A valve seat for use in a valve assembly, the valve assembly including a valve body defining a fluid inlet in fluid communication with a fluid outlet, the valve body having an inner body surface defining an interior chamber extending between the fluid inlet and the fluid outlet; a control shaft disposed in the interior chamber and coupled to the valve body for rotational movement relative to the valve body; and a valve element disposed in the interior chamber and coupled to the control shaft for movement in conjunction with the control shaft relative to the valve body through a range of positions between and including a closed position and an open position with the valve element having an outer surface defining an outer radial diameter, said valve seat comprising: a cylindrical body portion having an inner seat surface and an opposing outer seat surface, said cylindrical body portion defining a clearance hole extending from said inner seat surface and said opposing outer seat surface for receipt of said control shaft, said inner seat surface defining an inner radial diameter, and at least one seal disposed around said opposing outer seat surface adapted to sealingly couple said valve seat to said valve body, wherein said cylindrical body portion is formed from a polymeric material which maintains dimensional stability at temperatures ranging from -40 °C to 66 °C which is configured to self-adjust said inner radial diameter to correspond to the outer radial diameter of the valve element to maintain a portion of said inner seat surface in contact with the outer valve surface of the valve element through said range of positions, characterized in that said cylindrical body portion is non-continuous along a radial length and further has a first end and a second end which collectively define a lap joint therebetween, wherein said lap joint defines a gap between said first end and said second end with said first end and said second end configured to self-adjust said gap to adjust said inner radial diameter to correspond to the outer radial diameter of the valve element to maintain a portion of said inner seat surface in contact with the outer surface of the valve element through the range of positions, or in that said cylindrical body portion is non-continuous along a radial length and further has a first end and a second end with said first end disposed radially inwardly and overlapping said second end, wherein said cylindrical body is configured to self-adjust a length of overlap of said first end relative to said second end to adjust said inner radial diameter to correspond to the outer radial diameter of the valve element to maintain a portion of said inner seat surface in contact with the outer surface of the valve element through the range of positions. said valve seat comprising: a cylindrical body portion having an inner seat surface and an opposing outer seat surface, said cylindrical body portion defining a clearance hole extending from said inner seat surface and said opposing outer seat surface for receipt of said control shaft, said inner seat surface defining an inner radial diameter, and at least one seal disposed around said opposing outer seat surface adapted to sealingly couple said valve seat to said valve body, a cylindrical body portion having an inner seat surface and an opposing outer seat surface, said cylindrical body portion defining a clearance hole extending from said inner seat surface and said opposing outer seat surface for receipt of said control shaft, said inner seat surface defining an inner radial diameter, and at least one seal disposed around said opposing outer seat surface adapted to sealingly couple said valve seat to said valve body, wherein said cylindrical body portion is formed from a polymeric material which maintains dimensional stability at temperatures ranging from -40 °C to 66 °C which is configured to self-adjust said inner radial diameter to correspond to the outer radial diameter of the valve element to maintain a portion of said inner seat surface in contact with the outer valve surface of the valve element through said range of positions, characterized in that said cylindrical body portion is non-continuous along a radial length and further has a first end and a second end which collectively define a lap joint therebetween, wherein said lap joint defines a gap between said first end and said second end with said first end and said second end configured to self-adjust said gap to adjust said inner radial diameter to correspond to the outer radial diameter of the valve element to maintain a portion of said inner seat surface in contact with the outer surface of the valve element through the range of positions, or in that said cylindrical body portion is non-continuous along a radial length and further has a first end and a second end with said first end disposed radially inwardly and overlapping said second end, wherein said cylindrical body is configured to self-adjust a length of overlap of said first end relative to said second end to adjust said inner radial diameter to correspond to the outer radial diameter of the valve element to maintain a portion of said inner seat surface in contact with the outer surface of the valve element through the range of positions.