Abstract: A ball valve assembly has a lower support, an upper seat, a spherical ball, and linkages for rotating the ball. The lower support has a spherical support surface for the ball. The lower support also has a pair of guides for maintaining alignment of the ball and seat to prevent contact with the linkages. The upper seat has a skirt with a spherical inner surface having grooves for contacting the ball. The skirt and grooves seal and ensure alignment of the ball. The grooves also assist in the retention of lubricant to reduce friction. An optional insert is located in the skirt for low pressure sealing from below and above. Finally, the skirt has a pair of openings to provide relief for the operating links, and flat structures against which the guides of the lower support may restrain rotation of the upper support.

Abstract: A ball valve assembly has a lower support, an upper seat, a spherical ball, and linkages for rotating the ball. The lower support has a spherical support surface for the ball. The lower support also has a pair of guides for maintaining alignment of the ball and seat to prevent contact with the linkages. The upper seat has a skirt with a spherical inner surface having grooves for contacting the ball. The skirt and grooves seal and ensure alignment of the ball. The grooves also assist in the retention of lubricant to reduce friction. An optional insert is located in the skirt for low pressure sealing from below and above. Finally, the skirt has a pair of openings to provide relief for the operating links, and flat structures against which the guides of the lower support may restrain rotation of the upper support.