PURPOSE: To prevent the titled device from becoming an obstacle at the time of loading of a large-sized cargo, by a method wherein the top of a lower gas ventilation duct provided on a deck in a standing state is made into a tilting flange and an upper gas ventilation duct is made raisable and layable through a L-shaped hinge which is rotatable centering around a hinge shaft at the lower part of the lower edge part of the tilting flange.

CONSTITUTION: When a gas ventilation duct such as a funnel and an air vent pipe are provided on a self-sailing barge, a lower gas ventilation duct 8 is made to provided on a deck 19 in a standing state. A tilting flange 9' is formed on the top of the lower gas ventilation duct 8 and an upper gas circulation duct 7 is made raisable and layable by a hinge pin 13 provided close by the lower part of the lower edge of the tilting flange 9' and the upper part of the deck 19 through a rockable L-shaped hinge 11. A tilting flange 9 is formed on the bottom of the upper gas ventilation duct 7 and connected with the lower gas ventilation duct 8 at a standing time. With this construction, the gas ventilation duct can be prevented from becoming an abstacle at the time when a large-sized cargo is loaded on the deck.