The most elegant and simple lifting solution of skids and packaged units

[hirschaplin]

Hello,

I am working for a compressor manufacturer. For the last couple of projects delivering various gas compression systems I have been struggling to find the ultimate lifting facility (lugs, padeye etc.) for transportation and installation of our skids.

The best engineering just looks right, that perfect harmony between different elements creating confidence in the design. Yet it must be simple and easy to manufacture with as little engineering work as possible.

What is the best, most simple and elegant solution to lift a skid designed by H/I beams and other standard steel construction products.

Few criterias
- Safe and reliable usage for max. 5 lifts in the life time of the design
- Cost effective
- Simple design made with standard steel construction products - welded/bolted together
- Sometimes the lifting facility can be permanetly attached to the skid but sometimes the customer require that it can be removed after finalization
- Easy to understand the integrity and limits of the lifting facility - for example, it should not be necessary to run complicated calculations to understand how strong the design is - what rule of thumb can be used?
- How to attach the lifting facility to the H/I beam? How to reinforce the beam in the best, most simple way?
- Total overall weight between 2.000 and 50.000 kg divided by 4 lifting facilities.
- Material S355 steel grades
- Scalable for various sizes of beams, i.e. HEB 180 and HEB 400 in order to have consistency in our design between projects

Some example of previous lifting facilities, we are basically trying something new in each of the last projects... I don't like it. I want our design to be consistent.



Type 1

Type 2

Type 3

Type 4

Type 5

Type 6

Type 7

Type 8

Typically how our skids are lifted:

With your help I am hoping to find the best design that we thereafter can standardize for different lifting weights and beam sizes.

Thank you in advance.

 

[rb1957]

some of those designs look admirably well suited for the task intended.

So why don't you tell us what you don't like about these ?

5 looks nice
8 looks a bit clunky
3,6,7 look nice too, 7 might be a little over designed.
1,2,4 (side lifters) look to be limited in the lift direction ... maybe they use some other lifting rig ?

Do you Need something scaleable ? What's the cost to designing to the largest load ?

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

 

[dik]

I thought the welding on Type 2 was a little much for the 'tear out' strength... nice collection.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[sisaacs]

It's very hard to find a single solution for lifting points, but here are some things to consider:

1. Is it an issue to have a permanent lug sticking up within the skid deck? If so, #3, 5, 6, 7, and 8 won't work (unless they are bolted and removed after installation).
2. Will a lift point protruding from the side of the unit increase the shipping width to an unacceptable degree? If so, #1 is probably out.
3. Physical size of the shackle becomes an issue with #2 as the lifting force increases - eventually the diameter of the shackle body pushes the pin far enough out from the web of the beam there is not enough distance from the pin hole to the edge of the lug plate.
4. If the lugs are within the skid footprint, clashes between the slings and any piping connections on the side of the unit must be checked - relevant for all but #1.

In my personal opinion, #1 is a pretty solid design. If you size the pipe right, you can rig it with an eye loop, no shackle required, and the pipe resists the load efficiently. Also, depending on the size of the unit, #1 can be used to pull a unit on to the back of a picker truck with no crane required. But there will definitely be cases where it does not work.

 

[sisaacs]

Correction. My point 4 above would not apply to lug #2 or #4, as well as #1.

 

[rb1957]

the lugs in 5 could be nutted from below, and so removable.

the fittings on the upper deck could all be installed with nuts, if keeping the surface clear is a critical design driver.

funny, I see all the designs not attaching to the upper deck as poor, requiring a lifting fixture to keep the lift lines away from the structure.

I suspect that we're seeing a bunch of pix from the internet showing different lifting designs, without appreciation for the differing design drivers.


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

 

[rb1957]

"we are basically trying something new in each of the last projects... I don't like it. I want our design to be consistent."

a laudable goal but maybe "tilting at windmills" ? different designs could evolve from different design constraints. Sure, they are just as likely due to different designers (and their personal preferences).


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

 

[sisaacs]

In my experience, it's fairly easy to develop two or three "standard" designs that cover 80-90% of the units you will design, and that is worth doing. But as rb1957 says above, trying to find a single solution that works everywhere is probably more effort than it's worth.