When a vessel is carrying sulfur dioxide, the master shall ensure that:
(a) A cargo tank is dry before it is loaded with sulfur dioxide; and
(b) Air or inert gas admitted into a cargo tank carrying sulfur dioxide during discharging or tank breathing has a moisture content equal to or less than the moisture content of air with a dew point of -45 [deg]C (-49 [deg]F) at atmospheric pressure. [CGD 74-289, 44 FR 26009, May 3, 1979, as amended by USCG-2014-0688, 79 FR 58285, Sept. 29, 2014]