Fluid flow control valve with high temperature bi-directional shutoff

A valve comprising:

• a valve housing having an inlet and an outlet and a fluid flowpath connecting the inlet and the outlet;
• a ball element pivotably mounted in the valve housing, an exterior surface of the ball element defining a portion of a sphere, wherein all points on the exterior surface of the ball element are not equidistant from a natural pivot point of the ball element;
• a main seal disposed within the fluid flowpath and biased toward the ball element;
• a seal housing disposed between the main seal and the valve housing, a gap being formed between the main seal and the seal housing, the gap being exposed to fluid pressure within the valve the seal housing including a pair of stops positioned to span a ledge carried by the main seal and arranged to limit movement of the main seal toward and away from the ball element;
• and
• a secondary seal disposed between the main seal and the seal housing, the secondary seal preventing fluid flow through the gap,
• wherein a portion of the gap directly exposed to the fluid pressure is oriented substantially perpendicular to a direction of fluid flow through the valve housing, and
• wherein the secondary seal is arranged to shift in a direction substantially perpendicular to the direction of fluid flow through the valve housing.

A valve comprising:

• a valve housing having an inlet and an outlet and a fluid flowpath connecting the inlet and the outlet;
• a ball element pivotably mounted in the valve housing, an exterior surface of the ball element defining a portion of a sphere, wherein all points on the exterior surface of the ball element are not equidistant from a natural pivot point of the ball element;
• a main seal disposed within the fluid flowpath and biased toward the ball element;
• a seal housing disposed between the main seal and the valve housing, a gap being formed between the main seal and the seal housing, the gap being exposed to fluid pressure within the valve;
• and
• a secondary seal disposed between the main seal and the seal housing, the secondary seal preventing fluid flow through the gap,
• wherein a portion of the gap directly exposed to the fluid pressure is oriented substantially perpendicular to a direction of fluid flow through the valve housing;
• wherein the main seal is biased toward the ball element by a resilient member;
• and
• wherein the main seal is restricted in movement in direction towards and away from the ball element by the seal housing.

A method of operating a valve, comprising:

• providing a valve body having an inlet, an outlet and a seal assembly, wherein the seal assembly comprises a main seal, a seal housing, and a bellows;
• positioning the bellows between the main seal and the seal housing;
• biasing the main seal toward a ball element;
• providing the seal housing and the main seal with stops positioned to span a ledge carried by the main seal to thereby limit movement of the main seal toward and away from the ball element
• controlling a first flow through the valve by rotating the ball element eccentrically mounted to the valve body into and out of engagement with the main seal;
• and
• impeding a second fluid flow through the seal assembly by attaching a resilient seal to the main seal and the seal housing,
• wherein the main seal is moved away from the ball element exclusively through direct contact with the ball element when the ball element moves into a closed position.