The "bar" would fall under the ASME Below-The-Hook-Lifting-Devices scope (spreader bar/lifting beam), and would be designed, tested, and labeled/tagged per OSHA requirements. Hopefully, somebody already has one available rather than having to make one. If you're flexible on the length, that'll help.
On the chokers (the lines above the bar), I just call out the required safe capacity and minimum length of the lines.
On the slings (lines below the bar), I would just call out the load to be lifted at each end. Required sling capacity would depend on how they used it.
On the shackles, if I've designed a lug to fit a specific size shackle, I call out the nominal shackle size as well as the minimum capacity.
On all of this, you need more detail if the person doesn't own anything and is going to run out and buy it all. But generally, either the contractor, the rigging company, or crane rental company has all this stuff available, and just needs to know which to use. If you get too specific, you start ruling out items that are workable and on hand.
Delagina:
I agree with what JStephen said above, with the exception of some terminology issues. I think you seem to show two chokers (choker hitches) immediately above the pipe, and on up to the spreader beam. The wire rope parts above the spreader beam/bar and on up to the hook are just slings. But, the term sling is a slightly more generic term which includes a variety of different end hardware and arrangements. His concern about the length of the slings above the spreader beam is several fold: if the slings are too short (the angle btwn. them and the spreader is smaller than desired) and this puts excessive compression on the spreader during the lift; when these things get too long they influence the amount of lift height for a given boom length or boon tip height, and this can be a problem in lifting over some obstacles.
In the picture that you show, you should take care that the pipe can not move longitudinally with respect to the two chokers holding it, where it could slip out of one of them, if it became inclined during the lift. However you rig this pipe lift, you want the c.g. of the load to be immediately under the hook, on the vert. axis of the hook, so the pipe can’t/won’t rotate and slip in the chokers. The pipe will do this automatically when you start to lift, but will become inclined in that process. You might also need to provide some means of protecting the pipe from the chokers.
As JStephen suggests, I wouldn’t specify any of this stuff, I would let the rigging contractor provide a lifting plan and calcs. based on the lifting equipment he has on hand, or available to him. Then, I would check his proposals, plans and calcs. and review these with him. I would provide the load weight, dimensions, c.g. location, any special features which need consideration in the lift, and site specific feature which could influence the lift and equipment needed. Then let the rigger provide his own specific lifting plan for your review.
