US3419180A

US3419180A - Closure assembly for high-pressure, high-temperature vessels

Info

Publication number: US3419180A
Application number: US599870A
Authority: US
Inventors: Horace J Homrig; Robert B Emery
Original assignee: Halliburton Co
Current assignee: Halliburton Co
Priority date: 1966-12-07
Filing date: 1966-12-07
Publication date: 1968-12-31
Anticipated expiration: 1985-12-31

Description

Dec. 31, 1968 H. J. HOMRIG ET AL CLOSURE ASSEMBLY FOR HIGH-PRESSURE, HIGH-TEMPERATURE VESSELS Filed Dec. 7, 1966 ie\ x ROBE/2T 5. H1527 31 17 Ill i '18 II I m M.MM AM; v firm/(165m United States Patent CLOSURE ASSEMBLY FOR HIGH-PRESSURE,

HIGH-TEMPERATURE VESSELS Horace J. Homrig and Robert B. Emery, Duncan, 0kla.,

assignors to Halliburton Company, Duncan, Okla., a corporation of Delaware Filed Dec. 7, 1966, Ser. No. 599,870

4 Claims. (Cl. 220-46) ABSTRACT OF THE DISCLOSURE A closure assembly for pressure vessels having a follower member which is exposed to the pressure in the vessel and which is movable outwardly to expand a seal ring positioned between a tapered shoulder on the follower and an abutment on the closure body. The outer cylindrical surface of the seal ring engages a smooth cylindrical wall in the vessel to establish a seal between the closure assembly and the wall of the vessel. An abutment and a stop ring are positioned on the follower to engage a shoulder on the closure body when the follower has moved axially a suflicient distance to stress the seal ring to the elastic limit of the material in the ring. The closure assembly also includes a slip ring positioned between the seal ring and the closure body which cooperates with a tapered shoulder on the follower to urge the seal ring outwardly into engagement with the smooth wall of the vessel. At the same time, the slip ring is compressed radially inwardly into sealing relation with a cylindrical surface on the follower. The seal ring has an annular skirt positioned adjacent the follower shoulder, so that fluid pressure in the vessel acting on the skirt tends to urge the skirt to expand outwardly, thereby improving the seal between the seal ring and the wall of the vessel.

This invention relates to closures and more particularly to a removable closure assembly having self-sealing means for retaining very high-pressure and high-temperature fluids within a vessel.

Devices have been proposed heretofore for closing and sealing openings or mouths of high-pressure vessels, comprising a main closure body, a relatively soft pliant seal ring and follower means associated with the closure body and the ring which is adapted to cooperate with the seal ring and deform it into sealing relation with the wall of the opening. The follower is adapted to deform and seat the ring by the force of the fluid contained in the vessel acting on the follower. In some of the devices, the seal ring is initially seated by manual means and is then finally seated by the fluid within the vessel. These closures appear to be satisfactory for use in the familiar vacuum bottle and for use as stoppers for carbonated drink bottles which have been opened. However the effectiveness of these closures is limited to vessels which contain fluids at relatively low-pressure levels, i.e. several atmospheres.

To close and seal the mouth of a vessel containing fluids under high pressures, i.e. several thousand pounds per square inch, closures have been proposed which incorporate hard or substantially rigid members as sealing rings, sometimes fabricated of steel, that are tapered to match a tapered follower member which initially seats the ring against the wall of the opening in the vessel and against the closure body. The final seating of the ring is accomplished in a similar manner by allowing the pressure of the fluid within the vessel to act on the follower and urge the ring into a firm sealing relation with the wall. In order for such high-pressure closures to be removable and reusable, the hard seal ring must not be overstressed in order to maintain an effective seal. If the ring is overstressed, it will lose its resiliency and will not return to its original shape and size, and therefore it cannot be reused after the closure has been removed. In

addition, the ring may seize in the opening and prevent easy removal of the closure. This problem does not normally exist when the vessel contains fluid at pressures of up to a few thousand pounds per square inch and at normal or slightly above normal temperatures. However the problem becomes very apparent when it is desirable to provide a removable closure with sealing means for a vessel which is designed to contain fluids at pressures of up to about fifty thousand pounds per square inch and temperatures up to about seven hundred and fifty degrees Fahrenheit. Under such conditions, tapered steel rings easily become stressed beyond their yield strength by the very high pressure of the fluid acting on the follower member and therefore the rings lose their elasticity and become permanently deformed.

Accordingly it is a primary object of the present invention to provide a closure and associated seal means for vessels containing fluids under very high pressures and high temperatures wherein the closure is readily removable and wherein the sealing means is reusable.

Another object of this invention is the provision of a closure and hard seal-ring means therefor for an opening provided in the wall of a high-pressure vessel which utilizes forces of the fluid under pressure to firmly seat the seal and prevent escape of the fluid from the opening, and which includes a provision of means which limits the extent to which the seal ring can be stressed by the forces of the fluid.

A further object of the invention is to provide a closure assembly with hard seal ring means for closing and sealing an opening in a high-pressure vessel and pliant seal ring means associated with the hard ring means for providing a low-pressure seal for the opening.

In accordance with a preferred embodiment of the present invention, the foregoing and other objects are attained by the provision of a cylindrical closure body adapted to be secured in an opening in the wall of a highpressure vessel, a follower member slidably received in an axial bore formed in the closure body and having an annular tapered surface extending into the opening, and an annular steel ring disposed about the follower provided with an inner tapered surface which matches the taper on the follower and an outer surface designed to firmly seat against the wall of the opening when the follower is urged in an axial direction. The follower is moved axially by an amount necessary to initially expand the ring against the wall of the opening. An abutment in the form of an annular shoulder is provided on the follower spaced from a portion of the closure body by a predetermined amount controlled by a stop ring whereby the amount of further axial movement of the follower is positively limited. The force of the high-pressure fluid in the vessel is then allowed to act on the follower causing it to move further in an axial direction and expand the ring further to firmly seat the ring. The clearance between the abutment and the closure body is chosen such that the amount of axial movement of the follower is controlled by an amount which will place a stress on the seal ring up to but not exceeding the yield strength of the steel. When the axial loading is removed from the follower and the pressure in t'ie vessel is reduced, the seal ring will return to its original condition since it has not lost its elasticity.

The seal ring may be provided with an annular groove therein which will allow high-pressure fluid from the vessel to enter the groove and force a skirt portion of the ring outwardly into firm sealing relation with the wall of the opening.

A second annular steel ring may be provided with an external tapered surface which matches a second tapered surface formed on the first ring such that upon axial movement of the follower the taper on the second seal ring and the taper on the follower will combine to cause the seal ring to be expanded into seating engagement with the wall of the opening and will cause the second ring to be contracted into seating engagement with the follower.

The second ring may be provided with an externally received pliant O-ring for the purpose of providing a lowpressure seal for the closure when the axial loading on the follower is released.

The exact nature of this invention as well as other objects and advantages thereof will become readily apparent from a consideration of the following specification relating to the annexed drawing in which:

FIGURE 1 is a sectional view of a closure assembly constructed in accordance with this invention installed in the mouth of a high-pressure vessel;

FIGURE 2 is an exploded view in perspective, showing the various annular ring members which are adapted to be disposed about the follower member shown in FIG- URE l; and

FIGURE 3 is an enlarged, sectional view of the closure assembly showing the relationships of the various members under initial axial loading of the follower.

Referring now to FIGURES 1 and 3, there is shown a removable closure assembly generally indicated by the numeral for closing and sealing a cylindrical opening or mouth 12 of a vessel 14 designed to contain fluids at high temperatures and very high pressures. The closure assembly 10 includes an elongated follower member 16 having an enlarged lower end 17 provided with an external taper. The lower end 17 is fitted with a set 18 of tapered hard rings which are adapted to be stressed into sealing relation with the wall of mouth 12 and the follower member 16 when the follower member is drawn axially upwardly or outwardly of the mouth.

The wall of the vessel 14 is provided with a threaded counterbore 20 outwardly of the mouth 12 and is adapted to threadably receive an externally threaded, cylindrical closure body 22. A laterally extending shoulder 24 forms the bottom of the counterbore upon which a portion of the fiat face 26 of the inner end of the closure body 22 is adapted to seat. The outer end of the cylindrical closure body 22 is provided with appropriate means for facilitating screwing the body into the counterbore such as a laterally extending handle 28. The outer end of the closure body 22 may also be provided with a plurality of lifting eyes 30 or the like secured to the outer flat face 32 thereof.

An axially extending bore 34 is formed centrally of the closure body 22 and is dimensioned so as to slidably receive an elongated cylindrical stem portion 36 of the follower member 16. The upper end of the stem 36 is threaded as at 38 so as to enable the follower 16 to be removed axially with respect to the closure body 22 upon rotation of a threaded loading nut 40.

The enlarged lower or inner end 17 of the follower member 16 terminates in a cylindrical surface 41 closely adjacent the wall of the mouth 12 and a flat transverse face 42 to form a loading piston. The lower end portion 17 of the follower member 16 has a lateral annular shoulder 44 parallel to and spaced from the inner end face 26 of the closure body 22. A cylindrical portion 46 extends downwardly from the outer edge of the shoulder 44 and is concentrically disposed with respect to the wall of the mouth 12. Below the cylindrical surface 46 is formed a downwardly and outwardly tapering annular seat portion 48 which terminates closely adjacent the wall of the mouth 12 at the upper end of the cylindrical surface 41.

As illustrated in FIGURE 2, the set of seal rings 18 disposed about the lower end 17 of the follower member 16 comprises an upper, annular, hard slip ring 52 and a lower, annular, hard seal ring '54. The slip ring 52 and the seal ring 54 have matching tapered outer and

inner surfaces

56 and 58, respectively, and seal ring 54 has an additional inner tapered surface 60 which matches the tapered surface 48 of the follower member 16. The slip ring 52 has inner and outer parallel

cylindrical surfaces

62 and 64, top and bottom fiat

transverse faces

66 and 68, respectively, and an annular outer groove 69 adapted to receive an annular relatively soft O-ring 70 for purpose to be described more fully below. The seal rinf 54 has in addition to its several

tapered surfaces

58 and 60, inner and outer generally parallel

cylindrical surfaces

72 and 74, respectively, and an annular upwardly extending groove 76 formed in the lower tapered surface 60. The

rings

52 and 54 are made of steel and preferably of a heat treated alloy steel.

The slip ring 52 is dimensioned so as to provide a sliding fit with respect to the concentric cylindrical surfaces 46 of the follower member 16 and the cylindrical surface of the wall of mouth 12. The seal ring is dimensioned similarly with respect to its surface 74 and mouth 12. For example, the outer cylindrical surface 74 of the seal ring 54 may be dimensioned approximately .003 inch less than the inside diameter of the mouth 12. Radially inwardly of the slip ring 52 is an annular hard stop ring 78, also preferably made of high strength steel, having a generally rectangular cross section and which is adapted to be dis posed about the lower portion of the stem 36 of the follower member 16 resting on the shoulder 44. The several rings are shown in their respective positions in their initial seating arrangement in FIGURE 3.

To install the closure assembly 10, all of the rings shown in the exploded view of FIGURE 2 are assembled on the enlarged end 17 of the follower member 16 and the stem 36 is placed within and secured to the closure body by the nut 40, torqued on finger tight. The closure body 22 may then be screwed into the threaded counterbore 20 and firmly tightened until the lower end face 26 of the body 22 firmly abuts the lateral shoulder 24 forming the bottom of the counterbore 20. At this point, the hard rings 5-2 and 54 are not in sealing engagement with their respective surfaces, but the soft ()-ring 70 which is fabricated of a pliant material such as Teflon or equivalent high-temperature plastic seal material, is in a sealing relation with the mouth 12 to provide a low pressure seal.

An initial high-temperature, high-pressure seal is accomplished by torquing down the loading nut 40 so as to displace the follower member 16 upwardly and cause the seal ring 54 to be expanded radially outwardly by the forces produced by the combined effect of the tapered surfaces 58 and 60 coacting with the tapered surface 48 of the follower member and the tapered surface 56 of the slip ring 52. This axial movement of the follower member 16 also causes the slip ring 52 to be radially contracted into sealing engagement with the cylindrical surface 46 thereof and into sealing engagement with the face 26 of the closure body 22.

After thus torquing down the nut 42, the closure assembly with its seal means will retain fluid within the vessel 14 up to several thousand pounds per square inch, and a small clearance space will remain between the face 26 of the closure body 22 and the top surface 82 of the stop ring 78 as shown in FIGURE 3. The amount of the clearance 80 is chosen such that further upward axial movement of the follower member 16 will be allowed to take place and thereby increase the forces on the

rings

52 and 54 causing them to bear more firmly against their respective seating surfaces.

The

rings

52 and 54 are finally seated by further upward movement of the follower member produced by the pressure of the fluid contained in the vessel 14 acting on the face 42 of the loading piston portion of the follower member 16 as the pressure in the vessel rises. This additional movement of the follower member 16 is limited by the amount of the clearance space 80 so as to prevent overstressing of the rings of the seal set. The rings are allowed to be stressed up to the yield strength of the steel but not beyond its elastic limit, which may be in the neighborhood of about eighty thousand pounds per square inch. The various sizes of the rings, amount of torque, clearance spaces, etc., are designed to prevent overstressing of the rings so that they will not lose their elasticity.

In addition to the final seal produced by the action of the pressure of the fluid acting on the loading piston to further expand the seal ring 54, a further seal is produced by high-pressure fluid which enters the annular groove 76 in the seal ring 54 which forces a skirt portion 84 of the seal ring outwardly against the wall of the mouth 12. The provision of the annular groove 76 and the skirt portion '84, enables an effective seal to be accomplished without axial movement of the follower member 16.

Since the amount of axial movement of the follower member 16 is positively limited by the appropriate sizing of the stop ring 78 and the dimensioning of the shoulder 44 and other elements of the closure assembly, the seal rings 52 and 54 will resume their original condition when the axial loading on the follower 16 has been removed. Because of this feature, the entire assembly including the rings is easily removed from the mouth 12 and is reusable.

By the use of the present closure assembly, fluid such as oil at temperatures up to about seven hundred fifty degrees Fahrenheit and pressures up to about fifty thousand pounds per square inch may be retained in a vessel.

During assembly and disassembly of the closure, an effective low-pressure and low-temperature seal is provided by the O-ring 70 associated with the slip ring 52.

I claim:

1. A closure for vessels having a high-temperature seal comprising:

a closure body,

a follower member, said member being mounted coaxially in said body and being movable axially relative to said body, said member and said body having opposed shoulders,

said follower member including a pressure responsive surface, said surface being positioned for urging said member shoulder toward said body shoulder in response to fluid pressure acting on said surface,

a rigid and substantially incompressible seal ring disposed between said body shoulder and said member shoulder, said follower member having a substantially cylindrical surface adjacent said seal ring, said member shoulder being tapered outwardly from said cylindrical surface, said seal ring having a first inner tapered surface in position for engagement with said member tapered shoulder,

a rigid slip ring positioned between said seal ring and said body shoulder and being engageable with said body shoulder and being mounted coaxially on said follower cylindrical surface, said slip ring having an outer tapered surface, said seal ring having a second inner tapered surface in position to engage said slip ring tapered surface,

said follower member having a radial stop shoulder and said closure body having a stop shoulder in opposed relation to said member stop shoulder and spaced axially of said member,

a separable rigid stop ring disposed between said opposed stop shoulders in position to be engaged by said stop shoulders upon movement of said stop shoulders toward each other, said stop ring having a thickness which will permit limited axial movement of said stop shoulders toward each other while said slip ring tapered surface and said member tapered shoulder are in engagement with said seal ring tapered surfaces,

whereby said stop ring is separable to allow the use of a stop ring of a selected thickness and thereby limiting the relative axial displacement of said member tapered shoulder toward said slip ring to expand said seal ring radially without exceeding the elastic limit of the material of said seal ring.

2. The closure according to claim 1 wherein: said seal ring has an outer peripheral surface, an annular groove spaced radially inwardly from said peripheral surface, said groove forming a skirt portion in said seal ring and being positioned along said first seal ring tapered surface, whereby fluid which enters said groove forces said skirt portion into sealing relation with the smooth wall of the vessel.

3. The closure according to claim 1 wherein said slip ring has an annular groove in the outer peripheral surface thereof, and a pliable resilient ring in said groove.

4. The closure according to claim 1 wherein said seal ring has a rectangular cross section, whereby a maximum area. of contact with said stop shoulders is provided.

References Cited UNITED STATES PATENTS 2,389,118 11/1945 Buehner 220-46 2,810,494 10/ 1957 Smith 220-46 2,873,878 2/1959 Wolf 220-46 3,159,302 12/1964 Latham 220-46 3,339,787 9/1967 Pechacek 220-46 FOREIGN PATENTS 455,784 4/ 1959 Canada.

1,215,860 4/1960 France GEORGE E. LOWRANCE, Primary Examiner.