Abstract: A system includes an electric actuator having an actuation stem, a screw assembly, an electric drive, and a lock. The screw assembly is coupled to the actuation stem, wherein the screw assembly includes a male screw portion coupled to a female screw portion. The electric drive is coupled to the screw assembly, wherein the electric drive is configured to move the screw assembly to move the actuation stem. The lock is configured to hold a position of the actuation stem when not driving movement of the actuation stem.

Abstract: A bellows assembly is configured to mount between a movable valve structure and a stationary valve structure of a valve assembly. The bellows assembly comprises a bellows and a spacer. The bellows is configured to compress until a gap is closed relative to the spacer. The bellows assembly is configured to bear a load through the bellows before the gap is closed, and the bellows assembly is configured to bear the load through the bellows and the spacer after the gap is closed.

Abstract: A bellows assembly is configured to mount between a movable valve structure and a stationary valve structure of a valve assembly. The bellows assembly comprises a bellows and a spacer. The bellows is configured to compress until a gap is closed relative to the spacer. The bellows assembly is configured to bear a load through the bellows before the gap is closed, and the bellows assembly is configured to bear the load through the bellows and the spacer after the gap is closed.

Abstract: A system includes a ball valve. The ball valve includes a housing, a ball, and a first valve seat assembly. The housing includes a chamber, a first fluid passage intersecting the chamber, and a second fluid passage intersecting the chamber. The ball is disposed in the chamber and is configured to control fluid flow between the first and second fluid passages. The first valve seat assembly is disposed between the ball and the housing. The first valve seat assembly includes a first seat configured to seat against the ball both above and below a pressure threshold, and a second seat configured to seat against the ball only above the pressure threshold, wherein the second seat has a coefficient of friction that is lower than the first seat.

Abstract: A bellows assembly mounts between a movable valve structure and a stationary valve structure of a valve assembly. The bellows assembly includes a bellows and a spacer. The bellows compresses until a gap is closed relative to the spacer. The bellows assembly bears a load through the bellows before the gap is closed, and the bellows assembly bears the load through the bellows and the spacer after the gap is closed.

Abstract: A bellows assembly is configured to mount between a movable valve structure and a stationary valve structure of a valve assembly. The bellows assembly comprises a bellows and a spacer. The bellows is configured to compress until a gap is closed relative to the spacer. The bellows assembly is configured to bear a load through the bellows before the gap is closed, and the bellows assembly is configured to bear the load through the bellows and the spacer after the gap is closed.

Abstract: A system includes a ball valve. The ball valve includes a housing, a ball, and a first valve seat assembly. The housing includes a chamber, a first fluid passage intersecting the chamber, and a second fluid passage intersecting the chamber. The ball is disposed in the chamber and is configured to control fluid flow between the first and second fluid passages. The first valve seat assembly is disposed between the ball and the housing. The first valve seat assembly includes a first seat configured to seat against the ball both above and below a pressure threshold, and a second seat configured to seat against the ball only above the pressure threshold, wherein the second seat has a coefficient of friction that is lower than the first seat.