(a) All tank vessels, except unmanned tank barges, contracted for on or after July 1, 1969, shall have efficient guard rails or bulwarks on decks and bridges. The height of rails or bulwarks shall be at least 391⁄2 inches from the deck except that where this height would interfere with the normal operation of the vessel, a lesser height may be approved by the Commandant. At exposed peripheries of the freeboard and superstructure decks the rails shall be in at least three courses including the top. The opening below the lowest course shall not be more than 9 inches. The courses shall not be more than 15 inches apart. In the case of ships with rounded gunwales, the guard rail supports shall be placed on the flat of the deck. On other decks and bridges the rails shall be in at least two courses, including the top, approximately evenly spaced. All rails shall consist of solid or tubular sections or chains or wire rope or a combination thereof.

(b) Where it can be shown to the satisfaction of the Commandant that a vessel is engaged exclusively on voyages of a sheltered nature, the provisions of paragraph (a) of this section may be relaxed.

(c) Tank vessels contracted for prior to July 1, 1969, except unmanned tank barges, assigned a deeper load line under part 42 of subchapter E (Load Lines) of this chapter shall have efficient guard rails or bulwarks as required by paragraph (a) of this section. Otherwise, existing rails and bulwarks previously approved will be considered satisfactory so long as they are maintained in good condition. Minor repairs and alterations may be made to the same standards as the original construction.

(d) All tank vessels in ocean and coastwise service, except unmanned tank barges, constructed on or after June 15, 1987, must have suitable storm rails installed in all passageways and at the deckhouse sides on weather decks where persons on board might have normal access. Storm rails must be installed on both sides of passageways which are six feet or more in width. Tank vessels to which this paragraph applies constructed prior to June 15, 1987, may retain previously accepted or approved installations so long as they are maintained in good condition to the satisfaction of the Officer in Charge, Marine Inspection.