Variable geometry valve seat seal for simultaneous contact and release with valve body

A plug valve seat assembly comprising:

• a valve seat having a plug communication side and a valve body communication side, the body communication side having a top and bottom centerpoint and an extreme exposed edge and an extreme covered edge;
• a seat face on the valve body communication side of the valve seat;
• a seal received within a groove, the groove disposed within the seat face on the valve body communication side and forming a seal path substantially following the valve seat shape;
• a seal protrusion on the valve body communication side and a seal substructure bonded within the groove;
• wherein the seal path intersects the top and bottom centerpoint and the extreme exposed and covered edges;
• wherein the seal protrusion has a variable height and a variable width along the seal path;
• wherein the groove has a variable depth below the seat face and a variable width along the seal path.

A method of simultaneously sealing a plug valve along an entire seal path, the plug valve body including a pair of seats each seat having a seal, the method comprising the steps of

• forming a bubble tight seal to withstand the working pressure of a medium acting upon the seat when the plug valve is in the seated position, the seal formed by a seal protrusion with a constantly varying normal height and width and is symmetrical about a seat centerline;
• wherein each seal protrusion has a seal protrusion height that tapers from the valve seat centerline to an edge height, as each seal protrusion extends from upper and lower seal segments simultaneously to the covered and exposed edges;
• wherein each seal protrusion has a seal protrusion width that tapers from an edge width to the valve seat centerline;
• as each seal protrusion extends from covered and exposed edges simultaneously to the upper and lower seal segments.