Rigging with a hook through a hole in a plate
Rigging with a hook through a hole in a plate
(OP)
I have a lifting application that I am helping with. I have been taught that in general it is bad practice to rig something using a hook in a hole drilled through a plate. This is due to the large contact stresses at the edges of the hole. A better alternative is using a shackle so that you have a round pin through the round hole. However, when discussing this with a co-worker, he found several beam trolleys with a connection point that is no more than a hole through a flat plate. See the attached image. This tells me that maybe this isn't as bad a practice as I thought. Are there any restrictions to joining a load this way? Any thoughts?






RE: Rigging with a hook through a hole in a plate
RE: Rigging with a hook through a hole in a plate
RE: Rigging with a hook through a hole in a plate
BA
RE: Rigging with a hook through a hole in a plate
RE: Rigging with a hook through a hole in a plate
Thanks!
RE: Rigging with a hook through a hole in a plate
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Rigging with a hook through a hole in a plate
Take a look at the shapes and dimensions of most lifting hooks. They are kinda pear shaped over a good share of their body, with the large wearing area on the inside or bearing surface of the hook. Then, they will often have an even wider, shaped, flange area on the inside surface too. This gives them a fairly substantial and generous radiused bearing surface for wire rope or to mate with the hole in a lifting lug. The hole in the lifting lug generally must be bigger when a hook is used, to accept the full shape and body of the hook. It might also have doubler pls. (doughnuts, cheek pls.) on either side to thicken the lifting lug, and it is likely shaped (mating shape) to match the general shape of a hook. The thing that OSHA doesn’t like about this lifting arrangement is that it is often difficult to use a hook with a safety latch with a lifting lug pl. A lifting hook would fit quite nicely on the trolley that you show and load its lifting eye (suspension pl.) in a better fashion than a clevis or clevis pin would. I believe the proof load for most hooks is at least 2 w.r.t. their rated load and the design FoS is higher than that. Note also that when you design a lifting lug eye for use with a clevis pin in bearing, the pin dia. is best when it is only slightly smaller than the pl. hole dia.; and the thickness of the lifting lug pl. should be only slightly smaller than the width opening of the clevis. This matching thickness forces the use of the appropriate sized clevis; one with a smaller pin won’t fit over the doubler pls. No matter what lifting means you use, the lifting line, chain, wire rope, whatever, should not deviate from the plane of the lifting lug pl. by very much. Without special design attention, the lifting pl. is not intended to be loaded out of plane.
RE: Rigging with a hook through a hole in a plate
You can use ASTM BTH-1-2008 or 2005 as the standard US reference for a full-fledged design.
RE: Rigging with a hook through a hole in a plate
Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com
RE: Rigging with a hook through a hole in a plate