Gate valves are one of the most common types of valves used in marine piping systems. This is the recommended design used to fully shut off or fully turn on flow. Gate valves are installed as isolating valves and are not intended to be used as a regulating valves. They are inherently suited for wide open service, flow moves in a straight line with practically no resistance when the disc is fully raised. When seated tight, there is no wear or undue strain on the disc or seats. Each time the valve is partially opened there is the possibility of wire drawing or erosion on the seating surface by high velocity flow. Repeated movement of the disc near the point of closure under high velocity flow can make the disc drag on the seating surfaces and cause galling or scoring on the downstream side. A partially open disc may cause turbulent flow with vibration and chattering of the disc.