Hello Farid
That is an interesting question. According the ASME Section VIII, Division 1, these fitting fall under Table U-3 (page 6 in the 2010 edition). Paragraph UG-11(a)(2) state that such fittings can be used in accordance within the temperature-pressure ratings stated in the Standard, such as ASME B16.11. In such a case, a calculation is not even needed, provided the fitting complies with the temperature-pressure rating.
However, it is common practice to let PV Elite perform the analysis, as the pipe cap has to be included in the 3D model for clarity. When that is the case, the 12-1/2% must be deducted unless the cap has been measured and verified to have a different thickness.
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Sincerely,
Ray Delaforce
CADWorx & Analysis Solutions
Hexagon PPM