(a) An aluminum cargo tank and its dome must be enclosed by the vessel's hull structure or a separate steel cover.

(b) The steel cover for the aluminum cargo tank must meet the steel structural standards of the American Bureau of Shipping published in “Rules for Building and Classing Steel Vessels”, 1981.

(c) The steel cover for the aluminum tank dome must be:

(1) At least 3.2 mm ( 1/8 in.) thick;

(2) Separated from the tank dome, except at the support points; and

(3) Thermally isolated from the dome.