Posted By William I would appreciate it if someone could help clarify what the swl of a pad eyes is. Simple enough you think, but it never is with me. The pad eyes are being used for construction in a heavy fabrication yard for lifting 5 to 20 ton sections in place. On the pad eyes being used there is no SWL only PL, which means proof load, the load to be applied to certify the pad eye to lift a certain weight once it has been welded. What i would like to know is how much lower is the swl than the proof load? I would say at least 50% with further reductions if this is not a straight lift, or maybe it should be 25% as after all the factor of safety for shackles is 6:1, wire slings 5:1, lifting chains 4:1, material slings 7:1. Discussion regarding this would be appreciated as i am unsure whether there is a right or wrong answer. My second query is a pretty straightforward one. You have 2 gantry cranes in a heavy fabrication shop, one at the north end and one at the south end, the one at the north end has a swl of 5tonnes, the south crane has a swl of 32tonnes, both cranes can travel the full length of the fab shop. Halfway up the fab shop the Gantry's (heavy steelwork) which the cranes sit on change in size the one at the north end (5tonne crane end) is around one foot thick, but the south end (32tonne crane) is over 2 foot thick, i think i am right to suggest that there should not be loads over 5tonnes lifted at the north end as the Gantry's are obviously thinner and as a result not able to support the same amount of weight as the south end where the 32tonne crane sits. When i brought this up the reaction of a manager was he did not know and no-one has ever brought this up before, it seems pretty obvious to me.

Posted By Robert K Lewis Fully agree with Mitch. The designers of the article being fabricated need to do their calculations on this and specify precisely the pad eye to be used, eg type and proof load, the location of the eyes on the fabrication and the maximum angle between legs of the slinging arrangement. Without these you are dead in the water Similar thing applies for the gantry beams! Bob

Posted By Mitch Willaim, Once upon a time many many years ago I used to design, fabricated, equipment housings as part of the design process I had to calculate the C of G (very basic) and the the lifting "eyes" usually a ribbed plate with a circular hole the design of this was critical in terms of the stresses imposed on the eye itself, the rib and the super structure it was lifting. It also involved specifying the lifting equipment required, shackle etc and the length of chains or hawsers this did not allow the Slingers to make their own judgements. As I said earlier the design and implementation of lifting scheme is a complex and critical process and you should seek expert advice. Mitch

Posted By William Thanks for your help Mitch it has been very useful. May i contact you in the future? I am currently off work with a knee injury and not able to check things until i am back.