At least two placards reading “DANGER – KEEP AWAY” in letters not less than 6 inches in height on a contrasting background shall be located on offshore side of vessel transferring flammable liquids, combustible liquids, products or Class 1 and 2 liquefied petroleum gases, in such a position that placards may be readily seen by approaching craft. Only one such sign shall be required for barges. Such signs shall be furnished by the terminal at which the vessel is moored.