A diaphragm valve for high pressure use has a metal diaphragm which is actuated into and out of direct engagement with a valve seat by an air operator acting through a force multiplying lever assembly. The valve seat is confined by rigid interior and exterior sleeves while the sealing surface is contoured to have a concave configuration corresponding to the contour of the diaphragm in its deflected position. The air operator is provided with a stroke adjustment mechanism that is locked in adjusted position by a member that is generally accessible only when the operator is disconnected from the valve.

High pressure diaphragm valve

A valve actuator apparatus and method comprises an operator housing secured to a bonnet assembly. The bonnet assembly is secured to the valve body, and includes a bonnet stem movably within a bonnet housing for moving a gate within the valve body to open and close the valve. A downstop member is fixably secured to the bonnet stem and engages removable stem spacers which are added or removed to obtain a selected bonnet stem drift setting. The operator housing connects to a base ring that surrounds the bonnet housing and rotates to allow positioning of a fluid port in the operator housing. The operator housing may removed and replaced without altering the bonnet stem drift adjustment. A top shaft extends from the operator housing and rotates with respect to the bonnet stem to prevent torque transmission from the top shaft to the bonnet stem. A replaceable sealing cartridge sealingly supports the top shaft for axial movement within the operator housing.

Valve actuator apparatus

An actuator for opening and closing the gate of a surface safety valve includes a primary piston and an auxiliary piston. The primary drive piston is directly connected to the valve stem, while the auxiliary piston is slideably connected thereto. Extension movement of the auxiliary piston is stopped by a divider plate after initial breakaway forces are overcome. The thrusting force developed by the auxiliary piston during a valve opening operation is transmitted to the valve stem and the primary piston by a shuttle sleeve. The shuttle sleeve is radially spaced about the valve stem, thereby defining a bridge annulus which maintains fluid communication between the primary pressure chamber and the auxiliary pressure chamber at all times. The thrusting force produced by the auxiliary piston is combined with the thrusting force produced by the primary piston to break the static gate seal and overcome the gate drag during a first stage of operation. After breakaway has been accomplished, the auxiliary piston is mechanically decoupled from the valve stem, whereby the valve stem is driven only by the primary piston at a substantially reduced thrusting force level during a second stage of operation, thereby avoiding gate damage which might otherwise occur if the valve stem velocity was not restrained.

Dual stage valve actuator

A surface safety valve hydraulic actuator of modular construction. The actuator includes separately installable, removable, and interchangeable wirecutting and non-wirecutting spring modules, used with the same hydraulic cylinder and bonnet. The bonnet is attached to the body of the valve. A lower stem extends through a lower seal and into the valve body cavity, and is connected to the gate segments of the valve. A hydraulic cylinder is removably attached to the bonnet. An upper stem with a central bore is disposed in the cylinder chamber and carries a piston thereon, and extends through an upper seal in the top of the hydraulic cylinder. A spring module is removably attached to the hydraulic cylinder, and includes a spring can telescoped over the top of the cylinder. The spring can is rotatably connected to an annular spring retainer, which in turn is mounted on the cylinder. A coupling rod is inserted through the upper stem and screwed into the top of the lower stem. A spring coupler is connected to the upper end of the coupling rod, and bears upon the upper surface of a spring plate. In the non-wirecutting spring module, a single coil spring is disposed in the spring can between the spring plate and the spring retainer. In the wirecutting spring module, dual coil springs are used.

Modular hydraulic actuator

A valve is provided which includes a poppet enclosed in a plug of plastic material, such as Teflon, and which is biased against a seat by a compression spring so that a positive seal is provided even in the presence of cold flow in the plastic plug. A valve stem engages the poppet, and it serves to pull the poppet and plug away from the seat against the force of the spring when the valve is opened, and to force the poppet and plug against the seat when the valve is closed. The valve is closed by a pressurized fluid, such as air, and is opened by means of a spring when the air pressure is removed. The Teflon plug is provided with a sharp corner which contacts a conical seat creating a seal when the valve is closed. The sharp corner of the plug wipes the seat of the debris as the valve is opened and closed.

Spring loaded plug valve

Pressurized fluid is controlled by a reverse valve gate on a valve stem that extends through annular packing in a bore of a bonnet to a piston in an outer control chamber. Control fluid pressure moves the piston inward to open the valve against line pressure on the valve and/or spring pressure on the valve. In the absence of both line pressure and control pressure, the valve is closed by spring pressure. The control chamber construction permits quick replacement of control chamber seals. In the event of a fire, the control chamber seals disintegrate to release the control pressure and thus cause line pressure and/or spring pressure to close the valve. The valve stem packing may be conveniently expelled hydraulically for replacement. Various different control assemblies may be mounted interchangeably on the valve bonnet without disturbing the structure of the valve. An auxiliary control may be quickly mounted on the outer end of the control chamber to convert the shut-off valve to manual operation.

Safety shut-off valve

A shut-off valve in a fluid line closes by spring pressure and incorporates a control chamber wherein pressurized control fluid acting on a piston opens the valve in opposition to the spring pressure. A control system for the shut-off valve comprises a 3-way actuator pilot of the present invention in cooperation with a monitor pilot. The actuator pilot has a valve spool and four ports, namely, a supply port connected to a source of pressurized control fluid, a pilot port connected to the monitor pilot, a control port connected to the control cylinder of the shut-off valve, and an exhaust port for venting the control chamber of the shut-off valve. When the control system is in service and the monitor pilot senses an undue change in the pressure in the fluid line, the monitor pilot vents the actuator pilot to shift the valve spool therein to cut off the control fluid from the control port and simultaneously to place the control port in communication with the exhaust port to cause the shut-off valve to close.

Actuator pilot for fluid pressure monitoring safety system

A shut-off valve in a fluid line closes by spring pressure and/or line pressure and incorporates a control chamber wherein pressurized control fluid acting on a piston opens the valve in opposition to the spring pressure and/or line pressure. A 3-way actuator pilot normally places the control fluid in communication with the control cylinder but when vented cuts off the control supply fluid and releases the pressurized control fluid from the control chamber to cause the shut-off valve to close by spring pressure and/or line pressure. A monitor pilot responsive to pressure changes in the fluid line incorporates a relief valve and opens the relief valve by cam action to vent the actuator pilot whenever the pressure in the fluid line makes a predetermined departure from a normal pressure range.

Victor Eugene Derval

Papers

Safety shut-off valve

Actuator pilot for fluid pressure monitoring safety system

Fluid pressure monitoring safety system