(a) Unless exempted by the rules of UG-20(f) or
other rules of this Division, Fig. UCS-66 shall be used to
establish impact testing exemptions for steels listed
in Part UCS. When Fig. UCS-66 is used, impact testing
is required for a combination of minimum design metal
temperature (see UG-20) and thickness (as defined below)
which is below the curve assigned to the subject material.
If a minimum design metal temperature and thickness combination
is on or above the curve, impact testing is not
required by the rules of this Division, except as required
by (j) below and UCS-67(a)(2) for weld metal.
Why is there a dashed line running vertically at 0.394"? Does this denote another limit I am missing?
The dashed line represents the thickness required for a Charpy V-notch impact specimen. The impact or notch toughness behavior beyond the CVN specimen thickness line is influenced by component thickness.
