to be that if the equipment was not rated for 5000 lbs, you didn't use it. Now it seems like using multiple items with lower ratings is somehow OK, because 'one is backing up the other'? What are the ANSI regs on this?

 

[TMW]

ANSI Z133.1- 2000 is pretty clear on this.

"8.7.4 Prusik loops, split tails and work positioning lanyards used in a climbing system shall meet the minimum strength standards for arborist climbing lines.


3.23 Prusik loop. An endless loop of rope used to fashion the Prusik knot. The endless loop may be spliced or knotted with, at a minimum, double fisherman’s knot. The breaking strength of the loop shall meet minimum strength criteria for an arborist climbing line.


8.7.5 Carabiners used in securing the arborist climbing line and/or the work positioning lanyard to the arborist climbing saddle shall be of the self-closing positive-locking type with a minimum tensile strength of 5,000 pounds. Standard one-quarter-turn, twistlock carabiners do not have a positive-locking mechanism and shall not be used.

8.7.6 Rope snaps used in climbing shall be the self-closing type with a minimum in tensile strength of 5,000 pounds."


TMW

 

[Stumper]

Brian, I've asked the same questions. My understanding regarding prussik loops is that when using a closed loop both legs coming out of the knot are sharing the load. If you use a prussic loop of cord rated at 3300 lbs you have a theoretical support of 6600 lbs-well above the 5400 lb Ansi requirement. Actual strength may be lower due to knots and splices of course. Regarding the Ascenders ect you are probably right that some of it could not be issued by a company.*Using gear with high load ratings makes sense but the 5000 lb thing is rather arbitrary-so is the european standard of 22kn. Both standards insure that the gear can withstand double the force of a fatal fall. I find it interesting that the US military standard climbing/rapelling line has a new rope tensile rating of 4500 lbs. Military personnell unfortunately do have the occassional fatal fall but I don't recall ever hearing of one due to an undamaged rope failure.

 

[Nickrosis]

Considering the many approved options out there, I don't understand the reasons for cutting corners. If you're going climbing for recreational reasons, you don't have to follow ANSI, but it wouldn't be the best idea because it wasn't written for no reason.

Nickrosis

 

[MrPez]

A lot of this has been discussed under previous posts. Scroll the back issues and look up ratings.

The problem with many 'standards' is that they have high safety margins where lack of research cannot allow a more objective and reasoned approach. This works, but progress stops.

Accurate data needs to be gathered and tempered with experience to reach important decisions on risk. This is what gives Doctors the 'clinical eye' to decide what to do with a patient.