This specification covers carbon steel overboard discharge hull penetrations for system piping. Penetrations shall be classified as follows: Type I; Type II (Class 1 and Class 2); Type III (Class 1 and Class 2); and Type IV (Classes 1, 2, and 3). Doubler and insert plates shall be of material with physical properties equal to or better than the reinforced shell plate. Overboard discharges shall be combined to the maximum extent practicable to minimize the number of shell penetrations. Overboard discharges shall be located to minimize recirculation into suction seachests. Shell penetrations shall be located outside of cathodic protection areas. Penetration pipe extension past the shell plate shall be equal to the pipe wall thickness.

1.1 This specification covers carbon steel overboard discharge hull penetrations for system piping of NPS 1 through NPS 24 (see Note 1).

Note 1—The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such TRADITIONAL terms as nominal diameter, size, and nominal size.

1.2 The minimum pipe schedule and reinforcement dimensions presented in Tables 1-6 are based on specifications in 46 CFR, 56.50-95 and Navy Design Data Sheet 100-1.

1.3 This specification does not include sea chest penetrations.

1.4 This specification does not include penetrations in protective plating.