Shear mechanism for backpressure relief in a choke valve

A choke valve comprising:

• a body having an axial through hole passing from a first side of the body to a second side of the body, an outlet passageway coaxially aligned with the through hole and positioned at the first side of the body, and a radial inlet port intersecting the through hole between the first and second sides of the body;
• a valve seat coaxially housed in the through hole between the inlet port and the outlet passageway;
• a valving member axially reciprocable within the through hole between a first position bearing against the valve seat and a second open position spaced away from the valve seat;
• an actuator attached to the second side of the body for reciprocably moving the valving member between the first position and the second position wherein the actuator includes an axially reciprocable actuator shank;
• and
• a shearable mechanism having a stem interconnecting the actuator shank and the valving member and two split shear ring halves mounted in a mounting groove in the stem and retained therein by a retension device;
• whereby whenever the shearable mechanism is subjected to fluid pressure in excess of a predetermined value from the outlet passageway the shearable mechanism will shear thereby allowing the release of backpressure.

A choke valve comprising:

• a body having an axial through hole passing from a first side of the body to a second side of the body, an outlet passageway coaxially aligned with the through hole and positioned at the first side of the body, and a radial inlet port intersecting the through hole between the first and second sides of the body;
• a valve seat coaxially housed in the through hole between the inlet port and the outlet passageway;
• a pressure balanced valving member axially reciprocable within the through hole between a first position bearing against the valve seat and a second open position spaced away from the valve seat;
• an actuator attached to the second side of the body, the actuator having an axially reciprocating actuator shank for reciprocably moving the valving member between the first position and the second position;
• an antirotational device preventing the valving member from rotating within the through hole;
• and
• a shearable mechanism interconnecting the actuator shank and the valving member, the shearable mechanism comprising
• a stem, a first end of the stem positioned in a socket in one end of the actuator shank and a second end of the stem mounted to the valving member,
• a shear pin passing through the stem proximal to first end of the stem and passing through a wall of the socket in the actuator shank when the first end of the stem is located in the socket at less than a full depth of the socket;
• and
• a pair of split shear ring halves mounted in a mounting groove in the stem proximal to the shear pin, and a shear ring keeper device mounted over the shear ring halves and the shear pin to maintain the shear ring halves and the shear pin in position;
• whereby whenever the valving member is subjected to a fluid pressure in excess of a predetermined value from the outlet passageway the shear pin will shear and the stem will move further into the socket in the actuator shank thereby allowing the release of backpressure.

A choke valve comprising:

• a body having an axial through hole passing from a first side of the body to a second side of the body, an outlet passageway coaxially aligned with the through hole and positioned at the first side of the body, and a radial inlet port intersecting the through hole between the first and second sides of the body;
• a valve seat coaxially housed in the through hole between the inlet port and the outlet passageway;
• a pressure balanced valving member axially reciprocable within the through hole between a first position bearing against the valve seat and a second open position spaced away from the valve seat;
• an actuator attached to the second side of the body, the actuator having an axially reciprocating actuator shank for reciprocably moving the valving member between the first position and the second position;
• an antirotational device preventing the valving member from rotating within the through hole;
• and
• a shearable mechanism interconnecting the actuator shank and the valving member, the shearable mechanism comprising
• a stem, a first end of the stem positioned in a socket in one end of the actuator shank at less than a full depth of the socket and a second end of the stem mounted to the valving member,
• a pair of split shear ring halves mounted in a mounting groove in the stem proximal to the first end of the stem, and
• a shear ring keeper device mounted over the shear ring halves to maintain the shear ring halves in position;
• whereby whenever the shearable mechanism is subjected to a fluid pressure in excess of a predetermined value from the outlet passageway the shear ring halves will shear and the stem will move further into the socket in the actuator shank thereby allowing the release of backpressure.

A choke valve comprising:

• a body having an axial through hole passing from a first side of the body to a second side of the body, an outlet passageway coaxially aligned with the through hole and positioned at the first side of the body, and a radial inlet port intersecting the through hole between the first and second sides of the body;
• a valve seat coaxially housed in the through hole between the inlet port and the outlet passageway;
• a valving member axially reciprocable within the through hole between a first position bearing against the valve seat and a second open position spaced away from the valve seat;
• an actuator attached to the second side of the body for reciprocably moving the valving member between the first position and the second position wherein the actuator includes an axially reciprocable actuator shank having a shank socket;
• and
• a shearable mechanism having a stem interconnecting the actuator shank and the valving member, wherein a first end of the stem is positioned in the shank socket at less than a full depth of the shank socket;
• whereby whenever the shearable mechanism is subjected to fluid pressure in excess of a predetermined value from the outlet passageway the shearable mechanism will shear and the stem will move further into the shank socket thereby moving the valving member away from the valve seat to allow the release of backpressure.