Valves of the prior art which have a spherical type of valve member are called ball valves and generally have had an opening at the top of the body through which the ball and seals are installed into the body. Some prior art valves have provided an end entry for the ball or valve member so that the ball and seals could be installed from the end of the body and then a body closure secured over such end opening to seal the ball and seals therein and to provide one of the passages communicating into the valve.
Some of these prior valves, such as shown in U.S. Pat. No. 4,184,507, did not provide both upper and lower shafts on which the ball is mounted for rotation in the valve chamber within the body. Other valves, such as is shown in U.S. Pat. No. 4,137,936 and U.S. Pat. No. 3,656,498, provide both upper and lower openings through which the respective upper and lower shafts could be removed from the body after the closure members on such openings had been removed.
Prior ball valves have included both upstream and downstream seal rings against which the ball seals. U.S. Pat. No. 4,254,793 is illustrative of a ball valve having both upstream and downstream seals and the types of seals which are used therefor. U.S. Pat. No. 3,656,498, in addition to having the above mentioned upper and lower shafts, discloses a ball valve having only a single seal ring against which the ball is to seal both upstream and downstream. U.S. Pat. No. 4,206,904 discloses another end entry ball valve with a single seal ring against which the ball is to seal both upstream and downstream. This valve includes a ball which has a shaft on one side which projects into a recess in the body and a plug on the other side which engages in a window in the body and in a recess in the ball. When the end closure and the plug are removed, the body is sufficiently oversized so that the ball can then be pivoted to be removed through the end opening.
None of these references teach the use of a ball valve having an end entry through which the ball is readily removable and which does not require openings through the body for the shafts and the outer closures to seal such openings. Further none of these references teach an end entry ball valve through which the ball is readily removed without requiring that the valve body be oversized to allow pivoting of the ball. Also, none of these prior art patents suggest that a single seal ring could be used for a ball valve seal which would seal against pressure from both directions and provide a seal even after the valve had been exposed to sufficient temperature or fire to destroy or deteriorate the resilient seals.