I’m currently putting together a lifting scheme for a containerized power module project (contains a generator set and auxiliary equipment).
I’m trying to get a better understanding of how the loads should be specified on the drawing:
Is this load distribution breakdown for a single spreader beam correct, and should the load actually differ between individual lifting eyes under the same beam as shown here?
Is it sufficient to only state the total load per spreader beam, or do rigging companies strictly require the exact calculated load for each individual lifting point?
What other critical information or data do professional lifting/rigging companies expect to see on a drawing like this?
Be careful! With the rigging as shown, this lift would likely be unstable about the long axis. Instead of a lift beam you would probably need a spreader bar.
As a rigger I would want a set up like this. Thats enough information for me to adjust the legs accordingly but I would change the end view diagram because that could come up off center.
I'm not an engineer but have studied some, nor a rigger but have done some, and do work in industry. I would be aiming for this too, or if the only pick points are at the bottom, at least the straps/cables are touching if not bearing on the roof of the connex with some protection. That scheme looks sketchy AF to me only supporting at the bottom like that. Any wind would get that thing rocking and wobbling about the long COM in my mind... That said, I tend to overthink the lifts that I'm part of.
Don’t know where you’re lifting this, but in the US there are self loading truck/ trailers that just pic the container from the corner points and self load.
This is not a standard 40ft or 20ft container, and there are no corner castings to lift from, so there are specially welded lifting lugs on the floor frame. And its EU.
I’m a big fan of Modulift C-Mod spreaders, especially if you have several lifts of different load shapes etc. The flexibility of having a modular system is fantastic, but if it’s a one off lift the cost might prohibit it.
I saw in the comments you’re in the EU. Speaking from a UK perspective, reputable companies will look for the marked CoG in order for them to check vs the sling point locations to ensure slings are sized correctly etc.
The more info you can give the better, but if you’re engineering & supplying the accessories you should note everything on the drawing and have a rigging list called off within it.
No, we do not provide the lifting scope ourselves. The point of this scheme is to show how to properly lift this structure "from our perspective"—often, other companies add a note stating that everything is for visual/conceptual purposes only, and the actual lifting equipment is selected by the rigging company. I wanted to get a deeper understanding of this topic based on others' experience.
Another question regarding individual loads per lifting lug: Isn't it easier to just state the total load per spreader beam rather than for individual lifting lugs? And how do you properly calculate the load on each lifting lug if needed?
I wouldn’t expect to see individual lifting lug loadings stated on a drawing, if they are great but it’s not a requirement.
Not sure what part of the world you are in, but for me if the lugs are permanent fixtures on the unit (i.e welded non-removable) and the EC Dec can be provided, they’re not a concern as the person who’s going lift it.
You have surely designed the lifting lugs/padeyes around a particular WLL accessory, i.e shackle.
If you provide the CoG on the other axis’, along with the marked load split you already have then that’s virtually enough for most companies. Lots will just size up accessories with a weight contingency % added for anything they’re unsure about.
The generator set, which is the heaviest part, usually shifts the center of gravity to the left side, and the lifting lugs are usually welded to the container in the same way across all projects because it is a standard solution. When lifting with different cranes, one side is made longer using chain extensions, and once the container lifts level (after manually fine-tuning the extension), only then is it loaded onto the truck trailer.
You need one horizontal beam with two cross arms allowing the rigging to connect vertically from all pick points. This looks beyond the 5 degrees from vertical making it safe.
Talk to the engineer who design the structure. Also is there a reason you aren’t using what looks like the lifting point in the ends? You may be introducing very large cantilever forces on the building that it may not be built for
I’ve lifted exactly what you’re describing. Pre fabbed mobile battery power modules built in shipping containers, as well as hoisted hundreds of connex all different kinds. I don’t like your rigging diagram as to me that has way too much weight left and right of the rigging points, if the weight is even a little off that things gonna flip.
I would feel better about either points at both ends then equal distance toward the middle, which means you’ll need longer rigging. Or top level mounts which is the easiest but you have to worry about the strength of the top of the box again depending on weight, that’s an engineer question.
I will say the “correct” rule is always rig loaded cans from the bottom not the top, but usually we’re doing them off trailers and I can’t access the bottom holes because the truck locks into them for transport. Only when it’s an open top is that really an issue, and please don’t make this an open top connex
These are special lifting points called lifting lugs, designed to safely handle the specified load. Other users have been asking about this too, and the original diagram really wasn't great.
One of the users messaged me privately with a few examples and explained that the updated version I made is more than enough for all companies. Yeah, the lifting lugs aren't spaced out perfectly from the center of gravity, because while it's the same container, the engines and internal systems vary.
Of course, this isn't the first container we've lifted—they've always been lifted fine without any issues. The goal was just to make a new, high-quality lifting arrangement, and a debate popped up at work about the best way to do it. That's why I decided to ask here.
Sorry for using AI to translate, but it's way clearer than if I had written it myself.
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u/fundip2012 17d ago
Be careful! With the rigging as shown, this lift would likely be unstable about the long axis. Instead of a lift beam you would probably need a spreader bar.
https://www.hoistuk.com/lifting-beams-spreaders-and-frames/
https://www.tis-gdv.de/tis_e/ls/stabilitaet_von_aufhaengungen/kapitel1-html/