46 CFR §54.05-20

1. (a)The impact energies of each set of transverse Charpy specimens may not be less than the values shown in table 1 to § 54.05-20(a). Only one specimen in a set may be below the required average and the value of that specimen must be above the minimum impact value permitted on one specimen only. See § 54.05-5(c) for retest requirements.
2. (b)Transversely oriented Charpy V-notch impact specimens of ASTM A203 (incorporated by reference, see § 54.01-1) nickel steels must exhibit energies not less than the values shown in paragraph (a) of this section. Requirements for 9 percent nickel steels are contained in § 54.25-20. Other nickel alloy steels, when specially approved by the Commandant, must exhibit a no-break performance when tested in accordance with the drop weight procedure. If, for such materials, there are data indicating suitable correlation with drop-weight tests, Charpy V-notch tests may be specially considered by the Commandant in lieu of drop-weight tests. If the drop-weight test cannot be performed because of material thickness limitations (less than one-half inch), or product shape, or is otherwise inapplicable (because of heat treatment, chemistry etc.) other tests or test criteria will be specified by the Commandant.
3. (c)Where sufficient data are available to warrant such waiver, the Commandant may waive the requirements for toughness testing austenitic stainless-steel materials. Where required, austenitic stainless steels are to be tested using the drop-weight procedure and must exhibit a no-break performance. Where data are available indicating suitable correlation of Charpy V-notch results with drop-weight NDT or no-break performance, Charpy V-notch tests may be specially considered by the Commandant in lieu of dropweight tests. If the dropweight test cannot be performed because of material thickness limitations (less than one-half inch), or product shape, or is otherwise inapplicable (because of heat treatment, chemistry, etc.) other tests and test criteria will be specified by the Commandant.