GB2062177A - Ball valve - Google Patents

Abstract

A ball valve comprises a single piece body 10 with a ball-shaped, two-part valve member 20 and a separate stem 29 so formed that it cannot be blown out by internal pressure during servicing. The stem has an enlarged portion 30 within the valve chamber which is too large to pass the bearing 36, the portion 30 having a shoulder 42 for sealing engagement with a seat 40. A detachable bridge 51 provides a second bearing 52 for the stem 29 and also provides a thrust bearing to position the stem. A packing chamber 44 with packing 46 compressed by a gland 48 is provided. In assembly, the stem 29 is inserted from the interior of the ball chamber. <IMAGE>

Description

SPECIFICATION Ball valve This invention relates to ball valves, i.e. valves of the kind comprising a body having an inlet and an outlet opening aligned along a first axis and communicating with a chamber, disposed between said openings, in which is mounted a ball-shaped valve member having a passage extending there-through, the valve member being mounted for rotation, in the body, about a second axis transverse to the first axis between a position in which the passage through the valve member is in alignment with said inlet and outlet openings, thus connecting the inlet and outlet openings, and a position in which the passage through the valve member extends transversely to said first axis and said valve member cuts off said inlet opening from said outlet opening, the valve member being rotatabia between these positions, about said second axis, by means of a stem connected with said valve member and extending from the valve body.

While valves of this kind are commonly constructed with a body which is in a plurality of parts and which can be assembled about a corresponding valve member formed as a single integer, this construction prevents various difficulties in manufacture and in operation, particularly with regard to obtaining proper alignment between and sealing between the parts of the body to secure satisfactory operation.

To avoid these difficulties it is known, for example from British Patent Specification No. 911,111, to construct the body in a single piece and to make the ball-shaped valve member in two discrete parts, which, in assembly of the valve, are passed separately through the inlet or outlet openings into the central chamber and are fitted together therein, after which the operating stem, formed separately from the valve member parts, is introduced, along said second axis, through a stem passage extending along said second axis and providing a bearing for the stem, sealing means being provided in said stem passage around the stem to prevent leakage from the valve along the stem passage.

With this arrangement, as the construction is such as to allow the stem to be introduced, during assembly, through the stem passage from the outside of the valve body, it is necessary to provide means for preventing ejection, or blow out, of the stem under pressure within the valve, and to design such means to be detachable for servicing of the valve for example for servicing the sealing means provided between the valve stem and the valve. Unfortunately there is a danger, with such a design that if due care is not taken during servicing to ensure that the valve is turned off and isolated from fluid under pressure, removal, during servicing, of the means for preventing blow-out of the stem will result in the stem being ejected from the valve body by the fluid pressure within the valve, which is inconvenient and may even, depending on the conditions, be particularly dangerous.

It is an object of the present invention to provide a ball valve, having a one-piece body and a valve member of composite construction, which is free from the above noted disadvantage and in which the stem sealing means can readily be serviced without disconnecting the valve from the installation in which it is fitted and whilst the valve is under internal fluid pressure.

According to the invention there is provided a ball valve comprising a single-piece body having an inlet and an outlet opening aligned along a first axis of said body, a chamber defined within said body intermediate said inlet and outlet openings and communicating therewith, a ball-shaped valve member disposed in said chamber and having a passage extending therethrough, means supporting said valve member for rotation, in said chamber, about a second axis of said body transverse to said first axis, between an open position in which said passage extends in alignment with said inlet and outlet openings along said first axis and a closed position in which said passage extends transversely to said first axis and said valve member cuts off said inlet opening from said outlet opening, the valve further including an operating stem for said valvemember, a stem passage being formed through said body along said second axis, an operating stem for said valve member, means mounting said stem for rotation in said body about said second axis, inter-engaging coupling means on said stem and said valve member entraining said valve member for rotation with said stem, abutment means on said stem for preventing, by engagement with abutment means on said body, removal of said stem from said body by movement of the stem axially from the body along said second axis, said stem, from said abutment means thereon to the end of the stem outside the body part, being of a size to pass along the stem passage past said abutment means on said body, whereby in assembly of the valve said stem can be fitted into said stem passage by passing the stem through one of said openings into said chamber and extending the stem through said stem passage from the interior of said chamber, the valve further including sealing means for sealing said valve stem with respect to said body, said sealing means being disposed on the side of said abutment means bearing further from said chamber and being accessible from the exterior of said body whereby, in use, said sealing means can be replaced without disconnecting the valve body from any associated pipe fittings while the stem is prevented from blowing out of the valve body by said abutment means on the stem and body.

An embodiment of the invention is described below by way of example with reference to the accompanying drawings in which: Figure 1 is a cut-away, perspective view of a valve embodying the invention, and Figure 2 is a fragmentary view, in axial section and to a larger scale, showing part of the valve of Figure 1.

Figure 3 is a view in section, similar to Figure 2, of a variant of the valve, and Figure 4 is a view in section perpendicular to the sectional plane of Figure 3, of the variant valve.

As shown in Figure 1, a ball valve comprises a one-piece body 10 affording an inlet opening 12 surrounded by a fixing flange 14, and outlet opening (not shown), surrounded by a fixing flange 16, the inlet and outlet openings being aligned with one another along a common first axis and being connected with a central chamber 18, for a valve member, by respective passages extending along said first axis.

The valve member 20 is batl-shaped and has a cylindrical passage 22 therethrough which, in a fully open position of the valve, is coaxial with the inlet and outlet openings along said first axis. The ball 20 comprises two halves 20a and 20b which engage one another along respective planar mating faces lying in a plane which contains the axis of the bore 22.The last-mentioned plane also contains a second axis about which the ball 20 is rotatable in the valve body between said fully open position and a closed position in which the respective passage leading to each inlet or outlet opening is blocked by an imperforate portion of the periphery of the valve member 20 afforded by one or other of the halves 20a, 20b, and in which a sealing ring 24 disposed at the inner end of each said passage leading from an inlet or outlet opening is sealingly engaged with the surface of the respective half of the valve member 20.

The two halves 20a, 20b of the valve member 20 are held together and located in the desired relationship with respect to one another by means of a keeper ring 26 engaging around collar portions 28 of the valve member halves and by an interengaging key arrangement, not shown, disposed in the part of the valve member which is diametrally opposite the collar formations 28. The collar formations 28 and the keeper ring 26 are coaxial about said second axis.

The valve member 20 is movable between its open and closed positions from the outside of the valve via a valve operating stem 29 of overall cylindrical form having its axis coincident with said second axis and received in a coaxial stem passage extending from the chamber 18 in a spigot 30 of the valve body.

At its end which extends within the valve chamber 1 8 the stem 29 is formed with diametrally opposite parallel flats defining at this end of the stem 29 a driving key 30 which fits snugly in a corresponding key way provided by a rectangular section slot 32 extending diametrally across the collar formation 28.

The key 30 is formed in an end portion, of enlarged diameter of the stem 29 which adjoins a portion 34, of somewhat reduced diameter, extending over the major part of the axial length of the stem 29 and being of constant external diameter throughout. The portion 34 forms a journal which is rotatably received in a bearing 36 formed by a bore, along said second axis, in the body part 10, which bore 36, at its end nearest the said first axis opens in a flat annular coaxial shoulder 38 which faces into and defines part of the wall of the interior of the chamber 1 8.A slight frusto-conical countersink coaxial with the bore 36 is formed at the transition between the bore 36 and the annular face 38 and the enlarged end portion of the stem 29 is connected with the portion 34 via a correspondingly frusto-conical shoulder 42 which, when the valve is partially dismantled for servicing as explained in detail below, can make sealing engagement with the countersink 40 to limit movement of the stem 29 along said second axis out of the valve body.

The part of the stem passage which adjoins the bore 36 at the end of the latter furthest from the chamber 1 8 is of substantially greater internal diameter than the stem 29 and defines, with the stem 29, an annular packing chamber 44 filled by a suitable packing, preferably fire-safe packing, to provide a seal between the stem 29 and spigot 30.The packing 46 is maintained under axial compression by a gland 48 which, as shown in Figure 1, has two iugs 49 extending therefrom in diametrally opposite directions, each said lug 49 having a bore therethrough through which freely extends a respective screw threaded bolt 50 fixed in a flange provided by the spigot 30, each said bolt 50 extending parallel with said second axis and carrying, on the side of the respective lug 49 furthest from said axis a respective clamping nut by means of which the gland 48 can be urged, along said second axis, towards said first axis, to compress the packing 46.

Bolted to the end of the spigot 30 which is furthest from the valve member is a bearing element in the form of a bridge 51 which has a bore 52 therethrough coaxial with the bore 36 and affording a second bearing, of reduced diameter with respect to the bearing 36 and which receives a cylindrical journal formed by a reduced diameter portion 54 of the stem 29.An annular shoulder 56, facing away from the valve member 20, is formed on the stem 29 between the portion 34 and a portion 54 and forms, in conjunction with a shoulder provided by the side of the bridge 51 which faces towards the valve member and a thrust washer 58 disposed between the last mentioned two shoulders, a thrust bearing which limits axial movement of stem 29 out of the valve body to a position in which, as shown in Figure 2, a substantial axial clearance exists between the frusto-conical shoulder 42 and the countersink 40.

Thus, in normal use of the valve, the shoulder 42 is out of engagement with the countersink 40.

A portion 60 of the stem 29 of reduced diameter with respect to portion 54 projects from the bridge 51 and has a transverse bore receiving an operating bar 62. The portion 60 also carries a travel stop 64, serving, in conjunction with a stop peg 66 carried by the bridge 51, to limit angular movement of the stem 29 about said second axis to 90 degrees between said open and said closed positions of the valve. The travel stop 54 is in the form of a plate held in position on the portion 60 by a circlip 68 engaged in a corresponding annular groove in the portion 60.

As will be noted from Figure 1, since the nuts on the bolts 50 are accessible with the bridge 51 in place, it is unnecessary to disturb the bridge 51 merely to adjust the compression to which the packing 46 is subjected. However, should it be necessary, for example, to renew the packing 46, the bridge 51 may be unbolted from the spigot 30 and, after removal of the bar 62, circlip 68 and travel stop plate 64 may be removed from the stem 29 along said second axis (i.e. upwardly in Figure 2) after which the thrust washer 58 may be slipped off and the gland 48 removed to allow removal of the packing 46.

It will be noted that even should the interior of the chamber 18, in the region outside the valve member 20, be filled with fluid under pressure, the stem 29 will not be blown out of the valve body but will move outwardly only so far as is necessary to allov: the shoulder 42 to engage the countersink 40 and that under this condition leakage from the chamber 1 8 through the stem passage will be substantially prevented, even when the packing 46 has been removed, by the sealing engagement between the shoulder 42 and the countersink 40. Fresh packing can then be inserted and the valve re-assembled by a reversal of the procedure noted.

In initial assembly of the valve, the stem 29 is, of course, inserted through the stem passage in spigot 30 from the interior of the chamber 18, after having been introduced therein via the inlet or the outlet opening, before introduction of the two halves of the valve member 20.

The valve described with reference to the drawings, besides enjoying the advantages of known valves of the general type to which it belongs has the additional advantage of incorporating an operating stem which cannot be accidentally blown out from the valve body by internal pressure. Furthermore, the thrust washer 58, being disposed externally of the valve chamber, is not exposed to the fluid within the valve, as is the case in certain known valves incorporating a thrust washer for the valve operating stem internally of the valve, and replacement of the washer 58, if necessary, can easily be carried out without removing the valve from the installation in which it is fitted or disturbing the gland 48.

Furthermore, since the valve stem 29 is rotatably supported in two bearings spaced relatively widely apart along the axis of stem 29, angular movement of the stem 29 about axes perpendicular to its longitudinal axis is prevented, thus avoiding damage to the gland 48.

In Figures 3 and 4, which show a variant of the valve of Figures 1 and 2, parts which correspond to parts in Figures 1 and 2 have reference numerals greater by one hundred than the corresponding parts in Figures 1 and 2. Except in the respects noted below, the valve to which Figure 3 and 4 relate is substantially the same as the valve of Figures 1 and 2.

One of the respects in which the valve of Figures 3 and 4 differs from that of Figures 1 and 2 is that the packing incorporates a high integrity chevron stem seal 146, pre-loaded axially by a compression spring 200 which encircles the valve stem 1 29 at the upper end of the chamber 144. Furthermore the gland 148 does not extend into the packing chamber 144 but only extends into a counterbore 202 at the upper end of the chamber 144, the gland 148 being clamped against the annular end face of this counterbore with the interposition of a high temperature resistant gasket 204.

The seal 146 is pre-loaded by the gland 148 and spring 200 and is pressure energised, sealing at high and low pressures.

Furthermore, the gland 148 has, extending from its upper side, co-axial with the bore in the gland 148 through which the stem 129 passes, an enlarged counterbore in which is received a firesafe packing 206 which seals the periphery of the stem 129 with respect to the gland 148, and which is compressed axially by an annular rib provided on the underside of the bridge 1 51 and extending into the counterbore which receives the packing 206.

It will also be noted that the thrust bearing arrangement for the valve stem in the embodiment of Figures 3 and 4 is defined by the underside of the gland 148 and an opposing annular shoulder around the stem 129, rather than between the stem 29 and bridge 51 as in the embodiment of Figures 1 and 2.

In the event of the valve of Figures 3 and 4 being subjected to high temperatures, such as may occur in a fire and in the event of the primary seal 146 being thereby damaged or destroyed, the packing 206 will prevent effectively leakage around the stem past the gland 148, while the gasket 204 will prevent leakage from between the valve body and gland 148.

It should be noted that in either of the valves described, it is desirable that the depth, measured in the axial direction of the valve stem, to which the key 30, 130, is engaged in the slot 32, 132 in the normal state of the valve should be so great, compared with the clearance between the shoulder 42, 142 and the face 38, 1 38, that the key 30, 130 will not be disengaged from the slot 32, 132 even when the gland 48, 148 is removed and the stem projected from the valve body, so that an effective driving connection between the valve stem and the valve member is maintained under all conditions.

Claims (11)

1. A ball valve comprising a single-piece body having an inlet and an outlet opening aligned along a first axis of said body, a chamber defined within said body intermediate said inlet and outlet openings and communicating therewith, a ballshaped valve member disposed in said chamber and having a passage extending therethrough, means supporting said valve member for rotation in said chamber, about a second axis of said body transverse to said first axis, between a position in which said passage extends in alignment with said inlet and outlet openings along said first axis and a position in which said passage extends transversely to said first axis and said valve member cuts off said inlet opening from said outlet opening, the valve further including an operating stem for said valve member, a stem passage being formed through said body along said second axis, an operating stem for said valve member, means mounting said stem for rotation in said body about said second axis, interengaging coupling means on said stem and said valve member entraining said valve member for rotation with said stem, abutment means on said stem for preventing, by engagement with abutment means on said body, removal of said stem from said body by movement of the stem axially from the body along said second axis, said stem, from said abutment means thereon to the end of the stem outside the body part, being of a size to pass along the stem passage past said abutment means on said body, whereby in assembly of the valve said stem can be fitted into said stem passage by passing the stem through one of said openings into said chamber and extending the-stem through said stem passage from the interior of said chamber, the valve further including sealing means for sealing said valve stem with respect to the body, said sealing means being disposed on the side of said abutment means further from said chamber and being accessible from the exterior of said body whereby, in use, said sealing means can be replaced without disconnecting the valve body from any associated pipe fittings while the stem is prevented from blowing out of the valve body by said abutment means on the stem and body.

2. A ball valve according to claim 1 wherein said abutment means on said stem and said body part are interengageable sealingly to prevent leakage from the valve along said valve body when said sealing means is removed for replacement.

3. A ball valve according to claim 1 or claim 2 wherein said means mounting said stem for rotation in said body about said second axis includes a first bearing formed by a bore in said body part, defining part of said stem passage, and said abutment means on said body part is afforded by a surface onto which said bore opens and which faces towards said valve member, and further includes a bearing element having a bore therethrough affording a second bearing, a journal on said stem being received in said second bearing, said second bearing being disposed further from said chamber and from said abutment means on said stem than said first bearing, said bearing element beint detachably secured to said body and the stem on the side of said journal remote from said abutment means having a size to pass through said further bearing whereby after detachment of said bearing element from said body the bearing element can be withdrawn from the stem over the end of the latter remote from said chamber and said valve member, said sealing means being disposed between said bearing element and said bearing formed in said body part.

4. A ball valve according to claim 3, wherein said bearing element includes a shoulderfacing along said second axis towards said chamber, and wherein said stem includes a shoulder facing away from said chamber along said second axis, and wherein the ball valve includes thrust bearing means serving to limit movement of said stem along said second axis away from said chamber to a position in which a separation is maintained between said abutment means on the stem and said body, said thrust bearing means including said shoulders.

5. A ball valve according to claim 4 wherein said thrust bearing means includes a thrust washer disposed around said stem between said shoulders.

6. A ball valve according to claim 3, 4 or 5, wherein said sealing means includes a packing chamber surrounding said stem and forming part of said stem chamber, packing disposed in said packing chamber, a gland around said stem defining an end of the packing chamber further from said valve member than the other end of the packing chamber, and means for drawing said gland towards said valve member along said second axis to compress said packing, said detachable bearing element affording, while still secured to said body, access to said means for drawing said gland towards said valve member along said second axis.

7. A ball valve according to claim 3, 4 or 5, wherein said sealing means includes a packing chamber surrounding said stem and forming part of said stem chamber, an annular seal disposed in said packing chamber, a compression spring disposed in said packing chamber at an end thereof further from said valve member than the other end of the packing chamber, the spring being compressed, in the axial direction of the valve stem, between said sealing element and said bearing element, the bearing element being clamped to the valve body.

8. A ball valve according to claim 7 wherein said bearing element is clamped to said valve body with the interposition of a heat resistant gasket sealing the bearing element with respect to the valve body, and wherein further, heat-resistant sealing means is provided between said bearing element and the valve stem.

9. A ball valve according to claim 7 or claim 8 wherein said sealing element disposed in said packing chamber is a chevron seal.

10. A ball valve substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

11. Any novel feature or combination of features described herein.