GB1561019A

GB1561019A - Ball type valve

Info

Publication number: GB1561019A
Application number: GB46434/77A
Authority: GB
Original assignee: Royal Industries Co Ltd; Royal Industries Inc
Current assignee: Royal Industries Co Ltd; Royal Industries Inc
Priority date: 1976-11-26
Filing date: 1977-11-08
Publication date: 1980-02-13
Also published as: NO773795L; JPS5368440A; CA1073888A; DE2752364C2; NL7712696A; NO148608C; AU506868B2; NL172003C; NL172003B; FR2372362A1; DE2752364A1; JPS6046299B2; AU3039577A; NO148608B; FR2372362B1

Description

(54) BALL TYPE VALVE (71) We, ROYAL INDUSTRIES, INC., a corporation organized and existing under the laws of the State of Delaware, U.S.A., of 980 South Arroyo Parkway, Pasadena, California 91105, U.S.A., do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a ball type valve particularly though not exclusively for use in cryogenic applications and other high pressure applications.

High pressure butterfly valves for use in cryogenic applications are known. One such valve is disclosed in U.S. Patent No.

3,260,496. This valve has a disc with a spherical surface arranged in an offset relationship with the sealing means for providing zero leakage. The butterfly element of a butterfly valve exhibits high pressure drops in high pressure applications, resulting in the need to make the butterfly element relatively thick. Butterfly valves are generally usable at line pressures in the range of 300 Ibs. per square inch. Other known valves employing spherical seals and 7 or spherical valve elements are disclosed in U.S. Patents Nos. 2,809,011; 2,015,849 and 125,792. These Patents also disclose the feature of disposing a portion of a valve member on an offset centre for producing tight sealing.

Ball type valves are also known. Floating ball valves are subject to high loads and excessive wear in normal service. Known ball type valves require complex actuating mechanisms to unload the valve seat before rotation in a manner to protect the plastics seals from premature failure. In a floating or semi-floating ball valve, the valve seats support the ball and the line pressure urges the ball into contact with a stationary metal seat. Ball valves, as distinguished from butterfly valves, exhibit low pressure drops and may be used in the pressure range of 6002500 Ibs. per square inch. In cryogenic applications, sliding seals have been found unreliable. Accordingly, there is a need for an improved valve having a tight shutoff in high pressure applications.

According to this invention a valve com- prises : - a body having a passageway for fluid; an apertured ball having spherical sealing surfaces and being rotatable about a pivotal axis, the spherical sealing surfaces being offset from the axis and the spherical sealing surfaces on opposite halves of the ball being offset on opposite sides of the axis whereby each spherical sealing surface of the ball moves on an eccentric arc as the ball is rotated; trunnion means for rotatably supporting the ball within the body to allow the ball to be rotatably positioned within the passageway for controlling flow of fluid; respective sealing means mounted on the body on opposite sides of the ball for sealing coaction with the spherical sealing surfaces, each sealing means comprising dynamic sealing means carrying primary resilient sealing means for engaging the ball so as to provide tight valve shutoff, and the dynamic sealing means comprising a flexible diaphragm mounted on the body and mounting the primary sealing means for Co- action with the spherical sealing surfaces of the ball, and means for securing the diaphragm to the body and for preloading it to render, in use, the upstream diaphragm responsive to upstream pressure so as to allow the ball sealing means to move towards the ball when a higher line pressure prevails in I!le passageway; and means coupled to the trunnion means for rotating the ball so that each spherical sealing surface moves on its eccentric arc away from the sealing means at each side of the body without scuffing and deforming the sealing means.

The invention can provide a bi-directional, eccentrically mounted ball valve having spherical surfaces exhibiting minimum wear of the seats, a relatively long service life, particularly in applications where the valve must be opened to sustain high differential pressures relative to similar prior art valves. The ball of the valve of the invention is trunnion-mounted as distin guished from the known floating or semifloating ball valves and coacts with dynamic and primary resilient sealing arrangements for providing tight shutoff at cryogenic temperatures. The valve of the invention may include a pressure sensitive seal constructed to urge the seal against the ball. The valve structure may include a fire-safe sealing feature providing reasonably effective shutoff in the event of fire.

The invention will now be described by way of example, with reference to the drawings, in which: Fig. 1 is a cross-sectional view, with portions in elevation, illustrating the ball valve embodying the present invention; Fig. 2 is a side elevational view of the valve of Fig. 1; Fig. 3 is an enlarged cross-sectional view of the detailed area taken around the line 3 of Fig. 1; Fig. 4 is an enlarged cross-sectional view of the detailed area taken around the line 4 of Fig. 1; Fig. 5 is an enlarged cross-sectional view of the detailed area taken along the line 5 of Fig. 1; Fig. 6 is a diagrammatic illustration of the ball and sealing elements of the valve of Fig. 1 illustrating the eccentric action of the ball; Fig. 7 is a detached, top plan view of the seal retainer element for the valve illustrated in Fig. 1;; Fig. 8 is a partial sectional view taken along the line 8-8 of Fig. 7; and Fig. 9 is a partial, sectional view taken along the line 9-9 of Fig. 7.

Now referring to the drawings, the improved valve 10 of the present invention will be described in detail. The valve 10 comprises a body 11 having a fluid passage 12 defined therein. The valve control element comprises an apertured ball 13 having a central aperture 13A which has a diameter approximately the same as the internal diameter for the fluid passageway 12 and the associated piping coupled thereto (not shown). The ball 13 coacts with sealing means 14 which comprises a primary, sealing means 14S and a secondary, dynamic sealing means 14D (Fig. 3). The dynamic sealing means 14D mounts the primary sealing means 14S which coacts with the operative sealing surfaces of the ball 13, as will be explained in more detail hereinafter.The ball 13 is trunnion mounted at the top and the bottom by means of the trunnion elements 13T and 13B constructed integrally with the ball 13 proper, as illustrated, Fig.

1. The top trunnion element 13T is coupled to a control shaft 24 which is in turn coupled with a control wheel in a conventional fashion for controlling the position of the shaft 24 and thereby the position of the ball 13 within the fluid passageway for controlling the flow of the fluid.

The ball 13 is provided with sealing surfaces that are defined as a spherical surface for coacting with the sealing means 14. A diagrammatic representation of the construction and arrangement of the ball 13 is illustrated in Fig. 6 for purposes of explanation. The ball 13 is illustrated in Fig. 6 looking down onto the top of the ball and with the ball arranged in a fluid passageway 12 in a closed position. The operative sealing surfaces of the ball 13 are shown in sealing relationship with the seals 14. Viewing the ball 13 down from the top, the right hand spherical radius of the ball 13 is offset above the normal centre line or above the pivotal axis represented by the point P.

Similarly, the left hand spherical radius is offset below the normal centre line or Divot axis P. The ball 13 is constructed so that the offsets function in the illustrated plane only. Side planes for the ball 13 are defined on the ball intermediate the spherical surfaces and are arranged on the normal centre line for the ball. In this arrangement, the seals 14 are in sealing relationship with the spherical surfaces 13S for the ball 13. When the seal 13 is installed into the valve body 11, a rotation of the ball 13 in a 90 degree counterclockwise turn by means of its control element is necessary to align the ball aperture 13A with the fluid passageway 12 of the valve body 11. During this control operation the ball 13 will rotate on the pivot point P and as it rotates both spherical halves of the ball 13 will operate on an eccentric arc away from the seals 14 on each side thereof.The arrangement of the ball 13 so that it traverses an eccentric arc eliminates seal scuffing and deformation and renders the valve 10 bidirectional.

The sealing means 14 is mounted on the fluid body 11 adjacent the operative sealing surfaces 13S for the ball 13. The sealing means 14 comprises the primary, sealing element 14S, see Fig. 3. The dynamic sealing element 14D comprises a diaphragmlike metallic seal retainer 14D mounted upstream from the primary seal 14S. The over-all construction of the diaphragm seal retainer 14D is best illustrated from examining Figs. 7-9. The seal retainer 14D mounts a seal 14S at one end for sealing coaction with the operative sealing spherical surface 13S for the ball 13. The seal 14S may be constructed of any conventional material for example plastics, in accordance with the particular application of the valve 10. For cryogenic applications the seal 14S may be constructed of a "Teflon" plastics material. ("Teflon" is a Registered Trade mark.) The outer surface 14SS for the seal 14S is angularly defined relative to the coacting spherical surface 13S of the ball to provide a tight sealing relationship therewith when placed in engagement therewith as illustrated in Fig. 1. Associated with the seal retaining element 14D is a locking collar 15 mounted to the body 11 for securing the element 14D to the body 11. The locking collar 15 is defined to also secure the sealing element 14S to the element 14D in the seal retaining socket 14SR thereof. The locking collar 15 is arranged to abut the section of the element 14D having a reduced thickness for securing it to the valve body 11 and to overlie the top section of the seal 14S.A "Teflon" strip 16 is provided in a recess defined in the top of the retaining element 14D intermediate its ends for sliding engagement with the bottom surface of the locking collar 15, as best illustrated in Fig. 3. A loading ring 17 mounting a set screw 18 secures the locking ring 15 and thereby the seal retaining element 14D to the valve body 11. The loading ring 17 is arranged with a retaining ring 19 mounted between the outer surface of the loading ring 17 and the adjacent surface of the valve body 11. This arrangement allows the seal retaining element 14D to be preloaded so that a certain amount of tension is provided on the diaphragm seal retaining element 14D and thereby a certain amount of tension on the primary sealing element 14S.

This also renders the diaphragm sealing element 14D responsive to the upstream line pressures prevailing in the fluid passageway 12. As a result of the prevailing pressures in the fluid passageway 12 with which the valve 10 may be used, the seal retaining element 14D will move towards and away from the operative sealing surfaces 13S for the ball 13 to place the primary sealing surface 14SS of the seal 14S in sealing coaction therewith. In a normal high pressure application of the valve 10, the upstream pressure may be 2160 pounds per square inch which is sufficient to allow the metallic diaphragm 14DT to be responsive thereto.

Fig. 4 illustrates the detailed arrangement of the upper trunnion 13T, the valve body 11 and the ball element 13. The trunnion 1 3T is provided with a trunnion bushing 1 3TB completely surrounding the trunnion 1 3T and extending to the adjacent surface of the ball 13. A shim 20 is mounted in engagement with the body 11 and over a thrust washer 21 arranged in engagement with the adjacent surface of the ball 13. The lower trunnion 1 3B is similarly arranged. This arrangement is illustrated in Fig. 5 wherein a trunnion bushing 13BB is illustrated completely surrounding the trunnion 13B and a shim 20 and a thrust washer 21 are arranged intermediate the valve body 11 and the adjacent surface of the ball 13.

The remaining structure for the valve 10 comprises the control shaft 24 coupled to the upper trunnion 13T immediately above the bushing 13TB in a conventional relationship for controlling the position of the ball 13. The control shaft 24 is coupled in the usual fashion with the control wheel 15 for rotating the control shaft 14 and thereby the ball 13 in the fluid passageway 12. The valve body 11 is provided with a cover 22 which allows the valve 10 to be fully top loaded. The cover 22 is mounted to the valve body 11 and is secured by means of conventional fasteners such as the fastener 23 illustrated in Figs. 1 and 2. Upon removing the fasteners 23 from the valve body 11, the cover 22 may be completely removed thereby exposing the internal structure of the valve body 11 and the ball 13 mounted therein.This allows all of the internal parts and elements of the valve 10 to be readily removed and serviced without the necessity of having to remove the valve body 11 from the associated pipelines.

In the construction of the valve 10 of the present invention, the sealing arrangement employing the flexible, secondary sealing element 14D allows the sealing means 14 to move towards and away from the ball 13 without the necessity for sliding seals.

It will be recognized by those skilled in the art that sliding seals have been found to be unreliable, particularly in cryogenic applications. The sealing retaining element 14D additionally functions as a spring to provide the initial seating force for the primary seal 14S for providing a tight shutoff condition at the lower line pressures. At the higher line pressures, tight shutoff is provided as a result of the seal retaining element 14D providing additional seating forces due to its being responsive to the upstream line pressures which cause it to move toward the ball 13 and place the primary seal 14S in a tighter sealing relationship with the op era- tive sealing surface 13S of the ball 13.This advantageous function results through the provision of the thin, flexible section 14DT for the seal retaining element 14D which is backed up or is abutted by the adjacent surface of the locking collar 15. This ar rangement of the secondary sealing structure causes the element 14D to be responsive to the upstream line pressure and as the pressure builds up and the diaphragm action of the element 14D causes it to contact the adjacent surface of the ring 15, this allows the diaphragm stresses to be maintained within allowable limits at the higher differential pressures.

Other important aspects of the use of the secondary sealing arrangement disclosed bv the present invention is that the secondary metal element 14D provides seating in both directions for effective valve shutoff in the event of a fire. In the event that the resilient plastics element 14S disintegrates as the result of a fire, the internal line pressure will urge the secondary sealing element 14D into contact with the ball 13. An additional feature of the construction and functions of the secondary sealing arrangement is that it is constructed to be fully flexible to provide an angular degree of freedom in addition to axial freedom which allows the primary seal 14S to fully contact the operative surfaces of the ball 13 under adverse assembly tolerances.The loading ring 17 is designed for use in cryogenic environments to function as a Belleville spring in order to maintain sufficient gasket seating force at the sealing element 14S even during the time intervals that there is a rapid change in temperature from ambient to cryogenic temperatures. Although the metallic materials in the valve possess approximately the same thermal expansion coefficients, the various parts cool down at different rates depending upon their mass and proximity to the cvryogenic fluid being controlled.

Specifically, it will be recognized that smaller elements will shrink more quickly than the larger elements such as the valve body and some seating force will be temporarily lost until all parts stabilize at the lower temperatures.

It should be evident that the present invention has disclosed an improved eccentric ball valve having primary and secondary sealing features that coact to provide effective shutoff in high pressure applications as well as for cryogenic applications.

WHAT WE CLAIM IS:- 1. A valve comprising: a body having a passageway for fluid; an apertured ball having spherical sealing surfaces and being rotatable about a pivotal axis, the spherical sealing surfaces being offset from the axis and the spherical sealing surfaces on opposite halves of the ball being offset on opposite sides of the axis whereby each spherical sealing surface of the ball moves on an eccentric arc as the ball is rotated; trunnion means for rotatably supporting the ball within the body to allow the ball to be rotatably positioned within the passage- way for controlling flow of fluid;; respective sealing means mounted on the body on opposite sides of the ball for sealing coaction with the spherical sealing surfaces, each sealing means comprising dynamic sealing means carrying primary resilient sealing means for engaging the ball so as to provide tight valve shutoff, and the dynamic sealing means comprising a flexible diaphragm mounted on the body and mounting the primary sealing means for Co- action with the spherical sealing surfaces of the ball, and means for securing the diaphragm to the body and for preloading it to render, in use, the upstream diaphragm responsive to upstream pressure so as to allow the ball sealing means to move towards the ball when a higher line pressure prevails in the passageway, and means coupled to the trunnion means for rotating the ball so that each spherical sealing surface moves on its eccentric arc away from the sealing metans at each side of the body without scuffing and deforming the sealing means.

2. A valve according to claim 1 wherein the securing means includes means for preloading the diaphragm at a given tension to cause it to function as a spring to provide an initial seating force for the resilient sealing means for tight valve shutoff at a lower line pressure in the passageway.

3. A valve according to claim 1 or claim 2 wherein the securing means includes means for maintaining sufficient seating forces for the primary sealing means in response to changes in temperature.

4. A valve according to claim 3 wherein the means for maintaining sufficient sealing forces functions as a Bellville spring so as to maintain sufficient seating force during time intervals between rapid changes in temperature.

5. A valve according to any preceding claim wherein the resilient sealing means is of resilient plastics material and is shaped for sealing coacting with a spherical sealing surface of the ball.

6. A valve according to any preceding claim wherein the diaphragm comprises a thin, annular, metallic member having a section of reduced thickness, the securing means being arranged in abutting relationship with the section of reduced thickness so that as upstream pressure builds up the diaphragm moves into contact with the securing means to allow the diaphragm stresses to' be maintained within allowable limits at higher differential pressures.

7. A valve according to any preceding claim wherein the diaphragm has a retaining socket for securing the resilient sealing means adjacent one side of the diaphragm.

8. A valve according to claim 6 wherein the section of reduced thickness is of greater diameter than the remainder of the diaphragm.

9. A valve according to claim 6 or claim 8 wherein the securing means abuts the section of reduced thickness.

10. A valve according to any preceding claim wherein the means for preloading is arranged, with reference to the upstream seal, downstream of the securing means.

11. A valve according to any preceding claim wherein the resilient sealing means is plastics material and has an annularly defined sealing surface relative to the respective spherical -sealing surface of the ball to

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. as the result of a fire, the internal line pressure will urge the secondary sealing element 14D into contact with the ball 13. An additional feature of the construction and functions of the secondary sealing arrangement is that it is constructed to be fully flexible to provide an angular degree of freedom in addition to axial freedom which allows the primary seal 14S to fully contact the operative surfaces of the ball 13 under adverse assembly tolerances. The loading ring 17 is designed for use in cryogenic environments to function as a Belleville spring in order to maintain sufficient gasket seating force at the sealing element 14S even during the time intervals that there is a rapid change in temperature from ambient to cryogenic temperatures.Although the metallic materials in the valve possess approximately the same thermal expansion coefficients, the various parts cool down at different rates depending upon their mass and proximity to the cvryogenic fluid being controlled. Specifically, it will be recognized that smaller elements will shrink more quickly than the larger elements such as the valve body and some seating force will be temporarily lost until all parts stabilize at the lower temperatures. It should be evident that the present invention has disclosed an improved eccentric ball valve having primary and secondary sealing features that coact to provide effective shutoff in high pressure applications as well as for cryogenic applications. WHAT WE CLAIM IS:-

1. A valve comprising: a body having a passageway for fluid; an apertured ball having spherical sealing surfaces and being rotatable about a pivotal axis, the spherical sealing surfaces being offset from the axis and the spherical sealing surfaces on opposite halves of the ball being offset on opposite sides of the axis whereby each spherical sealing surface of the ball moves on an eccentric arc as the ball is rotated; trunnion means for rotatably supporting the ball within the body to allow the ball to be rotatably positioned within the passage- way for controlling flow of fluid;; respective sealing means mounted on the body on opposite sides of the ball for sealing coaction with the spherical sealing surfaces, each sealing means comprising dynamic sealing means carrying primary resilient sealing means for engaging the ball so as to provide tight valve shutoff, and the dynamic sealing means comprising a flexible diaphragm mounted on the body and mounting the primary sealing means for Co- action with the spherical sealing surfaces of the ball, and means for securing the diaphragm to the body and for preloading it to render, in use, the upstream diaphragm responsive to upstream pressure so as to allow the ball sealing means to move towards the ball when a higher line pressure prevails in the passageway, and means coupled to the trunnion means for rotating the ball so that each spherical sealing surface moves on its eccentric arc away from the sealing metans at each side of the body without scuffing and deforming the sealing means.

provide a tight sealing relationship therewith when in engagement therewith, and the diaphragm is characterised by providing effective valve shut-off in either direction in the event that the resilient sealing means is destroyed, in that the diaphragm is movable into sealing contact with the ball in response to a prevailing line pressure.

12. A valve constructed and arranged substantially as herein described and shown in the accompanying drawings.