(f) The term nominal thickness as used in Tables UCS-
56, UCS-56.1, UHA-32 and UHT-56, is the thickness of
the welded joint as defined below. For pressure vessels
or parts of pressure vessels being postweld heat treated
in a furnace charge, it is the greatest weld thickness in
any vessel or vessel part which has not previously been
postweld heat treated.
(1) When the welded joint connects parts of the
same thickness, using a full penetration buttweld, the
nominal thickness is the total depth of the weld exclusive
of any permitted weld reinforcement.
(2) For groove welds, the nominal thickness is the
depth of the groove.
(3) For fillet welds, the nominal thickness is the
throat dimension. If a fillet weld is used in conjunction
with a groove weld, the nominal thickness is the depth of
the groove or the throat dimension, whichever is greater.
(4) For stud welds, the nominal thickness shall be
the diameter of the stud.
(5) When a welded joint connects parts of unequal
thicknesses, the nominal thickness shall be the following:
(a) the thinner of two adjacent butt-welded parts
including head to shell connections;
(b) the thickness of the shell or the fillet weld,
whichever is greater, in connections to intermediate heads
of the type shown in Fig. UW-13.1 sketch (f);
(c) the thickness of the shell in connections to
tubesheets, flat heads, covers, flanges (except for welded
parts depicted in Fig. 2-4(7), where the thickness of the
weld shall govern), or similar constructions;
(d) in Figs. UW-16.1 and UW-16.2, the thickness
of the weld across the nozzle neck or shell or head or