Section 8(2)(a) in The Madras Port Petroleum Rules, 1963
(a)A bulk oil vessel shall commence discharging of dangerous petroleum, only during the day time, but a vessel which has commenced the discharge before sunset may continue to discharge even after sunset, provided that such discharging is continuous and without interruption. Should anything occur after sunset, which necessitates the repair or disconnection to the plant, pipes or connections, such discharge shall be discontinued until after sunrise.