Hi, I'm trying to use the alternative procedure of the appendix P for nozzle loads, but I don't understand clearly the difference between "t" and "T". According to the API 650 appendix P, "t" means: "Thickness of tank shell at location of nozzle" and "T" means "Thickness of the tank shell at the opening in question". I think that "t" means the nozzle thickness, but in the same page describe "tn" like the nozzle thickness. I'm really want somebody explains me the meaning of those terms. Thank you.