FLAPPER VALVE

摘要

A flapper valve includes a valve body having a hinge member. A flapper is pivotally mounted to the valve body through the hinge member. At least one of the valve body and the flapper includes a multi-stage valve seat. The multi-stage valve seat includes a first sealing zone and a second sealing zone that is distinct from the first sealing zone. The first sealing zone is configured to provide pressure containment at the valve body when the flapper is exposed to a first pressure and the second sealing zone is configured to provide pressure containment at the valve body when the flapper is exposed to a second pressure that is greater than the first pressure.