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6100 lbf load on 3 ton hoist

6100 lbf load on 3 ton hoist

6100 lbf load on 3 ton hoist

(OP)
I got a request from a fellow engineer at the plant asking about doing a planned engineered lift per ASME B30.2. The hoist they want to use is rated for 3 tons (i.e. 6000 lbf), and the item they want to pick is 6100 lb.

ASME B30.2 3.2.1.1(a) says “Planned engineered lifts shall be limited to powered cranes having a load rating of 5 tons and above.” I’m not yet sure how that difference will affect us. To me this seems like the proposed lift is outside the scope of ASME B30.2 and perhaps not allowed.

Is there another reference out there that would cover this subject more thoroughly? (e.g. OSHA section? CFR 1910.XX?)

BTW, I am planning to ask the manufacturer for guidance. They're usually quite interested in this sort of thing. Also, standards are nice, but the local authority having jurisdiction will govern.

RE: 6100 lbf load on 3 ton hoist

The answers can be searched for and found using OSHA website search utility. Can't remember exactly: hoists require safety factor of 4X? 6X? Can't remember. You can actually ASK an OSHA expert and find out for sure.

None of that matters, though.

What will the plaintiff's lawyer say during, and the jury decide after, the trial if/when your 6000 lbf-capacity hoist fails while trying to lift a 6100 lbf load? I think I know.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com

RE: 6100 lbf load on 3 ton hoist

tylerdawg is correct. There are places to cut corners in business. This is not one of them. Hoists and cranes are cheap. Lawsuits and human lives are not.

RE: 6100 lbf load on 3 ton hoist

Could you rig up a snatch block to ~ double the lift capacity?
Or, is the 6000 lb limit for the trolley/support structure?

RE: 6100 lbf load on 3 ton hoist

(OP)
tylerdawg & fegenbush,

Yes, I understand that there are serious safety and legal implications for doing something incorrect with lifting equipment. I do not want to belabor that point.

I really just want to find the best acceptable method for moving the equipment. If that happens to be brining in some other lifting device for this one event, so be it. I do have to prove that's necessary though. No one wants to spend an extra $15,000 for something that could've been done via an alternate procedure for $5,000 or less in planning and analysis costs.

When it comes to searching OSHA or other systems for rules and standards, I don't want to miss anything. There might be a specific rule that says this is or is not allowable in some way. That's the sort of information I'm hoping to find (or maybe find leads for) here.

Tmoose,

Although blocks would get the cable tension down, I believe the 3 ton rating includes the trolley. I don't think there are any additional/alternate pick points to use in the area. I'll have to double-check on the pick points though.

RE: 6100 lbf load on 3 ton hoist

Someguy79:
I certainly would take with the crane manfu’er. How old is the crane? What is the controlling design feature? A 6100lb. lift with a 3 ton cap’y. (6000lb.) crane is only a 2% overload w.r.t. the rating. I’m pretty sure that you will find in OSHA that cranes have to be load tested to 125% of cap’y. on some regular basis to be/stay certified. The same 125% applies to most all lifting components. And, this type of equip. is designed to a safety factor far greater than 1.25. I don’t think I would worry much about a carefully planed lift of 6.1k, as long as everything is in good shape. In the final analysis, it kinda comes down to a management decision with some good engineering judgement and guidance in making the determination to save $10 or $15,000.00, vs. some very small potential risk and liability. I’ll bet this kind of overload has happened more often than you would care to know, without anyone asking for your approval.

RE: 6100 lbf load on 3 ton hoist

Although I think the risk is low that your crane will fail and someone will be hurt, it is not my risk to take. Can you mitigate that risk by evacuating the building and moving it by remote control? Can you lift it not in the middle of the trolley or the middle of the rail span, where the capacity may be higher? Can you drain out the oil and get it to be 100 pounds lighter? Can you attach helium balloons to pick up 100 pounds? Can you put a cart under it to take off 100 pounds?

RE: 6100 lbf load on 3 ton hoist

You need to look at the lifting condition the hoist system is rated at. If the 3-ton hoist rating is based on some extreme lifting condition, and you can show your lift will be performed at conditions that put less than max stress on the hoist structures, then you might be OK. On the other hand, you will also need to account for the added mass of any lift fixtures/spreader bars used, which can be significant.

I gave the ASME B30.2 document you noted a quick scan and it does state a "planned engineered lift" is limited to powered lift systems rated at 5+ tons. But even a single planned engineered lift using a powered hoist rated at 5+ tons would require a substantial amount of documentation and analysis.

If this is a single lift requirement, I'd suggest hiring a crane or heavy fork lift for the day.

RE: 6100 lbf load on 3 ton hoist

(OP)
FYI, we'll probably be modifying the 6100 lb cofferdams to remove some weight. That's going to be a lot cheaper and easier to use than modifying the hoist and/or rigging.

Thanks to all of you for the comments and ideas.

RE: 6100 lbf load on 3 ton hoist



What am I missing here? 6 100 lb, lbs = 2.766 913 457 metric ton

RE: 6100 lbf load on 3 ton hoist

OP's using short tons (US ton = 2000 lbs) vs "real" tons = 2240 lbs

another day in paradise, or is paradise one day closer ?

RE: 6100 lbf load on 3 ton hoist

rb1957,

You mean short tons (2000lb) versus long tons (2240lb), as opposed to metric tonnes (~2208lb). Be careful, I have my MDCCCIIIV Mechanic's Calculator around here somewhere.

--
JHG

RE: 6100 lbf load on 3 ton hoist

as someone (Churchill?) said of the UK and the US ... "two peoples separated by a common language"

another day in paradise, or is paradise one day closer ?

RE: 6100 lbf load on 3 ton hoist

Please be careful about disparaging the imperial system of measurements with regard to ASME B30.2. Below is a cover page provided with the document. Pay particular attention to the last sentence of the notice, "Heed this notice: Criminal penalties may apply for noncompliance.". Also note that section VII states, "The values stated in customary (ie. imperial) units are to be regarded as the standard"

God bless the United States of America.unclesam

RE: 6100 lbf load on 3 ton hoist

fortunately I'm neither a citizen nor a resident of the good ole USofA ...

so they can "stick it", up until the time when some guy knocks on my door (or worse, I see the laser sight on my house ...)

another day in paradise, or is paradise one day closer ?

RE: 6100 lbf load on 3 ton hoist

Is that page actually furnished with the standard? Or is that one of the copyright-violators-but-it-doesn't-count-because-it's-a-law publishers that stuck that in?

Someguy, sounds like you got it covered. Anyway, a rental crane would be the other alternative, and it should be a LOT cheaper than $15,000, assuming you in a metropolitan area that has any kind of rental crane service.

There have been similar posts about "What do you do if your beam is overstressed 2%?", with a split in opinions between the "It's only 2% so it doesn't really matter" and "An overstress is an overstress no matter how small" camps. With no good definitive answer.

RE: 6100 lbf load on 3 ton hoist

tbulena,

that spec is interesting - it adds metric units in brackets after a lot of the numbers except for tons and also doesn't define ton (no long or short or no of lbs or kgs), therefore the original supposition may still be correct, i.e. someguy79 hasn't said why he's using short tons. Might be a good idea to double check the rating of his hoist....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: 6100 lbf load on 3 ton hoist

(OP)
Littleinch,

Here in the US "ton" means 2000 lb. If it's not obvious to an inspector just by looking at the tags on the lifting equipment, it will be assumed to be the typical units of measure here. If the manufacturer says it's rated in long tons, I need them to say so in writing and keep that info nearby and conspicuous in case an inspector comes by.

The CFR reference included above means that it's part of the Code of Federal Regulations (i.e. it's a national law).

rb1957,

Don't worry, I'm not going to show up at your door, and I don't think anyone else is going to bother about this either. BTW, I think that laser guided munitions use a wavelength that's not visible. So you don't have to worry about seeing a laser designating your house as a target.

RE: 6100 lbf load on 3 ton hoist

"BTW, I think that laser guided munitions use a wavelength that's not visible. So you don't have to worry about seeing a laser designating your house as a target." ... oh great ! that's so reassuring ... that I won't know it's about to happen ! maybe they do that for humanitarian reasons ??

another day in paradise, or is paradise one day closer ?

RE: 6100 lbf load on 3 ton hoist

Fascinating. When metrication arrived the ton to tonne (pronounced tonny) was one of the few that was so close it could really be used without conversion, but your ton is quite different. I'm still surprised it didn't add a conversion, but maybe it assumes everyone knows....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: 6100 lbf load on 3 ton hoist

their gallon is different too ... seriously, really, anyone, why 3.8lt/US gallon ?

another day in paradise, or is paradise one day closer ?

RE: 6100 lbf load on 3 ton hoist

(OP)
Why does the UK have a gallon measure at all? WTF does it correlate with? There must be some arcane historical reason, but I don't get it.

I'm not saying it's better than the metric system, but in the US, 1 gallon = 4 quarts = 8 pints = 16 cups = 128 fluid ounces.

Too bad this US customary system (some times referred to as Imperial) doesn't relate the length units to the volume units very well. For instance 1 cubic foot is approximately 7.481 gallons.

Also too bad, the time units we all use are terrible. There isn't a common base number (e.g. 10 in the metric system) and some of the units aren't standard. The year varies by a day sometimes, and even if adjusted for leap year, it has to be adjusted by a second or so once in a while. Can't we have a day divided into some base ten unit? That would be nice.

<p> end rant </p>

RE: 6100 lbf load on 3 ton hoist

An Imperial Gallon of fresh(ish) tepid(ish) water weighs 10(ish) Lb.

In practice, we don't really use gallons for very much at all any more. When petrol was merely ruinously expensive, we used to complain about its price per gallon - but now that it's well over a quid per litre, we can complain equally effectively in metric.

Fuel consumption is still popularly described in miles per (imperial) gallon. I think that may be about all that's left now.

A.

RE: 6100 lbf load on 3 ton hoist

I just saw gas selling here in TN at $1.68/ gal.

RE: 6100 lbf load on 3 ton hoist

someguy79 - Are you serious? - We invented it that's why.

The problem is that the US gallon was one of three "gallons" used when the colonisation of the continental US was being undertaken with the "Queen Anne" or "wine Gallon" being used more frequently which was established as exactly 231 cubic inches and becale the US gallon on independence.

The UK and its empire (at that time) established the current single Imperial Gallon in 1824, which is the current UK or imperial gallon.

Whilst the US gallon and the UK gallon both have 4 quarts = 8 pints, at that point it differs becoming 20 fl oz (imp) and 16 fluid oz (US). Unfortunatley it isn't a 5/4 conversion as the fluid ounce is different (!!), but the difference between a 6/5 fraction is negligible for most purposes - see below.

Hence from BS 350 - I imperial gallon = 4.54609 litres, a US gallon = 3.78541 litres and hence 1 imperial to a US gallon is 1.20095 or 0.832674 US to a UK.

The price of gasoline is still lots lower though in the US - basically 30p a litre compared to £1.10...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: 6100 lbf load on 3 ton hoist

(OP)
LittleInch,

Thanks for the laying out the arcane historical reasons for the differences. I've long suspected that it has to do with changes in the unit of measure associated with one ruler or other. It actually is interesting.

Oddly, I've never seen the 231 cu-in /gal conversion before. It's helpful.

RE: 6100 lbf load on 3 ton hoist

@someguy,

"but in the US, 1 gallon = 4 quarts = 8 pints = 16 cups = 128 fluid ounces" ...
the same in the UK, only different gallons, quarts, pints, fl. ozs, ...

another day in paradise, or is paradise one day closer ?

RE: 6100 lbf load on 3 ton hoist

"Fuel consumption is still popularly described in miles per (imperial) gallon. I think that may be about all that's left now." ... the metric equivalent is lts/100km ... more sensible as a measure of consumption, but an awful unit!

another day in paradise, or is paradise one day closer ?

RE: 6100 lbf load on 3 ton hoist

The problem with l/100km is that it is the inverse of what everyone has become used to so a high figure (good) in l/100km feels "bad".

I've been trying to promote miles per litre without much success. We all know what miles mean, we buy the stuff in litres so know the cost. Not many understand that 35 mp(UK)g equals 15p per mile as this would be 7.7 mpl at 1.20/litre.

Beer has a permanent dispensation from being metrified in the UK at least, and Ireland I think, but gallons can only be used as a "secondary" unit since 1995, i.e. anything can be sold in 4.54 litre ( 1gallon) containers. Most gave up some time ago and use nominal litre sizes (5 isn't far away...)

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: 6100 lbf load on 3 ton hoist

(OP)
If you want to talk odd units and vehicles, go about measuring emissions as grams/horsepower/hour. That's actually a pretty common unit here. At least it's common among those who keep track of emissions from vehicle engines. It mixes time bases (seconds used as a fundamental unit in hp vs hours), two different measurement systems are used (metric & US customary), and mixes mass units (lbm in the hp unit vs the gram).

About beer here, if you order a "pint" it might not be a pint at all. There is no regulation of what that means when ordering a drink in a restaurant, tavern, or bar. However, food labeling in stores is tightly regulated.

RE: 6100 lbf load on 3 ton hoist

isn't a high lt/100km bad ? don't I want to consume as few liters as possible ?

miles/lt ... OMG ! km/lt cross translates to mile/gallon. and 10 km/lt = 10lt/100km ...
so 1000km^2 = 10lt^2 ??

another day in paradise, or is paradise one day closer ?

RE: 6100 lbf load on 3 ton hoist

Sorry, wrong way around. Low l/100km seems bad compared to high mpg.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: 6100 lbf load on 3 ton hoist

The certificate I posted is indeed legit. Here is a link to the relevant US federal law: http://www.gpo.gov/fdsys/pkg/CFR-2011-title29-vol8...

While the OP specifically asked about parts of ASME B30.2, I was just having a bit of fun posting that certificate with its legal warnings.

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