EP1000282A1

EP1000282A1 - Ball valve with removable bonnet and cartridge unit

Info

Publication number: EP1000282A1
Application number: EP99923785A
Authority: EP
Inventors: Gilles Monod
Original assignee: M-Ball SA
Current assignee: M-Ball SA
Priority date: 1998-05-28
Filing date: 1999-05-28
Publication date: 2000-05-17
Also published as: WO1999061824A1; AU4054099A; FR2779203A1

Abstract

A ball valve (10) includes a bonnet (18) and a removable insert assembly in which a valve ball (40) and opposed seat rings (46) are contained within a cartridge (20) of separable shells (20a, 20b). Cylindrical spring seals (48) of resilient and impervious high density graphite or silicon rubber are mounted on a reduced diameter length of each seat ring. The spring seals (48) are compressed between shoulders on the seat rings (46) and facing annular recessed surfaces in the cartridge and urge the seat rings into dynamic sealing contact with the valve ball (40). The spring seals (48) also provide static sealing at the interface of the seat rings (46) and the cartridge (20). Connecting fittings on mating surfaces of the bonnet (18) and the insert assembly enable the assembly to be completely removed from the valve body with the bonnet (18) for easy access for repair or replacement of components within the cartridge.

Description

BALL VALVE WITH REMOVABLE BONNET AND CARTRIDGE UNIT

The present invention relates generally to ball valves, and more particularly to an improved valve construction having a valve body with a novel removable valve plug and seat ring cartridge suitable for use under extreme conditions of temperature and pressure.

Many ball valves have removable covers or bonnets to permit access to the interior of the valve body for replacing defective or worn plugs and seals without having to dismantle the entire valve from a pipe line. U.S. Patent 3,195,560 to Pofit discloses such a valve in which a rotatable spherical plug is seated within the valve body between annular dynamic seat rings. The rings are urged against the plug by externally disposed springs acting between the rings and the valve body. With the valve cover removed, the plug must be extracted before the seat rings or the springs can be replaced. A modification of this design uses a cartridge type insert. The valve plug and seat rings are pre-assembled in a conical cartridge of two half shells. By this arrangement, the critical components can be easily installed as one unit in the valve body. For example, U.S. Patent 2,885,179 to Hartmann shows a top entry ball valve in which the plug and seat rings are preassembled between two half shells to form a cylindrical cartridge which can be inserted in the valve body as one unit. The dynamic sealing effect obtains from resilient annular packings on opposite external sides of each seat ring compressed between the plug and the interior of the valve body. U.S. Patent 5,135,019 to DuPont similarly discloses a top entry ball valve designed for use in deep water. The spherical plug and seat rings are preassembled within a tapered cartridge of two half shells for replacement in the valve body as a single cartridge insert. The seals are pressed against opposite external sides of the plug by dish-type spring washers and resilient static seals acting in series between the plug and the valve body. U.S. Patent 4,587,990 to Pennell et al. discloses a ball valve in which the spherical plug, seat rings and a plurality of spiral springs are preassembled within a tapered cartridge of half-shells for inserting in the valve body. The seat rings include a plurality of circumferentially spaced bores which receive the springs and act against the interior of the cartridge to urge the seat rings into sealed engagement with the plug. In each of these valves there are no springs which are completely contained within the cartridge insert and which serve as a positive seal as well. Rather, the spring elements must be installed external to the cartridge insert, or a plurality of springs must be pre-installed around each seat ring or insert before being inserted in the valve body.

Accordingly, it is an object of the present invention to provide a novel ball valve construction in which the internal components are completely preassembled as an insertable cartridge for easy replacement or repair without dismantling the valve body from an installation, and in which unique spring seals are isolated from the valve body to maintain a positive dynamic seal. Another object of the invention is to provide a readily replaceable plug and sealing mechanism in a ball valve construction in which the sealing force applied to the plug is independent of the valve body.

Still another object is to provide a ball valve assembly in which the plug and spring sealing mechanisms are totally enclosed within an easily assembled cartridge.

A further object is to provide a ball valve construction in which internal components can be readily replaced without removing the valve body from a fluid line. Another object is to provide a ball valve construction in which an insertable cartridge is retained by the valve bonnet during insertion and extraction from the valve body.

Briefly, these and other objects and novel aspects of the invention are accomplished by an insert assembly for a ball valve body and bonnet in which a spherical valve plug and seat rings are assembled in a cartridge of mating shells. Cylindrical spring seals of resilient and impervious high density graphite or silicon rubber, are mounted on a reduced diameter section of the seat rings between a shoulder on the seat rings and an annular recessed surface of the cartridge for urging the seat rings into sealing contact with the plug. The spring seals also provide a positive seal at the interface of the seat rings and the cartridge. Connecting fittings on the mating surfaces of the valve bonnet and the insert assembly enable the assembly to be removed from the valve body while attached to the bonnet and then disconnected for replacement of worn components. For a better understand of the invention, reference will be made to the following detailed description taken in conjunction with the accompanying drawings wherein:

FIG. 1 represents a longitudinal sectional view of a one embodiment of a ball valve according to the invention;

FIG. 2 is a view in cross section of the ball valve taken along the line 2-2 of FIG.1 ;

FIG. 3 is an exploded perspective view of component parts of the ball valve of FIG. 1 ;

FIG. 4 is an enlarged view in cross section of a portion of the valve seat and seal spring of FIG. 2; FIG. 5 is an enlarged view in cross section of a bonnet-cartridge connector in the ball valve taken along the line 5-5 of FIG. 1 .

FIG. 6 is a view in cross section of the bonnet-cartridge connector taken along the line 6-6 of FIG. 5;

FIG. 7 is a view in cross section like FIG. 2 an alternate bonnet- cartridge connector for the ball valve of FIG. 1 according to the invention.

FIG. 8 is a longitudinal view in cross-section of another embodiment of the ball valve according to the invention;

FIG. 9 is an enlarged view in cross section of a portion of the ball valve of FIG. 8; FIG. 10 is an exploded view of component parts of the ball valve of FIG. 8.

FIG. 1 1 is an external view of still another embodiment of a ball valve according to the invention;

FIG. 12 is a cross sectional view of the ball valve of FIG.1 1 taken along the line 12-12 thereof; and

FIG. 13 is a cross sectional view of the ball valve of FIG. 1 1 taken along the line 13-13 of FIG. 12.

Referring now to the drawings, wherein like reference characters denote like or corresponding parts throughout the several views, FIGs. 1 -6 represent one embodiment of a ball valve 10 comprising a valve body 12 with aligned inlet and outlet flow passages 14 terminating at opposite ends with flanges 12a for installing in a flow line. A frustoconical cavity 16 formed between the flow passages on a central axis normal thereto tapers outwardly from a blind end 16a to a top entry 16b formed to receive an insert assembly including a cartridge 20 of two semicircular half-shells 20a and 20b joined together by fasteners 22 and retained in valve body 12 by a bonnet 18. Cartridge 20 forms an outer surface tapered to fit contiguously in cavity 16. Each half-shell 20a and 20b respectively includes a port 21 a and 21 b for communicating between the flow passages 14. Ports 21 a and 21 b are aligned with passages 14 by two studs 24 each threaded at one end into the base of bonnet 18 and the other end insertable into aligned blind holes 26 in the abutting faces of half-shells 20a and 20b. As best seen in FIGs. 5 and 6, each stud 24 is retained in a blind hole 26 by a pin 28 inserted through a respective half-shell 21 a or 21 b to engage opposite sides of a continuous groove 24a around the stud 24. Cartridge 20 is thereby concurrently removable with bonnet 18 from valve body 12, and separable from bonnet 18 upon removal of pins 28. Annular seals 34, bonded to the curved surfaces of cartridge 20 around ports 21 a and 21 b, prevent fluid in passages 14 from escaping through the interface of cartridge 20 and valve body 12.

Cartridge 20 houses a valve ball 40 with engaging surfaces 20c and lower and upper journals 42 and 43 for rotation in bushings 44 on an axis normal to the length of passages 14. A bore 41 through ball 40, preferably of the same diameter as passages 14, aligns with ports 21 a and 21 b when rotated 90 degrees from a closed position to a fully open position as shown.

As best seen in the portion of half -shell 20b shown in FIG. 4, each half-shell 20a and 20b has a valve seat ring 46, slidable in an annular recess 47 around port 21 a amd21 b, respectively. Surfaces 46a on rings 46 are urged axially against opposite sides of valve ball 40 by annular spring seals 48 which are axially compressed between shoulders 52 around recesses 47 and shoulders 53 around seats 46. Positive seals between valve ball 40, valve body 12 and seats 46 are thereby maintained independent of the position of cartridge 20 relative to and the wall of cavity 16. The material selected for seat rings 46 is preferably a metal composite suitable for use under extreme conditions of heat and chemical exposure such as duplex alloys and stainless or CrMo steels. Spring seals 48 are preferably made of a resilient and impervious material such as high density graphite or a silicone rubber for both resilience and sealing. A most preferred material is an elastically-compressible, expanded graphite having a precompressed density in a range of about 1.4 to about 2.2 g/cm³, and a compressed density in a range of about 0.9 to 1.2 g/cm³. Bonnet 18, with cartridge 20 attached, is secured to the top of valve body 12 by nuts 30 and washers 31 threadingly tightened on four corner studs 32 to sealingly compress annular seals 34 and a ring gasket 36 between the interfaces of cartridge 20, valve body 12 and bonnet 18. A valve stem 54 extends through a bore 55 bonnet 18 and includes a key 54a interlocking with a mating slot 43a in upper journal 43 for transmitting rotation of stem 54 to valve ball 40. A thrust bearing 56 between a shoulder 54b on stem 54 and a shoulder in bore 55 sustains axial loading and restricts upward movement of stem 54. Conventional components such as stem seal 57, packing 58 and gland 59 are compressed against a shoulder of base 55 by a packing flange 60 and six bolts 61 (only one shown) threaded into the upper end of bonnet 18 to prevent leakage around stem 54.

A lever 62 pivotally connected to valve stem 54 by a pin 63 provides for manual opening and closing valve ball 40. A stop 64 extending from the top of bonnet 18 engages leaver 62 when bore 41 of valve ball 40 is in a fully open position aligned with passages 14. As described, the components within cartridge 20 are preassembled for quick and easy replacement or repair of parts without dismantling valve body 12 from a pipe line. In assembly, valve ball 40, bushings 44, seats 46 and spring seals 48 are placed between half-shells 20a and 20b. As the shells are drawn together by fasteners 22, compression of spring seals 48 positively urges seals 46 against ball 40 creating a dynamic seal. With seals 34 bonded around each port 32, cartridge 20 is attached to bonnet 18 by studs 24 and pins 28 and then inserted into cavity 16. Stem 54, thrust bearing 56 and bonnet seal 36 are then secured in place with bonnet 18 secured to valve body 12 by nuts 30. Cartridge 20 and bonnet 18 are easily removed from valve body 12 as a single unit by removing nuts 30. Then cartridge 20 may be separated from bonnet 18 by removing pins 28 and disassembly by removing fasteners 22.

FIG. 7 shows an alternative means for securing a cartridge 20' to bonnet 18'. The joined half-shells 20a' and 20b' form a round boss 23 insertable in a mating recess 18a of an annular extension 18b on the facing surface of bonnet 18. Set screws 27 spaced around extension 18b engage a peripheral groove 23a around boss 23 to secure cartridge 20' to bonnet 18' .

FIGs. 4, 8, 9 and 10 disclose another embodiment of a ball valve

70 which is particularly suitable for use in chemical and pharmaceutical processes. It comprises a valve body 71 with aligned inlet and outlet passages 72 communicating with a frusto-conical cavity 74 open at both ends and tapering outward toward the top opening 71 a on a central axis normal to the length of passages 72. A cartridge 76, comprising a frustoconical shell 76a with a recess 76c intermediate its length, receives a semicircular shell 76b to form a continuous conical surface mating with the surface of cavity 74. With cartridge 76 fully inserted in cavity 74, a reduced diameter threaded end 76d of shell 76a extends through the bottom opening of cavity 74 and is secured by a gasket 78, pull nut 79 and screws 80.

Shells 76a and 76b include ports 82a and 82b which register with passages 72 by a guide pin 84 radially extending from the periphery of shell 76a and seated in a radial groove 85 in valve body 71. An annular static seal 86a bonded on the curved surface of shell 76a around port 82a seals the interface of cartridge 76 and valve body 71 . Another static seal 86b, bonded to the curved surface around port 82b and overlapping the peripheral juncture of shells 76a and 76b provide seals at the interface of both shells 76a and 76b and valve body 71 .

Like ball valve 10 of FIGs. 1 -3, cartridge 76 and its installed components are completely removable from cavity 74 without the dismantling valve body 71 from a pipe line by removing pull nut 79. A valve ball 88 with lower and upper journals 89a and 89b are rotatably supported in bushings 90 within cartridge 76 on an axis normal to the flow path through inlet and outlet passages 72. A bore 91 through ball 88 preferably the same diameter as passages 72, align with ports 82a and 82b when rotated 90 degrees from a closed position to a fully open position as shown. Seat rings 92 and annular spring seats 94 are arranged in cartridge 76 like similar parts in valve 10 of FIG. 4 and act in the same manner to maintain a positive seal between ball 88 and seat 92 as well as a seal between seat rings 92 and said cartridge 76.

Purging the contacting surfaces of valve ball 88 and seat rings 92 of contaminants is provided by introducing a cleaning fluid such as steam under pressure through a conduit 96 to a channel 97 (FIG. 9) encircling one of seat rings 92 and communicating with the interface of both seat rings 92 and ball 88. The pressure causes the cleaning fluid to pass through the gaps G in the interfaces and discharge with purged matter into inlet and outlet passages 72. Seals 98 prevent the cleaning fluid from leaking past the interface of journals 89 and cartridge 76. A bonnet 100 secures stem 54', gasket 98, bushings 90, stem cap 104, thrust ring 56' and ring gasket 36' in place with six bolts 106 screwed into threaded holes 106a. (FIG. 10). Packing 58', gland 59' and spring washer 66 are compressed against an annular boss 108 by a packing flange 1 10 and six bolts 1 12 screw into threaded holes 1 12a. Valve ball 88 is manually rotated by an actuating lever 1 14. But for the upper end of stem 54'; the entire upper section of the ball valve 70 is insolated from ambient atmosphere by a cover 1 16, secured by set screws 1 17, and upper and lower seals 1 18. Valve ball 88 is manually rotated by an actuating lever 114 which is limited in rotation in the fully open position by a stop 1 19 extending from the top of cover 1 16. Referring now to FIGs. 1 1 , 12, and 13, the inventive concept is shown applied to a two-way ball valve 120 having a valve body 122 with radially spaced ports 122a, b and c arranged along a single plane and communicating with a conical cavity 122d extending on an axis normal to the plane. Three arcuate segments 123a, b and c are joined to form a tapered cartridge 123 matching the shape of cavity 122d and inserted therein. Like half-shells 20a and 20b of FIGs. 1-3, each segment 123a, b and c has a valve seat ring 124 inserted in an annular recess, and an annular spring seal 126 compressed between a shoulder 55 on seat ring 124 and an annular recess 52 in segment 123 a, b or c. A valve ball 128 is rotatably retained within cartridge 123 and includes a bore 126a angled to direct flow between a selected pair of ports 122a, b and c, the selection being made by rotation of lever 130 through a valve stem 132 engaged at the rotational axis of valve ball 126.

If desired, a four-way ball valve (not shown) may be provided in accordance with the teachings of the present invention simply by increasing the number of cartridge members accordingly.

While preferred embodiments of the invention have been described in detail, various modifications, alterations and changes may be made within the scope of the invention as defined in the appended claims.

RECTIFIED SHEET (RULE 91) ISA/EP

Claims

1 . In a ball valve having a valve body with a central cavity communicating between inlet and outlet ports, an insert assembly comprising: a cartridge having separable sections joined together in the cavity with bores coaxial with the inlet and outlet ports; a valve ball with a through passage slidingly rotatable in said cartridge from a closed position to a fully open position between said bores

seat rings contained within said cartridge on respective opposite sides of said ball, characterized in that each of said seat rings forms with a respective bore an annular chamber with closed ends around the circumference of said ring; and the insert assembly further comprises annular elastic seals respectively compressed between said ends for urging said seat rings axially in dynamic sealing contact with said ball.

2. An insert assembly according to claim 1 , characterized in that it further comprises: a valve bonnet removably mounted on said valve body; and fastener means operatively connected to engaging surfaces of said bonnet and said cartridge for removably securing said cartridge to said bonnet during insertion and removal from the cavity.

3. An insert assembly according to claim 2, characterized in that said fastener means includes: holes formed in said cartridge surface ; studs extending from said bonnet surface with a portion inserted in said holes, said portions having opposed grooves ; and pins inserted through said cartridge into said grooves for holding said studs in place.

4. An insert assembly according to claim 2, characterized in that said fastener means includes: a circular recess in said bonnet surface; a circular boss with a circumferential groove extending from said cartridge surface insertable in said recess; and set screws extending through said cartridge into said groove for holding said boss in said recess.

5. An insert according to claim 1 , characterized in that said elastic seals are made of a resilient and fluid impervious material from a group consisting of high density graphite and silicone rubber.

6. An insert according to claim 5, characterized in that said graphite has a precompressed density in a range of about 1 .4 to about 2.2 g/cm3, and within said annular chamber, a compressed density in a range of about 0.9 to about 1 .2 g/cm3.

7. An insert assembly according to claim 1 , characterized in that said sections of said cartridge are mating half-shells secured together on either side of said valve ball forming a frustoconical shape.

8. An insert assembly according to claim 1 , characterized in that one of said sections of said cartridge is a semicircular segment secured in a matching recess in another of said sections to form a frustoconical.

9. An insert assembly according to claim 1 , characterized in that it further comprises: a channel encircling a seat ring and communicating with an interface of said seat rings and said valve ball ; and a conduit extending through said cartridge to said channel for introducing a cleaning fluid.

10. An insert assembly according to claim 1 , characterized in that said cartridge includes a portion extending through a bottom opening of the cavity ; a pull nut threadingly engages said extender portion to secure said cartridge in the valve body ; and set screws extending through said pull nut into the valve body locks said pull nut in place.

1 1. A ball valve comprising a valve body with a central cavity communicating between inlet and outlet ports; a cartridge having first and second sections joined together in the cavity with bores coaxial with the inlet and outlet ports, a valve ball including a through passage slidingly rotatable in said cartridge from a closed position to a fully open position between said bores; characterized in that each of said bores has an inwardly facing first shoulder and an inwardly facing second shoulder between said first shoulder and a respective one of said ports; in that seat rings are disposed at respective opposite sides of said ball and said second shoulders, each of said rings having an outwardly facing third shoulder axially spaced from said first shoulder to form an annular chamber; and in that an annular spring seals are respectively compressed within each of said chambers between said first and third shoulders for urging said seat rings in dynamic sealing contact with said ball.

12. An insert according to claim 1 1 , characterized in that said elastic seals are made of a resilient and fluid impervious material from a group consisting of high density graphite and silicone rubber.

13. An insert according to claim 12, characterized in that said graphite has a precompressed density in a range of about 1 .4 to about 2.2 g/cm3, and within said annular chamber, a compressed density in a range of about 0.9 to about 1 .2 g/cm3.

14. An insert assembly according to claim 1 1 , characterized in that said sections of said cartridge are mating half-shells secured together on either side of said valve ball.

15. An insert assembly according to claim 1 1 , characterized in that said first section of said cartridge is a semicircular segment secured in a matching recess in said second section.

16. An insert assembly according to claim 1 1 , characterized in that it further comprises : a channel encircling a seat ring and communicating with an interface of said seat rings and said valve ball; and a conduit extending through said cartridge to said channel for introducing a cleaning fluid.

17. A ball valve according to claim 1 1 , characterized in that said cartridge includes a portion extending through a bottom opening of the cavity; a pull nut threadingly engages said extender portion to secure said cartridge in the valve body; and set screws extending through said pull nut into the valve body locks said pull nut in place.

18. A ball valve characterized in that it comprises : a valve body having a ball element with a through bore; a plurality of ball-receiving cartridge members removably mounted in said valve body with said ball element disposed therebetween, each of said cartridge members having a bore with an open end confronting said ball element and defined by a first radial seal shoulder spaced from said ball element and a cylindrical inner surface extending therefrom toward the ball element; and a seal assembly carried by each cartridge member, said seal assembly including a tubular valve seat having a radial flange with a ball element engaging surface on one side and a second radial seal shoulder opposite said one side, said valve seat having a reduced diameter surface disposed in said cartridge bore and with said shoulders disposed in confronting relation forming a chamber, and a tubular seal element engaged between said shoulders and extending along said valve seat reduced diameter surface in said chamber, said seal element being formed of graphite and being compressed between said shoulders when said cartridge members are secured together with said ball element operatively disposed therebetween.

19. A ball valve characterized in that it comprises : a valve body having a ball element with a through bore; a plurality of ball-receiving cartridge members removably mounted in said valve body with said ball element disposed therebetween, each cartridge member having a bore with an enlarged open end confronting the ball element and being defined by a first radial seal shoulder spaced from the ball element and a cylindrical inner surface extending therefrom toward the ball element; a seal assembly carried by each cartridge member, said seal assembly including a tubular valve seat having a radial flange with a ball element engaging surface on one side and a second radial seal shoulder opposite said one side, said valve seat having a reduced diameter surface disposed in said cartridge bore and with said first and second seal shoulders disposed in confronting relation forming a chamber, and a tubular seal element engaged between said first and second seal shoulders and extending along said valve seat reduced diameter surface in said chamber, said seal element having a rectangular transverse cross-section formed of elastically- compressible expanded graphite, said seal element having a pre-compressed density in a range of about .9 to about 1 .2 g/cm3 and being compressed between said shoulders to a density in a range of about 1.4 to about 2.2 g/cm3 when said cartridge members are secured together with the ball element operatively disposed therebetween.

20. A ball valve characterized in that it comprises : a valve body with a central cavity communicating between inlet and outlet ports; a cartridge having separable sections joined together in the cavity with bores coaxial with the inlet and outlet ports; a valve ball with a through passage slidingly rotatable in said cartridge from a closed position to a fully open position between said bores ; a valve bonnet removably mounted on said valve body ; and fastener means operatively connected to engaging surfaces of said bonnet and said cartridge for removably securing said cartridge to said bonnet during insertion and removal from the cavity.

21 . An insert assembly according to claim 20, characterized in that said fastener means includes: holes formed in said cartridge surface; studs extending from said bonnet surface and aligned with said hole with a portion inserted in said holes, said portions having opposed grooves; and pins inserted through said cartridge into said grooves for securing said studs in place.

22. A ball valve according to claim 20, characterized in that said fastener means includes: a circular recess in said bonnet surface; a circular boss with a circumferential groove extending from said cartridge surface insertable in said recess; and set screws extending through said cartridge into said groove for holding said boss in said recess.