Factor of Safety - Equipment to be lifted (not lifting equipment) 1

[Joseph_L]

Hellow all,

I been tasked to add lifting eyes to an existing machine and to do a structual analysis of lifted machinery when it is lifted.
The machine will be lifted using a forklift/crane and hoist to a flat-bed truck for transferring.

I been researching regulations, and all I could possibly find was regulations on the 'lifting device'.
I could not find any regulations on the 'machine to be lifted'.

The machine has a frame made out of 2x2x0.125" square tube, and it is roughly 10ft by 4ft long.
I was thinking of welding a stud and screw lifting eyes on 4 corners.
What regulation should I follow? Or is there any regulation of the structure of the machine to be lifted?

Thanks very much
Joseph

 

[EnginerdNate]

All of the components that are 'lifting devices' (eyes, hooks, etc) should be rated for lifting and of course rated to lift your load (Some shackles, eyes, hooks, etc are only rated for pulling, not lifting.)

Anything on your actual device being lifted that is not in the above category would likely need 'manual' calculation to show it good as it's application specific. Unless you're truly weight constrained, get as much factor of safety as you can. 3:1 on yield strength is probably a good minimum.

 

[BrianE22]

Hoists and winches frequently use a safety factor of 5. The seems to jive with OSHA:

https://precast.org/2012/10/lifting...lifting apparatuses) shall,by five (5) times.

 

[EnginerdNate]

Another consideration is if any load imbalance could develop during the lift. When I compute factors of safety for lifting devices with multiple lift points (Say 4x hoist rings at each corner of a cubic structure) I typically calculate my minimum factor of safety by doing a 60/40 split in each direction even if theoretically the load will be perfectly centered under the four lift points.

 

[Turn_of_the_Screw]

To Nate's point, the load being lifted will experience the same loads as your lifting device, so apply the same standards. To Brian's point, SF of 5 is always a good starting point. If this is a one-off machine, I wouldn't hesitate to make the factor of safety 10, so long as it isn't too cost-prohibitive, and work your way down from there.

 

[saplanti]

Let us not forget that the lifting devices are for continuous use, not for one lifting. Therefore their safety factors are high between 5 and 8 perhaps 10 for some cases.

For the lifted equipment you need to consider dynamic inertial forces in addition to static weight. Perhaps an additional small factor for your satisfaction. You can provide limitation for horizontal, vertical lifting speeds, and inform the operator to consider either on drawing or by lifting procedure.

Keeping the load attached to the lifting equipment all together is essential. Sometime you may need strong back with essential lifting attachments, sometimes welded attachments in case there is no bolted attachment considered on the equipment by the supplier.

 

[Joseph_L]

Thank you all for your answers to this post!

Much appreciated!!