46 CFR § 78.47-38
Valves and closing appliances
April 15, 2021
(a) All valves and closing appliances, or other mechanisms which may be required to be operated for damage control purposes in case of emergency shall be conspicuously marked with letters at least 1 inch high identifying the control and the direction of operation. In all cases indication shall be provided to show whether the control is open or closed.
(b) [Reserved]