[hc]

Hey Guys,
My experience has been typically that the spec break is at the valve not a union or misc. set of flanges. This won’t matter if its flanged, socketwelded or threaded. The valve is included in the higher rating. Now an exception to this may be between a facility to pipeline spec break(b31.3 – Z662). Generally though even then your changing spec at the valve. Usually when a spec break occurs (and this is generally) at a building wall its usually a insulation/ET break only. If I see a spec break at a misc. set of flanges or a union I would automatic question it either on your drawing or on the P&ID. Hopefully this is what your asking.
HC