Fire-safe valve actuator

Abstract

A fire-safe valve actuator which cooperates with a bolted bonnet type valve to define a bolt chamber with an exterior shroud supporting the actuator housing and providing a substantially imperfect barrier to prevent an external fire from coming into direct contact with the bolts or studs and nuts that connect the bonnet to the valve body. The bolt chamber may also be filled with an insulation material. The actuator may have a return spring connected to the actuator stem through a bearing so that the winding and unwinding of the spring does not result in any substantial torque being applied to the actuator stem. Similiarly, any diaphragm in the actuator can be connected to the actuator stem by a bearing so that rotation of the stem will not impart torque to the diaphragm. Furthermore, a stop can be provided limiting outward movement of the stem under the influence of the spring and by further providing a suitable sliding engagement between the diaphragm-actuator housing and the stem, the actuator housing and diaphragm can be readily removed from the balance of the actuator without bleeding the line pressure down.

What is claimed is: 
     
       1. A bonnet and actuator assembly for use with a valve adapted for use in a line including a valve body and a valve member, the assembly being adapted to be connected to the valve body by bolts, comprising: a bonnet having a first outturned flange with bolt holes therein adapted to receive said bolts to bolt the bonnet to the valve body;   an actuator housing;   an actuator stem within said housing and adapted to be connected with said valve member in said valve body;   stem actuator means in said housing and connected to said stem for moving the stem;   a substantially imperforate shroud connected to said actuator housing and extending downwardly therefrom into engagement with said outturned flange outwardly of said bolt holes so as to protect said bolts connecting the bonnet with the valve body, when assembled thereon, from direct contact by heat from external fires and retarding heat induced deterioration of said bolts holding the bonnet to the valve body and,   a plurality of fastener bolts having heads which are accessible externally of said shroud for releasably connecting said shroud to said bonnet, whereby said bolts can be removed without disconnecting said bonnet from said valve body.   
     
     
       2. The assembly of claim 1, including a second outturned flange on the bonnet above the first flange adapted to receive said fastener bolts and to provide a chamber therebetween to receive the heads or nuts of the bolts when the bonnet is bolted to the valve body. 
     
     
       3. The assembly of claim 2 wherein said chamber contains a heat insulating material for further retarding the application of heat to the bolts. 
     
     
       4. The assembly of claim 2 wherein the second outturned flange is integral with said bonnet. 
     
     
       5. The assembly of claim 2 wherein the second outturned flange is rotatably mounted on said bonnet so that the actuator can be angularly oriented in different positions. 
     
     
       6. The assembly of claim 1 wherein said stem actuator means includes a spring disposed within said shroud and connected to said actuator stem to urge the latter in one direction; a stop for limiting movement of the actuator stem in said one direction; said stem actuator means including a motor for moving the actuator stem in the opposite direction and having a releasable connection with the actuator stem permitting the motor, actuator housing and shroud to be moved upwardly as a unit and removed from the bonnet while the actuator stem and spring remain in or on the bonnet whereby inspection or repair to the motor or actuator housing can be made without bleeding down the line in which the valve body is installed. 
     
     
       7. The assembly of claim 6 wherein the connection of the spring to the stem includes a bearing permitting the spring to wind and unwind during movement of the actuator stem without exerting substantial torque on the actuator stem. 
     
     
       8. The assembly of claim 7 wherein the connection between the motor and actuator stem likewise includes a bearing permitting the stem to be rotated without exerting substantial torque on the motor. 
     
     
       9. The assembly of claim 6 wherein said stop is provided by a seat in the bonnet and a seat carried by the actuator stem for engagement with the bonnet seat to form a seal therewith upon predetermined outward movement of the actuator stem. 
     
     
       10. A bonnet and actuator assembly for use with a valve which includes a valve body and a valve member .Iadd.within the valve body for controlling pressurized fluid flow through the valve and that is serviceable while the valve remains in a pressurized state, comprising: a bonnet adapted to be connected to a valve body;   an actuator housing;   an actuator stem within said actuator housing and adapted to be connected with said valve member in said valve body;   stem actuator means in said housing:   means releasably connecting the stem actuator means with the actuator stem so that when the stem actuator means is released, it is slidable outwardly along said stem;   said actuator housing having a sliding connection with the actuator stem;   resilient means connected between the actuator stem and the bonnet urging the actuator stem outwardly of the actuator housing;   stop means carried by the actuator stem and bonnet and limiting movement of the actuator stem outwardly of the actuator housing; and   means releasably connecting the actuator housing to the bonnet which, when released, permits the actuator housing and stem actuator means to be removed from the bonnet .Iadd., allowing said actuator housing and stem actuator means to be slid outwardly along said actuator stem .Iaddend.while .Iadd.said actuator stem remains connected to the valve member within the valve body and the valve remains in the pressurized state, .Iaddend.the stop means .[.limits.]. .Iadd.limiting .Iaddend.outward movement of the actuator stem under the influence of said resilient means.   
     
     
       11. The assembly of claim 10 wherein the resilient means is a compression spring and its connection to the actuator stem includes a bearing permitting the spring to wind and unwind during movement of the actuator stem without exerting substantial torque on the actuator stem. 
     
     
       12. The assembly of claim 11 wherein the connection between the stem actuator means and the actuator stem like-wise includes a bearing permitting the stem to be rotated without exerting substantial torque on the stem actuator means. .Iadd. 
     
     
       13.  A bonnet and actuator assembly for use with a valve adapted for handling fluids under pressure and which includes a valve body and a valve member within the valve body for controlling pressurized fluid flow through the valve and that is serviceable while the valve remains in a pressurized state, said assembly comprising: a bonnet adapted to be connected to the valve body;   an actuator housing adapted to be connected to said bonnet in a fluid pressure isolation relation to the valve;   an actuator stem within said housing and adapted to transmit valve opening and closing forces to said valve member through said bonnet;   stem actuator means within said actuator housing for moving said actuator stem inwardly with respect to said bonnet;   resilient means for urging said actuator stem outwardly with respect to said bonnet;   stop means for limiting movement of said actuator stem outwardly with respect to said bonnet;   means for releasably connecting said actuator housing to said bonnet;   and means for releasably connecting said actuator housing to said actuator stem such that when said actuator housing is released form said bonnet, said stem actuator means is removable with said actuator housing from said bonnet and actuator stem while the flowpath of the valve remains in the pressurized state, said stop means limiting the outward movement of said actuator stem under the influence of said resilient means. .Iaddend. .Iadd.   
     
     
       14.  The assembly as claimed in claim 13, wherein said resilient means includes: a spring retainer plate connected to said actuator stem below said stem actuator means;   and a spring disposed about said actuator stem between said bonnet and said spring retainer plate. .Iaddend. .Iadd.15. The assembly as claimed in claim 14, including bearing means for permitting said spring retainer plate to rotate with respect to said actuator stem. .Iaddend. .Iadd.16. The assembly as claimed in claim 13, wherein:   said stem actuator means includes a diaphragm connected to said actuator housing and a diaphragm plate connected to said diaphragm;   and said means for releasably connecting said stem actuator means to said actuator stem includes a thrust element connected to said actuator stem, said diaphragm plate being abuttable with said thrust element to transfer downwardly directed force to said actuator stem, said diaphragm plate being movable upwardly with respect to said thrust member. .Iaddend.   
     
     
        .Iadd.7.  A valve actuator for use on a valve having a flowpath therein adapted for handling fluids under pressure and serviceable while the flowpath is in a pressurized state, said actuator comprising: an actuator housing adapted to be connected and disconnected in a fluid pressure isolating relationship to the flowpath of the valve with which the actuator is to be used;   at least one actuator stem in said actuator housing longitudinally movable between a first and second position;   stem actuator means in said actuator housing and in said pressure isolation relationship to the flowpath of the valve;   means for effecting operable engagement between said stem actuator means and each actuator stem for urging each stem in an inward direction toward a selected one of its first and second positions such that inward movement of said stem actuator means causes inward movement of each actuator stem;   said stem actuator means being operably disengaged from each actuator stem when each actuator stem moves in an outward direction such that said stem actuator means is free to be removed outwardly, relatively away from said engagement with each actuator stem while the flowpath of the valve remains in the pressurized state;   and spring means operably retained during removal of said stem actuator means for urging each actuator stem toward the other of the selected first and second positions. .Iaddend. .Iadd.18. A valve actuator for use on a valve having a flowpath therein adapted for handling fluids under pressure and serviceable while the flowpath is in a pressurized state, said actuator comprising:   an actuator housing adapted to be connected and disconnected in a fluid pressure isolation relationship to the flowpath of the valve with which the actuator is to be used while the flowpath of the valve is in the pressurized state;   a diaphragm assembly mounted within said actuator housing, said diaphragm assembly including a diaphragm connected to said actuator housing and a diaphragm plate connected to said diaphragm;   an actuator stem positioned in said actuator housing;   a spring positioned about said actuator stem;   means for transmitting forces generated in an outward direction by said spring to said actuator stem;   means for transmitting inward forces from said diaphragm plate to said actuator stem and;   said actuator housing and said diaphragm assembly being outwardly removable with respect to said actuator stem and said spring while the flowpath of the valve remains in the pressurized state. .Iaddend.