US3802504A

US3802504A - Automatic safety valve

Info

Publication number: US3802504A
Application number: US00153617A
Authority: US
Inventors: H Garrett
Original assignee: Brown Oil Tools Inc
Current assignee: Baker Hughes Holdings LLC
Priority date: 1971-06-16
Filing date: 1971-06-16
Publication date: 1974-04-09
Anticipated expiration: 1991-04-09

Abstract

A self-contained, automatic valve assembly designed to be anchored at the subsurface location within a well casing which extends into a subterranean formation employed to store pressurized gas. The valve is supported by a retrievable packer which anchors the valve within the casing and forms a seal to force the gas to flow through the valve. Operation of the valve is governed by a bellows control which moves a valve stem to closed position to terminate flow through the valve in response to a drop in casing pressure.

Description

United States Patent 1191 Garrett Ap r. 9, 1974 AUTOMATIC SAFETY VALVE 3,527,297 9/1970 Todd 166/154 [75 Inventor: Henry U. Garrett, Houston, Tex.

Primary Examiner-Marvin A. Champion [73] Ass1gnee: Brown Oil Tools, Inc., Houston, Assistant Examiner |ack Ebe] Attorney, Agent, or Firm-Carlos A. Torres [22] Filed: June 16, 1971 121 App]. No.: 153,617 [57] ABSTRACT A self-contained, automatic valve assembly designed LS. L I I I u to be anchored at the subsurface location a well I 166/152 166/224 casing which extends into a subterranean formation [51] Int CL 132,) 33/00 employed to store pressurized gas. The valve is sup- [58] Field 133 142 ported by a retrievable packer which anchors the 166/152 2 1317/46; 6 valve within the casing and forms a seal to force the gas to flow through the valve. Operation of the valve is [56] References Cited governed by a bellows control which moves a valve stem to closed position to terminate flow through the 2 77 D lf PATENTS 137/5 0 valve in response to a drop in casing pressure. 3,45 7 l 9 o ison 1 3,593,784 7/1971 Brown et al. 166/125- 19 Claims, 9 Drawing Figures 'PATENTEDAPR 9 m4 SHEET 1 0F 3 A Tree/v5) mimim 91914 (LAMA-Tm A T TOENEY 1 AUTOMATIC SAFETY VALVE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automatic safety equipment designed to regulate the flow of fluids through a flow conduit. As used herein, the term fluid is intended to encompass both liquids and gases. In the preferred application, the present invention relates to a self-contained, automatically closing safety valve designed to be anchored in an in-place well casing extending into a gas storage reservoir to prevent the escape of stored gas through the casing following failure of or damage to the casing or the wellhead structure.

During the slack gas usage months, gas produced in one geographical area is often piped to depleted gas formations located in the colder climates where it is stored for use in the colder months. Well structures .extending intothe storage formations normally include a single string of casing through which the gas is injected into the formation during the storage phase and through which gas is extracted during the usage phase. Safety equipment is required to be employed within the casing to automatically terminate gas flow in the event the wellhead structure or casing should fail.

In order to prevent automatic safety equipment from being damaged and to position the equipment in its most useful location, it is desirable that the equipment be positioned as far as possible below the surface of the well. Such placement protects the equipment from surface impact and minimizes the amount of casing exposedto leakage. Because the gas moves in one direction when it is being injected into the subsurface formation and in another direction when it is being extracted from the formation, subsurface valves employed in the equipment must be capable of permitting such flow while maintaining-their ability to close automatically in the event of uncontrolled flow..

.2. Description of the Prior Art Subsurface safety equipment customarily employed in well conduits includes valving mechanisms which are I included in thewell conduit as an integral part of the well conduit itself. Such mechanisms are lowered into the desiredsubsurface location as a part of the conduit when the well is completed. Retrieval of these integral mechanisms for repair or replacement requires that the well conduit be withdrawn from the well. Anotherprior art system which eliminates the need for extracting the entire well conduit for repair or replacement of the safety equipment employs a specially designed landing nipple which is included as a part of the well conduit when the conduit is lowered into the well. A retrievable valving and control assembly may then be lowered' through the conduit to latch into special recesses provided in the nipple.

In many of the older storage formations, the casing is cemented in palce and cannot be retrieved from the well. Other circumstances also make it impossible or undesirable to remove the casing from the well bore to equip it with safety equipment. Conventional safety valves are not designed to be employed in such unequipped casing.

SUMMARY OF THE INVENTION The valve of the present invention is designed to be run into a well casing and anchored in place with a retrievable well packer. The packer may include dogs to engage the collar recess between tubing sections or may have slips with friction teeth to anchor along the smooth casing wall. v v

The valve design includes a tubular valve housing through which a substantially tubular valve stem moves linearly to open or close the valve flow passage. In one axial position of the stem, slots cut through tubular walls both in the stern and in the housing align radially to open the flow passage. The passage is closed by moving a sealing surface on the stem into engagement with a seating surface formed in the housing. Movement of the stem through the housing is governed by a pressure responsive, bellows equipped control means.

The bellows chamber of the control means is enclosed and is completely filled with an incompressible fluid. A two-way valve mounted within the fluid moves between axially separated seating surfaces to protect the bellows from damage due to exposure to high pressures. Movement of fluid in the bellows is slowed by a small orifice opening to provide a damping-effect which protects the components of the control means from damage caused by sudden pressure changes. Closing of the valve is effected by sudden release of a compressed spring to provide a snap closing action which ensures complete seating of the stem against the housing seat. Spring forces are also employed to both provide a closing force in the event of damageto the bellows section and to assist in resetting the snap action mechanism when the valve is reopened. A pressure bypass passage is opened across the closed valve by a setting tool for equalizing reopening of the valve.

The packer is preferably of the type which may be wireline set and retrieved to minimize operating expenses and to reduce losses in production time. A relatively large, unimpeded flow passage is opened through the valve to increase the rate of fluid flow through the assembly. The sealing and seating surfaces employed in the closure means of the valve are withdrawn from the flow path of the fluids when the valve is open to prevent abrasive cutting and wear. An operator extending axially through the center of the valve stemis designed to be pushed down bythe setting mechanism ,to depress a sealing piston which opens the bypass passage. A seal piston extends between the operator and the valve stem to protect the internal components of the control mechanism from damage caused by the accumulation of sediment or debris.

The foregoing and other features and advantages of the present invention will be more fully understood from the following specification, claims and the related drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical elevation, partially in section illustrating the automatic safety valve of the present invention anchored by a retrievable packer at a subsurface location in a well casing;

FIG. 2 is a partial, vertical elevation, in quartersection, illustrating the valve and control portions of the present invention with the'valve in a stabilized, closed position;

FIG. 3 is a view similar to FIG. 2 illustrating the valve and control components immediately following movement of the closure components of the valve from open to closed position prior to stabilized closure;

FIG. 4 is a view similar to FIG. 3 illustrating the valve in a stabilized, fully opened position;

FIG. 5 is a view similar to FIG. 2 illustrating a surface operated latching device attached to an operator in the valve to hold the valve in closed position as an emergency measure;

FIG. 6 is a view similar to FIG. 2 illustrating a surface operated setting mechanism telescoped over the end of the operator employed to open a pressure bypass to equalize pressure across the closed valve so that the assembly may be released and moved through the well casing;

FIG. 7 is a horizontal cross-sectional view taken along the line 7-7 of FIG. 4;

FIG. 8 is a horizontal cross-sectional view taken along the line 8-8 in FIG. 3; and

FIG. 9 is a horizontal cross-section taken along the line 9-9 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT The automatic safety valve assembly of the present invention is indicated generally at 10 in FIG. 1. Components included with the assembly 10 include a packer P, a valving section V and a control section C. The assembly 10 is illustrated anchored in position at a subsurface location within a tubular well casing W. The packer P is of conventional construction and includes an elastomeric seal S and radially expansible and retractable anchoring devices A. As illustrated in FIG. 1, the anchoring elements A are dogs which have been expanded into an annular collar recess formed between upper and lower casing sections Wa and Wb, respectively, joined together by a collar Wc. As is customary, setting of the packer causes the anchoring dogs A to extend radially and simultaneously causes the elastomeric seal S to expand radially outwardly. Expansion of the packer seal forms a pressure-tight seal between the body of the packer and the surrounding walls of the casing W. Once set, the packer anchors the assembly in place and forces all the fluids in the casing W to flow through the valve section V.

The packer P may be similar to that described in US. patent application, Ser. No. 857,047, filed Sept. 11, 1969, entitled ANCHOR ASSEMBLY FOR WELL TOOLS SUCH AS PACKERS AND THE LIKE or similar to that described in US. Pat. application, Ser. No. 272, filed Jan. 2, 1970, entitled TOOL STRING AS- SEMBLY FOR USE IN WELLS. Any packer employed to anchor the valve mechanism V within the casing W is preferably retrievable and includes a large central I opening to permit relatively unimpeded flow of fluid through the assembly. Where collar recesses are not available, or where otherwise desired, the anchoring dogs A may be replaced by conventional slips having friction creating teeth formed along their external surfaces.

Details in the construction of the valve and control portions of the present invention are illustrated in FIG. 2 which shows the valve components as they appear in a stabilized, closed position. The valve section V includes a tubular valve housing 11 which is threadedly engaged to the base of an adapter section 12. The adapter section 12 isin turn connected to the body of the packer P to support the depending valve section V and control section C. A tubular control housing 13 is threadedly secured to the base of valve housing 11 and is employed to support and protect pressure responsive bellows and spring components contained within the control C.

A linearly movable valve stem 14 is carried within the valve housing 11 and is mounted to be moved axially within the tubular valve housing 1 1 under the influence of the bellows and spring control components contained within the control housing 13. The valve stem 14 is of composite construction and includes a tubular sealing head 15 threadedly engaged to a detent holder 16 which in turn is threadedly secured at its lower end to a recocking sleeve '17. The outer external surface of the head 15 is equipped with a circumferentially extending seal mount which supports an annular seal 18 of a suitable elastomeric material. The seal 18 encircles the head 15 and, when the valve stem 14 is in its uppermost axial position as illustrated in FIG. 2, the seal 18 is designed to engage and seal against a seating surface 19a formed in an annular seat ring 19 to prevent flow through the valve. The ring 19 is removably mounted between the base of adapter 12 and an inwardly developed shoulder 20 formed along the internal wall of the valve housing 11. When the seating surface 19a becomes worn, the ring may be removed and replaced by simply unthreading the valve housing 11 from the adapter 12.

When the valve stem 14 is in its lowermost axial position as illustrated in FIG. 4 of the drawings, circumferentially developed slots 21 formed through the walls of valve housing 11 communicate with similar slots 22 formed through the tubular walls of the stem head 15 to provide a flow passage through the valve V. The flow passage permits liquids or gases in the casing W above and below the set packer seal S to flow in either direction through the valve V and packer P.

The stem head 15 supports an axially movable central operator 23. The operator includes an upper segment 23a having a tapered head 23a, a downwardly facing annular shoulder 23b formed below the head 23a and a second downwardly facing shoulder 23c formed along the shank of the upper segment. A lower body segment 23d threadedly engaged to the upper segment 23a is equipped with an upwardly facing shoulder 23e formed at its base. An annular debris seal 24 encircles the shank of control 23 to prevent sand and silt and other debris from falling down between the operator and the surrounding stem head. A coil spring 25 mounted between the seal 24 and an annually developed shoulder in the stem head 15 biases the seal 24 upwardly into engagement with the shoulder 23b. An O-ring seal 26 of a suitable elastomeric material extends about the seal 24 to provide a sliding, sealing engagement with the internal walls of the stem head 15. A removable snap ring 27 set within a receiving groove formed in the wall of stem head 15 provides an upper axial restraint to retain the seal 24 within the receiving bore formed by the surrounding walls of the stem head 15.

An axially movable valving piston 28 having upper and lower annular O-

ring seals

28a and 28b carried along its outer circumferential surface is mounted between the operator 23 and the stem head 15 to control opening and closing of a pressure bypass passage. A he- I lical spring 29 positioned between the piston 28 and the upper surface of detent holder 16 functions to retain the upper end of the piston in engagement with the shoulder 230 formed on the operator 23. Sliding sealing engagement between the operator 23 and holder 16 is provided by an O-ring operator seal 23f.

Upper axial movement of the piston 28 is limited by an inwardly developed shoulder 31 extending from the inner wall of the Stem head 15. Axially developed bores 28c extend through the upper end of the piston 28 to provide a pressure relief passage which when opened permits relatively large pressure differentials across the closed valve to be slowly equalized before the valve is reopened. As will be seen, when the piston 28 is in its uppermost axial position in engagement with the shoulder 31, bypass flow passages 30 extending radially through'the walls of the stem head are bridged by the O-

rings

28a and 28b which seal the passages .30 from the area between the operator 23 and the internal walls of the stern head 15. With the valve stem 14 and piston 28 at their uppermost positions, the main sea] I may be difficulat or impossible where a relatively high pressure differential exists across the valve. As best illustrated in FIG. 6, pressure equalization across the closed valve is effected with the use of a suitable surface operated setting mechanism F which engages the operator 23 and moves it downwardly throughthe closed valve stem 14. In this position, the operator 23 forces the piston 28 downwardly against the resisting force of spring 29 to open the flow passages 30. The low pressure area existing within the stem head 15 is thereby communicated through openings F-l formed in the base of the setting mechanism F,vthrough the annular area between the operator 23 and the surrounding walls of the stem head 15 and through the radial flow passage openings 30 to the area within the well casing, externally of the valve V and below the seal S.

A triggering mechanism 33 surrounds the lower operator segment 23d and is employed to control the radial movement of a plurality of metal spherical detent balls 34. The ballsare positioned for radial movement in a bore 16a formed in the detent holder 16 and are designed to'moveinto and out of engagement with a recess 11a formed along the internal wall of valve housing 11. The triggering mechanism 33 also includes a downwardly tapered annular shoulder section 33b formed along its outer surface which is employed to urge the detent balls 34 radially outwardly when the member 33 is moved axiallydownwardly. A helical spring 330 encircles operator segment 23d and is re.- strained at its upper end by engagement with the shoulder extending inwardly from detent holder 16 and at its lower end, by engagement with a shoulder extending radially inwardly from the base of triggering component 33. Axially extending bores 33a formed in the component 33 prevent pressure differentials from developing across the member which would impede its movement. As may be seen by reference to FIG. 5, the shoulder 23e provides a lower limit to travel of the component 33 over the operator 23.

The opening and closing movements of the valve stem 13 through the housing 11 are provided by bellows and spring drives contained within the control housing 13. The bellows portion of the control C includes a lower bellows section 35 and an upper bellows section 36 which enclose' lower and upper bellows areas B-l andB-2 respectively. The areas B-1 and B-2 are completely filled with a non-compressible fluid such as a light weight oil to provide bellows protection in a manner to be described. The lower bellows section 35 is housed within a lower housing portion 13a and the upper section 36 is housed in an upper control housing portion 13b. The upper and lower housing portions are threadedly secured to a central housing member 13c.

An alignment sleeve 37 threadedly engaged to the cenensure complete filling of the internal areas of thebellows with the non-compressible fluid. A cap 40 is threadedly engaged with the lower end of end structure 38 to provide a filling opening through which the bellows areas may be filled with liquid. The bellows sections are joined to their end structures by a suitable leakproof means such as soldering or welding or otherwise and resilient annular O-ring seals are positioned between threadedly engaged components to provide a leakproof seal of the area confined 'within the bellows.

The central portion of alignment sleeve 37 includes a restricted opening 41 which functions as a damping orifice to restrict the flow of liquid which in turn preventsv short duration, transient pressure changes from operating the valve or causing damage to the control mechanism.

An axially movable safety valving sleeve 42 is mounted for axial movement within the fluid contained in the areas B-1 and B-2. The member 42 includes an annular resilient seal member 43 which is designed to be moved axially between a lower seatingvsurface 44 formed along the upper axial end of alignment sleeve 37 and an upper seating surface 45 formed along an inwardly directed shoulder extending from the housing section 13c. A coil spring 46 mounted between the seal sleeve 42 and the alignment sleeve 37 biases the sleeve 42 and seal 43 into engagement with the upper'seating surface 45. The sleeve 42 includesan upwardly extending tubular support section 47 which is surrounded by a teflon sleeve 48. The sleeve 48 acts as a smooth underlying surface against which the bellows section 36 may slide. Radial openings 47a extend through the sleeve 47 to ensure complete liquid filling of the area The top of bellows 36 is secured to an axially movable upper end assembly 50. A depending sleeve 51 threadedly engaged to the lower end of the assembly extends over a portion of the bellows 36 and terminates in a radially projecting shoulder 51a. A spring 52 is mounted between shoulder 51a and the upper surface of the internal shoulder formed on the housing section and functions to close the valve in the event of bellows failure. The upper end of end assembly 50 is threadedly engaged to a bushing 53 which provides an upper restraining shoulder for a resetting spring 54. The lower end of spring 54 is mounted against an inwardly extending shoulder 17a formed on the recocking sleeve 17. A closure spring 55 is mounted about sleeve 51 between relatively movable shoulders 17b and 51a. Radial openings 17b extending through the sleeve 17 prevents a pressure differential from developing across the walls of the sleeve. Casing pressure is communicated into the control C through openings in a protective screen 11b which cover pressure communication ports 56. The ports 56 extend through the valving housing walls and communicate. with a bellows control area B-3 formed between the bellows housing 13 and the outer surface of bellows section 36.

The lowermost end of housing 13 is equipped with a removable cap 57 which protects a conventional gas valve 58. The valve 58 is employed to inject a gas into a pressure dome B-4 formed between the housing section and the external surface of bellows section 35.

In the operation of the assembly 10, the pressure of the gas in pressure dome 84 determines the pressure at which the valve will open and close. Under normal operating conditions where gas is being injected into the formation or is being extracted from the formation, the differential between the pressure in dome B-4 and control area 8-3 is insufficient to move the valve to closed position and the closure components of the valve are as illustrated in FIG. 4. Stated differently, the pressure in the well conduit and in area 8-3, is greater than that in the dome, area B-4, causing the bellows section 36 to contract and the section 35 to elongate or expand which in turn holds the valve stem 14 at its lower position. In this position, the seal 18 and seat surface 190 are out of the flow path of the gas moving through the valve V. The pressure in control area B-3 is the same as that existing in the well casing below the seal S. When the casing pressure drops below the dome pressure, corresponding to failure of the casing or wellhead structure, the pressure in area B-3 falls. The decrease in pressure permits the gas charge in the dome 13-4 to foreshorten the bellows section 35 as illustrated in FIG. 6. This movement of bellows section 35 causes bellows section 36 to elongate. The end assembly 50 is moved upwardly by elongation of bellows section 36 causing the bushing 53 to engage the base of trigger mechanism 33 and push it upwardly against the force of spring 33c. Raising of the triggering mechanism 33 permits detent balls 34 to retract radially out of recess 11a which releases the valve stem 13 from the valve housing 11. During the initial portion of the upward movement of bellows section 36, spring 55 is compressed by the upward movement of shoulder 51a with respect to valve stem 14 which, until the balls 34 are released, remains stationary. When the balls 34 move out of the recess 11a, the compressed force of spring 55 is suddenly released to swiftly move the valve stem 14 upwardly through the surrounding housing 11 to provide a snap action closure. Immediately preceding closure, the bellows 35 is compressed as illustrated in FIG. 3. The initial upward movement of the assembly 50 also compresses spring 330. When the detent balls 34 are in their radially retracted position where they are held by engagement with the internal walls of the valve housing 11, the engagement between taper surface 33b and balls 34 retains the spring 33c in compressed condition.

After damage'to the well structure has been repaired, the valve may be reopened by pressuring up from the wellhead or by lowering a suitable mechanism down through the casing to depress the valve stem. During the downward movement of the stem 14 as the valve is being reopened, the spring33c remains compressed until the detent balls are aligned with detent recess 1 1a. At this point, the balls are free to move radially outwardly and the compressed force of spring 330 acts against the tapered surface 33d to push the balls outwardly into locking engagement with the recess 11a so that the valve assumes the position illustrated in FIG. 4. The resetting spring 54 is compressed during the return movement of the bellows 55 caused by the pressure increase in the well following valve closure. The force of the compressed spring is released to snap the stem 14 fully open during the resetting operation so that the valve closure surfaces are completely withdrawn from the valve flow passage.

An important feature of the present invention is the provision of the safety closure spring 52 which assures closure of the valve in the event of bellows failure. When the valve is in open position, the spring 52 remains in compression. Loss of pressure sealing in the bellows area releases the force of spring 52 which trips the valve into closed position. Thus, when the bellows sections or the dome are ruptured or otherwise begin to leak, the well pressure in area B-3 is communicated into the bellows areas and the dome. When this occurs, the bellows section 36 is permitted to expand with the assistance of the spring 52. The expansion trips the triggering mechanism 33 and causes the valve to close.

FIG. 5 of the drawings illustrates a latching mechanism L which includes resilient collet members L-l having inwardly tapered lower end surfaces L-2. If for any reason, the valve closure members should fail to automatically close, the latching mechanism L may be lowered through the well casing until the lower, tapere surfaces L-2 of collet fingers L-l hit and slide over the upper, tapered surfaces 23a" of the operator 23 causing the collets to spread outwardly and latch about the operator shoulder 23b. A subsequent upward force exerted through the latching mechanism L causes the valve stem 14 to be moved upwardly which closes the valve by seating the primary seal'18 against seat 19a.

Because the

bellows sections

35 and 36 may be exposed to extremely high pressure differentials, the control C is provided with a means for preventing over contraction or over expansion of the bellows sections which would permanently distort the bellows and thereby destroy them for their intended usage. This safety provision is provided by the safety valving sleeve 42. When the valve is open as illustrated in FIG. 4, the spring 46 is compressed and the sleeve 42 is held at its lowermost axial position by the end assembly 50. In this position, the seal 43 engages the lower seating surface 44 and pressure existing in the bellows area B-2 is isolated from that existing in the bellows area 8-1 to prevent over extension of the bellows 35. Since the upper section B-2 is filled with an incompressible fluid, extremely high pressures may be tolerated without damage to the bellows sections. In the absence of the protected seal provided by sleeve 42 and seal 43, high pressures in the upper bellows area B-2 will be communicated to the bellows area B-l causing the lower bellows to over expand outwardly and the upper bellows to over contract inwardly. In the opposite situation, where the pressure in control area B-3 falls below a predetermined value, the valve sleeve 42 is automatically moved upwardly under the influence of the spring 46 causing the seal 43 to seat against the upper seating surface 45. The incompressible fluid filling bellows area B-1 prevents the dome charge from overcompressing the bellows 35 and the seal 43 prevents communication of the high pressures existing in bellows area B-l to bellows area B-2 which thereby protects bellows 36 from over extension outwardly. The bellows section 36 however remains free to expand and contract within the limits required for proper operation of the valve. By this means, relatively high pressures may be employed in the pressure dome B-4 without damage to the bellows components.

While the valve assembly has been described with referenceprimarily to its use as an automatic safety valve for use in the event of damage to the well casing or wellhead structure, it may be appreciated that the valve-may function as a check valve through which gas may be injected into the well but through which gas is prevented from flow-ing out of the well. Operation of this type may be effected by establishing a gas charge in dome chamber B-4 which maintains the valve in closed position under normal operating conditions where gas is neither being injected into nor extracted from the formation. Thus, gas pressure in dome 8-4 is low enough to permit the valve to open under the influence of a high gas pressure exerted from the wellhead during gas injection which biases the valve stem into open position.

From the foregoing, it will be appreciated that the assembly of the present invention provides a means whereby maximum producing rates may be achieved by minimizing pressure losses since production may be effected through the well casing. Moreover, by employing a retrievable packer which may be operated on a wireline, the assembly may be quickly and easily replaced or repaired and the valve may be quickly positioned at any desired subsurface location. The bellows protection permits the control to function well even where high pressures are encountered and the snap action closure and opening ensures proper operation of the valve. The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated constructionmay be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. An automatic safety valve for use in a well conduit comprising: I

a. valve body means having a flow passage with inlet and outlet means extending through at least a portion of said valve body means;

b. movable valve closure means connected with saidvalve'body means for opening or closing said flow passage to respectively permit or terminate the flow of fluids or gases through said flow passage;

c. pressure responsive control means connected with said closure means for automatically moving said closure means into open or closed position to respectively open or close said flow passage in response to pressure conditions present within said well conduit;

d. a substantially circular valve seat surface connected with said closure means and said flow pase. valve stem means included in said closure means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage, said valve stem means and said seat surface being mounted for linear movement with respect to each other;

f. surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit; and

g. pressure bypass means operable when opened to equalize pressure at the inlet and outlet ends of said flow passage when said closure means is in closed position.

2. Anautomatic safety valve for use in a well conduit comprising:

a. valve body means having a flow passage with inlet and outlet means extending through at least a portion of said valve body means; V

b. movable valve closure means connected with said valve body means for DPF ning or closing saidflow passage to respectively permit or terminate flow of fluid or gases through said flow passage;

' c. pressure responsive control means connected with said closure means for automatically moving said closure means into. open or closed position to respectively open or close said flow passage in response to pressure conditions present within said well conduit;

- d.v a substantially circular valve seat surface formed in said valve body means and encircling said flow passage;

e. valve stem means included in said closure means, said stern means being mounted for linear move ment within said valve body means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage;

f. surface operable anchoring and sealing meansfor respectively anchoring said valve body means at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit, said anchoring. and sealing means including a retrievable packer means with radially expansible and retractablesecuring means, a radially expansible and retractable elastomeric seal and a I whereby said bellows is moved responsive to a pressure difference in said first and second areas;

i. compressed spring means connected with said stem means and said bellows means urging said stem means toward closed position;

j. release means connected with said spring means for releasing said compressed spring means from its compressed position when movement of said bellows means exceeds a predetermined amount; and

k. connecting means linking said spring means and said stem means to produce a fast, powering movement of said stem means to closed position by the expansion of said released spring means.

3. An automatic safety valve as defined in claim 2 further including bellows protection means including a noncompressible fluid contained within said bellows means, a first chamber means enclosed within a portion of said bellows means and filled with said .fluid and a selectively closable safety seal means operable by motion of said bellows means to seal said fluid in said first chamber means whereby the portion of said bellows means surrounding said first chamber means is prevented from contracting when said safety seal means seals said first chamber means.

4. An automatic safety valve as defined in claim 3 wherein:

a. said bellows means includes a second, enclosed bellows chamber means connected through said safety seal means with said first chamber means;

b. incompressible fluid is contained in said first and second chamber means; and

c. said safety seal means is operable by movement of said bellows means to seal either said first or second chamber means whereby fluid in the unsealed chamber means is isolated from the fluid in the sealed chamber means to prevent contraction of the bellows means in said sealed chamber means.

5. An automatic safety valve as defined in claim 4 further including restrictive flow orifice means in said first and second bellows chamber means for forcing displaced fluid to flow through said orifice means for damping mechanical movement of said bellows means.

6. An automatic safety valve as defined in claim 2 wherein said release means includes:

a. radially movable detent means extending through said stem means and adapted when in radially extended position to engage and lock with said valve housing means for preventing relative axial movement between said stem means and said valve housing means to hold said closure means in open position; and

b. triggering means operable by movement of said bellows means for permitting said detent means to retract radially whereby said compressed spring means is suddenly released to snap said stem means into engagement with said seat means.

7. An automatic safety valve as defined in claim 6 further including:

a. resetting spring means connected with said triggering means and compressed when said closure means is moved into closed position to thereby urge said detent means radially outwardly into reengagement with said valve housing and to snap said stem means into fully open position when said closure means is reopened; and

b. safety spring means connected with said bellows means for moving said stem means into closed position when the pressure in said first chamber means falls below a predetermined minimum value.

8. An automatic safety valve for use in a well conduit comprising:

a. valve body means having'a flow passage with inlet and outlet means extending through at least a portion of said valve body means;

b. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit or terminate the flow of fluids or gases through said flow passage,

c. pressure responsive control means connected with said closure means for automatically moving said closure means into open or closed position to respectively open or close said flow passage in response to pressure conditions present within said well conduit; I

- d. a substantially circular valve seat surface connected with said closure means and said flow passage; I

e. valve stem means included in said closure means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage, said valve stem means and said seat surface being mounted for linear movement with respect to each other;

f. surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit;

g. contractible and expandible bellows means included in said control means and connected with said valve stem means for forming a pressure seal between a first internal control pressure area and a second external pressure area whereby said bellows is moved responsive to a pressure difference in said first and second pressure areas;

h. compressed spring means connected with said stem means and said bellows means urging said stem means toward closed position;

i. release means connected with said spring means for releasing said compressed spring means from its compressed position when movement of said bellows means exceeds a predetermined amount; and

j. connecting means linking said spring means and said stem means to produce a fast, powering movement of said stern means to closed position by the expansion of said released spring means.

9. An automatic safety valve for use in a well conduit comprising:

b. movable valve closure means connected with said valve body means for opening or closing saidflow passage to respectively permit or terminate flow of fluids or gases through said flow passage;

d. a substantially circular valve seat surface formed in said valve body means and encircling said flow passage;

e. valve stem means included in said closure means,

said stem means being mounted for linear movement within said valve body means and including sealing means for sealingly engaging and disengaga ing said seat surface to respectively terminate or permit flow through said passage;

f. surface operable anchoring and sealing means for respectively anchoring said valve body means at a subsurface location within a well conduit and for forming a seal between said well condiut and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit, said anchoring and sealing means including a retrievable packer means with a radially expansible and retractable elastomeric seal and a flow opening extending axially through a supporting packer body; A

g. a substantially tubular valve housing means included in said valve body means and connected to and supported by said packer body with said inlet end of said flow passage opening through the walls of said housing means and said flow passage outlet end opening into said packer flow opening;

h. pressure bypass means extending through said valve stem means and operablewhen opened to equalize pressure at the inlet and outlet ends of said flow passage when said control means is in closed position; and v an axially movable operator carried within said valve stem means and operable when moved axially with respect to said valve stem means to open said pressure bypass means and to activate said release means.

10. An automatic safety valve as defined inclaim 9 further-including protective seal means extending between said valve stem means and said operator means for preventing debris from entering between said operator means and said stem means.

11. An automatic safety valve for use in a well conduit comprising:

a. a substantially tubular valve housing means having a flow passage with-inlet and outlet means extending through at least a portion of said valve housing means;

b. circumferentially extending housing slot means formed in said valve housing means for forming said inlet means of said flow passage;

c. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit-or terminate the flow of fluids or gases through said flow passage;

d. pressure responsive control means connected with said closure means for automatically moving said closure means into open or closed position to respectively open or close said flow passage in response to pressure conditions present within said well conduit;

e. a substantiallycircular valve seat surface formed in said valve housing means and connected with said closure means and said flow passage; and

f. valve stem means included in said closure means and substantially tubular along at least a portion of its length, encircled by said seat surface and being mounted for linear movement within said valve housing, said stem means including:

i. annular sealing means carried along the external surface of said stem means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said flow passage; and

ii. stem slot means forming a portion of said flow passage with said stem means being movable axially within said valve housing means to move said housing slots and said stem slots into radial coincidence or to move said seat surface into engagement with said annular seal means to respectively open or close said passage means to permit or terminate fluid or gas flow through said well conduit.

12. An automatic safety valve for use in a well conduit comprising:

b. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit or terminate the flow of fluids or gases through said flow passage;

0. a substantially circular valve seat surface connected with said closure means and said flow passage;

d. valve stem means included in said closure means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage, said valve stem means and said seat surface being mounted for linear movement with respect to each other;

e. control means connected with said stern means and movable in response to pressure conditions present within said well conduit for automatically controlling movement of said stem means to open or close said flow passage;

f. surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means toprevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit; and

g. spring biasing means included with said control means and connected with said stem means for moving said stem means into a position closing said flow passage upon predetermined movement of said control means.

. 13. An automatic safety valve as defined in claim 12 further including:

a. pressurized bellows chamber means included in said control means tending to move said control means toward a position for closing said flow passage when the pressure in said conduit is lower than that in said chamber means; and

b. safety spring biasing means urging said control means to the position closing said flow passage for causing closure of said flow passage when the pressure in said pressurized chamber means becomes substantially the same as that in said well conduit.

14. An automatic safety valve as defined in claim 12 wherein said control means further includes reset spring means for snapping said valve stem means fully open as said stem means is moved from closed toward open position.

15. An automatic safety valve as defined in claim 12 wherein said control means includes:

a. a liquid filled bellows chamber having a first bellows portion externally exposed to the well pressure;

b. a pressurized gas dome acting externally on a second portion of said bellows chamber; and

c. a liquid valving means included internally of said bellows chamber and operable by movement of said bellows chamber to seal said first and second bellows portions from each other whereby pressure tending to collapse said first bellows portion beyond a predetermined maximum value is isolated from said second bellows portion and pressure tending to collapse said second bellows portion beyond a predetermined maximum valve is isolated from said first bellows portion.

16. An automatic safety valve as defined in claim 15 further including damping flow passage means connecting said first and second bellows portions for'restricting fluid flow between said portions as said liquid valving means is moved between positions sealing on or the other of said first and second bellows portions.

17. An automatic safety valve as defined in claim 15 wherein said control means further includes reset spring means for snapping said valve stem means fully open as said stem means is moved from closed toward open position.

18. An automatic safety valve for use in a well conduit comprising:

d. a substantially circular valve seat surface connected with said closure means and said flow passage;

e. valve stem means included in said closure means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow thorugh said passage, said valve stem means and said seat surface being mounted for linear movement with respect to each other;

g. contractable and expansible bellows means included in said control means and connected with said valve stem means for. forming a pressure seal between a first confined control pressure area and a second pressure area whereby said bellowsmeans is moved responsive to a pressure-difference in said first and second areas; and

h. bellows protection means including a noncompressible fluid contained within said bellows means, a first chamber means enclosed within a portion of said bellows means and filled with said fluid, and a selectively closable safety seal means operable by motion of said bellows means to seal said fluid in said first chamber means whereby the portion of said bellows means surrounding said first chamber means is prevented from contracting when said safety seal means seals said first chamber means.

19. An automatic safety valve as defined in claim 18 wherein:

a. said bellows means includes a second, enclosed bellows chamber means in fluid communication with said first chamber means;

c. said safety seal means is operable by movement of said bellows means to permit fluid flow between said first and second chamber means or to seal either said first or said second chamber means whereby fluid pressurein the unsealed chamber means'is isolated from the fluid pressure in the sealed chamber means to prevent contraction of the bellows means in said sealed chamber means beyond ,a predetermined maximum amount.

Claims

1. An automatic safety valve for use in a well conduit comprising: a. valve body means having a flow passage with inlet and outlet means extending through at least a portion of said valve body means; b. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit or terminate the flow of fluids or gases through said flow passage; c. pressure responsive control means connected with said closure means for automatically moving said closure means into open or closed position to respectively open or close said flow passage in response to pressure Conditions present within said well conduit; d. a substantially circular valve seat surface connected with said closure means and said flow passage; e. valve stem means included in said closure means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage, said valve stem means and said seat surface being mounted for linear movement with respect to each other; f. surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit; and g. pressure bypass means operable when opened to equalize pressure at the inlet and outlet ends of said flow passage when said closure means is in closed position.

2. An automatic safety valve for use in a well conduit comprising: a. valve body means having a flow passage with inlet and outlet means extending through at least a portion of said valve body means; b. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit or terminate flow of fluid or gases through said flow passage; c. pressure responsive control means connected with said closure means for automatically moving said closure means into open or closed position to respectively open or close said flow passage in response to pressure conditions present within said well conduit; d. a substantially circular valve seat surface formed in said valve body means and encircling said flow passage; e. valve stem means included in said closure means, said stem means being mounted for linear movement within said valve body means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage; f. surface operable anchoring and sealing means for respectively anchoring said valve body means at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit, said anchoring and sealing means including a retrievable packer means with radially expansible and retractable securing means, a radially expansible and retractable elastomeric seal and a flow opening extending axially through a supporting packer body; g. a substantially tubular valve housing means included in said valve body means and connected to and supported by said packer body with said inlet end of said flow passage opening through the walls of said housing means and said flow passage outlet end opening into said packer flow opening; h. contractible and expansible bellows means connected with said valve stem means for forming a pressure seal between a first internal control pressure area and a second external pressure area whereby said bellows is moved responsive to a pressure difference in said first and second areas; i. compressed spring means connected with said stem means and said bellows means urging said stem means toward closed position; j. release means connected with said spring means for releasing said compressed spring means from its compressed position when movement of said bellows means exceeds a predetermined amount; and k. connecting means linking said spring means and said stem means to produce a fast, powering movement of said stem means to closed position by the expansion of said released spring means.

3. An automatic safety Valve as defined in claim 2 further including bellows protection means including a noncompressible fluid contained within said bellows means, a first chamber means enclosed within a portion of said bellows means and filled with said fluid and a selectively closable safety seal means operable by motion of said bellows means to seal said fluid in said first chamber means whereby the portion of said bellows means surrounding said first chamber means is prevented from contracting when said safety seal means seals said first chamber means.

4. An automatic safety valve as defined in claim 3 wherein: a. said bellows means includes a second, enclosed bellows chamber means connected through said safety seal means with said first chamber means; b. incompressible fluid is contained in said first and second chamber means; and c. said safety seal means is operable by movement of said bellows means to seal either said first or second chamber means whereby fluid in the unsealed chamber means is isolated from the fluid in the sealed chamber means to prevent contraction of the bellows means in said sealed chamber means.

6. An automatic safety valve as defined in claim 2 wherein said release means includes: a. radially movable detent means extending through said stem means and adapted when in radially extended position to engage and lock with said valve housing means for preventing relative axial movement between said stem means and said valve housing means to hold said closure means in open position; and b. triggering means operable by movement of said bellows means for permitting said detent means to retract radially whereby said compressed spring means is suddenly released to snap said stem means into engagement with said seat means.

7. An automatic safety valve as defined in claim 6 further including: a. resetting spring means connected with said triggering means and compressed when said closure means is moved into closed position to thereby urge said detent means radially outwardly into reengagement with said valve housing and to snap said stem means into fully open position when said closure means is reopened; and b. safety spring means connected with said bellows means for moving said stem means into closed position when the pressure in said first chamber means falls below a predetermined minimum value.

8. An automatic safety valve for use in a well conduit comprising: a. valve body means having a flow passage with inlet and outlet means extending through at least a portion of said valve body means; b. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit or terminate the flow of fluids or gases through said flow passage; c. pressure responsive control means connected with said closure means for automatically moving said closure means into open or closed position to respectively open or close said flow passage in response to pressure conditions present within said well conduit; d. a substantially circular valve seat surface connected with said closure means and said flow passage; e. valve stem means included in said closure means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage, said valve stem means and said seat surface being mounted for linear movement with respect to each other; f. surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing Means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit; g. contractible and expandible bellows means included in said control means and connected with said valve stem means for forming a pressure seal between a first internal control pressure area and a second external pressure area whereby said bellows is moved responsive to a pressure difference in said first and second pressure areas; h. compressed spring means connected with said stem means and said bellows means urging said stem means toward closed position; i. release means connected with said spring means for releasing said compressed spring means from its compressed position when movement of said bellows means exceeds a predetermined amount; and j. connecting means linking said spring means and said stem means to produce a fast, powering movement of said stem means to closed position by the expansion of said released spring means.

9. An automatic safety valve for use in a well conduit comprising: a. valve body means having a flow passage with inlet and outlet means extending through at least a portion of said valve body means; b. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit or terminate flow of fluids or gases through said flow passage; c. pressure responsive control means connected with said closure means for automatically moving said closure means into open or closed position to respectively open or close said flow passage in response to pressure conditions present within said well conduit; d. a substantially circular valve seat surface formed in said valve body means and encircling said flow passage; e. valve stem means included in said closure means, said stem means being mounted for linear movement within said valve body means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage; f. surface operable anchoring and sealing means for respectively anchoring said valve body means at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit, said anchoring and sealing means including a retrievable packer means with a radially expansible and retractable elastomeric seal and a flow opening extending axially through a supporting packer body; g. a substantially tubular valve housing means included in said valve body means and connected to and supported by said packer body with said inlet end of said flow passage opening through the walls of said housing means and said flow passage outlet end opening into said packer flow opening; h. pressure bypass means extending through said valve stem means and operable when opened to equalize pressure at the inlet and outlet ends of said flow passage when said control means is in closed position; and i. an axially movable operator carried within said valve stem means and operable when moved axially with respect to said valve stem means to open said pressure bypass means and to activate said release means.

10. An automatic safety valve as defined in claim 9 further including protective seal means extending between said valve stem means and said operator means for preventing debris from entering between said operator means and said stem means.

11. An automatic safety valve for use in a well conduit comprising: a. a substantially tubular valve housing means having a flow passage with inlet and outlet means extending through at least a portion of said valve housing means; b. circumferentially extending housing slot means formed in saiD valve housing means for forming said inlet means of said flow passage; c. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit or terminate the flow of fluids or gases through said flow passage; d. pressure responsive control means connected with said closure means for automatically moving said closure means into open or closed position to respectively open or close said flow passage in response to pressure conditions present within said well conduit; e. a substantially circular valve seat surface formed in said valve housing means and connected with said closure means and said flow passage; and f. valve stem means included in said closure means and substantially tubular along at least a portion of its length, encircled by said seat surface and being mounted for linear movement within said valve housing, said stem means including: i. annular sealing means carried along the external surface of said stem means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said flow passage; and ii. stem slot means forming a portion of said flow passage with said stem means being movable axially within said valve housing means to move said housing slots and said stem slots into radial coincidence or to move said seat surface into engagement with said annular seal means to respectively open or close said passage means to permit or terminate fluid or gas flow through said well conduit.

12. An automatic safety valve for use in a well conduit comprising: a. valve body means having a flow passage with inlet and outlet means extending through at least a portion of said valve body means; b. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit or terminate the flow of fluids or gases through said flow passage; c. a substantially circular valve seat surface connected with said closure means and said flow passage; d. valve stem means included in said closure means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage, said valve stem means and said seat surface being mounted for linear movement with respect to each other; e. control means connected with said stem means and movable in response to pressure conditions present within said well conduit for automatically controlling movement of said stem means to open or close said flow passage; f. surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit; and g. spring biasing means included with said control means and connected with said stem means for moving said stem means into a position closing said flow passage upon predetermined movement of said control means.

13. An automatic safety valve as defined in claim 12 further including: a. pressurized bellows chamber means included in said control means tending to move said control means toward a position for closing said flow passage when the pressure in said conduit is lower than that in said chamber means; and b. safety spring biasing means urging said control means to the position closing said flow passage for causing closure of said flow passage when the pressure in said pressurized chamber means becomes substantially the same as that in said well conduit.

15. An automatic safety valve as defined in claim 12 wherein said control means includes: a. a liquid filled bellows chamber having a first bellows portion externally exposed to the well pressure; b. a pressurized gas dome acting externally on a second portion of said bellows chamber; and c. a liquid valving means included internally of said bellows chamber and operable by movement of said bellows chamber to seal said first and second bellows portions from each other whereby pressure tending to collapse said first bellows portion beyond a predetermined maximum value is isolated from said second bellows portion and pressure tending to collapse said second bellows portion beyond a predetermined maximum valve is isolated from said first bellows portion.

16. An automatic safety valve as defined in claim 15 further including damping flow passage means connecting said first and second bellows portions for restricting fluid flow between said portions as said liquid valving means is moved between positions sealing one or the other of said first and second bellows portions.

18. An automatic safety valve for use in a well conduit comprising: a. valve body means having a flow passage with inlet and outlet means extending through at least a portion of said valve body means; b. movable valve closure means connected with said valve body means for opening or closing said flow passage to respectively permit or terminate the flow of fluids or gases through said flow passage; c. pressure responsive control means connected with said closure means for automatically moving said closure means into open or closed position to respectively open or close said flow passage in response to pressure conditions present within said well conduit; d. a substantially circular valve seat surface connected with said closure means and said flow passage; e. valve stem means included in said closure means and including sealing means for sealingly engaging and disengaging said seat surface to respectively terminate or permit flow through said passage, said valve stem means and said seat surface being mounted for linear movement with respect to each other; f. surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids or gases in said well conduit from flowing axially past said sealing means without first flowing through said flow passage whereby closure of said closure means may terminate flow of fluids or gases through said well conduit; g. contractable and expansible bellows means included in said control means and connected with said valve stem means for forming a pressure seal between a first confined control pressure area and a second pressure area whereby said bellows means is moved responsive to a pressure difference in said first and second areas; and h. bellows protection means including a noncompressible fluid contained within said bellows means, a first chamber means enclosed within a portion of said bellows means and filled with said fluid, and a selectively closable safety seal means operable by motion of said bellows means to seal said fluid in said first chamber means whereby the portion of said bellows means surrounding said first chamber means is prevented from contracting when said safety seal means seals said first chamber means.

19. An automatic safety valve as defined in claim 18 wherein: a. said bellows means includes a second, enclosed bellows chamber means in fluid communication with said first chamber means; b. incompressible fluid is contained in said first and second chamber means; and c. said safety seal means is operable by movement of said bellows means to permit fluid flow between said first and second chamber means or to seal either said first or said second chamber means whereby fluid pressure in the unsealed chamber means is isolated from the fluid pressure in the sealed chamber means to prevent contraction of the bellows means in said sealed chamber means beyond a predetermined maximum amount.