Abstract: Disclosed is a safety valve installed in a tank of a vessel carrying oil or chemical substance to discharge supersaturated gas produced in the tank and to adjust an internal pressure to a normal level when a negative pressure is produced in the tank. The valve comprises a lower body; an upper body mounted onto the lower body; a valve stem extended from the upper body to the lower body; and a disc provided on the valve stem and positioned between the upper and lower body to shut out a communication between the upper and lower body. The disc has a groove on an underside thereof, with a protruded portion being formed along an edge of the disc, a Teflon bushing is interposed between the disc and the valve stem, and the disc has a large diameter than an internal diameter of the lower body.

Abstract: Disclosed is a safety valve installed in a tank of a vessel carrying oil or chemical substance to discharge supersaturated gas produced in the tank and to adjust an internal pressure to a normal level when a negative pressure is produced in the tank. The valve comprises a lower body; an upper body mounted onto the lower body; a valve stem extended from the upper body to the lower body; and a disc provided on the valve stem and positioned between the upper and lower body to shut out a communication between the upper and lower body. The disc has a groove on an underside thereof, with a protruded portion being formed along an edge of the disc, a Teflon bushing is interposed between the disc and the valve stem, and the disc has a large diameter than an internal diameter of the lower body.