Blown wire on #1 BD Stopper

[Szyjakowski]

you ever seen Cliffhanger...what if BD harness buckles were really made of lead.

I would bet it was a freak inperfection in the material + bad timing. glad your okay.

[JosephH]

I managed to blow the wire on a #2 stopper a few years ago. We had meandered off up some old aid route towards the top of Beacon, reached a section with some hard moves protected by what I thought was a bomber placement. It was a bomber placement. Sadly, I forgot about metal fatigue. I think the wire blew on my third try at the sequence; the first two falls had been less than 10'. The last one was significantly longer. I called BD (not really to complain, just to tell them what had happened) and they sent me a new nut.

 

Ah - it was a #2 then - yours is the one we found then. That is now the last free pitch of "Lost Warriors".

[korup]

Cool response from BD-

 

Thanks for the email regarding your #1 stopper.

 

During production of the Black Diamond Stoppers, the batches go through 4 separate testing phases

1) We test the cable alone in single strand configuration to confirm strength requirements of the cable

2) we test the cable over a simulated stopper to confirm the behavior of the

cable of the bend at the end of the stoppers

3) we test the cable in a loop to confirm the swaging process

4) we test a statistical sampling of the final batch to confirm the finished product. This test is performed using a 10mm pin which is a CE standard and represents a carabiner.

 

Given the exhaustive testing performed on all BD PPE (personal protective equipment), I find it most unlikely that the stopper in question 'snuck

through'. I'm sure there is a logical explanation.

 

The #1 Stopper final product rating is 2kN (450lbs) and is intended for progression only (ie. aid climbing) which is what you were doing. The reality is that depending on how you clipped into it, and the exact circumstances of the situation, this load is easily attainable. Let me

explain further. If you clipped directly into the piece with a runner or daisy from your harness and gently lowered onto it - then the load the piece

would see would be your bodyweight (195lbs). If however, you clipped a biner or draw through the piece, then clipped your lead line through the biner and weighted the lead line - the force on the piece is actually twice

your body weight - your body weight on one side added to the force it takes the belayer to hold your body weight (not taking friction into account is your body weight once again) equals the load the piece has to be able to

hold - in effect twice your bodyweight or approximately 400lbs.

Either way you were clipped in, it is amazing how much force can be generated by an extremely small shock load onto the piece (ie. your feet

slipping and losing your stance on the wall, bounce testing, etc). If you're interested Duane Raleigh wrote a great article in Rock & Ice issue October 2004 - Climb Safe Series regarding shock loading daisy chains, etc.

 

Bottom line is that loads of 2kN are easily attained in the field.

 

I am curious to whether the cable at the biner end of your stopper was slightly damaged. It doesn't take much to damage the 1/16" galvanized

cable; a yank with a nut tool, accidentally getting the nose of a biner hung up, etc.

 

All stoppers are labeled with a date code (4 digit number) which is located on the 3sigma tag under the plastic shrink tube. If you still happen to have this piece I can do further investigation into the exact batch that

this stopper came from and get even more specific details regarding that exact batch. Feel free to email me directly with the Date Code. Also, I would be very interested to see the piece. Please send it to:

 

Kolin Powick

Quality Assurance Manager

Black Diamond Equipment, Ltd

2084 East, 3900 South

Salt Lake City, UTAH 84124

[catbirdseat]

... If however, you clipped a biner or draw through the piece, then clipped your lead line through the biner and weighted the lead line - the force on the piece is actually twice

your body weight - your body weight on one side added to the force it takes the belayer to hold your body weight (not taking friction into account is your body weight once again) equals the load the piece has to be able to

hold - in effect twice your bodyweight or approximately 400lbs. ..

This isn't what you were doing, though, was it?

[korup]

Correct CBS. The only thing on the piece was the aider; clipping that piece would have been pretty silly...

Edited July 12, 2005 by korup

[tomtom]

Re: BD Stoppers--Bounce Test Data

 

From - Tue Feb 16 14:36:39 1999

From: Chris Harmston <chrish@bdel.com>

Newsgroups: rec.climbing

 

I have measured forces up to 1000 lbf while bounce testing. I was using BD Etriers and bounced with about a six inch free fall bounce. It is easy to break small Stoppers if vigorously bounce testing. I weigh 190 lb.

 

I have seen several small stoppers break in the field due to bounce testing and due to lead falls.

 

Rated strengths are stated as 3 sigma failure loads. There is not a 20 to 30% buffer. They break close to what they are rated. 3 Sigma is three standard deviations below the average breaking strength. Average batch test results (n = 10) range from 600 to 700 lbf for #1 and #2 Stoppers. Batch standard deviations range from 6 lb to 50 lb. When combined into a years worth of data our rating computes to 450 lbf. The weakest sample I have seen in the last year failed at 535 lbf. The strongest failed at 808 lbf. 3 Sigma means that there is a 99.87% chance that the sample will be stronger than the rating. This also means that there is a 0.13% chance that a sample will fail below the rating. All this data is for brand new equipment that has never seen any fatigue due to placement, removal, falling on, bouncing on, etc. These small units get worn fairly quickly and can break eventually. Inspect your gear often. If you have to use these for lead protection then follow the advice of most of this group. Back them up. Sometimes the only option you have is a small nut. Better than nothing in many situations. Beware of the limitations of your gear though. Chris

 

On Tue, 16 Feb 1999 mdimeo@brooktree.com wrote:

>In article <36C8F69A.82BF48A1@boeing.com>,

> Mike Garrison <mike.garrison@boeing.com> wrote:

>> ratagonia@zdnetmail.com wrote:

>> > Catalog say 2kN or 450 lbf for #1 & #2. Not hard to generate this kind of

>> > load in a fall.

>> That's an understatement. My body weight is close to 1 KN.

>> Just jumping up and down I can generate about 2 KN.

>

>Ooh, a verifiable experiment. I like it. How about you try it out?

>I've always wondered how much force a bounce test really generates.

>Clip a biner to a bolt low to the ground. Slide the head down a #1 stopper.

>Clip one end to the bolt biner. Clip an aider or sling to the other end.

>Don safety glasses. Bounce. See if you can break it. I'm really curious.

>

>Off the top of my head, I'm betting biner flex, aider stretch, etc. will

>prevent breakage. Time to find myself a low bolt, though my weight is only

>around 0.73kN.

>-m@

 

Chris Harmston (chrish@bdel.com).

Quality Assurance Manager. Materials Engineer BS, ME.

Black Diamond Equipment Ltd.

2084 East 3900 South, SLC, UT 84124 phone: 801-278-5552

 

Go Fish

[korup]

Email from BD-

 

I received your sample in the mail and have had a chance to go over it, look at it under the microscope, dig up some paperwork on the order and do some additional testing. Here is my summary:

 

#1 Stopper - Date Code #2289 (SKU#225201)

MO#31592, Cable SA MO#30946

 

*RM testing of single strand cable is all above spec and typical (ref test log#21267)

*WIP testing of cut cable lengths over simulated stopper is all above spec and typical (ref test log#21339)

*WIP testing of cable loop to confirm swage is all above spec and typical (ref test log#21649)

*Final Batch testing of finished product is all above spec and typical. (ref test log#21750)

 

Basically, all testing data shows that this batch of stoppers is typical.

 

 

 

Additional Testing

 

*I grabbed 5 more #1 stoppers (different batch) and tested them - all modes were cable at nut, at typical loads of approx 700+ lbs.

*I even managed to find two #1 stoppers from the same batch as yours and tested them - again - all modes were cable at nut, at typical loads of approx 700+ lbs

 

 

Placement Hypothesis

 

The interesting aspect about your sample is that it broke at the biner end. All testing I have performed over several thousands of orders of raw material cable, final batches of stoppers etc has the cable break AT the stopper, never at the biner. This is what has led me to believe that in

your case it was a function of the placement. As you suggested, possibly the one biner, attached to the other biner, and the exact circumstances of the placement caused enough torquing to force the failure mode to the cable

at the biner end of the cable loop. I tried to replicate this at the lab but was not successful.

 

I then thought that perhaps the nose hook of your oval wire was caught in the loop of the #1 stopper - and perhaps the narrower thickness and sharper radius was the culprit. I tested that set-up in the lab and was successful

at forcing the failure mode to the cable at the biner. I tested two stoppers using this set-up: one failed at cable at biner, the other failed as is typical with cable failing at the nut.

 

Do you think it's possible that your ovalwire nose hook was caught on the wire of the stopper?

 

To conclude, based on the original manufacturing order testing, as well as the additional testing performed, I have the utmost confidence that your stopper was within manufacturing specifications and the cause of the break

was due to variables found during placement and loading.

 

 

 

A replacement #1 stopper will be in the mail to you this week. Thanks again for bringing this to my attention.

 

 

Kolin Powick

Quality Assurance Manager

Black Diamond Equipment, Ltd.

[forrest_m]

I have to say, this is an impressive testimonial to BD - granted it is in their own best interest to investigate this kind of thing, but still, they put a substantial amount of time into the multiple responses, additional testing, replicating the failure mode, etc. And then, finally, after demonstrating that the breakage was almost certainly due to pilot error, not manufacturing flaw, they still send you a new piece.

[korup]

Yup, very impressive. However, I am quite sure the piece was not caught in the nose slot, and 'biner to 'biner connections are normal (at least aiding), so I am not sure what lessons I can take for future placements.... any thoughts out there?

[forrest_m]

I like his suggestion that there may have been some damage to the cable. A lot of breakage-type failures require some place to start, concentrating the loads in one place which leads to successive failures in the surrounding material. It seems like even slight damage to that tiny cable might be enough? Another argument for religiously examining your gear...