Out of plane buckling in lifting lug
Out of plane buckling in lifting lug
(OP)
Hi,
I'm designing classics lifting lugs for a pressure vessel (construction code ASME VIII div.1), like these: https://mechanicalc.com/static/img/LugAnalysis/The...
In some other calculations (not so many) I found a sort of "out-of-plane buckling" check. Is it necessary? Because many people don't consider it in designing and I don't know why. Thanks
I'm designing classics lifting lugs for a pressure vessel (construction code ASME VIII div.1), like these: https://mechanicalc.com/static/img/LugAnalysis/The...
In some other calculations (not so many) I found a sort of "out-of-plane buckling" check. Is it necessary? Because many people don't consider it in designing and I don't know why. Thanks





RE: Out of plane buckling in lifting lug
For out of plane bending, the assumption is that an appropriate spreader beam is employed.
RE: Out of plane buckling in lifting lug
There's something here: https://mechanicalc.com/reference/lug-analysis
Do I have to consider it? For a vessel that I'm designing, if I don't consider this "buckling", lifting will be 10mm of thickness; if yes, it shall be 30mm. This is strange.
RE: Out of plane buckling in lifting lug
RE: Out of plane buckling in lifting lug
Most, if not all, of my designs have met this requirement. Sticking a 1" pin through a 1/4" lug doesn't sound right to me.
From the Crosby shackle catalog:
If you come close to using 80% of the shackle spread on a 2130 shackle, the lug thickness is going to be much greater than 25% of the hole diameter.
All that said... I'm a vessel engineer not a rigging engineer.
RE: Out of plane buckling in lifting lug
RE: Out of plane buckling in lifting lug
Some types of lifting lugs are placed near the top head (or at a transition) and project upward for some distance. In the horizontal position this makes the lifting lug act as a cantilever beam. It is conceivable that if the lug's span is long enough and the b/t ratio low enough then it could experience lateral-torsional buckling. I believe that paying attention to this possibility and designing the lug with a low b/t ratio should account for this condition. For instance, a "relatively thin" lifting lug might have plenty of strength to support the vessel in pure tension (vertical position), and even adequate bending strength in the horizontal position. But if the lugs are too thin then lateral buckling may be a failure mode.
RE: Out of plane buckling in lifting lug
RE: Out of plane buckling in lifting lug
Regards
r6155