Section 116.433 - Windows and air ports in fire control boundaries(a) Windows or air ports must be of tempered or laminated glass of at least 6.5 millimeters (0.25 inches) in thickness. The use of other glazing material such as polycarbonate sheets may be approved by the Commandant for specific installations.(b) Windows or air ports in bulkheads adjacent to passageways must not extend below a point 910 millimeters (36 inches) above the deck unless storm rails, that are structurally independent of the glass, are fitted in the passageway.(c) Windows or air ports in A-Class bulkheads must be fitted with frames of steel or equivalent material. Glazing beads or angles of steel or equivalent material must be installed to hold glass in place in windows or air ports in a fire control boundary in event of a fire if:(1) Where a steel frame is used, it is not arranged to retain the glass in place; or(2) A frame of aluminum or other material with low melting point is used.(d) A window or air port that is adjacent to an embarkation station, escape route, or survival craft stowage must be:(1) Of A-Class construction; or(2) Fitted with shutters, operable from outside the space, of steel or equivalent material.(e) A window installed in an internal fire control boundary must comply with the requirements of § 72.05-30 in subchapter H of this chapter, except that fire window frames and glazing material listed by Underwriters Laboratories may be used in B-Class bulkheads.(f) Windows in doors in fire control boundaries must comply with the requirements of paragraphs (a) through (e) of this section.(g) Windows complying with paragraphs (a) through (d) of this section may be installed in the external boundaries of stairtowers if there are no unprotected openings in the side of the vessel below the windows and if the windows are not exposed to any other parts of the vessel at an angle of less than 180 degrees.CGD 85-080, 61 FR 900, Jan. 10, 1996, as amended at 62 FR 51350, Sept. 30, 1997