I am also having a vessel built from the exact same material of construction that you listed above SA 516 Gr 70 backer with 316L Stainless Steel.
I am also in process of having numerous other alloy vessels fabricated and the same process applies. (2-1/4 Chrome with 347 Stainless steel clad...
I am looking for a software to help set up a inspection program that will cover Sec. I, IV, VII vessels primarily.
I have looked at several of the ones out there but so far the most impressive is the OSS software Ultra Pipe.
Does anyone have any other suggestions?