As we know that ASME VIII-2 Edition 2007 uses "pressure area stress" calculation theory for nozzle reinforcement problems. while earlier in Edition 2004 it was "AREA REPLACEMENT " theory........so i want to know that which design theory is used by PD 5500 code....? I m a student and i must require answer of the question. please help me....i have tried a lot from the code but does not work...