Straight line flow rotary valves with the valve member flow passage (21) turned away from the pipeline flow axis (22), to dispose the valve internals to an access port (50) located downstream on the same flow axis of the valve member (11 ). Another embodiment is used in place of pipe elbows where the rotary valve internals are accessed through a port (50) on the same flow axis (22) as the upstream pipe. In both valve body embodiments, the flow is turned again, downstream of the valve member (11), to communicate with the connecting downstream piping which, in the first embodiment is along the same axis as the upstream pipe (22), and in the second embodiment, is on a different axis (39), and, is generally 45 or 90 degrees turned from the upstream pipe. In both embodiments the flow turns in a component (12) installed, through the body access port (50). In all embodiments the turning component also services as the pressure boundary access cover over the body opening (50). In a variety of embodiments the turning component (12) additionally services as the valve seat (13), and as a behind the seat seal (16). Sealing member embodiments include floating and trunnion-mounted ball and partial ball valves, and butterfly valves. The preferred embodiment of butterfly valve has a removable resilient seal material (71) such as PTFE or a graphite-based laminate, retained to the valve disc member (11) to facilitate complete repair of all flow isolation surfaces without having to remove the disc member from the valve through the access port (50). Method for removing and installing valve internals through the access port is disclosed.
If a split body valve is welded into the line, the line must be cut so that the body bolts can be removed to access the internal valve member. Cutting a pipeline is very costly. After lines greater than 21/2" are cut the pipe ends and the valve ends have to be machined to achieve the beveled butt weld end dimension in accordance with American National Standard Institute B16.25. Then after the valve has been repaired it must be rewelded back into the flowline. Finally, depending on the nature of the valve installation, non-destructive testing, ranging from dye checking to full penetration x-ray is done. Removal and reinstallation costs often are the most expensive step in the repair of a welded in split body or end entry valve.
Some manufacturers of split body valves will suggest removing the body bolts and pulling the valve apart. The problems with this method are many. The piping to which the valve is attached, cannot be sprung apart without placing undesirable stresses in the piping. These stresses can become the root cause of future pipe rupture, which can be catastrophic in high pressure or hazardous medium situations. Furthermore, even after using the heavy duty slings and come-alongs to spread the valve apart, there is usually not enough space between the two sections of the split body to properly remove and reinstall the internals, and, misaligned trim (internals) is often the result. Lastly, but not least, this method can also be very dangerous as there is a risk of the sprung pipe letting go or moving. If this were to happen while repair personnel were working in the valve, that part of the mechanic's body (head, hands, arms, etc.) which is between the two valve body sections could be crushed.
Two of the three primary types of industrial service rotary valves have inline repairable (bonneted) designs. They are top entry (spherical plug) ball valves and plug (tapered and straight cylinder) valves. The other rotary valve widely used in the industrial/commercial environment is the butterfly valve. Butterfly valves are made in a side entry design, and therefore are not inline repairable. To repair a butterfly valve at least one valve pipe connection must be opened. It suffers from the same problems that a split body or side entry ball valve does when it comes to insitu repair. Tapered plug valves, due to their requirement to have linear seating force (gravity and/or some mechanical assist) are generally always top or bottom entry. While the technology described in this patent is presently indicative of that found in the spherical, near spherical or partially spherical plug (ball) and the butterfly valve, it is not intended to exclude its application to plug valve art.
Several types of top entry, inline repairable ball valves have been proposed for example, in the U.S. Pat. Nos. 2,998,223 to Baxter (1961), 4,562,860 to Walter, Costa, and Eminger (1986), 4,637,421 to Stunkard (1986), 4,718,444 to Boelte (1988), 3,154,094 and 3,179,121 to Bredtschneider et al. (1961). All of these patents were issued for resilient seated valves with a service limitation of about 450 degrees Fahrenheit. Resilient seats, often made of Teflon brand PTFE (polymer) a trademark of E. I. dupont de Nemours & Company, Wilmington, Del., U.S.A., can be forced into a confined ball and seat ring(s) cavity from the top down as is done in a top entry ball valve. It is important to note that this forcing of the valve trim often results in damaged balls and soft seat rings rendering the valve useless as a positive isolation device. Changing the soft seats out of a top entry ball valve is likened to changing a bicycle tire. There is a lot of prying and pinching and often the resilient seat material, like the tire inner tube, gets punctured. The difference between the tire and the valve seals is that a tire can be patched while the valve seals, once damaged by a screwdriver or any other prying instrument, are scrap. For this reason, the easy assembly of the split and side entry body is widely used. A means by which resilient seats could be installed, while the valve is completely connected to the pipe, and at the same time minimizing the risk of damaging them in the process, would advance the art.
The problems found with installing valve components in a top entry soft seated valve are compounded in a metal seated valve, as there is much less compressibility in the metal internals as they are forced into the valve, compared to the soft, low friction surface of resilient seat material. Ironically, it is with metal seated valves that some type of valve internal access is vital to the long term user acceptance as valves of this type are, due to severe service conditions, more inclined to be welded in place, especially in power plant environments.
Many high temperature ball valves are of the floating ball design. With this design the ball is suspended between a belleville spring loaded upstream guide and the downstream valve seat. Both the upstream guide and the valve seat are radiused to mate with the spherical shape of the ball. The spring is essential to the accommodation of thermally induced movement of the valve components which occurs in high temperatures services. The spring loads are best applied by a compression of the seat/ball/upstream guide and belleville spring along the flow axis of the valve. Use of the split body or side entry enables a loading force to be applied against the guide spring as torque is being applied to the fasteners that join the valve body parts together.
(a) U.S. Pat. No. 5,313,976 to Beasley (1994) discloses a top entry floating ball design valve. Using a smooth planar wall surface and a special square belleville, this design is an attempt to solve the problem of assembling a valve with a springloaded guides from the top down. With this design the downward force (perpendicular to the flowline axis) needed to urge the square spring into the narrow gap between the body wall and the upstream ball guide can compromise alignment by cocking the guide and ball components. Also, this design may work at the first factory assembly, however, once a valve has been in service the smoother planar wall will no longer be smooth and will require restoration to render it useful each time the valve is repaired. Field machining the planar wall will be very difficult because special tooling may be required to true up the bottom corners of the square area.
(b) Furthermore, planar wall restoration will result in the need for thicker (oversized) belleville spring to make up for the material lost to a grinding and/or machining operation. This problem becomes especially apparent when the ball and seat required a substantial surface repair in way of machining, grinding and lapping, further reducing the compression value of the guide spring. It then becomes a maintenance problem having to order a special spring when the valve is repaired, especially since the size of the spring may not be known until the smoothing out of the planar wall (and member seat) is finished. By this time it may be too late to purchase a specialized spring due to factory lead times. Reusing the old belleville with a diminished critical ball loading dimension can result in valve seat failure, and, a lock-up condition wherein the ball drops and becomes seized and inoperable.
(c) Lastly, in regards to the Beasley design, in an attempt to make the insertion of the square belleville easier its strength can be compromised due to size reduction. This can result in premature spring failure and the same problems as with undersized springs as indicated above.
Now that ball valves are being used as flow control valves in high pressure and temperature service it is important to have a valve body design that permits nondestructive access to the internal members. Control valves, especially those involved with severe pressure breakdown in the order of thousands of pounds per square inch, experience accelerated wear. Therefore inspection and repair are done frequently.
(d) U.S. Pat. No. 5,305,986 to Hunt (1994) discloses a split body (floating) ball valve which due to its high temperature and pressure capability, is very likely to be welded into the pipeline. Being a split body valve presents a major drawback to this design since every time the valve is in need of inspection and repair the line must be cut and rewelded. Being able to effectively spring load the guide and yet have easy access to the inner workings of this valve would be a significant improvement of this design.
(e) With respect to non-rotary valve prior art, there are hundreds of patents which disclose various designs of gate and globe valves for use in industrial plant services. In high pressure and temperature applications, such as those existing in power plants, the gate and globe valve seats are permanently attached to the valve body. Therefore, seat grinding, machining and very often, minor and major weld repairs, must take place at the valve location, as most power plant feed water and steam valves are welded in the line. Not being able to remove the valve to a shop means that specialized portable tools must be brought to the site. This tooling, besides being expensive to make, purchase, or difficult to schedule when rented (with or without an engineer/technician), is often very difficult to set-up, and, does not usually bring the same surface finish results as does a machine shape with heavier, stationary lathes, boring mills, etc. Undesirable machine tool surface chattering is a field problem encountered when using lighter weight portable machines to cut very hard metallic valve seats.
(f) Furthermore, there are many industrial repair situations where it is unsafe to expose workers to the area immediately surrounding a valve. Nuclear plant valves are a good example of this. When extensive valve seat repairs are necessary it is not unusual to use up several technicians' radiation exposure allowances. Hazardous chemical environments are another example of this.
(g) Also, as is often the case with smaller (3 inch and under) high pressure (ANSI Class 1500, 2500 and 4500) gate and globe valves, once the valve seat is damaged and repaired to a point where the seating material is gone, the valve, which is in otherwise good condition is cut out of the line and discarded.
(h) Flanged end joints are often the preferred design for valves where, due to a split body, end entry (rotary valves) or low pressure service (gate and globe valves) the valves are removed from the pipe for maintenance. Collectively, flanged end valves present a serious environmental problem due to the known leak rate of this connection method. The Clean Air Act is guiding industrial plants to ways to reduce harmful fugitive emissions.
(i) In addition to concerns about fugitive emissions and worker safety in the chemical industry, many industrial plants would prefer to weld valves in line, rather than flange them, if there was a way to easily perform repairs without having to remove complete valves from the line. Removal and reinstallation cost of flanged valves is a very costly part of the repair process.
OBJECTS AND ADVANTAGES
The primary object of this invention is to improve upon the superior assembly method and very tight shut-off capabilities of split body and side entry rotary valves by making them field repairable without having to open pipe connections. Accordingly, there are several related objects and advantages of present invention as follows:
(a) to provide a valve design that now can be welded into the pipeline and becomes an integral part of the line, as opposed to flanged or clamped, thereby eliminating the possibility of flange seal failure. This will greatly increase industrial plant safety, (especially where dangerous medium is flowing in the line) save maintenance dollars, and, reduce the amount of environmentally harmful fugitive emissions, which occur due to bolted flange leaks.
(b) to provide a welded inline high pressure ball valve and, butterfly valves, with not only a readily removable disc or ball closing member, but one, whereby the valve seat is actually removed before the closing member.
(c) to provide unprecedented repair capability to the high pressure ball valve and butterfly valves whereby, due to the removable seats, seat restoration procedures (which generally are the most time consuming part of a valve repair)like rough machining, welding, postweld heat treatment, post weld machining, grinding and lapping can all take place in a shop rather than in the plant or field. Being able to perform these labor intensive procedures in a shop will promote general safety in the work place, better repair quality, and faster repair turnaround without the need for specialized portable machine tools.
(d) to provide the inline removable seats in the ball and butterfly valves as a means to reduce the amount of time spent in:
1.) a radioactive atmosphere such as can occur in nuclear plants
2.) areas of an industrial plant where hazardous or lethal chemicals are part of the process.
3.) very hot or very cold field repair locations.
This object is especially important since the amount of exposure or potential exposure increases dramatically when a valve used in a dangerous service is opened for repair. Having to perform extensive seat work, in place, in these environments is a very demanding and undesirable task.
(e) to provide an inline repairable valve which does not require the lifting or disturbance of the valve actuation, whether it is of the manual, pneumatic, electric, or hydraulic type. This benefit will facilitate a quicker repair without the risk of damaging the actuation or actuation accessories such as gages, positioners, limit switches, regulators, filters, solenoids, etc., during removal and reinstallation handling.
(f) to provide a location for the easy installation and removal of one, or a set of stacked of multiple orifices in the flow passageway of any of the rotary type valves covered in this invention. Such orifice(s) will provide noise reduction, cavitation reduction and flow control.
(g) to provide a welded inline floating ball and trunnion-mounted ball valve that can easily be disassembled and reassembled using the same method of compressing the spring-loaded guide or the upstream seat, respectively, as is presently utilized. This is accomplished by turning down on the bolts holding the access port component, located on the downstream side of the valve sealing member, rather than attempt to force close tolerance sealing members in from the top of the valve, risking damage to parts and immediate failure of the valve in operation.
(h) to provide another form of angle entry rotary valve that can be installed in place of a pipe elbow. This will, in addition to all the objects and advantages mentioned above, provide for less new construction welding (since the valve and elbow location are the same only two pipe welds are required instead of four) more compact pipe design (desirable in high solids flow where minimal pipe flow resistance is required), an elbow inspection and line access (clean-out) port, and, last, but not least, an elbow wear element that can be repaired or replaced.
(i) to provide a means by which the soft (resilient) seals of a soft seated floating ball valve can be removed with ease and reinstalled without risking the seal damage that often occurs when forcing soft seats into a top entry type valve.
BRIEF DESCRIPTION OF THE DRAWINGS
Further properties of the invention will be brought out in the description which now follows, with particular embodiments of the invention being shown in the accompanying drawings which are given by way of example without any limitations being implied and in which:
FIG. 1 is a cross sectional partially exploded view of the main components of angle entry rotary valve (hereinafter referred to as AERO valve), showing the body, valve member, seat, yoke, operator, stuffing box, stem and a component singular to the AERO valve . . . the downstream valve component (hereinafter referred to as the DVC). The DVC, its lower and upper seals, and nuts are shown in the exploded portion of the Figure;
FIG. 2 is a cross sectional view showing FIG. 1 assembled;
FIG. 3 is a cross sectional view of the bolted flange type DVC;
FIG. 4 is an elevational view from the third flow axis of the bolted flange type DVC;
FIG. 5 is a cross sectional view of a separate threaded-in seat with a pressure sealed DVC;
FIG. 6 is a cross sectional view of the "straight pipeline body" with a butterfly valve member;
FIG. 7 is a cross sectional view of a double-seated, trunnion-mounted ball valve with a thread-in DVC and a metal-to-metal lower DVC seal rather than a resilient sealing material;
FIG. 8 is a cross sectional view of a double-seated floating ball similar to FIGS. 1 and 2, with sealing on both sides of the ball;
FIG. 9 is a cross sectional view of the "turned pipeline body" AERO valve with a butterfly member;
FIG. 10 is a fragmentary sectional view showing the addition of flow control elements in the downstream flow port of a upstream-seated, trunnion-mounted ball type embodiment.
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REFERENCE NUMERALS IN DRAWINGS
__________________________________________________________________________
10 body 11 valve member
12 downstream valve component (DVC)
13 downstream seat
13a
threaded-in seat
13b
threaded-in seat seal
13c
seat in double seated valve
14 upstream seat guide
15 seat guide spring
16 lower DVC seal 17 lower stem shaft
16a
metal-to-metal DVC seal area
17a
lower stem shaft
17b
upper stem shaft
17c
one piece stem shaft
18 upper DVC seal 19 body bolts
20 first cylindrical passageway
21 second cylindrical passageway
22 first (pipeline) axis
23 first cylindrical body chamber
24 second cylindrical body chamber
25 fifth cylindrical passageway
26 sixth cylindrical passageway
27 seventh cylindrical passageway
28 second (main body) axis
29 shaft coupling
30 fourth (DVC) axis 31 fifty (outlet) axis
32 yoke 33 valve operator
34 third (closure element) axis
35 stem packing gland
36 packing gland bolts
37 stuffing box
38 third flow passageway in the
39 second axis in the turning pipe
turning pipe body body
40 lower DVC seal area in body ID
41 bottom of lower DVC seal in
valve body inside diameter
42 lower DVC ID seal area
43 top of lower DVC seal area
44 lower DVC guide and gland
45 recessed OD of DVC
46 flanged DVC boltholes
47 body outlet passageway weld
48 flanged DVC upper seal area
49 DVC passageway outlet hole
50 valve internal access port
51 DVC flange
52 body seal area for upper DVC
53 body chamber planar wall(s)
54 DVC lifting boltholes (threaded)
55 trunnion shaft
56 trunnion shaft cover (bolted)
57 pressure seal ring
58 pressure seal spacer ring
59 segmented retainer ring
60 pressure seal draw-up plate
61 DVC lifting holes (threaded) for
pressure sealed & threaded
62 body reinforcing bar
63 spanner wrench holes
64 threaded-in DVC retainer
65 threaded-in DVC retainer weld
66 pressure breakdown element
67 segment ring body groove
68 threaded DVC retainer lower
69 upstream seated valve seat
holder
circumference area
69a
seat for 69 above
70 stem-to-ball slot location
69b
seat holder OD seal for above
71 butterfly member seal
71a
butterfly member seal
retainer (bolted)
71b
butterfly member seal
retainer bolts
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The angle entry rotary (AERO) valve has three primary embodiment categories, each having to do with a variation of design shaped around the concept of turning the fluid flow path to accommodate easy-in-the-pipeline (inline) accessibility to the closure member of the valve.
The first embodiment category as shown in FIGS. 1-2, and 5-10 show the main body types relative to the pipeline flow requirements, i.e., is the valve for a straight or turning pipe. These embodiments are called the "valve body embodiments". The second category of embodiments relate to the valve flow control or flow isolation members, i.e., whether the rotating sealing member is a floating ball, trunnion-mounted full or partial ball, a butterfly, a soft seated floating ball or a flow control valve. These embodiments, hereinafter referred to as the "valve member embodiments", are shown in FIGS. 1-2 and 5-10. The last group of embodiments are shown completely or partially in all Figures. This group, called the "downstream valve component (DVC) embodiments", relates to the function of this major valve component and to the various means by which it is installed in the AERO valve body.
To more fully understand the overall nature of the angle entry rotary valve we will refer to FIG. 2. The remaining Figures illustrate the various embodiments which this patent application is intended to include.
FIG. 2 shows a typical floating ball type AERO valve in the "straight pipeline" valve body embodiment, whereby the generally cylindrical or conical flow passageway 20 along the first axis 22 turns approximately 45 degrees to form a second flow passageway 21 along axis 28. Flow in passageway 21 proceeds through the sealing member 11 and into the DVC 12 where it is turned to communicate with the third cylindrical passageway 26 whose axis 31 is approximately 90 degrees to the second axis 28. This passageway is then turned approximately 45 degrees to return flow to the first axis 22 through passageway 27. The angles of flow passageway intersection in the straight pipeline body embodiment can vary greatly. FIG. 7 shows flow angles of approximately 25 degrees at the intersection of passageways 20 and 21, 70 degrees at the intersection of passageways 21 and 26 which occurs in the DVC passageway 25, and 45 degrees at the intersection of passageways 26 and 27.
Passageway turns at the intersection of each axis can be mitered, or, as shown in the preferred embodiment of FIGS. 7 and 10, rounded to a contour that would minimize any turbulent effect as media flows through the valve.
The second body embodiment, called the "turned pipeline body" is shown in FIG. 9 whereby the first generally cylindrical or conical flow passageway 20 along the first axis 22 proceeds past the sealing member 11 and into the downstream valve component 12 where it is turned 45 or 90 degrees in passageway 25 to communicate with the second flow generally cylindrical or conical passageway 38 along axis 39 which connects, without any further turning, to the pipeline. This body embodiment would be used at a location that would otherwise be a 45 or 90 degree pipe elbow.
The third, "special" valve body embodiment, is one in which the flow passageway intersection angles and/or the number of flow passageways and/or the flow passageway lengths are altered to effect substantially increased or decreased flow coefficients or to a valve into a fit into predetermined open pipe dimension.
The valve shown in FIGS. 6,7 and 9 show the preferred body embodiment of a completely cast or forged body with sufficient wall thickness, to meeting industry standards for pressure boundary and to accommodate joint stress allowances. FIG. 7 shows a substantial increase of wall thickness at the point where flow passage way 25 and 26 converge as this is a point of highest pipe loading stress concentration. The valves shown in FIGS. 1,2,5,8 and 10 are fabrications showing welded-on 47 valve outlet passageways. This method of construction is another means of construction, especially for odd sizes. To strengthen the valve body when the outlet pipe is welded on, a webbing, usually consisting of the same material as the valve body, connecting the outside body of passageway 26 and 21 can be added as shown in the embodiment of FIG. 5. Lastly, with regard to body configuration, the welded-on outlet pipe can be eliminated altogether when the piping to which a valve is being installed can connect directly to the main body adjacent to the discharge side of the DVC. This can be done with either 45 degree elbow for valves which have the same inlet and outlet centerline, or by straight pipe for valves of the turned pipe design as shown in FIG. 9.
Valves covered in this document will be subject to standards of various organized bodies duly recognized as the industry's manufacturing guidelines. The preferred embodiment for connecting the AERO valve to the pipe will be by means of a socket weld or butt weld in accordance with American National Standards Institute (ANSI) B16.25. Valves may, however be of the flanged, ring type joint, wafer body, lugged, or clamped but style end connections or any workable combination of joint thereof. Valve body wall thicknesses will conform to ANSI B16.34 1988 with ratings in the 150, 300, 600, 800, 900, 1500, 2500 and 4500 classes and be built to intermediate, limited, and special class ratings in all pipe sizes as allowed. Materials of body construction will be per customary requirements for given service conditions. Frequently used material swill be low alloy carbon steel, stainless steel and nickel and nickel alloy materials.
A wide variety of yoke designs and valve operators are used and wide known in the art. Operators including lever 33, handwheel, worm gear in FIG. 7, spur and bevel gear, motor, air and hydraulic units suitably rated for the service conditions and operating torque requirements. Each Figure, except FIGS. 3 and 4, show the typical valve stem shaft (17 and 32 in FIG. 2) and stuffing box (37 in FIG. 2) arrangement to be utilized. Materials of construction will again vary according to the requirements of service conditions. Typically, a graphite and/or carbon stem packing will be installed and compressed in the stuffing box for valves exposed to flow mediums in excess of 450 degrees Fahrenheit while PTFE or other appropriate material will be used in lower temperature and cryogenic service conditions.
Reference has been made to the DVC previously to describe the low path of the AERO valve. The embodiments of the DVCs vary depending on whether the valve access 50, at the end of axis 28 furthest from the flow line axis 22, is a bolted down flange style as shown in FIGS. 1-4, 6,8 and 10, threaded as shown in FIG. 7, or a pressure seal style shown in FIG. 5.
The bolted flange DVC embodiment, detailed in FIGS. 3 and 4, combines four key features into one component. Hence the need for a new part name "DVC" which more appropriately describes the multiple functions this part performs in the AERO valve. Three of the DVC features are found in almost every valve known, i.e., the seat, the seat to body seal and the cover, or bonnet. The fourth feature, often a part of general isolation and control valve body flow passageways, but not a part of a multifunctional internal component, but is integral to the DVC, is a flow turning passageway. This passageway 25, in all body and valve member embodiments, communicates with the flow passageways on axis 21 and 26 to effect a continuous flow from the axis created for valve maintenance 28 to the axis of the pipe flow line 31. The passageway can be one of intersecting cylindrical chambers (mitered) as shown in FIGS. 1, 2, and 8 or, can be a contoured arched chamber of a generally cylindrical shape as shown in FIGS. 3, 5, 6, 7, and 9.
The preferred threaded and pressure sealed DVC embodiments differ from the flanged embodiment in that the seat is separated from the main DVC in the pressure seal style, and, the threaded style utilizes a threaded retainer to fix the DVC in to the valve. A separate seat is required in the pressure seal style due to the fact that, during assembly, the upward pull of the DVC would relax the force required to position the DVC seat to sealably mate with the valve member. A threaded retainer 64 (plug or plate) is preferred in the threaded-in DVC due to the fact that this design makes the DVC manufacturing easier. With this design it is easier to make sure that the DVC flow outlet hole 49 and the contiguous flow passageway 26 are concentric after the DVC is completely threaded into the body.
The pressure sealed DVC can be clamped (Greylock style) or, as shown in the preferred embodiment in FIG. 5, bolted through a DVC draw-up ring 60. The pressure seal configuration, like the flanged, is widely known in the art. By drawing the DVC 12 and its seal ring 57 against a spacer ring 58 and segmented ring 59, the later of which are inserted into a full circumferential groove 67 in the inside diameter of the valve body, the AERO valve access port is sealed. When a pressure seal arrangement is used for the downstream valve component it is preferred that a separate seat ring 13a is bolted (with a gasket 13b), welded, or, as shown in its preferred embodiment in FIG. 5, is threaded and gasketed into the inside diameter of the valve body 10 to communicate with the rotatably disposed closure member 11 and to compress the gasket and to prevent leakage from finding a path between the seat ring 13b and the valve body 10. The pressure sealed downstream valve component can be used with all of the various body and valve member embodiments described herein.
The threaded-in DVC is the same as the bolted DVC except for the means by which it seals off the access port 50. The upper DVC seal body area 52 is deeper, and, therefore lower into the valve body as shown in FIG. 7. It is also threaded to accommodate the retainer 64 compression function. The seal 18, in the preferred embodiment, is a non-metallic material suitable for the service desired. In the preferred embodiment a snap-type retaining ring is fitted into a circumferential internal body groove above the retainer 64 to lock the retainer in its design position. Another locking embodiment, as shown in FIG. 7, is to place a spot weld 65 joining the retainer to the body. The bottom of the retainer is in the preferred embodiment flat or equipped with a thin push plate, generally made of the same material and in the same diameter as the threaded retaining plug (plate), to provide straight axis compression of the upper DVC seal 18. The retaining ring's lower circumference 68 protrudes slightly below the seal shoulder 52 in very close diametrical clearance so as to prevent the seal material from extruding into the valve body, and, thereby diminishing the effectiveness of the seal. The retaining ring 64 is turned into the AERO valve body 10 (by use of the spanner wrench holes 63) a prescribed distance as measured from the top of the valve body at the access port 50. This distance will assure that the upper and lower DVC seals are sealably compressed and that the valve seat is positioned to perform the sealing function with whatever member embodiment is used.
For easy removal of the DVC in valves with the threaded retainer a hole 61 is drilled and tapped into the top center of the DVC, wherein a threaded eyebolt can be installed and a sling can be attached to the bolt at the time of DVC removal to enable the DVC to pull from the valve body. Naturally, the eyebolt and sling would be used for reassembly. Large valves may require more than one eyebolt hole.
The angle of flow passageway turn in the DVC can vary depending on the overall flow requirements and end to end length of the valve. The inside of the DVC passageway 25 can be one of gradually reducing or expanding diameters, or one of dramatic diameter change(s). The later may be used for very severe service conditions where it may be prudent to take a large pressure drop at the outlet of the DVC 49, where the diameter would be substantially reduced, rather than across the valve seat and member. This would reduce the damaging effects to the shutoff sealing surfaces on the seat and member when high velocity erosive flow occurs, especially when a valve is operating within twenty-five percent of the closed position for extended time periods.
The material used in the DVC is generally the same as the valve body material with the exception of the seat surface. This area will contain either a soft inserted material such as PTFE or a hard material such as a weld overlay or a sprayed metal hardcoating. For very severe service conditions where highly erosive forces are known to exist, a weld or thermal spray hardcoating can be applied to the flow passageway 25.
The word "downstream" in DVC refers to the side of the valve which is exposed to medium flow after it passes through the first 20 and second 21 passageway and the valve closure member 11. The term "downstream" is used to indicate the direction of flow when the valve is primarily intended to flow in one direction only (unidirectional). However, the term will also be used to describe the component even if flow is intended to be in both pipeline directions (bidirectional). Valves shown in all Figures are bidirectional with the exception of FIGS. 1, 2 and 5 which, as shown, are unidirectional, but, can be configured to be in the outside diameter of the upstream seat guide 14 and providing seating shoulders in the valve body where the guide ring 14 communicates with the valve body.
Referring to FIG. 1 the inside of the valve body is comprised of two cylindrical chambers 50 and 46, and a third chamber 52 which houses the upper DVC seal 18. The third chamber can be angled or radiused to house a metal seal ring 18 as shown in FIGS. 1-3, 6, 8-10. FIG. 5 shows a conventional pressure seal design. Additionally, chamber 52 can be flat to accommodate a gasket, or lengthened and threaded to accommodate a threaded and gasketed DVC.
Referring to FIG. 2, the first chamber 50 disposes the closure member (ball) 11, upstream seat guide (a ring with a radius on the surface which communicates with the ball member to assure true alignment of the ball) 14 and the closure member guide (belleville) conical loan spring 15. The second body chamber 24 houses the downstream valve component and its upper 18 and lower seal 16. The shoulder 41 is the demarcation between the two body chambers.
The DVC in FIGS. 3 and 4 is a cylindrical component of varying outside diameters to accommodate the access port cover (integral flange) 51, the turning passageway 45, the lower guide and gland 44 and the lower seal inside diameter retaining surface 42. The seat which communicates with the closure member is radiused to mate with ball surface as shown in various ball valve Figures or in the case of a butterfly closure member, it can be of a radius or taper angle. Load on the seat is determined by the overall protrusion of the DVC through the second body chamber 24 and into the first body chamber 50 after being secured to the valve body.
In the preferred DVC embodiment, the lower seal ID retaining surface 42 accommodates a die formed graphite or polymer-based ring 16 (material will depend on operating temperature and other conditions) with a seal height of one to 5 times the seal cross sectional dimension. The seals cross section is determined by the following formula: ##EQU1##
Anti-extrusion rings, generally made of braided carbon or PTFE etc., or a compressed mesh of any of numerous woven metals compatible with the service conditions, can be placed at the top, or, at the top and bottom of the lower DVC seal to further extend the seal life. Further, instead of the lower DVC seal ring being one center ring with separate anti-extrusion ring, the anti-extrusion rings can be die formed into the center ring so that the seal is one piece. The center ring can also be a stack of rings as opposed to one monolithic ring. This stuffing box-like seal design allows for substantial seal compression to assure positive long term sealing over the smallest diameter possible, thereby reducing the need for expanding the body diameter to accommodate a spiral wound type gasket which requires a wider sealing surface on a plane perpendicular to the DVC loading axis 28. This stuffing box-like seal is also more forgiving in this sealing application whereby one compression source 19 is required to simultaneously engage two separate seal locations, i.e., the "to atmosphere" upper DVC seal 18 and the "behind the seat" lower DVC seal 16. The lower seal inside diameter retaining surface 42 and the first valve body chamber 50 overlap and the diametrical clearances here and between the second body chamber 24 and the lower guide and gland 44 fully retain the lower downstream valve component seal.
Another embodiment of the DVC is to directly mate the lower DVC to the body effecting a 360 degree continuous metal-to-metal sealing contact. Stainless steel or other suitable DVC material or hardface overlays would be necessary to give these sealing surfaces integrity and longevity. Assuming that some lapping of this lower DVC mating surface would be required over years of service, and that any such lapping will seal contact surfaces, the upper DVC seal 18 must be a graphite or resilient polymer, and not a metal ring, to accommodate the greater compression dimension that will occur from lapping the lower seal. Assuring the dimensional relationship between the lower metal-to-metal seal and the DVC seat will have to be part of the routine maintenance procedure. The addition or removal of body or DVC material may be required to reestablish all critical sealing and valve member-to seat dimensions.
Another embodiment of the DVC is used in upstream seated valves like the one shown in FIG. 10. Here the DVC does not perform the functions of valve seat, or behind-the-seat seal. Therefore, it has no seat or lower DVC seal area.
The outside diameter of the DVC 45 between the lower guide and gland and the cover is reduced to minimize binding which can otherwise occur during the removal and reinstallation of this component. As in FIG. 7 the outside surface of the DVC may be substantially reduced in mass by reducing wall thickness, contouring the surface to match the flow passageway and adding rib supports as may be required for the DVCs structural integrity.
The outlet hole 49 of the downstream valve component is generally of a circular or oval shape, but can be of a variety of shape configurations if the service application requires altering a valves flow pattern.
OPERATION OF THE DVC
The DVC is a stationary component in an operating valve. In all AERO valves, the DVC turns the flow passageway that allows inline access to the valve internals back toward the direction of the connecting downstream pipe, and, it is the removable pressure boundary part that permits access to the inside of the valve. The sealing functions of the DVC can depend largely upon which type of member embodiment is used and whether or not the DVC has a seat.
In the single and double seated floating ball valves shown in FIGS. 1, 2, 5 and 8 and in the double seated trunnion-mounted ball valve shown in FIG. 7, the DVC 12 provides the compressive load necessary to suspend the ball in the floating ball valve, and, to mate the valve member to the seats in the floating ball and downstream seat of the trunnion ball valve. In the pressure seal embodiment shown in FIG. 5 a separate seat ring 13a performs the downstream ball suspension and loading functions. In the single upstream seated valve shown in FIG. 10, the DVC functions as an access port cover and flow turning element. In the butterfly valves shown in FIGS. 6 and 9, the DVC neither suspends the ball nor loads the disc to the seat. It does, however, provide a fixed circumferential mating surface for the disc member to seal against.
OPERATION AND DESCRIPTION OF VALVE MEMBER EMBODIMENTS
The repair operation/method of all AERO valve embodiments is unlike any other rotary valve type. It has all the best features of a top entry and a split body/side entry valve. The repair of the AERO valve, with the exception of being done on an angled axis relative to the pipe, is the same as repairs to a split body valve or side entry valve. In the typical embodiment, the DVC is removed through access port 50, and all of the valve parts that need to come out for service can be retrieved through this location. After necessary repair work is complete the DVC is inserted back into the AERO valve body chamber through the AERO valve access port 50 and positioned to stem shaft connections (70 in slotted ball styles), and aligned so that the DVC flow discharge port 49 lines up with the valve body flow passage along axis 31 for straight pipe valves and 39 for turning pipe valves.
Prior to DVC installation the lower DVC seal ring 16 is carefully placed around the DVC at 42 and the upper seal 18 is placed on the body mating surface 52. (In the threaded and pressure seal DVC embodiments the upper DVC seal can be installed after the DVC is placed into the valve). Then the DVC is placed into the valve body and fastened in its stationary position in body cylinders 23 and 24. Drilled and tapped holes opposite each other 54 on the flanged DVC 51 and on top center 61 on the screwed and pressure sealed DVC, serve as anchor points for (eye)bolts or studs to which a lifting sling is attached for DVC handling during removal, repair and reinstallation.
The use of ball valves and butterfly valves to control or isolate the flow of fluids is very well known in the art. Valves are selected based on their flow characterization, flow capacity, degree of shut-off capability, body pressure rating and user acceptance of the different designs available. Valves built using the "straight pipe" AERO body design will, given equal inside flow diameters as valves built with a split body, side entry or top entry, (hereinafter referred to as conventional (rotary) valves) have a reduced flow capacity. This is due to the frictional loss associated with the plurality of flow passageways in the AERO valves compared to only one passageway in conventional valves. In some service applications this comparable flow reduction may not be of consequence since a flow reduction is often desired. In others it will necessitate an enlargement of the AERO valve internal flow passages to achieve large flow coefficients. AERO valves built using the "turning pipe" embodiment shown in FIG. 9 will not reduce line flow rates any more than would a pipe elbow of equal length, radius and internal diameter.
Unlike conventional valves, "straight flow pipe" AERO valve stem 17, yoke 32 and operator base plate (topworks) will be on an angled plane relative to the pipeline, rather than on a parallel plane with the pipe. The "turned flow pipe" AERO valve will, however, have the same topworks orientation as do the conventional valves. In horizontal pipe installations the angled operator will have minimum effect on the ease of opening or closing a valve regardless of the valves flow direction, especially if the valve is equipped with a bevel or worm gear operator with the face of the handwheel facing the person turning the valve to the desired position, as shown in FIG. 7. In vertical pipe installations, with the flow up, the valve non gear operator will operate very much like a direct wheel or T-handle operated Y type globe valve in a flow down service, i.e., with the handwheel face slanted toward the ground. In vertical pipe installations with the flow down, as is most often the case on industrial and power boilers, particularly in waterwall drain duty, the AERO valve will provide an easier angle of operation for the person as the handwheel will be facing slightly upwards. Ergonomically, this is a preferred handwheel position for a person as this position will allow a plant operator to utilize his or her entire body to manually cycle a valve, rather than just the upper body, to more a valve member requiring high turning torque.
Rotary valves using the AERO valve body will consist of a full round and modified sphere ball, a fractional ball (which has an outside surface area which, at its widest part, is approximately the dimension of the outside diameter of the valve seat), V-ported ball or a butterfly valve disc member. These members generally rotate 90 degrees to cycle from the full open to the full closed position, and vise versa. Some valves, however, may cycle less than a full 90 degrees and other may cycle up to 180 degrees or more in their normal operation.
The floating AERO ball valve in FIGS. 1, 2 and 5 shows the typical arrangement of valve components, i.e., a cylindrical body interior 23 housing a belleville member loading spring 15, which communicates directly with the planar upstream body wall 53 and the flat upstream side of the upstream seat guide 14. The radiused opposite side of the upstream seat guide 14 along with the radiused downstream seat suspend the ball 11 on center with the valve stem 35 axis 34. In the preferred embodiment shown in FIGS. 1 and 2 the downstream seat is not spring loaded. The downstream seat may be a resilient PTFE type material or a hardfaced material insert, or, as shown in FIGS. 1 and 2, and previously written, it is a hardface material applied directly to the seat surface base metal, and therefore considered integral to the seat. The belleville spring 15 provides a preload to hold the ball against the seat under low operating pressure. After the line pressure against the upstream side of the closed ball has exceeded that which the spring has applied, the spring becomes inactive as a loading force and the valve is sealed using the force of differential line pressure acting over the exposed surface on the upstream side of the ball member. Once past the seat in the floating ball the medium proceeds through the flow passage 25 of the DVC where it is turned to communicate either directly with the pipeline (turned pipeline valve) or to another passageway which then connects with the pipeline.
FIGS. 6 and 9 show the typical butterfly AERO valve member embodiments. In FIG. 9 the flow medium moves into the first passageway 20 along the flow axis 22 communicates directly with the valve member 11 or as shown in FIG. 6, is turned to communicate with a second flow passageway which is in the same axis as the valve member 11 and DVC 12. Unlike many ball valves which require a spring preload, the butterfly valve simply relies on torque loading of the member against the seat. This loading torque is often boosted in high pressure valves by offsetting the disc 11 on the shaft 17 to render a camming effect of the member 11 to the seat 13. Member and seat sealing configurations can vary depending upon the service conditions and user history. Typically, rubber, polymer or graphite-based resilient seat materials are used with the valve whereby the valve member retains a resilient sealing material and the seat is either the valve body material or a more durable metallic overlay. For reasons explained below, the later closure seal arrangement is the preferred AERO valve embodiment.
Like FIG. 1, the AERO butterfly valves shown in FIGS. 6 and 9, have DVC seats 11 which will be removed as part of the routine repair teardown. Unlike the floating ball design in FIG. 1, where the ball member can be pulled out of the valve (after
