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 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). Doubl