Metal to Metal Ball Valves Characteristics
General soft seated ball valves working temperature is limited up to 400°F, but metal-seated ball valves are guaranteed for a maximum service temperature of 800 °F.
KOSEN metal-seated ball valves adopt seat spring structure, which can push upstream seat tightly against the ball surface creating a reliable sealing even if extremely low pressure. Metal-seated ball valves maximum allowable seat leakage: Air: ANSI/FCI 70-2 Class V, metal-seated ball valves are absolute fire safe design. Metal-to-metal contact is designed between ball and seat, where is unconditional fire safe function. Flexible graphite gasket can prevent fluid leakage from between body & seat or body & adapter even if high temperature environments to reach fire-safe purpose. In addition, other sealing components such as stem packing can also reach fire-safe function and prevent external leakage, so all parts of the valve will not be damaged by high temperature service. As general ball valves, metal-seated ball valves are provided with blow-out proof stem& anti-static device.
The ball surface of hard sealed ball valve adopts advanced spraying technology. Through the treatment of various working conditions, the maximum hardness can reach hrc78. The sealing surface of the valve seat is processed, and the maximum hardness can reach hrc72. The ball and valve seat are matched for grinding, and all sealing areas of the whole sealing surface of the ball valve are precision ground. Suitable for high temperature and high pressure water, steam, petroleum, coal, fiber, thick and corrosive media, as well as media with particles. The metal sealed ball valve has two structures: floating ball and fixed ball. The metal seat ring is in contact with the spherical surface. The uniform spring load acting on the seat ring forms a seal between the seat ring and the spherical surface.
Due to the spring load, the auxiliary seal expands to realize the sealing between the valve body and the valve seat. The spring load is sufficient to provide a reliable sealing between the valve seat and the ball. Under low pressure, a sealing grease injection system can be designed between the sealing surface of the valve seat and the ball.