API 650 shell thickness input for reinforced nozzle

Dear Experts,

I was just wondering if it's really correct to include reinforcement thickness of the nozzle to the thickness of the shell when calculating API 650 for storage tanks. Wherein the nomenclature said that t=shell thickness at the opening connection.

Please advise

Thanks

In appendix P of API650, Figures Figures P-2A...P-2F consider the Stiffness Coefficients for cases "Reinforcement on shell", so I understand that these figures already included the assumption that there is a tP= thickness of reinforcing pad plate (assumed =t)

Normally we should use the appropriate figure and "t" is "tank shell thickness at nozzle connection, exclusive of reinforcing pad thickness or extra-thickness of insert plate" (as is clearly stipulated in the original work Billimoria and Hagstrom’s "Stiffness Coefficients and Allowable Loads for Nozzles in Flat Bottom Storage Tanks").

Best regards.