US3842853A

US3842853A - Fire safety valve

Info

Publication number: US3842853A
Authority: US
Inventors: W Kelly; J Fredd
Original assignee: Otis Engineering Corp
Current assignee: Halliburton Co
Priority date: 1970-04-06
Filing date: 1972-04-28
Publication date: 1974-10-22
Anticipated expiration: 1991-10-22

Abstract

A heat responsive safety valve having a fusible material holding the valve at an open position. In one form, a fusible threaded sleeve secures a cap over the valve stem to lock the valve open. In another form, the fusible material restrains radially movable latch members which releasably hold a plate locking the valve open. In a further form of the invention, a body of fusible material directly restrains a plate holding the valve open. In each form of the valve the fusible material melts or otherwise weakens at a predetermined temperature releasing the valve to close, shutting off flow through the conductor controlled by the valve as a fire prevention measure.

Description

United States Patent Kelly et al.

154] FIRE SAFETY VALVE [75] Inventors: Warner M. Kelly, Houston; John V.

Fredd, Dallas, both of Tex.

[73] Assignee: Otis Engineering Corporation,

' Dallas, Tex.

[22] Filed: Apr. 28, 1972 [21] Appl. No.: 248,499

Related US. Application Data [63] Continuation-impart of Ser. No. 25,976, April 6,

1970, Pat. No. 3,659,624.

[52] 11.8. CI. 137/75, 137/72 [51] Int. Cl. Fl6k 17/38 [58] Field of Search 137/71-77; 220/89 B; 169/19 [56] References Cited UNITED STATES PATENTS 166,452 8/1875 Brown et al. 137/72 X 1,206,341 11/1916 Leavitt 137/72 X 1,243,998 10/1917 Smyly 137/75 1 1 Oct. 22, 1974 1,771,716 7/1930 Lovekin 137/77 2,035,49 3/1936 Morse 220/89 B X Primary Examiner-Alan Cohan Assistant ExaminerRichard Gerard Attorney, Agent, or FirmH. Mathews Garland [5 7 ABSTRACT A heat responsive safety valve having a fusible material holding the valve at an open position. in one form, a fusible threaded sleeve secures a cap over the valve stem to lock the valve open. In another form, the fusible material restrains radially movable latch members which releasably hold a plate locking the valve open. In a further form of the invention, a body of fusible material directly restrains a plate holding the valve open. In each form of the valve the fusible material melts or otherwise weakens at a predetermined temperature releasing the valve to close, shutting off flow through the conductor controlled by the valve as a fire prevention measure.

9 Claims, 8 Drawin2 Figures FIRE SAFETY VALVE This application is a continuation-in-part of our application Ser. No. 025,976 entitled FIRE SAFETY VALVE, filed April 6, 1970 and now U.S. Pat. No. 3,659,624.

This invention relates to safety devices and more particularly relates to a fire safety valve for a flow line.

Flow conductors in well heads, pipe lines, and the like are particularly susceptible to fire, especially when they are carrying flammable fluids such as oil and gas. When fire occurs due to a leak in such a conductor, or in the vicinity of such a conductor and its valves, damage is minimized by an immediate closing of such valves. Conventional valves have no means for closure responsive to temperature, and, of course, if within a tire area, often cannot be reached to be manually closed. Also, conventional valves often contribute to a fire hazard in the sense that the packing in such valves may be sufficiently damaged by a fire that the valve itself becomes a contributor to the hazard with flammable fluid leaking outwardly feeding the fire from the valve. While many systems have been employed in the past to detect and function responsive to fires, they generally are somewhat complex in nature, expensive, and may be subject to malfunction.

It is an especially important object of the invention to provide a new and improved safety device to provide protection against fire hazards.

It is an especially important object of the inventionto provide a new and improved safety valve operable responsive to exposure to a fire.

It is another-object of the invention to provide a fire safety valve which is mechanically held at an open position by a fusible material and released for movement to a closed position responsive to the melting or destruction of such material by a fire or exposure otherwise to a temperature above a predetermined level which might effect a fire in a system including the safety valve.

It is a further object of the invention to provide a fire safety valve of the gate valve type having a valve stem held by a locking cap connected with the valve body by a fusible bushing.

It is another object of the invention to provide a fire safety valve of the gate type having a valve stem supported at open position by a locking cap assembly including radially movable latching balls held in a locking position by a member restrained against movement by a body of fusible material.

It is another object of the invention to provide a fire safety valve of the gate type including radially movable arcuate latch segments restrained by fusible material at a position holding a valve stem restraining plate.

It is a still further object of the invention to provide a fire safety valve restraining cap having a valve stem holding member restrained against movement by a body of fusible material extrudible through a port in a holding cap. I

These and other objects of the invention will be apparent from reading the following description of fire safety valves embodying the invention taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a side view in section of a gate type valve including a valve stem restraining cap held by a fusible threaded sleeve;

FIG. 2 is an enlarged fragmentary side view in section and elevation of a gate valve stem restraining cap assembly embodying the invention;

FIG. 3 is a view in section along the line 3-3 of FIG.

FIG. 4 is a fragmentary side view in section and elevation of the assembly of FIG. 2 with the valve stem and cap assembly parts moved to positions at which the valve is closed;

FIG. 5 is a fragmentary side view in section and elevation of another form of gate valve stem restraining cap assembly embodying the invention;

FIG. 6 is a reduced view in section along the line 6-6 of FIG. 5;

FIG. 7 is a fragmentary side view in section and elevation of the assembly of FIG. 5 with the parts moved to positions at which the valve is closed; and

FIG. 8 is a side view in section of a still further form of gate valve stem restraining cap assembly.

In accordance with the invention, one form of fire safety valve locking apparatus embodying the invention includes a valve stem restraining cap secured over the free end of the valve stem by a threaded fusible metal sleeve on the valve body. In another form of fire responsive valve locking apparatus useful with a gate valve, a valve stem restraining cap assembly includes radially movable locking balls held outwardly at looking positions by a valve stem locking member restrained against movement by a body of fusible material. In a further form of the invention, a restraining cap assembly for holding a gate valve at an open position includes a locking disc supporting radially movable arcuate latch segments restrained against outward movement by a ring of fusible material. Another form of valve stem locking apparatus for use as a safety device with a gate valve includes a stem holding cap against a body of fusible material extrudible through a port responsive to a force from the stem.

A fire safety valve illustrated in FIG. 1 is normally a pressure responsive valve controllable from a remote location by fluid pressure. The valve has a body 111 provided with a flow passage 112 and

flanges

113 and 114 for connection into a flow line. Flow through the passage 112 is controlled by a gate valve 115 having a port and connected with a valve stem 121 which extends upwardly into a pressure chamber 122 provided within a vessel 123 secured on a base 124 by a lock ring 125. A valve stem guide flange is formed integral with a base 124 and provided with a ring seal 131 which seals around the valve stem within the guide flange. The base 124 is secured by a plurality of bolts 132 to the valve body 111. A coil spring 133 is confined between the plate 124 and an annular piston 134 rigidly secured, as by welding, on the valve stem in the chamber 122. A ring seal 135 around the piston seals within the cylinder chamber. The cylinder chamber is vented to the atmosphere below the piston by a bleed port 140. An upper end portion of the valve stem 121 extends through an externally threaded nipple 141 formed on the head end of the vessel 123. A ring seal 142 is an internal annular recess of the nipple 141 seals around the stem 121 so that pressure may be maintained in the cylinder 122 above the piston 134. A conduit 143 containing a valve 144 is connected into the head of the cylinder 123 to provide fluid pressure for holding the piston 134 downwardly against the spring 133 to maintain the valve 115 at the open position shown in FIG. 1. A valve similar to that of FIG. 1 is an Otis Type U Surface Safety Valve illustrated at Page 3834 of the Composite Catalog of Oil Field Equipment and Services, l96869 Edition, published by World Oil, Houston, Texas. The conduit 143 may be connected to a controllable source of fluid pressure which reacts responsive to any desired condition, such as excessive heat which would relieve fluid pressure within the chamber above the piston to allow the spring to lift the valve to its closed position.

In accordance with the invention, the valve 115 is locked at its open position by an internally threaded cap 145 secured on the nipple 141 over the upper end of the valve stem 121 by a fusible internally and externally threaded bushing 150. The bushing 150 is formed of a material which readily reacts to a predetermined temperature level causing it to either disintegrate by melting or to weaken sufficiently that it loses the structural strength to hold the cap on the nipple against the force of the stem. The bushing may be made of such metals as lead, solder, a low temperature melting metal sold under the trademark Serrocast. Preferably, the melting temperature of the bushing 150 is within the range of about 350 to 450 F., as any temperature above this range is going to provide a dangerous environment to the fire safety valve and the flow system of which it is a part. The bushing, of course, may also be formed of a fusible plastic which has sufficient strength to resist the normal forces applied while breaking down either by melting or by reduction of its strength to permit it to stretch sufficiently at the desired temperature to release the stem.

The bushing is provided with a lower external annular end flange 151 for gripping the safety bushing when threading it on the nipple. So long as the fusible safety bushing is intact, the cap 145 engages the upper end of the valve stem 121 holding the valve open in such a manner that it is closable only when the valve is enveloped in a fire or sufficiently close to a fire that the flow system including the valve is endangered. The heat from such a fire or nearby fire melts the fusible bushing or sufficiently weakens it that the force of the spring 133 can lift the valve stem to disengage the cap 145 and release the stem to close the valve. The upper end of the valve stem forces the cap 145 off the nipple 141. It will be apparent that coincident with the release of the valve stem by the fusible safety bushing, the fluid pressure within the cylinder 122 above the piston 134 must also be reduced to permit spring action and line pressure to close the valve. The fire safety system on the valve 110 is generally used only under special operating conditions of the valve where it is desired that the valve be restrained against closing in the event of a malfunction of the fluid control system. An example of such an operating condition is encountered when the valve is used as a master valve in a well head and wireline operations are being carried out in the well through the well head. In this situation, if the valve were permitted to suddenly close responsive to some failure or malfunction of the pressure control system of the valve supplying the fluid into the chamber 122, the valve would cut the wireline passing through the valve flow passage 112 and the port 120 in the valve 115. Such an accident could necessitate substantial expense in retrieving the wireline and equipment connected thereto. While it is desirable under such circumstances to protect the valve against a control fluid pressure malfunction, it is further desirable that in so protecting the valve it not be restrained against closure in the event of fire. Thus, during wireline operations the valve is locked open by the cap secured on the nipple 141 by the fusible safety bushing 150. When a wireline operation is completed and the wireline is withdrawn through the valve, the valve is returned to normal fluid pressure responsive operation by unscrewing the locking cap 145 and the fusible bushing from the nipple on the cylinder body.

FIG. 2 shows a safety locking cap assembly which may be engaged on the threaded nipple 141 of the valve 110 for holding the valve stem 121 to lock the valve out of service in the open position illustrated in FIG. 1. The assembly 160 includes an internally threaded outer cap sleeve 161 and an internal cap 162 which telescopes into the sleeve 161 against an internal shoulder surface 163 provided in the sleeve. The inner cap 162 has a plurality of circumferentially spaced radial bores 164 which are aligned with an internal annular recess 165 provided in the sleeve 161. The bores 164 and the recess 165 are sized and positioned to accommodate locking balls at the positions shown in FIG. 2 when the valve is locked open. The cap 162 has a bleed port 171 in the end portion 172. A disc of fusible material 173 is disposed within the cap on a valve stem holding member 174 engageable with the upper end of the valve stem 121 for locking the valve stem downwardly at the valve-open position. The member 174 has an external annular recess 175 which is alignable with the ports 164 and the balls 170 when the locking cap parts and the stem move to the valveclosed positions of FIG. 4. The member 174 has a lower end external annular recess which receives a locking ring 181 engaged in the sleeve 161 to hold the member 174 and the disc 173 in the cap assembly prior to installation of the assembly on the nipple 141 of the valve.

The safety cap assembly 160 is placed on the threaded nipple 141 of a valve for locking the valve out of service in the open position. The cap assembly is threaded onto the nipple to the position shown in FIG. 2 at which the member 174 engages the top end of the valve stem 121. Pressure in the passage 112 through the valve and the spring 133 bias the valve stem upwardly against the member 174 applying an upward pressure against the fusible disc 173. The upward force on the disc tends to lift the cap 162 which is restrained against upward movement by the balls 170. The balls 170 are held by the member 174 outwardly in the recess 165 of the sleeve 161, preventing upward movement of the cap 162.

When the valve is exposed to excessive heat, the disc 173 melts and is extruded through the port 171 of the cap 162 by the piston effect of the member 174 which is forced upwardly by the valve stem 121. As the fusible metal is extruded, the member 174 is allowed to move upwardly in the cap 162. When the recess 175 of the member 174 is aligned with the locking balls 170, the balls are cammed inwardly into the recess 175 from the recess 165 releasing the cap 162 for upward movement. The upwardly moving valve stem 121 lifts the member 174, the cap 162, and the locking balls upwardly, as shown in FIG. 4, allowing the valve stem to move to the closed position.

When the assembly 160 is to be reused, the remaining fusible metal is cleaned from the parts and the parts are reassembled with a new fusible disc 173 in place within the cap 162 between the member 174 and the cap, and the other parts of the assembly are returned to the positions shown in FIG. 2.

Another heat responsive valve stem locking cap assembly 190 is shown in FIG. 5. The assembly 190 includes a cap 191 having an internalannular recess 192 which communicates with a plurality of circumferentially spaced radial bleed ports 193 provided in the cap. An annular ring of fusible material 194 is disposed in the cap recess holding four arcuate locking segments 195 against radial outward movement for locking a disc 200 in a position on the valve stem 121 preventing upward movement of the stem. The segments 195 rest on an internal flange 196 in the cap 191. The member 200 has a downwardly and outwardly sloping locking shoulder 201 against which the locking segments 195 rest in the position of the parts shown in FIG. 5.

When the cap assembly 190 is engaged on a valve, the valve stem 121 is urged upwardly against the member 200 which earns the arcuate segments 195 outwardly against the fusible ring 195. The ring 194 prevents outward movement of the segments, thereby locking the member 200 on the stem to hold the stem downwardly at the valve-open position. When the valve is subjected to excessive heat, the fusible ring 194 melts, and the upward force of the valve stem against the member 200 cams the segments 195 outwardly extruding a major portion of the fusible metal through the side ports 193. Some of the fusible metal melts around the segments and on the member 200. When a sufficient quantity of the fusible ring is melted for the outward camming action on the segments 195 to move the segments to the positions represented in FIG. 7, the member 200 is released for upward movement and is ejected from the cap, as seen in FIG. 7, releasing the valve stem to move upwardly so that the valve closes. The cap and segments may be reused by melting the fusible metal from the parts, casting a new fusible ring 194 in the cap 191, and reassembling the parts as shown in FIG. 5. It will be recognized that the fusible ring may be made in segments to facilitate assembly in the cap and avoid casting the metal in place in the cap.

A still further form of heat-responsive cap assembly 210 for holding a valve open in accordance with the invention is illustrated in FIG. 8. the cap assembly includes a cap 211 having an upper cylindrical section 212 and an enlarged lower internally threaded section 213. The upper section of the cap is provided with a bleed port 214 in the cap end 215. A body of fusible material 220 is disposed in the upper cap portion 212. A non-fusible plate or plug 221 is positioned in the cap against the fusible body to transmit upward force from the valve stem 121 to the fusible material. In operation the cap assembly 210 is threaded on the nipple 141 in the same manner as the arrangement shown in FIG. 1. The cap assembly is threaded downwardly on the nipple until the lower face of the member 221 engages the top end face of the valve stem 121 so that the valve stem is held at a lower end valve-open position. When the valve is exposed to excessive heat, the fusible material 220 melts, and the upward force of the valve stem on the member 221 applies sufficient force to the fusible material that it is extruded from the cap 211 through the port 214 permitting the member 221 to move upwardly in the cap allowing the valve stem to be lifted as the valve is closed. While it is preferred that the force of the valve stem be applied to the fusible material through the plate 221, it will be recognized that the upper end face of the valve stem may directly engage the lower end face of the body of fusible material 220, though such arrangement is not necessarily desirable as the melting fusible material might tend to get into the valve mechanism and either interfere with its operation or require excessive maintenance to clean the valve parts.

It will be recognized that while each of the cap assemblies embodying the invention has been illustrated and described in terms of use with gate valves, as shown in FIG. 1, such cap assemblies may be used in connection with other valve arrangements so long as the cap assembly is engaged on the valve over the stem end to hold the stem at a desired position. Any valve arrangement may be employed so long as the cap assembly is positioned to mechanically lock the valve stem against movement with the cap assembly engaging the valve stem end face.

What is claimed and desired to be secured by Letters Patent is:

1. A heat-responsive cap assembly for use with a valve having a valve housing and a longitudinally movable stem to lock the stem at a first position and release the stern for movement to a second position responsive to a temperature in excess of a predetermined value, said assembly comprising: cap means engageable with said valve housing at the free end of said stern of said valve; and fusible means in said cap means between said stem and said cap means retaining said cap means in engagement with said housing whereby said cap means holds said valve stem at said first position, said fusible means being adapted to release said cap means from engagement with said valve housing responsive to a force applied by said valve stem when the temperature of said fusible means exceeds a predetermined value, said fusible means comprising a body of fusible material within said cap assembly and having a surface engageable with an end face of said valve stem and said fusible material being extrudable from said cap assembly above said predetermined temperature to release said stern for movement to said second position.

2. A cap assembly in accordance with claim 1 wherein said cap comprises a cylindrical body having a bleed port in an end face thereof and said fusible means comprises a body of fusible material in cylindrical form disposed within said cap between said bleed port and an end face of said valve stem when said assembly is engaged on said valve housing.

3. A cap assembly in accordance with claim 2 said fusible means further including a non-fusible plate member in said cap adjacent to said fusible material for applying force from an end face of said valve stem to said fusible material.

4. A cap assembly for use with a valve having a valve housing and a longitudinally movable stem for engagement with said stem to hold said stem at a first position and operable responsive to a predetermined temperature to release said valve stem for movement to a second position, said cap assembly comprising: an annular ring engageable on said valve housing around said stem at the free end of said stem; radially movable iatch members within said ring adapted to move between stem locking and stem release positions; and fusible means within said ring for holding said latch members at said stem locking positions and releasing said latch members responsive to a predetermined high temperature to permit said members to move to said stem release positions.

S. A cap assembly in accordance with claim 4 including a stem locking member within said ring for holding said stem at said first position when said latch members are at said stem locking positions and releasable by said latch members when said latch members move to said stem release positions to release said valve stem for movement to said second position.

6. A cap assembly in accordance with claim 5 wherein said latch members comprise locking balls.

7. A cap assembly in accordance with claim 5 wherein said latch members comprise arcuate circular segments.

8. A cap assembly in accordance with claim 7 wherein said annular ring has an inner annular recess and radial bleed ports communicating with said recess; said fusible means comprises an annular ring of fusible material within said inner recess of said annular ring; and said circular segments are disposed within said inner recess of said annular ring inwardly of said ring of fusible material; and including a valve stem locking plate releasably held within said circular segments for engaging the free end face of said valve stem for holding said valve stem at said first position and for releasing said valve stem for movement to said second position responsive to said predetermined high temperature effecting disintegration of said fusible ring permitting said segments to move radially outwardly releasing said valve stem locking plate.

9. A cap assembly for use with a valve having a valve housing and a longitudinal movable stem for engaging said stem to hold said stem at a first position and for releasing said stem for movement to a second position responsive to a predetermined high temperature, said assembly comprising: an annular ring adapted to be secured on said valve housing around the free end of said valve stem, said ring having an inner annular recess; an internal cap having a cylindrical side skirt and an end face provided with a bleed port, said skirt being insertable into said annular ring and having circumferentially spaced radial bores alignable with said recess in said ring when said cap is in operating holding position in said ring; a valve stem holding member within said inner cap and movable within said cap between a valve stem holding position and a valve stem release position, said member having an external annular recess alignable with said radial bores in said inner cap at said valve stem release position; a fusible body disposed in said inner cap between the internal end face of said cap and said valve stem holding member for holding said member at said first valve stem locking position; and radially movable locking balls in said radial bores of said inner cap, said balls being held at a first outward position in said bores projecting into said inner recess of said annular ring when said valve stem locking member is at said holding position and said balls being movable inwardly into said external recess of said valve stem holding member when said member is at said release position, said balls releasing said inner cap for movement in said annular ring to release said valve stem, said fusible material being adapted to disintegrate at a predetermined high temperature to release said valve stem holding member for movement to said release position.

Claims

1. A heat-responsive cap assembly for use with a valve having a valve housing and a longitudinally movable stem to lock the stem at a first position and release the stem for movement to a second position responsive to a temperature in excess of a predetermined value, said assembly comprising: cap means engageable with said valve housing at the free end of said stem of said valve; and fusible means in said cap means between said stem and said cap means retaining said cap means in engagement with said housing whereby said cap means holds said valve stem at said first position, said fusible means being adapted to release said cap means from engagement with said valve housing responsive to a force applied by said valve stem when the temperature of said fusible means exceeds a predetermined value, said fusible means comprising a body of fusible material within said cap assembly and having a surface engageable with an end face of said valve stem and said fusible material being extrudable from said cap assembly above said predetermined temperature to release said stem for movement to said second position.

4. A cap assembly for use with a valve having a valve housing and a longitudinally movable stem for engagement with said stem to hold said stem at a first position and operable responsive to a predetermined temperature to release said valve stem for movement to a second position, said cap assembly comprising: an annular ring engageable on said valve housing around said stem at the free end of said stem; radially movable latch members within said ring adapted to move between stem locking and stem release positions; and fusible means within said ring for holding said latch members at said stem locking positions and releasing said latch members responsive to a predetermined high temperature to permit said members to move to said stem release positions.

5. A cap assembly in accordance with claim 4 including a stem locking member within said ring for holding said stem at said first position when said latch members are at said stem locking positions and releasable by said latch members when said latch members move to said stem release positions to release said valve stem for movement to said second position.