Testing Rquirements for Horizontal Lifelines

[andriver]

Hello,

My company is doing some work in a plant that has an existing horizontal lifeline comprised of wire rope that runs to a turnbuckle which is connected to an anchor plate in concrete columns. I do not have any details on the embedment for the anchor bolts in the anchorage point and I was wondering if we could load test the horizontal lifeline to approve it as a tie-off point.

I did read in OSHA "Personal Fall Arrest Systems - Non-Mandatory Guidelines for Complying with 1926.502(d)" that "Testing of installed lifelines and anchors prior to use is recommended."

What tests would you conduct, are they the same as those you would conduct for a body harness? The phrase "testing installed lifelines prior to use" implies that testing the system does not automatically exclude a tested system from being used in service.

What procedure would you all recommend for testing a lifeline to demonstrate its adequacy for service?

 

[JStructsteel]

I would think a 5:1 load test on the anchor would be sufficient. If it fails, what would be the fix? Perhaps a new anchor would just be the way to go.

 

[andriver]

I would like to test the whole system, would this require testing the anchor and the wire rope separately? The span is over 100' passing through eyes roughly every 15' At the eyes there are Crosby clips on either side to prevent sag accumulating at one spot. There is a small "stub" piece at every eye location to double the wire rope thickness at those locations to prevent abrasion I assume. I could engineer a new system, with new anchorage points with known material etc, but the span would make this a costly solution. I would prefer to test the system as a cost savings measure, but am looking for a formal approach.

 

[thaidavid40]

Is this system an "engineered system" (or did you reverse-engineer it, i.e.,: analyze it for load capacity)? If it is an "engineered system", then you have a 2:1 safety factor on the ultimate capacity for the line and its components. If the fall protection uses a fall limiter, then the usual static-equivalent maximum load for that is 900 pounds. At a 2:1 load factor, that is a factored 1,800 pounds falling live load. Run through the components using this live load for your analysis. If it is not an "engineered system", then you must test it to the OSHA maximum 5,000-pound ultimate load capacity (but not to a 5,000-pound falling load!).
Dave

Thaidavid

 

[andriver]

thank you all for your responses.

I believe it to be an engineered system, I am currently waiting on info from the owner that hopefully will provide the PE stamped drawings, and a maintenance schedule. This would make me feel better.

I have reverse engineered the system, but I still have two unknowns (sag at every span, and anchor embedment). I also don't know when this was installed although the components are all stainless and look to be in good condition from what I can reach.

My issue is, if I get no information from the owner, how can I test this system (if permitted) to feel warm and fuzzy letting the field use it? Do I just suspend 5000 lb load from the center span and for how long? Does a 5000 lb load test allow for more than one to be tie-off to the system (5000 lb/2 = 2500 lb with a 2:1 FOS). There have to be situations where an existing lifeline with no information available was tested in order to verify its adequacy.

Thanks in advance for input.

 

[thaidavid40]

You definitely don't want to hang a 5,000-pound load on that cable! I believe the test load would be the same as the factored design load: 1,800 pounds. And this is a static load - not a falling load. Don't take an 1,800-pound load and push it off the end of a platform. This load should be applied statically (very slowly) until fully-supported equilibrium (or failure!).
Dave

Thaidavid

 

[CANPRO]

Personally I would test the anchors and not the static line itself. Above posters are correct (for North America anyway) that you design to twice your maximum arrest force(MAF). If the maximum is 900lbs, this must be stated on the drawings. Note that not all lanyards limit the MAF to 900lbs, some are 990lbs and some are 1200lbs (or more I think, I usually specify max 990lbs). I would make sure the static line and fittings could be confirmed for their required capacities - if anything is in question, replace it.

If the capacity of your anchors is less than 5000lbs in any direction, this must be stated on the drawings. If nothing is specified people will assume an anchor labelled as "Fall Arrest Anchor" will have a 5000lbs ultimate capacity.

 

[andriver]

Thank you CANPRO,

I think I agree with your procedure, of testing the anchors themselves, and then inspecting the hardware and replacing any questionable or worn components.

 

[Lomarandil]

Except that for a horizontal lifeline, the anchorage design loads could be much higher than the MAF of the harness -- due to cable geometry and depending on sag. They may even be higher than the OSHA standard 5000 lbf ultimate.

In my mind, you'd either need to test the entire system or adjust your anchorage test load accordingly. And I think the former is easier.