Hello Gams

The code (ASME) does not give a procedure for computing a half pipe jacket on a flat head. As the head is generally a lot thicker than the half pipe, you can just compute those half pipes as cylinders. If you are worried about the effect of pressure from the half pipes on the flat head, you can treat the portion under one of those jackets as a flat plate in accordance with section UG-34 of ASME Section VIII, Division 1. This will have to be a hand calculation as you cannot put half pipe jackets on a flat head in PV Elite