When
specifying RTJ orifice flanges, check
to see if there is possible interference
between the tap hole and the bottom
of the ring groove. The location of
the center of the pressure tap hole
for a RTJ orifice flange is 3/4"
from the face of the flange, and the
standard tap hole diameter for nominal
pipe sizes 4" and larger Is 1/2".
A groove depth of 1/2" would
produce a breakthrough of the tap
hole in the bottom of the ring groove.
RTJ flange tap orifice flanges have
an undesirable gap between the flange
face, ID of the RTJ plate holder and
orificeplate - face. This is a relatively
large gap in small line sizes. A RTJ
flange tap orifice flange is not consistent
with - flow-metering practice and
should be avoided if possible.
