Fall Protection on Standing Seam Panels 1

[xez]

Hi Everyone,

Fall protection is new to me and I am stuck with a few questions. Any help is greatly appreciated.

We have an anchor system that will be used on a standing seam insulated panel. Per OSHA design requirements, the anchor was designed to a 5,000 lb single point load. Since the load will be transferred onto the standing seam system, is it practical to use the 5,000 lb load for the panels?

The standing seam panels are fastened through the interior facer (26 gauge) along with a clip (24 gauge) to give us a total sheet thickness of 0.042''. Panels are fastened into 18 gauge material. I am concerned with the shearing of the 18 ga material or the interior sheet when a 5,000 lb load is induced on the panel. Does the system need to be designed to this or is there another design load we use? I don't see why we need a 5,000 lb load for a single lifeline.

Thanks in advance for your advice/input.

 

[Ron]

bcng...I hope you're not using a standing seam panel to sustain a 5000 lbf load. The anchor must be in something more substantial than the panel....even a purlin might have a problem with that, particularly with fastener pull-through. Fasten your system to the primary structure, not the panels or purlins.

The 5000 lbf requirement is a static load to compensate for the dynamic load that falling would create. When considering worker life safety, it is much better to be conservative.

 

[jberg]

An option for standing seam roofs is using a manufactured system (Capital Safety, MSA, Miller, etc.). They need to be installed and the support framing engineered by their certified installation companies and meet the minimum gauge thickness requirements. Off the top of my head, I don't remember the requirements, but I would speak with the sales reps from Capital Safety (

http://wwww.capitalsafety.com),

but the other companies are good too, I just had a lot of help from Capital Safety. The website is down right now (9pm CST on 10/8/12), but I know Gary Underwood (He was in Midwest Sales) really helped me when I was just learning about fall protection 8 years ago.

JWB

 

[a2mfk]

I agree with Ron. I have designed a few of these for steel fabricators and they can be difficult even with using rolled steel. They may need to work off lift equipment that is rated for fall arrest loads rather than try to make it work with the structure.

 

[MiketheEngineer]

You could put up perimeter guardrails - think scaffolding.

Also, little known is that OSHA allows the force to be only TWICE the anticipated load. We use a load of about 2,000 lbs after extensive testing. So if you are using a specifically designed system - usually with a shock absorbing lanyard or SRL - you might get that to work.

Or you might use a horizontal life line - sometimes hard to find anchorage points.

Good Luck

 

[xez]

Sorry. Let me clarify. We are using a custom manufactured standing seam roof clamp/anchor developed by Guardian Fall Protection (similar to

http://www.guardianfall.com/product..._images2.tpl&category_id=41&product_id=1974).

The calculations for this anchor using a 5000lb load have been verified by a PE.

Since this anchor can sustain the 5000lb load, it would be transferred onto the panel and its connections. I'm concerned that the load will widen the fastener holes or shear.

 

[PUEngineer]

I think most fall protection specifications require a load test to the ultimate values and limit the permanent deformations to some small amount. I'm sure someone more familiar could elaborate or correct me. So, if you're worried, I would imagine the load test would be a good indication of whether you need to worry. Is there some kind of load testing procedure?

 

[CANPRO]

that looks like its meant to be used as TRAVEL RESTRAINT not fall arrest. Big difference in the loads. With travel restraint you're limited to your safe working area and not expected to fall (ie you don't need to design for 5000lbs). Check your local OSHA for required design loads for travel retraint.

 

[MiketheEngineer]

What exactly does the mfg say??

 

[xez]

We are the standing seam manufacturer. The job is designed and is complete with the installation phase. Post-installation, customer wants to use these anchors on our panels. Since the anchor itself has been calculated and won't fall of our panels, we will need to check the roof system to make sure that we can support that 5000 lb load, which I don't believe we can. The insulated panel is fastened at the interior (with a clip) onto a 18 ga supports..

 

[dhengr]

You should certainly read that (your) state’s OSHA rules on this matter, and discuss this matter with the local OSHA people to get their take on the matter. They are generally helpful when you come to them in the first place rather than waiting for a problem to develop or for a citation from them because of a problem.

With any piece of equipment like you showed, you should get (they should provide) testing reports and certification papers from a reputable lab. Along with complete instructions for its use. Their certification stops where the yellow painted parts touch your roofing seam, and it is always your responsibility to actually design and certify the attachment system adequacy. I’m not sure I like the idea of tightening four bolts on a roofing seam as a means of securement. And, you don’t usually have the sharpest guys in the world doing this with torque wrenches either. Designing that piece of equipment for 5k is no great shakes, nor is testing it when you can bolt it to a W 14x730 column, but you have to show that you can get that 5k down into adequate structure to take that loading. As MiketheEngineer mentioned there are a couple work-arounds to reduce that 5k loading.

I don’t like the design of that piece of equip. because it applies the 5k load up 6" above the standing seams. And, this will tend to lift the high side of the locking bracket off the standing seam, literally roll it up about the lower corner of the clamp, a difficult load direction to justify. I would like to get that 5k load right down at the top of the standing seam and generally in a parallel plane to the roof. That loading is more likely taken by many fasteners from the sheet to the structure using the roofing sheet as a long shear diaphragm. Maybe you need to span several sheets of roofing with the yellow device, and make it stiffer in its plane parallel to the roof to distribute the 5k to more sheets/fasteners. Remember, the 5k load is an ultimate (about to fail) loading and you can be peeling sheets off the roof at that point as long as you hold the load.

That particular piece of equip. might not be the best solution to work with your roofing. That requirement wasn’t part of the original roofing system design. So, now there may have to be some give-n-take in the final solution to get the customer something workable.

 

[msquared48]

I've looked at these in the past too, and it seems to me that the load was able to be reduced to something in the order of 1800 to 2200# from the 5000# OSHA requirement if I remember correctly. Been a couple of years...

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[JedClampett]

I talked to a manufacturer called Fall Arrest systems

http://www.fall-arrest.com/default.asp

a while back about this issue. If you listen to them there's a large aomunt of load redistribution, overstress and hand waving involved. I wouldn't trust their designs for hanging my 5000 lb. Cadillac (not really) but if I was slipping off a roof, I would count on them.

 

[jgailla]

I had msquared's experience as well. The load was reduced to somewhere around 2000 pounds, but I also can't remember exactly why.

 

[MiketheEngineer]

I beliesve and through our testing - we found that a 250 lb man falling 6' (length of lanyard) and using a shock absorbing lanyard creates a force right around or less than 1,000 lbs. That is why we typically use 2,000 lbs. Remember - all of our people MUST tie off ALL the time and use the proper lanyard

 

[TXStructural]

The OSHA construction standard says:
--
1926.502(d)(15) Anchorages used for attachment of personal fall arrest equipment shall be independent of any anchorage being used to support or suspend platforms and capable of supporting at least 5,000 pounds (22.2 kN) per employee attached, or shall be designed, installed, and used as follows:

1926.502(d)(15)(i) as part of a complete personal fall arrest system which maintains a safety factor of at least two; and

1926.502(d)(15)(ii) under the supervision of a qualified person.
--

I don't think the device shown fits the allowances under 1926.502D)(15)(i-ii), since it is not a complete system. You have to design for 5000 lbs (ultimate) unless you meet these criteria. I doubt you will reach sufficient capacity without permanent deformation to (or perforation of) the roofing from the clamping forces required, even if the anchorage is not subjected to fall loads.

 

[DixonMcQueen]

Hello all,

The OSHA construction code above is indeed how the fall protection community regulates itself for the most part: 5,000 lbs or 2:1 against failure. Another resource you may find helpful is the ANSI Z359 "Fall Protection Code" - particularly Z359.6, the requirements for design.

In effect, the OSHA code recognizes that engineers can be 1) unjustifiably expensive or unnecessary if a piece of structure is OBVIOUSLY strong enough, or 2) hard to get a-hold of at 3am when you suddenly have to make an emergency repair. In short, the code allows an on-site supervisor, shift lead, or other person of similar “competent” responsibility to designate an 'un-certified' (non-engineered) anchorage so long as he or she is certain it can clearly support 5,000lbs and allows for adequate fall clearance. This number is conservative because the non-engineer individual is probably not checking load combinations when designating an anchorage. ‘Certified’ anchorages are designated when an engineer designs them with a 2:1 factor of safety against ultimate failure. No horizontal lifeline should ever be supported by a non-certified anchorage.

Referenced in passing above is the fact that most equipment has some sort of native shock absorption built into it to either protect the worker or the structure. One user above mentions witnessing testing that resulted in anchorage loads of around 1,000 lbs which does not surprise me at all: all equipment/lanyards lists the "MAF" (maximum arresting force) on the label, and on most equipment the MAF is 900 lbs.

The Capital Safety post products mentioned above are the “Leap” posts, designed and lab-verified to perform on standing-seam roofs. The posts are sacrificial with a built-in shock absorption mechanism. Miller, XS Platforms, Latchways, and others all have similar systems. In a fall event then flop over and lay flat against the roof, loading the roof diaphragm in plane as they pay out a shock absorber to limit the load transferred to the roof structure. This process can also add to your required fall clearance, so keep an eye on that. If you're interested I can send you a test video by capital safety, they nearly all operate on the same principal. So long as you install them per the manufacturer's instructions, you can rest assured it will perform as it has in their verification tests. Any given manufacturer should be able to provide you whatever documents you need for settling your own nerves.

The Guardian product you reference is obviously rigid. The SRL block mounted in the unit will probably limit your MAF to 900lbs, but then that needs to be resisted by the roof deck. Keep in mind, the code allows you to yield the structure (ie your roof decking) so long as it doesn't fail. If you don't want the deck deformed at all, you may want to consider other products. You also want to make sure you’re using SRL’s designed for ‘leading edge’ work. I can explain this further if you’re interested.

I've tried to address most concerns in the thread; if I missed something, let me know. In the interest of disclosure I am a structural engineer by trade and licensure, currently working in a design-build fall protection group. We design, supply, and install products and systems produced by a number of different manufacturers. I can't figure out if this forum supports private messages; if it does, feel free to contact me that way or via this thread.