UHA-51(d) Exemptions from Impact Testing for Base
Metals and Heat Affected Zones. Impact testing is not
required for Table UHA-23 base metals for the following
combinations of base metals and heat affected zones (if
welded) and MDMTs, except as modified in UHA-51(c):
UHA-51(d)(1) for austenitic chromium–nickel stainless
steels as follows:
(a) Types 304, 304L, 316, 316L, 321 and 347 at
MDMTs of ?320°F (?196°C) and warmer;