This interpretation is not intended to be applied to existing
The means of closing air pipes should be weathertight and
of an automatic type if the openings of the air pipes to which the
devices are fitted would be submerged at an angle of less than 40°
(or any lesser angle which may be needed to suit stability requirements)
when the ship is floating at its summer load line draught. Pressure
vacuum valves (P.V. valves) may be accepted on tankers.
Wooden plugs and trailing canvas hoses should not be accepted
as closing devices for air pipes in positions 1 and 2.