Design for lifting / rigging 2

[geesamand]

I'm revising some of our machinery to improve the lifting hardware. Specifically we're going from the "soft metric" US-style eyebolts with long shanks to DIN 580 lifting eyes. I cannot leave them in the original locations. They are permanently attached to the machine and used only in installation/removal/major maintenance tasks. I have some basic questions about quantity of lifting points, load distribution assumptions, practical assumptions about the equipment used in the field for installation, etc. My intent is not to proscribe the rigging method to my customers (as I'm not qualified to make such recommendations), but I do want to have a clear vision of at least one easy conservative way to rig it when I finalize the eyebolts.

We sell the machinery and the unloading, installation, and startup are the customer's responsibility. So I'm designing for a multitude of riggers all over the world. I want to transparently use the standards as much as possible for everyone's safety and satisfaction.

What rigging standards might I consult? I would most prefer rigging standards that are used in Europe and/or North America. I already checked the harmonized list of CE standards, and rigging / design for lifting does not appear anywhere.

Thanks,

David

 

[IRstuff]

Presumably, the existing eyebolts are installed with reinforcement and thought as to placement. Trying to put new eyebolts elsewhere risks damage to the structure, and or handling damage through imbalance, etc.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[boo1]

ASME B30.20-2003 Structual and Mechanical Lifting devices. Section 20-1.2.2 Construction

https://www.remispowersystems.com/uploads/content_files/ASMEStandards.pdf

ASME BTH-1-2008 Design of Below the Hook Lifting Devices, Chapter 3

 

[MikeHalloran]

1. Search on | asme-bth | .
2. Read this:

http://www.leea.co.uk/includes/down...=6&PHPSESSID=9e315f5ac73bfa3e00dc12ed39749e17

Mike Halloran
Pembroke Pines, FL, USA

 

[geesamand]

Thanks for the links to the ASME and CEN standards.

The eyebolt locations are sufficiently reinforced.

David

 

[geesamand]

I reviewed ASME BTH 30.20. Only chapter 20-1 had any applicability, and really contributed nothing to answering my questions.

I read the suggested LEEA reference, which nodded toward EN 13155 and the LOLER. LOLER had nothing specific and since EN 13155 is $350, I don't intend to buy it just to confirm that it contains only fluffy talk of responsibilities and common sense. (I admit a bit of bias against the CE standards)

I'd like to state my problem another way in the hopes of getting a good answer:
Where should I located the eyebolts on the load in order to be as easy to rig and safe? Preferably done in a way where a field rigger can easily assess the load capabilities and lift it using common chains/hooks/slings/etc.

It's easy enough to put enough eyebolts on the load and make sure they surround the CG, but I wanted to be diligent and see if there is a way to do it "well" in the eyes of the individuals downstream. If I can't find anything in the standards world I'll just pick up a riggers handbook and go by that.

 

[dhengr]

Geesamand:
You have to design your lifting eyes so that there is really a limited number of practical ways they can possible be loaded and used. Then you have to also design/check them for all the ways some damn fool in the field might load them, without causing/allowing them to fail. You are right, you don’t want to dictate the exact lifting equipment or methods to be used, at any given time. But, you do have to dictate enough, to protect your own equipment and lifting eye design, so that they can’t come back at you when they drop it. You do have to be qualified enough to design around their worst case loadings. Keep it simple. The question then becomes, what would any other prudent engineer do with this design to make it safe. You have to design to meet the current applicable codes, and you should expect that the field people will follow these too. But, you should probably design for that damn fool too. Various riggers handbooks and texts on the subject are not all bad, since those are likely what the field people will be looking at. Several of the ASME stds. are good for basic guidance, particularly ASME BTH-1. I don’t know much about the DIN or EU stds., don’t use them regularly, but it is reasonable to assume that they must all follow the same basic engineering mechanics and design principals. Like you, I’m pissed at the thousands we are forced to spend on stds. and codes which don’t say much, and have gotten so complex and verbose as to make real engineering very difficult. But, you better have and follow the applicable ones.

I wouldn’t put more lifting eyes on your equip. than are needed. That would just confuse the issue and give the field guys options to screw up, and that’s part of what you want to avoid. You might even consider getting rid of the old eyes or at least disabling them, so the two groups can’t be mixed in use. Show us some sketches of your equip., with dimensions, weights, etc., we can’t see it from here. Imagine trying to discuss your OP if you had no idea what the equip. looked like. What do the old and new eyebolts look like, how are they different, how are they oriented on the equip? The thinking being... so they can’t be loaded in a way not intended, sling angle vs. eyebolt orientation, etc. This isn’t rocket science it is just good basic structural and mechanical engineering, with some experience and judgement thrown in.

 

[geesamand]

The lift here is a right-angle gear reducer. There is the rectangular gearbox section with main gear components and an electric motor that mounts off to the side.

We use either 3 or 4 eyebolts located on the top corners of the gearbox. The motor is somewhat less massive than the gearbox so the total CG is inside the gearbox on the motor side. I prefer 4 eyebolts BTW.

I'm trying to decide:
1) Is 4 eyebolts better for rigging than 3?
2) Since we expect customers to rig directly to the eyebolts (no spreader), each sling/chain will not have the same tension. Do I need to account for that?
3) Aside from using DIN 580 eyebolts and ensuring they are installed correctly with clearly visible markings, do I need additional guidance for the customers?

Thanks,

David

 

[MikeHalloran]

1} Four are always better than three, not least because you don't necessarily lose control of the load when one chain or strap fails.

2} It would be nice to tell the customers approximately where the CG is, and approximately how much weight to expect on each corner in a straight up lift.

3) Tell 'em to call a rigger if they're not confident in their ability and equipment.





Mike Halloran
Pembroke Pines, FL, USA

 

[dhengr]

Geesamand:
Four lifting eyes, one at each corner of the gear box, and the motor hanging off one side of the gear box, and centered on the gear box? I’d design for the two lifting eyes nearest the motor to take the whole load, half to each sling. The two away from the motor balance the whole system, take a considerably smaller load and may have smaller lifting eyes, and/or shallower sling angle. Remember, the main hook will want to be directly over the C.G. The smaller eyes would be a hint to the field crew, the larger hooks just wouldn’t fit in the eyes. The two main eyes may have to be adjusted again if the motor is off center, and then I’d design both for the bigger load. Could you put an simple instruction plate on the top of the gear box, showing the C.G. (* here), the weight and a few simple lifting instructions. You usually want to spec. the min. sling length (which implies sling angle) for the load or lifting eye cap’y. You could show the min. sling angles in a simple diagram, maybe two side views, greater angles won’t overload the eyes. Then watch the lifting eye orientation so that the slings are generally in the same planes as the eyes. Some engineers do consider the prospect of one sling failing, but which one, and why not two slings failing, and where do you stop? The rigger is supposed to inspect his equipment before using it. Slings, chains, hooks, clevises, etc., constantly used and abused equip. are typically designed with a FoS of 4 or 5 to ultimate. I’m not sure that any code or std. req’rs. that for your gear box corners or lifting eyes, which might be used a half dozen times during the life of the system, as long as corrosion and the like aren’t a problem. But, you should check that FoS based on the stds. of the country into which you are selling.

 

[MikeHalloran]

A placard with a sling angle limit is a good idea.
Be sure it's mostly language- independent.

Some yacht builder friends of mine used a super-short sling to install a unit in a low-overhead compartment. The sling bent part of my equipment. No real harm done, but the yacht builder wanted my unit straightened and repainted, in place, under warranty of course. A proper placard might have prevented the damage, or at least allowed us to deny the warranty claim. Instructions in English would not have helped; their workforce is, er, international.



Mike Halloran
Pembroke Pines, FL, USA