CA2908684C - Valve with stop mechanism - Google Patents

Abstract

In the specification and drawings, a valve is described and shown having a first and second valve seat carrier, a valve seat associated with each valve seat carrier, and a valve ball between the valve seats. The valve further includes a stop mechanism operatively connected to at least a first valve seat, the stop mechanism limiting travel of the first valve seat towards the valve ball such that the valve ball may be push away from a sealing engagement with the first valve seat.

Description

VALVE WITH STOP MECHANISM
David A. Buck PRIORITY CLAIM
[001] This application claims priority from Application Serial No.
13/960,497, filed August 6, 2013, which application was a continuation-in-part of Application Serial No. 13/863,918, filed on April 16, 2013 and this application claims benefit from U.S.
Provisional Application Serial No. 61/924,316, BACKGROUND OF THE INVENTION

[002] In many examples of drilling for oil or gas wells with standard U.S.
technology, a drive bushing is turned by a rotary table. The drive bushing has a square or hexagonal passage therethrough slidably receiving a long square or hexagonal member known as a kelly. One potential hazard in drilling for oil or gas is encountering pressures which are not balanced by drilling fluid in the hole. One of many safety devices are valves on the kelly, on the lower end immediately above the uppermost drill pipe joint and on the upper end between the kelly and the swivel. The idea is to actuate the blowout preventer to seal around the outside of the drill string and to close the kelly valve or valves to keep well fluids from returning through the drill string. An analogous valve, known as a safety valve, is used in analogous situations in completion and workover operations.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[003] Figure 1 is an exploded perspective view of an embodiment described herein.

[004] Figure 2 is a side elevation view of an embodiment described herein.

[005] Figure 3 is a sectional view of an embodiment described herein.

[006] Figure 4 is a side elevation view of an embodiment described herein.

[007] Figure 5 is a sectional view of an embodiment described herein.

[008] Figure 6 is a sectional view of an embodiment described herein.

[009] Figure 7 is a sectional view of an embodiment described herein.

[0010] Figure 8 is a section view of one valve embodiment within a sub housing.

[0011] Figure 9 is a side elevation view of an embodiment described herein.

[0012] Figure 10 is a side elevation view of an embodiment described herein.

[0013] Figure 11 is a perspective view of an embodiment described herein.

[0014] Figure 12 is a side elevation view of an embodiment described herein.

[0015] Figure 13 is a sectional view taken along the line A-A of Figure 12.

[0016] Figure 14 is an exploded perspective view of an embodiment described herein.

[0017] Figures 15A and 15B are views of an inter-locking structure for securing the tongue structures to the valve seat carriers.

[0018] Figure 16 is an exploded view of an alternative embodiment of valve described herein.

[0019] Figure 17 is a cross-sectional view of the valve illustrated in Figure 16.

[0020] Figure 18 is an exploded view illustrating an alternative spring arrangement.

[0021] Figure 19 is a cross-sectional view of a still further alternative embodiment of the valve described herein.

[0022] Figure 20 is an exploded view of the embodiment seen in Figure 19.
DETAILED DESCRIPTION

[0023] As required, detailed embodiments of the present invention are disclosed herein.
However, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. As such, any feature(s) used in one embodiment can be used in another embodiment. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting, but rather, to provide an understandable description of the invention. While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.

[0024] Alternate embodiments may be devised without departing from the spirit or the scope of the invention. Additionally, well-known elements of exemplary embodiments of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the invention.

[0025] Before the present invention is disclosed and described, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The terms "a" or "an," as used herein, are defined as one or more than one. The term "plurality," as used herein, is defined as two or more than two.
The term "another," as used herein, is defined as at least a second or more. The terms "including" and/or "having," as used herein, are defined as comprising (i.e., open language). The terms "connected" and/or "coupled," as used herein, are defined as connected, although not necessarily directly, and not necessarily mechanically.

[0026] Relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

The terms "comprises," "comprising," or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises ... a" does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0027] As used herein, the term "about" or "approximately" applies to all numeric values, whether or not explicitly indicated. These terms generally refer to a range of numbers that one of skill in the art would consider equivalent to the recited values (i.e., having the same function or result). In many instances these terms may include numbers that are rounded to the nearest significant figure.

[0028] Herein various embodiments of the present invention are described. In many of the different embodiments, features are similar. Therefore, to avoid redundancy, repetitive description of these similar features may not be made in some circumstances.
It shall be understood, however, that description of a first-appearing feature applies to the later described similar feature and each respective description, therefore, is to be incorporated therein without such repetition.

[0029] Described now are exemplary embodiments. Referring to the drawings, beginning with FIGS. 1 to 3, an exemplary embodiment of a valve 100 is shown. The valve can be employed as a kelly valve, a safety valve, or any other application where a cartridge type valve or ball valve is employed. The valve 100 (FIG. 2) includes a housing 102 with a threaded drill pipe pin 104 at the lower end and a threaded drill pipe box 106 at the upper end. In one embodiment, the housing 102 can be constructed of one piece, two pieces, or a plurality of pieces. As shown in FIG. 3, the valve housing 102 has a cavity 108 therein which can contain a valve mechanism 110.

[0030] Referring to FIGS. 1, in this embodiment of valve mechanism 110 includes a bracket 112, an actuator or valve stem 114, an actuator key 116, a lower valve seat cartridge 118 (sometimes also referred to as a "valve seat carrier"), a spring 120, a lower valve seat 122, seals 124 and 126, a valve ball 128, an upper valve seat 130, and a ring 132. In the embodiment of FIG. 1, seals 124a are teflon rings, seals 124b rubber o-rings, seals 124c parbak o-rings, and seal 126 a poly-pak ring. Naturally, these seals are merely one example of the many different combinations of seals which could be employed.

[0031] The valve mechanism 110 can be secured within the housing 102 with cap 134 (FIG.
3). In one embodiment illustrated in FIG. 8, cap 134 may be formed by upper sub housing member 102a which threads into lower sub housing member 102b. Upper sub housing member 102a presses against upper valve seat 130 to secure it in place within lower sub housing member 102b. In an alternative embodiment not illustrated, the cap 134 may be an element separate from the upper sub housing and includes threads which mate with complementary threads on the inner wall of the housing 102, thereby allowing the cap 134 to be screwed into the housing 102 in order to secure the valve mechanism 110 within the housing 102. The valve mechanism 110 can be removed from the housing 102, for example in order to replace the valve mechanism 110 or to perform maintenance on the valve mechanism 110 (e.g., replace seals), by unscrewing the cap 134 and removing the valve mechanism 110 from the housing 102.

[0032] In this embodiment, when the valve mechanism 110 is in an assembled state, the lower valve seat cartridge 118 is seated against the lower portion of the bracket 112. The lower valve seat cartridge 118 can have one or more protrusions 136 which engage one or more corresponding slots 138 formed in a first tongue 140 and a second tongue 142 of the bracket 112, thereby securing the lower valve seat cartridge 118 to the bracket 112.
All of the bracket 112 or portions of the bracket 112 (such as the first tongue 140 and the second tongue 142) can be constructed of a high strength, flexible material, such as a comparatively thin steel sheeting, including spring steel. In one example, the flexible material has a thickness ranging between about 50/1000 of an inch and about 3/8 of an inch, or any sub-range there between, although certain embodiments could be outside this range depending on the material used. In one preferred embodiment, bracket 112 is formed of spring steel about 100/1000 of an inch thick.
In certain preferred embodiments, bracket 112 is formed by water jetting or laser cutting the steel sheeting. Certain embodiments of bracket 112 are intended to be flexible by hand. In other words, the tongues 140 and 142 may be flexed apart sufficiently to allow the valve to be assembled and disassembled as described below. One example of being flexible by hand is flexing under about 10 lbs to 100 lbs force (or any sub-range there between) applied to the tongues 140 and 142.

[0033] The spring 120 is seated against the lower valve seat cartridge 118.
The spring 120 can be a wave spring, a coiled spring, or any other type of spring or force exerting device (whether conventional or future developed). The lower valve seat 122 is positioned against spring 120 and valve ball 128 is seated against the lower valve seat 122.
Upper valve seat 130 is engaged with first tongue 140 and the second tongue 142 of the bracket (as is further described below), and the upper valve seat 130 is positioned against the valve ball 128. Seal 1249, such as a Teflon 0-ring, is positioned between the lower valve seat 122 and the valve ball 128, and seals against the passage of fluid between the lower valve seat 122 and the outer surface of the valve ball 128. Similarly, seal 1249, such as a Teflon 0-ring, is positioned between the upper valve seat 130 and the valve ball 128, and seals against the passage of fluid between the upper valve seat 130 and the outer surface of the valve ball 128.

[0034] As shown in FIG. 1, in this embodiment the upper valve seat 130 includes a channel 144 around its circumference. As depicted in FIGS. 3, 5, and 6, the upper valve seat 130 includes a notch or planar section 146 and a side projection 168 extending from notch 146 with a channel or groove 148 formed in side projection 168. In this embodiment, the groove 148 is vertically extending in the sense that it extends into projection 168 in a direction of the axis along which the valve is assembled and disassembled, i.e., the line along which the parts are separated in FIG. 1. The first tongue 140 and second tongue 142 of the bracket 112 each include a lip 150 that engage notches 146, thereby connecting the bracket 112 to the upper valve seat 130.

[0035] In the illustrated embodiment, ring 132 is a split ring (as shown in FIG. 1), which can allow the ring 132 to be placed around or located about the upper valve seat 130, or removed from the upper valve seat 130. This ring 130 includes a first recessed portion 152, a second recessed portion 154, a first extended portion 156, and a second extended portion 158. In an assembled state, ring 132 sits within channel 144 and can be rotated around the upper valve seat 130 while traveling through the channel 144.

[0036] Referring to FIGS. 1, 3, 5, and 6, actuator 114 is connected to the actuator key 116 through opening 160 in the second tongue 142 of the bracket 112. The actuator key 116 includes a rib 162 that engages socket 164 of valve ball 128, thus mechanically connecting the actuator 114 with the valve ball 128. Rotation of the actuator 114 causes the valve ball 128 to rotate from a closed position (shown in FIGS. 3, 5, and 6) in which fluid is prevented from flowing through the valve mechanism 110, to an open position (not shown) in which fluid is able to flow through the valve mechanism 110 by traveling through passageway 166 of valve ball 128. FIG. 7 shows the valve mechanism of FIG. 6, but rotated 90 degrees about its vertical axis.

[0037] When the valve mechanism 110 is in an assembled state, the lower valve seat 122 and valve ball 128 are both biased toward the upper valve seat 130 by spring 120.
The spring 120 sits in the lower valve seat cartridge 118 and exerts a force on the lower valve seat 122 which presses the lower valve seat 122 towards the upper valve seat 130, resulting in a compressive force between the lower valve seat 122, seals 124 and 126, valve ball 128, an upper valve seat 130. The compressive force can allow seals 124 and 126 to form a proper seal around the valve ball 128 which prevents the passage of fluids.

[0038] In operation of an embodiment, the valve mechanism 110 can be quickly and easily assembled without the use of specialized tools. For example, bracket 112, lower valve seat cartridge 118, spring 120, lower valve seat 122, seal 124, valve ball 128, and seal 126 are first seated against each other as described above. Next, first tongue 140 and second tongue 142 are flexed away from each other allowing side projections 168 of the upper valve seat 130 to pass between the lips 150 of the first tongue 140 and the second tongue 142, and allowing the upper valve seat 130 to be seated on the valve ball 128. The first tongue 140 and second tongue 142 are then flexed towards each other to engage lips 150 with notches 146. Next, the bracket 112 is moved downward such that the lips 150 additionally engage and sit within the adjacent grooves 148. The ring 132 is then located about the upper valve seat 130 and placed within channel 144. The ring 132 is next rotated around the upper valve seat 130 until the ring 132 reaches a second ring position (depicted in FIGS. 3 and 5) where the first extended portion 156 and the second extended portion 158 are substantially aligned with the respective projections 168, and in which the lips 150 of the first tongue 140 and the second tongue 142 are obstructed by, and are prevented from exiting the notches 146 by, the first extended portion 156 and the second extended portion 158, thereby securing the first tongue 140 and the second tongue 142 of the bracket 112 to the upper valve seat 130. The valve mechanism 110 can then be placed within the housing 102 and the cap 134 can be screwed onto the housing 102.

[0039] In operation of this embodiment, in order to disassemble the valve 100 and valve mechanism 110, the process described above is to a certain extent reversed.
For example, the cap 134 can be unscrewed from the housing 102 and the valve mechanism 110 can be removed from the housing 102. The ring 132 is then rotated around the upper valve seat 130 until the ring 132 reaches a first ring position (depicted in FIG. 6) where the first recessed portion 152 and the second recessed portion 154 are substantially aligned with the respective projections 168, and in which the lips 150 of the first tongue 140 and the second tongue 142 are unobstructed by, and are able to exit the notches 146 by passage through, the first recessed portion 152 and the second recessed portion 154, thereby releasing the first tongue 140 and the second tongue 142 of the bracket 112 from the upper valve seat 130. If desired, the ring 132 can then be removed from the upper valve seat 130. Alternatively, the ring 132 can remain about the upper valve seat 130 located within channel 144, for example to allow for the quick and/or easy reassembly of the valve mechanism 110. Next, the bracket 112 is moved upward such that the lips 150 disengage from the grooves 148. The first tongue 140 and the second tongue 142 are then flexed away from each other to disengage lips 150 from notches 146. Next, first tongue 140 and second tongue 142 are flexed further away from each other (if necessary) allowing projections 168 of the upper valve seat 130 to pass between the lips 150 of the first tongue 140 and the second tongue 142, and allowing the upper valve seat 130 to be unseated from the valve ball 128. Bracket 112, lower valve seat cartridge 118, spring 120, lower valve seat 122, seal 124, valve ball 128, and seal 126 can then be unseated from each other. The above procedure can also allow the valve mechanism 110 to be quickly and easily disassembled without the use of specialized tools. If desired, seals 124, 126, and/or other components of the valve mechanism 110 can be repaired or replaced for example when the valve mechanism is in a disassembled or partially disassembled state. The valve 100 and valve mechanism 110 can then be reassembled for continued use.

[0040] Referring to FIGS. 9 to 14, an alternative embodiment of valve mechanism 110 is shown. In this embodiment, the first tongue 140 (Figure 10) and the second tongue 142 (Figure 9) of the bracket are separate, independently formed pieces. The protrusions 136 of the lower valve seat cartridge 118 engages the corresponding slots 138 of the first tongue 140 and the second tongue 142. The first tongue 140 and/or the second tongue 142 can be secured to the lower valve seat cartridge 118 by friction, such as friction between the outer rim of the protrusion 136 and the inner rim of the slot 138 and/or friction between the protrusion 136 and the slot 138, which is induced or increased by the biasing force of the spring 120 (Figure 13).
The first tongue 140 and/or the second tongue 142 can also be secured to the lower valve seat cartridge 118 by glue, such as a downholc epoxy, and/or a weld. Typically, the tongues 140/142 are intended to be permanently attached to the lower valve seat cartridge 118.
However, there can also be embodiments where the tongues 140/142 may be secured to the lower valve seat cartridge 118 (e.g., via epoxy or a weld) in a manner that the connection of the tongues 140/142 to the lower valve seat cartridge 118 is sufficiently weak such that the tongues 140/142 can be detached from the lower valve seat cartridge 118 by hand.

[0041] Another feature of this embodiment is seen in Figure 13. The side projection 168 includes an upwardly sloped shoulder 170. This upwardly sloped shoulder 170 is on the lower side of side projection 168, i.e., the side more proximate lower valve seat cartridge 118.
Although not explicitly shown, it can be understood how, during valve assembly, sloped shoulder 170 may assist tong 142 in spreading and being seated in channel 148 of side projection 168. It may be visualized that when lip 150 is below side projection 168 in the assembly process, downward force placed on upper valve seat 130 will cause sloping shoulder 170 to engage and to spread apart lip 150. Eventually lip 150 will spread sufficiently to move past side projection 168 and snap into place within channel 148.

[0042] Figures 15A and 15B illustrate a modified version of the tongues 140 and 142 engaging valve seat cartridge 118. In this embodiment, it can be seen that the upper end of slots 138 in tongues 140 and 142 have a "lower" step 171 formed in them. A mating "upper" step 172 is formed on the top end of protrusion 136. Figure 153 clearly illustrates how steps 171 =and 172 form an inter-locking structure which acts to resist outward movement of tongues 140/142 which would otherwise tend to allow the tongues to disengage from protrusions 136.
Naturally, steps 171 and 172 are merely one example of an inter-locking structure which could be formed between tongues 140/142 and protrusions 136 and any number of conventional or future developed inter-locking structures could be employed in the alternative.

[0043] Figures 16 and 17 illustrate a still further embodiment of the present invention. Figure 16 is an exploded view of the valve which generally includes the first valve seat carrier 218, the second valve seat carrier 219, first valve seat 230 engaging valve seat carrier 218, second valve seat 231 engaging second valve seat carrier 219, and the ball valve 128 positioned between the valve seats 230 and 231. This valve is similar to previous embodiments in that the valve seat carriers are connected via tongues 140/142 engaging the projections 168 and protrusions 136 on the respective valve seat carriers. However, the particular manner of securing the relative positions of the valve seat carriers is not critical to this embodiment and the bracket 112 in Figure 1 could be employed or any other conventional or future developed structure for securing the two valve scat carriers could likewise be employed.

[0044] Valve seats 230/231 differ from previous embodiments of the valve seats. As in earlier embodiments, the valve seats include a body 232 with a seal groove 233 (i.e., a groove for accepting a sealing member to prevent flow between the valve seats and the internal wall of the valve seat carriers), but this embodiment also includes at least one tongue section 234 extending away from the surface of the valve seat which engages valve ball 128. The tongue section 234 includes an outwardly projecting lip 235. In the Figure 16 embodiment, valve seat 230 has three tongue sections 234, but in other embodiments, the valve seat could have more than or fewer than three tongue sections.

[0045] Figure 16 also shows how the inside surface of valve seat carriers 218 and 219 will have an inner circumferential groove 239 (seen on valve seat carrier 219 in Figure 16). It will be understood that the tongue section 234 on valve seats 230 will flex inward to be inserted into valve seat carriers 218/219, past shoulder 240, such that the projecting lips 235 rest in circumferential groove 239. The cross-section of the assembled valve seen in Figure 17 best illustrates how the lips 235 rest in groove 239. Shoulder 240 limits movement of valve seat 230 away from valve ball 128. It can also be seen how the springs 241 form a biasing mechanism which biases the valve seats 230/231 toward ball valve 128. However, as suggested by the position of valve seat 230, the lips 235 cannot move past the shoulder 243 of seat groove 239 and thereby limit the movement of valve seat 230 towards the valve ball. Thus, the valve seat tongue 234 and lip 235 act as a stop mechanism operating between the valve seat carriers and the valve seats and only allow limited movement between the valve seat carriers and the valve seats. The biasing mechanism shown in Figures 16 and 17 is a single larger coil spring 237.
Howeverõ the biasing mechanism could be any conventional or future developed biasing device, . For example, Figure 18 illustrates a series of smaller coil springs 237 position in spring apertures 241 formed in valve seat shoulder 240.

[0046] If it is assumed in Figure 17 that pressure is acting on the left side of valve ball 128, it may be visualized how this pressure will act (when the valve ball is in the "closed" position) to force valve seat 230 and valve ball 128 to the right toward valve seat 231.
However, the travel of valve seat 230 is limited by the stop mechanism of lips 235 acting in groove 239, while valve ball 128 is allowed to continue moving to the right until its travel is arrested by valve seat 231 engaging valve seat shoulder 240 on valve seat carrier 219. It can be seen that in this position, valve ball 128 engages the o-ring seal 124 on valve seat 231, but valve ball 128 has moved out of sealing engagement with o-ring seal 124 on valve seat 230. Thus, this stop mechanism limits the travel of valve seat 230 towards valve ball 128 such that the valve ball may be pushed away from a sealing engagement with the valve seat 230. As one example, this travel distance is between about 0.0001 and about 0.75 inches, and most preferably about 0.1 inches, and therefore allows that degree of travel by the valve seats. However, the degree of allowable travel of the valve seats could vary considerably from this range in different embodiments.

[0047] Because the seal between valve ball 128 and valve seat 130 is not maintained, pressurized fluid may flow around valve ball 128 and equalize pressure on the left side of the ball and its hollow interior (see flow lines in Figure 17). It will be understood that this differs from certain prior art ball valves where the valve seat could follow the valve ball and the seal would be maintained between both valve seats and the valve ball. This prior art arrangement resulted in the force of pressurized fluid acting on the left valve seat and the left valve ball surface being transmitted to the opposite valve seat and ultimately to the structure maintaining the relative position of the two valve seats (in Figure 1, tongues 140/142).
The operation of this force over time may have undesirable effects by causing fatigue of the tongue structure and other parts of the ball valve.

[0048] Figures 19 and 20 illustrate an alternative stop mechanism structure.
Figure 20 shows the valve seat carriers 218 and 219 with a pin aperture 254 formed through their protrusions 136 and pin groove 252 formed on the outer surface of the valve seats 250 and 251, along with the seal grooves 256. The cross-sectional view of Figure 19 illustrates how the retaining pin 253 extends through the pin aperture 254 to engage the pin groove 252, It can be envisioned how retaining pin 253 will act limit the movement of the valve seats to the width of the pin groove 252 much like the of lips 235 acting in grooves 239 of Figure 15 to 18.
However, Figures 19 and 20 may be considered as disclosing the reverse structure of Figures 15 to 18, i.e., Figures 19 and 20 show a lip (retaining pin 253) formed on the valve scat carrier and a groove formed on the valve seat. It will be understood that Figures 15 to 20 disclose merely two examples of stop mechanisms and those skilled in the art will sec many different ways to implement other stop mechanisms between the valve seat carrier and the valve seat, all of which should be considered as falling within the scope of the present invention.

[0049] In Figures 16 to 20, the second valve seat and second valve seat carrier have substantially the same stop mechanism structure as valve seat /valve seat carrier. however, in alternate embodiments valve seat 231/valve seat carrier 219 may have a different stop mechanism structure or potentially no stop mechanism structure (e.g., valve seat 231 and valve seat carrier 219 are formed as a single unitary structure).

[0050] The embodiments shown in the drawings and described above are exemplary of numerous embodiments that may be made within the scope of the appended claims.
For example, while the illustrated embodiments disclose utilizing the ring 132 to help retain the tongues 140 and 142 of bracket 112, other embodiments could completely exclude the ring 132 (e.g., Figures 9 to 14) and simply rely on the spring biasing lip 150 to remain in groove 148.
Likewise, while protrusions 136 and side projections 168 are shown in the figures as different structures, other embodiments could utilize the same structure for protrusions 136 and side projections 168. It is also contemplated that numerous other configurations may be used, and the material of each component may be selected from numerous materials other than those specifically disclosed. In short, it is the applicant's intention that the scope of the patent issuing herefrom will be limited only by the scope of the appended claims.

Claims (29)

CLAIMS:

1. A valve, comprising:
a. a first and a second valve seat carrier;
b. a first valve seat associated with the first valve seat carrier and a second valve seat associated with the second valve seat carrier;
c. a valve ball between the valve seats;
d. a stop mechanism operatively connected to at least the first valve seat, the stop mechanism comprising a slot and a stop member acting between the first valve seat and the first valve seat carrier, the stop mechanism thereby limiting travel of the first valve seat towards the valve ball such that the valve ball is allowed to move away from a sealing engagement with the first valve seat; and e. at least one spring biasing the first valve seat toward the valve ball along an entire length of travel of the first valve seat.

2. The valve of claim 1, wherein the stop member comprises a lip formed on the first valve seat and the slot is formed in the first valve seat carrier.

3. The valve of claim 1, wherein the stop member comprises a pinning member extending through the first valve seat carrier to engage the slot formed in the first valve seat.

4. The valve of claim 1, further comprising a second stop mechanism operatively connected to the second valve seat, the stop mechanism comprising a slot and a stop member acting between the second valve seat and the second valve seat carrier, the stop mechanism thereby limiting travel of the second valve seat towards the valve ball such that the valve ball is allowed to move away from a sealing engagement with the second valve seat.

5. The valve of claim 4, wherein at least one spring biases the second valve seat toward the valve ball.

6. The valve of claim 1, wherein the travel of the valve seats is between about 0.0001 inches and about 0.75 inches.

7. The valve of claim 1, wherein the at least one spring comprises a single coil spring positioned on a shoulder in the first valve seat carrier.

8. The valve of claim 1, further comprising a valve housing into which the valve seat carriers are inserted.

9. The valve of claim 1, further comprising seals positioned between the valve ball and the valve seats.

10. The valve of claim 9, further comprising an actuator engaging the valve ball.

11. The valve of claim 1, wherein the at least one spring comprises a series of individual coil springs positioned on a shoulder in the first valve seat carrier.

12. A ball valve comprising:
a. a first and a second valve seat carrier;
b. a first valve seat cooperating with the first valve seat carrier and a second valve seat cooperating with the second valve seat carrier;
c. a valve ball positioned between the valve seats;
d. a first stop mechanism operatively connected to the first valve seat and a second stop mechanism operatively connected to the second valve seat, the stop mechanisms comprising a slot and a stop member acting between the valve seats and the valve seat carriers, the stop mechanisms configured to limit travel of the valve seats towards the valve ball such that the valve ball is allowed to move away from a sealing engagement with the valve seats; and e. at least one spring biasing the first valve seat toward the valve ball and at least one spring biasing the second valve seat toward the valve ball, wherein the springs maintain a biasing force on the valve seats after the valve ball moves away from sealing engagement with the valve seats.

13. The valve of claim 12, wherein the slot is formed on an external surface of the valve seats.

14. A valve, comprising:
a. a first and a second valve seat carrier;
b. a first valve seat associated with the first valve seat carrier and a second valve seat associated with the second valve seat carrier;
c. a valve ball between the valve seats;
d. a stop mechanism operatively connected to at least the first valve seat, the stop mechanism comprising a slot and a stop member acting between the first valve seat and the first valve seat carrier, the stop mechanism thereby limiting travel of the first valve seat towards the valve ball such that the valve ball is allowed to move away from a sealing engagement with the first valve seat; and e. wherein at least one biasing mechanism associated with each valve seat biases the valve seats toward the valve ball, both at a time when the first or second valve seat engages the valve ball and at a time when the valve ball has moved out of engagement with the first or second valve seat.

15. A valve, comprising:
a. first and second valve seat carriers;
b. a first valve seat associated with the first valve seat carrier and a second valve seat associated with the second valve seat carrier;
c. a valve ball between the valve seats;
d. a stop mechanism operating between each of (i) the first valve seat carrier and the first valve scat and (ii) the second valve seat carrier and the second valve seat, the stop mechanism comprising a groove formed in the valve seat carriers and a tongue and lip formed on the valve seats, wherein the lip engages and is retained in the groove, whereby the stop mechanism limits the travel of the valve seats towards the valve ball such that the valve ball is allowed to move out of sealing engagement with the valve seats; and e. a biasing mechanism biasing each valve seat toward the valve ball.

16. The valve of claim 15, wherein the movement of the valve seats is between about 0.0001 inches and about 0.75 inches.

17. The valve of claim 15, wherein the biasing mechanism is a series of individual coil springs positioned on a shoulder in the valve seat carrier.

18. The valve of claim 15, wherein the biasing mechanism is a single coil spring positioned on a shoulder in the valve seat carriers.

19. The valve of claim 15, further comprising a plurality of tongues formed on the valve seats.

20. The valve of claim 15, further comprising a seal preventing the flow of fluid between the valve seat carriers and the valve seats.

21. The valve of claim 15, further comprising a tongue between the valve seat carriers maintaining the relative position of the valve seat carriers.

22. The valve of claim 21, further comprising a valve housing into which the valve seat carriers are inserted.

23. The valve of claim 15, wherein both valve seats have a body which at least partially travels within their respective valve seat carrier.

24. The valve of claim 23, further comprising seals positioned between the valve ball and the valve seats.

25. The valve of claim 24, further comprising an actuator engaging the valve ball.

26. A valve having a central flow passage extending there through, the valve comprising:
a. a first valve seat carrier having a first projection on an outer surface of the first valve seat carrier with a first step formed on the first projection;

b. a second valve seat carrier having a second projection;
c. a first valve seat associated with the first valve seat carrier and a second valve seat associated with the second valve seat carrier;
d. a valve ball positioned above the first valve seat carrier and below the second valve seat carrier along an axis extending through the valve's central flow passage, such that the flow passage extends sequentially through the first valve seat carrier, the valve ball, and then the second valve seat carrier;
e. a stop mechanism associated with each said valve seat, the stop mechanism limiting the travel of the valve seats towards the valve ball such that the valve ball is allowed to move out of sealing engagement with the valve seats;
f. an independently formed tongue, the tongue including (i) a first aperture having a second step formed approximate the first aperture, and (ii) a second aperture;
g. wherein the second step on the first aperture engages the first step on the first projection, thereby resisting disengagement of the tongue from the first projection;
h. wherein the second step is an inner step and the first step is an outer step; and i. wherein the second aperture of the tongue engages the second projection.

27. The valve according to claim 26, wherein the first step is formed on a side of the first projection which is most proximate the second projection.

28. The valve according to claim 26, wherein the first projection extends radially outward relative to the central flow passage.

29. The valve according to claim 26, wherein the tongue is positioned radially outward of the valve scat carriers.