Just to be clear on this. The tank has been hydro tested and there need to be re-pads installed on the shell wall for pipe supports to attach too. Does API 650 allow this without a new hydrostatic test to be performed? Every where I see in 650 it really is not clear other than section 7.2.1.12 and that paragraph is unclear as well. Does 7.1.1.12 state I can weld reinforcement plates or does this mean I can weld small attachments to reinforcement plates before or after hydro?
When you said "reinforcement plates" I read "shell nozzle repads". However, you are only looking at pipe support pads. You may be in the gray area between a "new" tanks (API 650) and a tank "placed in service" (API 653). I think your pads can be welded to the tank after hydro. I suggest that you follow API 653 in this regard. Avoid going over shell butt welds, MT the completed welds if the shell is higher than Group III steel. If the steel is over 1/2" thick, consider UT for laminations or other defects prior to welding. You'll need to get an engineer and the owner to sign off on it.
IFRs what is you interpretation of 7.2.1.12? I still would like to know if this allows reinforcement plates to be welded on the tank before or after hydro? My interpretation of this paragraph is only allowing small structural attachments to be welded to the reinforcement plates that has already been installed.