Build My Own FeedQC Lab: Strength of a worn belay loop and when to retire a harness
The following QC Lab was originally posted a few years back on the old BD website after Todd Skinner died in Yosemite when his belay loop broke. I feel belay-loop strength is still a relevant subject and wanted to bring it back to everyone’s attention, especially since I still get emails from people asking me about belay loop strengths and when they should retire a harness. Below I do my best to answer a few of these questions, while most likely actually posing more questions, as well as provide some super-unofficial non-complete experimental data on belay loops that my QC crew and I performed.
How strong is a belay loop?
From the Black Diamond Harness Instructions: A Black Diamond harness belay loop can withstand 15 kN (3372 lbf) of force.
CE requirements : The CE required testing is a bit difficult to describe, but basically, the belay loop must withstand 15 kN for a period of 3 minutes.
Actual Black Diamond test data: Though our inline batch test rating is 3372 lbf, we regularly see belay loops test to over 6000 lbf, with a historical average of over 5000 lbf.
** Note: I've tested several other manufacturers’ belay loops and they all are in the same ballpark for ultimate strength.
How long should a harness last?
Again, from the Black Diamond Harness Instructions:
CARE AND MAINTENANCE
♦ Machine wash your harness in warm water on a gentle cycle. Use a mild soap, no bleach. Anytime your harness gets wet, allow it to drip dry away from direct sunlight before storing.
♦ Harnesses must not come into contact with corrosive materials such as battery acid, solvents, gasoline or chlorine bleach.
♦ Do not allow your harness to be exposed to temperatures above 140° F (60° C) or below -80° F (-62° C).
♦ Do not sew, resew, burn or singe loose threads, bleach the webbing, file a buckle, modify, or change a harness in any way.
STORAGE AND TRANSPORT
♦ Never store a wet or damp harness.
♦ Store all of your gear in a clean and dry environment, out of direct sunlight and away from heat sources.
♦ Keep harnesses and other sewn climbing equipment away from gnawing rodents and pets.
♦ The nylon in your harness will weaken with age if not stored free from mildew, UV light, temperature extremes or other harmful agents. If a harness has been properly stored for ten years or more, retire it.
♦ With normal use and proper care, the life expectancy of your harness is approximately three years, and can be longer or shorter depending on how frequently you use it and on the conditions of its use.
Factors that reduce the lifespan:
♦ Falls
♦ Abrasion, cuts, wear
♦ Heat
♦ Sunlight
♦ Corrosives
INSPECTION AND RETIREMENT
Inspect your harness for signs of damage and wear before and after each use. It is vitally important that your harness be in good condition. A damaged harness must be retired immediately.
Retire a harness immediately if:
♦ There is any kind of rip or hole in the webbing.
♦ The webbing is burnt, singed, or melted.
♦ There are any torn threads, or heavy abrasion to the webbing.
♦ Bar tacks are abraded or showing wear.
♦ One of the buckles is cracked, corroded, has a burr, or is damaged or deformed in any way.
♦ The webbing is faded from exposure to ultraviolet light.
If a harness has been involved in a severe fall, but is not obviously damaged, it still may be ready for retirement. If you have any doubts about the dependability of your harness, retire it and get a new one.
Anytime you retire a piece of gear, destroy it to prevent future use.
**Note: most other climbing gear manufacturer's have similar warnings, instructions, timelines on their products as well.
What could have happened to Todd's belay loop?
When I first heard of the accident, I was hypothesizing that he just missed clipping into his belay loop—maybe he was tired, with tons of gear, ropes, rack, pack etc all clustered around—and when he clipped his GriGri to his harness, he just missed the belay loop and leaned back for the rappel. I couldn't believe that his belay loop broke—because like I mentioned in the rope breakage report, I am a firm believer of "belay loops just don't break." There must have been some outside circumstances involved. It raises many questions:
Could Todd's belay loop have been SO worn that it broke under bodyweight?
Could it have been affected by acid?
Could it have been affected by some other chemical (bleach, DEET, etc) that caused it to weaken?
Could it have been so worn, dried out by the sun, or rotten, etc. that it failed under body weight?
Could it have been affected by some other outside circumstances that caused it to fail during rappelling?
Some Unofficial, Incomplete, One-Data Point, For-Curiosity-Only Experiments
To satisfy my own curiosity I decided to test several belay loops with different levels of wear: cut approx 50% through, cut up to 80% through, cut close to 90% through, two tacks cut, all tacks heavily abraded on a file surface, structural web heavily abraded on a file surface, etc. By no means are these experiments complete or conclusive as there are many variables that were not, but could be looked at like: belay loop construction (2 tacks vs. 4 tacks, protective non-structural layer over top of the tacks), material used (nylon vs. polyester), UV degradation, environmental, wear, etc, etc. Basically, the results were what I was expecting. Belay loops are burly—really burly. To have one fail at body weight loads, or even small shock loads which could happen during rappelling is possible, but the belay loop would have to be SO worn through that it seems very unlikely.
Below are some photos of the different belay loops I tested (before they were pulled to failure) and their tested values.
50% cut through—one side —3480 lbf:
~75% cut through—both sides (not the best photo)—2918 lbf:
~ 90% cut through—one side—777 lbf:
2 of 4 tacks cut—3970 lbf:
All tacks heavily abraded across file surface—5280 lbf:
Structural webbing heavily abraded across file surface—4805 lbf:
All tacks heavily abraded across file surface—5338 lbf:
All tacks heavily abraded across file surface—7429 lbf:
A Final Word
Is this incident going to cause every climber out there to start wanting two belay loops, or tying a backup webbing belay loop in their current harness or throw their harness away altogether and buy a new one immediately? It shouldn't. Reputable manufacturer's make burly harnesses—bottom line—and don’t forget that there are some negatives/concerns about using two belay loops at once in some situations (i.e. tri-axial loading carabiners, etc.)—not good.
Harnesses, and belay loops in particular are super strong for sure, but we can't forget that gear does wear out. Every climber is responsible to know the history of his or her gear and act accordingly. When people ask me about worn gear, or gear that's been dropped, or has undergone a strange or peculiar event, I always have to play the conservative card of "when in doubt, retire it"—because the last thing you want to be thinking of in the back of your mind when you're 20 feet above your last piece of sketchy gear is... "geez, I wonder if that's that biner that I dropped that time," or "I sure hope my harness is in good enough shape to withstand this monster whipper I'm about to take." It's not worth having to worry about—I personally have a hard enough time worrying about trying NOT to fall…
Climb safe,
Kolin Powick
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Kolin Powick (KP) is a Mechanical Engineer hailing from Calgary, Canada. He has nearly 20 years of experience in the engineering field and has been Black Diamond's Director of Global Quality since 2002. Kolin oversees the testing of all of Black Diamond's gear from the prototype phase through continual final production random sample testing.
United States / English 
14 Mar 2011, 4:12PM
Lots of good chatter on this topic as always.
BD recommends tying into the two tie -in points, and belaying off the belay loop (that’s why it’s called a belay loop after all)
Bjorn – there are several advantages to using a belay loop in my opinion.
1) It keeps the belay device a little further away from you – so it’s easier to thread, see and use – this becomes more important when it’s dark, you’re wearing gloves, or you’re cold and tired.
2) Similarly – belaying off the belay loop keeps your entire system more organized – especially for multipitch climbing. Ropes tied into the tie in points – belay device off the belay loop. Simple, tidy, clean. Keeping the junkshow to a minimum is always preferred.
3) Crossloading – crossloading is real possibility. Ideally you don’t want to triaxially load a carabiner – they aren’t designed to take loads like that. However, in most typical climbing scenarios, the loads at the belayer are very low, and this isn’t really much of a concern. But I would always argue, why not stack anything and everything in your favor, and if possible, reduce one variable – using a belay loop (if your harness has one) – just takes that possibility of cross loading totally out of the system.
And to your comment (“for me it is a single point without any backup”) – technically you are correct, and climbers are taught, for good reason, about redundancy. Just know that belay loops are incredibly burly… as well, remember usually you’re only climbing with one rope, one belay biner, and one belay device – also no backup.
However, what about the Alpine Bod? It’s true, it doesn’t have a belay loop:
http://www.blackdiamondequipment.com/en-us/shop/climb/harnesses/alpine-bod-harness
in the BD instructions,
http://www.blackdiamondequipment.com/uploads/black-diamond/files/MM5873_A%20Alpine%20Bod%20Harness.pdf
We recommend tying in around both the buckled waistbelt and the crotch loop. (ie. no carabiner when tying in)
However, when belaying or rappeling, we recommend using a locking biner around both the buckled waistbelt and crotch loop. And belaying using that locking carabiner.
So Jason, what you were going to do is correct: use a locking carabiner to connect the two tie-in points and belay from that.
Don’t let the discussions about crossloading freak you out too badly. As I said above, in most typical climbing situations, the loads aren’t that high – and you also must remember, that just because you’re using a locking carabiner to connect to the tie-in points doesn’t mean that it WILL get cross-loaded, it just means that it is possible for this to happen. Many moons ago when I started climbing, I too used a locking carabiner through both tie-in points. I just always checked (like multiple, multiple times during the belaying of a pitch) that I wasn’t cross loaded. I finally saw the light and starting using the belay loop to belay from (it’s called that for a reason)
Bottom line: Always use your gear according to the Manufacturer’s instructions - if you’re harness has a belay loop, use it to belay from – and tie in to the tie-in points. If you’re harness doesn’t have a belay loop, use according to manufacturer’s recommendations – just try to be aware of the advantages/disadvantages or associated risks involved.
There you have it
KP
20 Feb 2011, 11:21PM
Kolin, this is some very good data. What about in the case of the Alpine Bod harness that has no belay loop? I was just going to snap a locking carabiner in the tie in points but since reading about cross loading, it makes me think twice about it. Funny thing is this is how we climb and rappel in the Marine Corps. Every climbing school in the Corps teaches how to tie a Swiss seat, attach a locking biner to the are that would be the belt and than tie the climbing rope to the biner. Makes me think twice about ever rapping with Marine Corps equipment again.
16 Jan 2011, 10:42AM
Hi!
Thanks for all interesting information, which still keeps me wondering
why I shouldn´t use a carabiner (that goes through leg and waist loop -like a rope) that is attached to an ATC/Gri-Gri or similar, instead of using the
belay loop (which for me is a single point without any backup).
Is "the belay loop" approach (i.e. when belaying) different companies
recommendations, or is it scientificly confirmed that the carabiner is
affected by different forces, compared to - when only using the belay loop.
Rgs
Bjorn
14 Oct 2010, 1:36PM
wondering how you tell the manufacture date on your harnesses by the various serial #'s... for example; RN#81935, BD651003, PO# 41938...?
5 Jun 2010, 11:34AM
Thank you for clarifying the issue about the usage of belay loop and tie-in points. I learned my climbing skill in Australia where safety was adamant and I was always warned to use the belay loop for belaying and rappelling (as Peter said above).
But when I went back to Indonesia, I was told (repeatedly) to use the tie-in point to clip my carabiner. I think BD or other leading harness manufacturers should write to the climbing federation here that their common practices is actually extremely dangerous. Many of the new climbers were informed wrongly and it will be scary thought to imagine what might happened.
Thank you for the info.
2 Jun 2010, 8:20PM
Great information, thank you for sharing the results of your tests. I work in a gear shop so I am glad to be able to reference this information when customers ask. Obviously something else besides wear was responsible for causing Todd's belay loop to fail. There is a lot of misinformation out there in the climbing community and the more we know the safer we can all be.
Speaking of misinformation, Alex Jones' question about where to belay from: the belay loop is for belaying and rappelling. The tie-in points (the two loops that the belay loop is connected to) are for tying in with your rope/ropes. The tie-in points are NOT for clipping a carabiner to, as this creates the potential for cross loading your belay carabiner and causing it to fail. BD and all other climbing harness manufacturers will confirm this.
2 Jun 2010, 4:02PM
In response to Alex's post, here's the way I understand the question of belaying from both the leg loops and waist belt as opposed to belaying off only the belay loop: While putting your belay carabiner through both the leg loop webbing and the waist belt webbing would theoretically take an extra link out of the "chain" and thus increase redundancy, it is also very easy to load your belay carabiner in a triaxel loading situation, that is, when you have three different directions of pull on the same carabiner (leg loops - waist belt - climbing rope to fallen climber). Belaying directly off the belay loop eliminates this possibility and ensures that your carabiner is only loaded in two directions.
1 Jun 2010, 1:48PM
tanks, text was so interesting.
actually i am doing a study about the forces generates in a climbing fall and what we do to know when a harness whas subjet to a hard force, and is better to change it.
i am industrial designer in the universidad industrial de santander, Colombia.
i really would appreciate if you can give me some information about materials, for the 3d modeling and tension´s deformation
31 May 2010, 11:01PM
I always have comments by other climbers and friends on where the best place to belay from, whether the two loops that the belay loop is connected to is a stonger point and to place the biner through both of these loops or use just the belay loop itself. Any insight on strength ratings for this?
30 May 2010, 7:50AM
I usually will back a belay loop up from the beginning of its use with an extra piece of webbing, but I always tie the webbing so that the new loop is larger than the belay loop and not under weight. If for some strange reason my loop breaks, I have a temporary backup to get me off the mountain, but I couldn't see my belay loop ever breaking in the first place, but always a good idea to back up gear...maybe make a smaller dynex loop that is larger than the belay loop for an additional backup...gives climbers that extra peace of mind.
27 May 2010, 11:45AM
So no one really knows for sure what happened to 'Todd Skinners' harness?? I had heard he had a daisy chain or two girth hitched to his harness for years and that caused the loop to not rotate, and thereby randomly exposing different parts of the belay loop to wear; instead focusing the wear on one spot (but the only way I can think of to get a lot of wear at one spot would be to tie the climbing rope into the belay loop and not the tie in points, which I doubt he did). This is just here say. Does any one know for real? Is it in the AAC's annual Accidents book? Thanks.
26 May 2010, 3:00PM
Very interesting, thanks for sharing!
Does that mean nobody ever found out the exact circumstances of Todd Skinner's accident, and the reasons his belay loop failed?