(a) Each hold space, void space, cofferdam, and spaces containing cargo piping must have:
(1) A fixed mechanical ventilation system; or
(2) A fixed ducting system that has a portable blower that meets § 154.1205(i) and (j).
(b) A portable blower in any personnel access opening must not reduce the area of that opening so that the opening does not meet § 154.340.