Trunnion ball valve

Abstract

A trunnion ball valve comprising first and second seat assemblies located at the inner ends of inlet and outlet passages. Each seat assembly comprises a seat 184, 186 with a tubular body 184a, 186a and an annular seat head 188, 190 at one end of the tubular body. The seat head has an annular sealing face 192, 194 in sealing contact with the outer surface of a valve ball 148. Each seat assembly also has an inner seat support comprising a tubular body on which the tubular body 184a, 186a of the seat is mounted, an outer seat support 172, 174 comprising a tubular body 172a, 174a located radially outwardly of the tubular body of the seat, and an annular recess at one end for receipt of the annular seat head 188, 190 and a spring 208, 210 which biases the seat towards the valve ball. The valve ball 148 is pivotable between a first, open position in which a passage extending through the valve ball is aligned with and communicates with the inlet and outlet passages and a second, closed position in which the passage extending through the valve ball is not aligned with, and does not communicate with, the inlet and outlet passages. [Figure 5]