You may be right. I thought it was mean, but may be minimum. Regardless, they should be right around that value or higher.
Ringling Bros. Accident
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You may be right. I thought it was mean, but may be minimum. Regardless, they should be right around that value or higher.
Jay Ashworth
Well-Known Member
Thank you for the clarification, Lava, this is clearly why I am NOT a rigging guide. That said, my solution would be to say if you're buying things from somebody who does not indicate what the measurement is a measurement of, clearly, on each use, then buy from someone else.
Sent from my SPH-L720
Sent from my SPH-L720
Jay Ashworth
Well-Known Member
BillConnerFASTC
Well-Known Member
By saying it complies with the ANSI standard, which I believe prescribes the the marking, does indeed provide a competent person *exactly what that measurement measures*. If you don't like it, the fact there is an ANSI process that allows for public input and requires the requirements to be reached by consensus of affect parties.
Jay Ashworth
Well-Known Member
BillConnerFASTC
Well-Known Member
I don't know what you would suggest if an ANSI standard - one developed by all interested parties - isn't good enough for you. Perhaps a 2300 page document that congress turns out?
A bit of history: I was befuddled and confused by the building and fire codes for stages when I began as a theatre consultant 30 years ago, because they were based on a notion of theatre in the early 1900s and thinks had changed. I asked, was invited to participate in the process, and 27 years later am the senior member of NFPA's Assembly Occupancy Committee and have seen the code modernized quite a bit. (Granted - it still feels like 1960's in some regards - but I think much better.) So get involved - it's not that hard - and demonstrate that your proposal is necessary for safety.
Jay Ashworth
Well-Known Member
I would suggest that if manufacturers are going to use pounds (pounds-force, actually, I think) or kN, or what have you, as multiple different types of measurement, some with builtin safety factors, and some without, that they ought to say "breaking strength" or "working load" or whatever parameter label is pertinent, right next to the number, exactly as I suggested.
That doesn't seem especially complicated -- unless you are purposefully obfuscating the number so as to make more money whilst pushing liability off to others -- and is *much* more effective communication than *merely* putting that into a standard, no matter how small the document or how easy it is to find. And my concern is *solely* the communication, not how that number came to be whatever number it is.
The number of professionals *in-specialty* who have disagreed on, or misunderstood, ratings - just in the conversations here in the last 30 days - is my evidence that that's necessary; I have specifically in mind the Trim Chains megathread.
That doesn't seem especially complicated -- unless you are purposefully obfuscating the number so as to make more money whilst pushing liability off to others -- and is *much* more effective communication than *merely* putting that into a standard, no matter how small the document or how easy it is to find. And my concern is *solely* the communication, not how that number came to be whatever number it is.
The number of professionals *in-specialty* who have disagreed on, or misunderstood, ratings - just in the conversations here in the last 30 days - is my evidence that that's necessary; I have specifically in mind the Trim Chains megathread.
I would agree with that. Perhaps all equipemnt needs to be marked with a rating and either it being MBS (and decide whether thats mean or minumum) or WLL AND the safety factor used. Honestly I'd prefer all equipment to list MBS, as most WLL safety factors (eg spansets) are not sufficient for overhead rigging.
BillConnerFASTC
Well-Known Member
I am not surprised by how many didn't know that climber's carabiniers are marked in minimum breaking strength, partly since I didn't know, but am a little surprised not many looked it up. It took me at most 20 minutes to find out what the rating meant, howvir was used, and some graduate project that tested them - before and after impacts.
As far as changing the rating marking on a device made primarily for climbers, not entertainment rigging, probably in the 1000s of climbers for every rigging use, I think if I were a climber I'd be pissed, because it would add cost and some confusion to what I'd always seen and used.
But work to change the standard. Personally, I think educating riggers is a better way to go and I agree I wish they'd just mark minimum breaking strength on everything, so the person using it could apply their own design factor based on the application.
As far as changing the rating marking on a device made primarily for climbers, not entertainment rigging, probably in the 1000s of climbers for every rigging use, I think if I were a climber I'd be pissed, because it would add cost and some confusion to what I'd always seen and used.
But work to change the standard. Personally, I think educating riggers is a better way to go and I agree I wish they'd just mark minimum breaking strength on everything, so the person using it could apply their own design factor based on the application.
Jay Ashworth
Well-Known Member
You've still misunderstood me, Bill.
I'm not talking about changing which measurement those manufacturers quote. I'm simply advocating that they *label the measurement everywhere they use it*. They're welcome to rate that 45kN as MBS. Just *say*
"45kN MBS" or, where there's space, "45kN Min Bkg Strength".
That's all I'm suggesting; I'll have to go back and reread my earlier comments to see how I'm giving a different impression.
I'm not talking about changing which measurement those manufacturers quote. I'm simply advocating that they *label the measurement everywhere they use it*. They're welcome to rate that 45kN as MBS. Just *say*
"45kN MBS" or, where there's space, "45kN Min Bkg Strength".
That's all I'm suggesting; I'll have to go back and reread my earlier comments to see how I'm giving a different impression.
BillConnerFASTC
Well-Known Member
I understand what you want, but I also understand why it's not economically practical for the manufacturers to change all their dies or whatever they use to stamp the rating in, especially if not everyone has to do it since it will add to cost, and further it could confuse the prime climbing customers who are use to a rating as it is and would be confused by the change. I believe it is simply not worth it to the manufacturers to incur additional costs for the benefit of a very small minority of users, especially if voluntary and not required for all thier competitors as well.
BillConnerFASTC
Well-Known Member
Someone else addresses the subject: http://www.stage-directions.com/29-all/news/theatre-buzz/6131-defining-terms.html
Jay Ashworth
Well-Known Member
He seems to be suggesting that the climbing shackles are marked "MBS". And that seems to be contrary to what I've been reading here.
Sent from my SPH-L720
Sent from my SPH-L720
Climbing shackles don't exist to my knowledge. Theres climbing carabiners (usually marked MBS) and shackles (most common use is crane/ship rigging) which are marked WLL.
News stories floating around that the women involved have retained a lawyer, and while litigation is not currently pending, a thorough investigation on the women's behalf is underway. It's still uncertain that all of the women will walk again, and physical therapy is ongoing for most of them.
Jay Ashworth
Well-Known Member
BillConnerFASTC
Well-Known Member
Jay - I don't know if you misunderstood Mr. Sapsis, but I thought he clearly stated that while much hardware manufactured and used by industry is marked with a working load, hardware manufactured and used for climbing and related recreational/sporting use is marked with minimum breaking strength. Either may or may not indicate which it is, and therefore users should find out before using the device and not succumb to assumptions.
I wish it were all labeled with MBS because I prefer to apply my design factor and not what a manufacturer thinks is suitable for all applications. I find it much more time consuming to determine what the design factor is for a piece of hardware labeled with a WLL than to determine if it is WLL or MBS.
Is there any regulation regarding the stamped rating or is it just how the separate industries (climbing recreational/entertainment rigging) evolved? To rephrase- Is there a governing body over climbing hardware that says you must stamp MBS and it's in kN? I would wager the manufacturers are building to the needs of their client community, so do climbers typically consider WLL when purchasing hardware?
I'm guessing at some level it comes into play since you're dealing with pretty dynamic loads. I would also guess that there may be more injuries or fatalities involved with climbing than with entertainment rigging since it's more accessible to the general public and just easier for a greenhorn to get involved with (and possibly over their head if not guided by a professional).
I'm guessing at some level it comes into play since you're dealing with pretty dynamic loads. I would also guess that there may be more injuries or fatalities involved with climbing than with entertainment rigging since it's more accessible to the general public and just easier for a greenhorn to get involved with (and possibly over their head if not guided by a professional).
BillConnerFASTC
Well-Known Member
Strad - I believe the ANSI standard for the typical climbing carabiner requires labeling MBS in kN or pounds - but that is not a statutory law, just a standard that meets the ANSI requirements for their designation. It seems the ANSI fall protection standards require same, but I have not bought them - quite steep - nor read more than summaries which may mislead. So I'd say that yes, there is a "standard" that requires labeled devices and MBS, but not a law or governmental entity in this country that enforces that. (read my Protocol article on Codes vs Standards for more on this.)
I'm not sure there is a standard as clear for, say, a turnbuckle or shackle, but usually not too hard to find via Google. Crosby seems to use a design factor of 5 - so if its marked or shown in data to be a 1000 WLL, then its 5000 MBS. That's probably OK for a static condition - like a lot of dead hung - but theatre rigging that lifts - with the combination of dynamic loading, the "overhead" factor, and tradition - generally has a design factor of 8 or 10 - so that 1000 pound WLL turnbuckle is only 500.
Keep in mind that the structural framing of a building is probably designed using a factor of 3 and may be lower in some cases.
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