PEHasan, I'd suggest that you approach your weld cap supplier for some dimensions of the weld caps.UG-32 design for 2:1 semi-ellipsoidal heads require the head shape to be truly ellipsoidal, or if manufactured using two radii then the crown radius must be 0.9D and knuckle 0.17D.Most weld cap suppliers I've encountered manufacture their caps using two radii, that are not necessarily within the 0.9D, 0.17D limits.This would mean that the UG-32 design for 2:1 S/E heads will not be valid for the weld cap.It would need to be designed to Appendix 1.
John
ASME B16.9 table I-10 (Dimensions of Caps), General Note (2) indicates that "The shape of these caps shall be ellipsoidal and shall conform to the shape requirements as given in the ASME Boiler and Pressure Vessel Code."
Given that, if a manufacturer tells me that their cap conforms to ASME B16.9, then I can assume that the shape is ellipsoidal, and thus these formulas should apply.
If used for piping (B31.3) the cap does not need to be calculated. It shall be the same thickness as the calculated pipe wall. So the maximum allowable pressure is depending on the temperature and the selected schedule size.