I have a very large fabricated pipe spool (some 40Tonnes) which as it cannot be broken down further requires to be lifted whole and becuse of it's weight we cannot safely use soft slings. The intention is to weld lifting lugs onto the piping, where possible via re-inforced trunnion type attachments [to try and introduce the loads into the 'pressure' shell gradually].
My question is - can I use the specified yield strength of the material [A671 CC65; Ys=35ksi]as a basis for design for the lift, or am I, since the spool has been designed under B31.3 limited to the basic allowable stress [21.7ksi] or even the 1.33 x S allowed for occasional loads.
To be frank I would only intend to use 0.6 x Ys = 21KSi, and even then with a minimum 5:1 SF, but this has had me wondering, if the B31 code would cover this potentially high stress/ low cycle operation, bearing in mind the future use this piping will see.

None of the codes (as far as I know) include erection and installation in their rules. This being so, one would have to resort to good engineering practice. How this first time operation would be include in the fatigue set is anyone's guess I suppose. However, as this is a mass of 40 000 kg, great care is needed. It is possible to use a lifting lug design that imposes shear rather than bending stresses in the piping, and if this is the case, the bending stresses with its attendant snatch problems would be eliminated. If the item is lifted with a suitably arranged spreader, then shear type lugs should not be a problem, and the weld stresses, and the direct stresses in the lugs should be fairly easy to analyse as a simple free body. Bending stresses are bad news, and to drop this item would be a disaster to say the least.

Shear type lugs would have a longer weld length, and would need more time to clean up after installation (unless left in place). This would entail grinding and checking the surface with dye penetrant after making good.