Patent Application
20170254717
Technical Field
The present invention relates to equipment that automatically tests valve bodies for leaks. In particular, the invention relates to equipment used to automatically detect leaks from a valve body or valve actuator during long-term cycle testing in a high pressure marine environment.
Background
Fluid flow valves are known in the art, and typically comprise a valve body with an inlet, an outlet, and a closure member between the inlet and outlet. The closure member can be actuated between an “on” position that allows fluid to flow through the valve, and an “off” position that stops fluid from flowing through the valve, using an actuator that manipulates the position of the closure member from the exterior of the valve body. The closure member can be fully “on” allowing for maximum available throughput, fully “off” completely stopping fluid flow, or partially “on” allowing a fluid flow rate less than maximum possible through the valve body.
Fluid flow valves have particularly important applications in subsea oil and gas exploration and production. Valves located in subsea environments can be subjected to thousands of pounds of pressure, and need to function reliably under such conditions even after thousands of on/off cycles.
In one embodiment, a valve test assembly comprises: a test frame; a torque motor secured to the test frame; an actuator shaft coupled to the torque motor; a torque sensor that measures the amount of torque applied to the actuator shaft; a valve attachment area on the test frame; a bubble catch plate secured to the test frame between the valve attachment area and the torque motor; wherein the bubble catch plate comprises a funnel surface facing the valve attachment area, further wherein the bubble catch plate comprises a gas tube orifice connected to a gas capture tube on a side of the bubble catch plate opposite the valve attachment area.
In another embodiment, the funnel surface comprises an angled surface. In another embodiment, the funnel surface comprises at least one groove.
In another embodiment, the valve test assembly further comprises a gas flow meter coupled to the gas capture tube. In another embodiment, the valve test assembly further comprises a valve attached to the valve attachment area of the test frame.
The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which, like reference numerals identify like elements, and in which:
The present invention is an apparatus, method and system for long-term cycle testing of a valve body for leaks in a subsea environment. One embodiment of a test assembly according to the present invention is shown in
As depicted therein, test assembly 100 comprises a test frame 102. The valve 108 undergoing testing is secured to the frame 102 in one embodiment by bolts 126 located at a valve attachment area of the test frame 102. Other means of securing the valve to the test frame can be used, such as clamps. The portion of the test frame 102 that the valve is secured to may comprise holes or angled surfaces that allow bubbles generated by the valve to percolate up towards the bubble catch plate 106.
The valve 108 comprises an inlet 122, an outlet 124, and an actuator 120. The actuator 120 is connected to a torque motor 116 through a shaft 128. The amount of torque applied to the shaft 128 is measured by torque sensor 104.
Disposed above the valve 108 is a bubble catch plate 106. The bubble catch plate 106 can also be secured to the test frame 102. Bubble catch plate 106 is designed to catch any bubbles that emerge from the valve 108 and direct them to gas capture tube orifice 112. Gas capture tube orifice 112 is an orifice in the bubble catch plate 106 that allows gas bubbles to pass through the bubble catch plate, and into gas capture tube 114. The shaft 128 passes through the bubble catch plate 106 through water and gas tight connection, such as passing the shaft through a rubber diaphragm. In a preferred embodiment, the bubble catch plate is made of a clear or translucent material so that the presence of bubbles can be visually confirmed.
In one embodiment, the bubble catch plate comprises a funnel surface facing the valve. The funnel surface can be any shape that, when impacted by a rising bubble, diverts the direction of travel of the bubble towards the gas capture tube orifice. Most generally, the funnel surface is an inclined surface that directs a rising bubble towards a portion of the surface or bubble catch plate further away from the valve.
Funnels are generally known and used in the art to direct the flow of solids or liquids under the influence of gravity. The most iconic form of a funnel is an inverted frustum of a cone or pyramid with a hole near the apex of the narrow portion of the frustum. When liquids or solid particles are poured into the large end of the frustum, they are directed towards the small end of the frustum as they fall under the force of gravity. The walls of the frustum may be smooth or may comprise surface features, such as ridges or channels, which further direct the flow of solids or liquids through the funnel.
The present invention uses a funnel surface to direct the flow of a bubble that is rising in a liquid, against the force of gravity, because it is less dense than the liquid. As used herein, a funnel surface is at least a portion of a funnel that redirects flow in a particular direction. The funnel surface can be a portion of a frustum (a curved or flat surface, which may be smooth or may include other surface features) or an entire frustum. The frustum need not be a frustum of a regular geometric shape, but preferably is.
In the embodiment disclosed in
With further reference to
While the inlet side of the valve is pressurized, the torque motor cycles the valve actuator between on and off positions. All of the gas that enters the valve inlet should pass through the valve body and out through the valve outlet. Any leaks in the valve will produce bubbles 130 that rise up from the valve body. Rising bubbles 130 impact the bubble catch plate 106, and are directed towards and through the gas capture tube orifice 112 and into the gas capture tube 114, where they are analyzed by a gas flow meter (not shown).
The test bath temperature can be varied during the valve test to simulate cold conditions (for example, about −18 degrees Celsius), hot conditions (for example, about 150 degrees Celsius), or any desired temperature in between. During the test, the valve is cycled between the on and off positions any desired number of times, but preferably thousands of cycles, while the gas flow meter continuously monitors the test bath for bubbles.
The benefits of the present invention over the prior art are numerous and substantial. In the prior art, a test valve assembly was visually monitored for bubbles by a human operator. The operator would watch as the valve was cycled between the on and off positions, and note the number and approximate size of any bubbles that emerged from the valve assembly. This arrangement required diligent focus and attention on the part of the operator. The bubbles that are produced by a leaky valve can be very small and intermittent.
By contrast, the valve testing assembly of the present invention can be continuously monitored by a computerized system that is connected to the torque motor and the gas flow meter. Once the system is set up and turned on, the accuracy of the system is independent of operator skill or ability. The system also allows for long-duration tests without risk of operator fatigue. Furthermore, the inventive system herein is capable of making quantitative measurements, whereas a human operator's observations are more qualitative. Also, the results are highly consistent between tests
Virtually any type of valve, including ball valves, can be tested using the test assembly described herein. The valve testing assembly of the present invention is particularly useful for testing valves used in subsea environments of oil and gas exploration activities.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed.
