Activation system for pipeline plug
A pipeline plug includes a plug body. The plug body includes an outer housing. The interior of the outer housing defines a pressure vessel. The pipeline plug includes a pressure head coupled to the plug body, a seal assembly, a gripper assembly, a movable head, and an actuation mechanism. The actuation mechanism includes a leadscrew, the leadscrew coupled to the movable head. The actuation mechanism includes a captive nut, the captive nut positioned within the pressure vessel. The actuation mechanism includes a motor, the motor operatively coupled to the captive nut and adapted to rotate the captive nut.
1. A pipeline plug comprising:
a plug body, the plug body including an outer housing, an interior of the outer housing defining a pressure vessel;
a pressure head coupled to the plug body;
a seal assembly;
a gripper assembly;
a movable head;
an actuation mechanism, the actuation mechanism including:
a leadscrew, the leadscrew coupled to the movable head;
a captive nut, the captive nut positioned within the pressure vessel; and
a motor, the motor operatively coupled to the captive nut and adapted to rotate the captive nut;
a brake assembly, the brake assembly including a brake stator coupled to the outer housing and a brake rotor coupled to a rotating component of the actuation mechanism; and
a brake failsafe system, the brake failsafe system including:
a brake release cylinder formed in the outer housing;
a brake release piston positioned within the brake release cylinder; and
a brake release leg, the brake release leg coupled to the brake release piston, the brake release leg engaging the brake assembly such that movement of the brake release piston due to differential pressure across the pipeline plug causes the brake assembly to disengage.
2. The pipeline plug of claim 1 , further comprising a gearset operatively coupled between the motor and the captive nut.
3. The pipeline plug of claim 2 , wherein the gearset comprises harmonic gearing, epicyclic gearing, or planetary gearing.
4. The pipeline plug of claim 2 , wherein the gearset is annular, and wherein the leadscrew passes through the gearset.
5. The pipeline plug of claim 1 , further comprising a diaphragm, the diaphragm fluidly separating the brake release cylinder from fluid outside the pipeline plug while allowing pressure from the fluid outside the pipeline plug to be transmitted to the brake release cylinder.
6. The pipeline plug of claim 1 , wherein the leadscrew is mechanically coupled to the movable head by a frangible link.
7. The pipeline plug of claim 1 , further comprising a thrust structure mechanically coupled to the outer housing.
8. The pipeline plug of claim 7 , further comprising a bearing positioned between the thrust structure and the captive nut.
9. The pipeline plug of claim 1 , wherein the motor is annular, and wherein the leadscrew passes through the motor.
10. The pipeline plug of claim 1 , wherein the movable head, gripper assembly, seal assembly, and pressure head are tapered such that longitudinal movement of the movable head toward the pressure head caused by rotation of the captive nut causes the gripper assembly and seal assembly to extend radially outward.
11. A brake failsafe system for a pipeline plug including a brake assembly, the brake failsafe system comprising:
a brake release cylinder formed in an outer housing of the pipeline plug;
a brake release piston positioned within the brake release cylinder; and
a brake release leg, the brake release leg coupled to the brake release piston, the brake release leg engaging the brake assembly such that movement of the brake release piston due to differential pressure across the pipeline plug causes the brake assembly to disengage.
12. The brake failsafe system of claim 11 , further comprising a diaphragm, the diaphragm fluidly separating the brake release cylinder from fluid outside the pipeline plug while allowing pressure from the fluid outside the pipeline plug to be transmitted to the brake release cylinder.