The code does not say you can not do it. But, you need to prove it can do the job by calculations. Don't know about you but I would not use it. Also, the only way you can prove it by calculation is by FEA for this kind of arrangement. Why give give yourself grieve.
we have done our own FEA that gives us an effective thickness of the dimple jacket. we want to take that effective thickness and subtract it from the calculated required thickness of the shell due to external pressure.
I see. You must be in an industry other than chemical/oil & gas. I can see a dimpled shell is good way to stiffen the shell without the use of extra thickness or stiffening rings (sort of like the corrigation in gauge thickness sheets) Just curious what this shell is for, ie., what kind of equipment?
this particular tank will be used in the chemical industry. no internal pressure, but it needs to be rated for full vacuum and there is no room for structural stiffening rings under the outer sheathing, so the shell would have to be thick since it is about 14 feet long. using dimple jacket would allow us to thin out the shell considerably and save a lot of cost.
This would be different from most dimple jacket applications. First your jacket would need to go clear to the ends of the vessel, or you would need to change wall thickness at ends of the jacket. Secondly you need to consider the NDT on the jacket to shell welds since they are now part of your rating.
I have seen this done on half-pipe jobs, but is more straight forward.
How do you evaluate the buckling criteria on a jacket that is already dimpled?
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Rust never sleeps
Neither should your protection
