46 C.F.R. § 154.418
General
An integral tank must not be designed for a temperature colder than −10 °C (14 °F), unless the tank is specially approved by the Commandant (CG-ENG).
An integral tank must not be designed for a temperature colder than −10 °C (14 °F), unless the tank is specially approved by the Commandant (CG-ENG).