FIELD OF THE INVENTION The present invention is directed to a flow line coupling assembly for joining lengths of pipe used for conveying fluids such crude oil and particularly in offshore operations.

BACKGROUND OF THE INVENTION

Prior art pipeline couplings are either screw type connectors or are connector assemblies which require welding and take an extremely long time to assemble. Neither type of pipeline coupling has been acceptable for use in pipeline laying in offshore operations. The screw type connector have been unreliable in the harsh conditions of offshore operations. The other connectors take so long to make up that their use is economically prohibitive. The couplings which require welding are also limited to the use of materials which have good welding characteristics. This precludes the use of materials such as UNS, 31803, ASTM, A182, F6NM which do not weld very well but would otherwise be superior in other respects for use in pipelines. These and other difficulties experienced with the prior art flow line couplings have been obviated by the present invention.

It is, therefore, a principle object of the invention to provide a flow line coupling which can be coupled in a very short time.

A further object of the insertion is the provision of a flow line coupling which is not limited to the use of materials which have good welding characteristics. Another object of the present invention is to provide a flow line coupling which provides a good metal to metal seal and is reliable for an extended period of use.

With these and other objects in view, as. will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

BRIEF SUMMARY OF THE INVENTION

The present invention is a coupling assembly for leak proof connection of the ends of two lengths of pipe or tubing. One end of a first pipe is coupled to a coupling box which is

integrally formed on the end of a second pipe. The coupling box can also be a separate unit which is connected to the ends of both pipes. The coupling box has threads for engaging a nut for securing the coupling. The coupling box has a bore for receiving the end of the first pipe. The bore also contains an engager for operatively coupling the nut to the first pipe. The engager includes a split ring which has a longitudinal slot. The split ring has internal circumferential projections or gripping teeth which are aligned with external circumferential projections or gripping teeth on the end of the first pipe. As the nut as the nut is tightened, the split ring is compressed so that the gripping teeth of the split ring are brought into engagement with the gripping teeth of the first pipe. The split ring and the first pipe are then moved relative to the coupling box so that an outer tapered surface at the end of the pipe is forced into a metal to metal sealing contact with an inner tapered surface within the bore of the coupling box.

BRIEF DESCRIPTION OF THE DRAWINGS

The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings, in which:

FIG. 1 is a side elevational view of a first embodiment of a flow line coupling embodying the principles of the present invention;

FIG. 2 is a vertical cross-sectional view of the flow line coupling of FIG. 1 prior to the tightening of the nut; FIG. 3 is a vertical cross-sectional view of the low line coupling of FIG. 1 after tightening of the nut;

FIG. 4 is a side elevational view of a first pipe which forms part of the flow line coupling;

FIG. 5 is a bottom plan view of the pipe of FIG. 4; FIG. 6 is a top plan view of a coupling box which is operatively connected to a second pipe of the flow line coupling;

FIG. 7 is a vertical cross-sectional view of the coupling box taken along the line VI- VI of FIG. 5 and looking in the direction of the arrows;

FIG. 8 is a side elevational view of the coupling box;

FIG. 9 is a top plan view of a split ring which forms part of the flow line coupling of FIG. 1;

FIG. 10 is a side elevational view of the split ring of FIG. 9;

FIG. 11 is a vertical cross-sectional view of the split ring taken along the line XI-XI of FIG. 9 and looking in the direction of the arrows;

FIG. 12 is a top plan view of an actuating ring which forms part of the flow line coupling of FIG. 1;

FIG. 13 is a side elevational view of the actuating ring;

FIG. 14 is a vertical cross-sectional view of the actuating ring, taken along the line XIN-XIV of FIG. 9 and looking in the direction of the arrows;

FIG. 15 is a side elevational view of a nut which forms part of the flow line coupling of FIG. 1;

FIG. 16 is a vertical cross-sectional view of the nut of FIG. 15 taken along the line XVI-XVI of FIG. 15 and looking in the direction of the arrows; FIG. 17 is a bottom plan view of the nut of FIG. 15;

FIG. 18 is a vertical cross-sectional view of coupling box, split ring, actuating ring; and nut assembled to form a coupling box assembly;

FIG. 19 is a vertical cross-sectional view of a second embodiment of a flow line coupling; FIG. 20 is a vertical cross-sectional view of the coupling box portion of the flow line coupling of FIG. 18;

FIG. 21 is a vertical cross-sectional view of the nut portion of the flow line coupling of FIG. 18;

FIG. 22 is a vertical cross-sectional view of the coupling box assembly for the embodiment of FIG. 19;

FIG. 23 is a vertical cross-sectional view of a third embodiment of a flow line coupling prior to tightening of the nut;

FIG. 24 is a view similar to FIG. 23 showing the coupling after tightening of the nut;

FIG. 25 is a plan view of the split ring portion of the third embodiment; and FIG. 26 is a front elevational view of the split ring of FIG. 25.

DETAILED DESCRIPTION OF THE INVENTION

Referring first to FIGS. 1-3, a first embodiment of a flow line coupling embodying the principles of the present invention is generally indicated by the reference numeral 10 and is shown operatively connecting an upper pipe 12 to a lower pipe 14. The flow line coupling 10 includes a "pin" 16 at the lower end of the upper pipe 12 and which is integral part of the pipe. The outer surface of the pin 16 has a profile which is formed, as for example, by machining. The flow line coupling 10 also includes a coupling box 18 at the upper end of the pipe 14 and which is integral with the pipe 14. The inner surface of the coupling box 18 has a profile which is complementary with the outer profile of the pin 16 and is formed, as for example, by machining. The flow line coupling 10 includes an engager in the form of a split ring 20 and an actuating ring 22 which are located between the pin 16 and the coupling box. The flow line coupling 10 also includes a nut 24 which is located externally of the coupling box 18. The nut 24 has internal threads 26 for engaging external threads 28 of the coupling box for enabling the nut 24 to be tightened on the coupling box for forming a tight seal between the pin 16 and the coupling box 18 in a manner to be described hereinbelow.

The elements which make up the coupling box 10 are shown in FIGS. 4-17. Referring first to FIGS. 2, 4 and 5, the pin 16 has a first inner surface 29 and a first vertical cylindrical outer surface 36 which is concentric about the central longitudinal axis 32 of the pipe 12. The first inner surface 29 defines a first cylindrical bore 30 which has a bottom opening 34. The first outer surface 36 has a plurality of circumferential projections or outwardly facing gripping teeth 38 spaced from the bottom opening 34. Surface 36 has a first primary tapered portion 40 adjacent the bottom opening 34 and a first secondary tapered portion 41 between the first primary tapered portion 40 and the gripping teeth 38. The first primary tapered portion 40 is substantially closer to the central longitudinal axis 32 than the first secondary tapered portion 41. Each tapered portion 40 and 41 tapers inwardly toward the bottom opening 34.

Referring specifically to FIGS. 6-8, the coupling box 18 has a second outer surface 31 which contains the external threads 28. The coupling box 18 has a second annular inner surface, generally indicated by the reference numeral 42, which defines a second annular bore,

generally indicated by the reference numeral 44, which has a top opening 45. The bore 44 has a small diameter portion, generally indicated by the reference numeral 46, which is substantially spaced from the top opening 45 and a large diameter portion, generally indicated by the reference numeral 48, adjacent the top opening 45. The second inner surface 42 has a second primary tapered portion 50 at the small diameter portion 46 of the bore 44 and a second secondary tapered portion 52 between the second primary tapered portion 50 and the top opening 45. The tapered portions 50 and 52 taper outwardly toward the top opening 45. The second inner surface 42 of the coupling box has an upwardly and inwardly facing annular cam surface 54 at the lower end of the large diameter bore portion 48 and above the second secondary tapered portion 52 of the coupling box. The lower end of the large diameter bore portion 48 has a narrowed section 53 just below the cam surface 54. The second inner surface 42 also has an annular groove 43 for receiving an annular elastomeric sealing ring 47, see FIGS. 2 and 3. The coupling box 18 has an annular upper edge surface 51.

Referring specifically to FIGS. 15-17, the nut 24 has a vertical third outer surface 55 and a vertical third inner surface 56. The third inner surface 56 defines a third circular bore

60 which has an upper opening 58 and a lower opening 62. The bore 58 has a large diameter portion, generally indicated by the reference numeral 64, adjacent the lower opening 62, a small diameter portion, generally indicated by the reference numeral 66, adjacent the upper opening 60 and an intermediate diameter portion, generally indicated by the reference numeral 68, located between the small diameter portion 66 and the large diameter portion 64. A downwardly facing annular surface 70 is located between the small diameter portion 66 and the intermediate diameter portion 68 of the bore 58. The upper end of the third inner surface 56 has an annular groove 71 for receiving an annular elastomeric sealing ring 73, see FIGS. 2 and 3. The lower end of the inner surface 56 has an annular groove 75 for receiving an elastomeric sealing ring 75. A central portion of the inner surface 56 has an annular groove

79 for a purpose to be described. The third inner surface 56 at the large diameter bore portion 64 has the internal threads 26. The nut 24 has a downwardly facing annular surface or shoulder 69 just above the threads 26.

Referring specifically to FIGS. 9-11, the split ring 20 has an upper end, generally indicated by the reference numeral 72, and a lower end, generally indicated by the reference numeral 74. The split ring 20 has a vertical fourth inner surface 76 which define a fourth

bore, generally indicated by the reference numeral 78. The fourth inner surface 76 has a plurality of circumferential projections or inwardly facing griping teeth 80. The split ring 20 has an annular outer engaging surface 82 which tapers inwardly toward the upper end of the ring 20. The lower end 74 of the split ring 20 has an outwardly and downwardly facing annular cam surface 84. A vertical slot 86 extends all the way through the split ring 20. The split ring 20 is made of a metal which is sufficiently resiliently flexible to enable the split ring to be constricted so that its diameter is reduced upon application of sufficient external force to the outer engaging surface 82 of the split ring.

Referring specifically to FIGS. 12-14, the actuating ring 22 has an upper end, generally indicated by the reference numeral 88, and a lower end, generally indicated by the reference numeral 90. The actuating ring 22 has an upwardly facing end surface 92 and an annular inwardly facing engaging surface 94 adjacent the lower end of the actuating ring 22. The engaging surface 94 tapers outwardly toward the lower end 90 of the actuating ring 22. The actuating ring 22 has an outer surface 89 which contains an annular groove 91 near the upper end of the actuating ring. A plurality of threaded horizontal bores 93 extend from the groove 91 entirely through the actuating ring 22.

Referring specifically to FIG. 18, the flow line coupling 10 of the present invention is assembled by first positioning the split ring 20 within the bore of the coupling box 18 so that the outwardly facing cam surface 84 of the split ring rests against the inwardly facing cam surface 54 of the coupling box. The actuating ring 22 is applied to the upper end of the load ring 20 so that the lower end of the actuating ring is positioned between the split ring and the inner surface of the coupling box, wherein the inwardly facing engaging surface 94 of the actuating ring 22 engages the outwardly facing engaging surface 82 of the split ring 20. A snap ring 95 is positioned in the annular groove 91 of the actuating ring 22. The nut 24 is threaded onto the upper end of the coupling box 18 by means of the threads 26 and 28 until the downwardly facing surface 70 of the nut 24 engages the upwardly facing end surface 92 of the actuating ring 22 as shown in FIG. 18. At this point, the annular groove 79 is horizontally aligned with the annular groove 91 so that a portion of the snap ring 95 is also located in the groove 91. When all of the elements 20, 22, 24, and 18 of the coupling box are assembled as shown in FIG. 18, they define a coupling box assembly, generally indicated by the reference numeral 96. At this point, the nut 24 is in its upper loosening position and

the coupling box assembly 96 is ready to receive the lower end of the pipe 12, i.e., the pin 16. The pin 16 is inserted into the third circular bore of the nut 24 and through the rings 20 and 22 so that the lower end of the pin lies within the small diameter portion 46 of the coupling box as shown in FIG. 2. The nut 24 is tightened on the coupling box 18, to move the nut downwardly relative to the coupling box 18 from its upper loosening position shown in FIG. 2 to its lower tightening position shown in FIG. 3. The actuating ring 22 is forced downwardly by the downwardly facing annular surface 70 of the nut 24. The actuating ring 22, in turn, forces the split ring 20 slightly downwardly and inwardly due to the wedging action between the tapered surfaces 82 and 94. The annular cam surface 54 provides resistance against downward movement of the split ring 20 and enables the split ring to be constricted by the actuating ring 22. This causes the inwardly facing griping teeth 80 to move inwardly into gripping engagement with the outwardly facing gripping teeth 38 of the pin 16. Subsequent tightening of the nut 24 causes the rings 20 and 22 to move downwardly an additional amount and also causes the pin 16 to move downwardly due to the locking engagement between the gripping surfaces 80 and 38. The narrowed section 53 of the large diameter bore portion 48 insures that the gripping teeth 38 and 80 remain in engagement during the downward movement of the split ring 20. Eventually the annular tapered portions 40 and 41 of the pin 16 engage the annular tapered portions 50 and 52, respectively, of the inner surface of the coupling box 18 to form a metal to metal double seal between the pin 16 of the pipe 12 and the coupling box 18 which forms the upper portion of the pipe 14. At this point, the shoulder 69 of the nut is close to the upper end surface 51 of the coupling box to prevent the nut from being tightened any further than what is required to achieve a metal to metal seal between the pin 16 and the coupling box 18.

The flow line coupling 10 of the present invention is uncoupled by reversing the assembling procedure described above. When the nut 24 is unthreaded so that the nut moves upwardly relative to the coupling box 18, the actuating ring 22 is also drawn upwardly through the interengagement of the nut 24 and actuating ring 22 with the snap ring 95. The upward movement of the actuating ring 22 causes the actuating ring to disengage from its wedging action with the split ring 20. This enables the split ring to return to its normal open position, as shown in FIG. 2, wherein the inwardly facing gripping teeth 80 to move out of engagement with the outwardly facing gripping teeth 38 of the pin 16. The pin 16 can then

be removed from the coupling box assembly 96. The time required to make the coupling will be substantially less than 10 minutes and, realistically within 6-8 minutes. Additional time may be required where back pressurization of the sealing areas is required by a customer. Back pressurization for testing for treating the effectiveness of the metal to metal seal between the pin 151 and the coupling box 152 is provided by drilling ports into the coupling box to accommodate the required pressure fittings, see for example, pressure fittings 122 in the coupling box of the second embodiment of the invention shown in FIGS. 19-22. It is likely that, with the use of quick connect hose couplings, the pressure testing could be completed in 2-3 minutes. In the embodiment of the invention described above, the coupling box is an integral part of the lower pipe 14. The coupling box can be a separate double ended unit, wherein the lower end of the coupling box is identical to the upper end of the coupling box for interacting with the upper end of a lower pipe which has an integral pin that is comparable to pin 16 of the pipe 12. A second set of rings 20 and 24 and a nut 24 are also employed in interactive fashion with the lower end of the coupling box and the pin which is an integral part of the lower pipe.

Referring to FIGS. 19-21, there is shown a second embodiment of a flow line coupling, generally indicated by the reference numeral 98, and is shown operatively connected to the upper pipe 12 which includes the pin 16. The flow line coupling 98 includes a coupling box 100 which is integrally connected to the upper end of a lower pipe 14'. The flow line coupling 89 also includes the split ring 20 which forms part of the flow line coupling embodiment 10.

Referring specifically to FIGS. 19 and 20, the coupling box 100 has a second outer surface 104 and a second inner surface 106. The. second inner surface 106 defines a second annular bore, generally indicated by the reference numeral 110, which has a top opening 112.

The bore 110 has a small diameter portion, generally indicated by the reference numeral 114, near the lower pipe 14' and a large diameter portion, generally indicated by the reference numeral 116 adjacent the top opening 112. The second inner surface 106 has internal threads 108 at the large diameter lower portion 116. The second inner surface 106 has a second primary tapered portion 118 at the small diameter portion 114 of a second bore 110 and a second secondary tapered portion 120 between the threads 108 and the primary tapered

portion 118. The tapered portions 118 and 120 taper outwardly toward the top opening 112. The second inner surface 106 of the coupling box 100 has upwardly and inwardly facing annular cam surface 121 at the lower end of the large diameter portion 116 and above the second secondary tapered portion 120 of the coupling box 100. The lower end of the large diameter bore portion 116 has a narrowed section 123 just below the cam surface 121. The second inner surface 42 also has an annular groove 124 for receiving elastomeric sealing ring 128 and an annular groove 126 for receiving an elastomeric sealing ring 130. Ports 122 extends from the outer surface 104 to the inner surface 106 of the coupling box 100 for receiving pressure fittings that arc adapted to be connected to quick connect hose couplings for pressure testing. The coupling box 100 has an annular upper edge surface 129.

Referring specifically to FIG. 21, the nut 102 has a vertical third annular outer surface 131 and a third annular out inner surface 132. The third inner surface 132 defines a third circular bore 134 which has an upper opening 136 and a lower opening 138. The lower end of the third outer surface 131 has external threads 140. An annular protuberance 142 extends outwardly from the third outer surface 131 above the threads 140. The protuberance 142 has a downwardly facing annular horizontal surface 144 just above the threads 140. The lower end of the third inner surface 132 has a tapered portion 146 which tapers outwardly toward the bottom opening 138.

Referring to FIG. 22, the flow line coupling 98 is made up by first positioning the split ring 20 within the bore 134 of the coupling box 100 so that the outwardly facing cam surface 84 of the split ring rest against the inwardly facing cam surface 121 of the coupling box. The nut 102 is applied to the coupling box 100 by inserting the lower end of the nut between the split ring 20 and the upper end of the coupling box and threading the nut 102 onto the coupling box until the tapered surface 146 of the nut engages the tapered surface 82 of the split ring 20 as shown in FIG. 22. When the coupling box 100, split ring 20, and nut

102 are assembled as shown in FIG. 22, they define a coupling box assembly, generally indicated by the reference numeral 148. At this point, the nut 102 lies in its upper loosening position and the coupling box assembly 148 is ready to receive the lower portion or pin 116 of the upper fluid pipe 12. The pin 16 is inserted into the third circular bore of the nut 102 and through the split ring 20 so that the lower end of the pin lies within the small diameter portion 114 of the coupling box. The nut 102 is tightened on the coupling box 100 to move

the nut downwardly relative to the coupling box from its upper loosening position shown in FIG. 22 to its lower tightening position shown in FIG. 19. The downward movement of the lower end of the nut 102 forces the split ring 20 slightly downwardly and inwardly due to the wedging action between the tapered surfaces 82 and 146. The annular cam surface 121 provides resistance against the downward movement of the split ring 20 and enables the split ring to be constricted by the lower end of the nut 102. This causes the inwardly facing gripping teeth 80 to move inwardly into gripping engagement with the outwardly facing gripping teeth 38 of the pin 16. Subsequent tightening of the nut 102 causes the split ring 20 to move downwardly an additional amount and also causes the pin 16 to move downwardly due to the locking engagement between the gripping surfaces 80 and 38. The narrowed section 123 of the large diameter bore portion 114 of the coupling box ensures that the gripping piece 38 and 80 remain in engagement during the downward movement of the split ring 20. Eventually the annular tapered portions 40 and 41 of the pin 16 engages annular tapered portions 118, respectively, of the inner surface of the coupling box 100 to form a metal to metal double seal between the pin 16 of the pipe 12 and the coupling box

100 which forms the other portion of the pipe 14'. At this point the downwardly facing annular surface 144 of the nut 102 is at or very close to the upper end surface 129 of the coupling box 100 to prevent the nut from being tightened any further than what is required to achieve a metal to metal seal between the pin 16 and the coupling box 100. A flow line coupling 98 is uncoupled by reversing the assembling procedure described above.

The pressure fitting ports 122 are vertically spaced and the elastomeric seal is located between the ports 122 and also between the metal to metal sealing areas. This arrangement enables the metal to metal sealing areas to be independently tested and verified. Referring to FIGS. 23 and 24, there is shown a third embodiment of a flow line coupling, generally indicated by the reference numeral 150 and is shown operatively connecting an upper fluid pipe 156 to a lower fluid pipe 158. The flow line coupling 150 includes a "pin" 151 at the lower end of the pipe 156 and which is an integral part of the pipe. The flow line coupling also includes a coupling box 152 at the upper end of the lower pipe 158 which is an integral portion of the pipe 158, a nut 154 and a split ring 160. The pipe 156 has a first outer surface 164, a first cylindrical inner surface 166, a first vertical bore

168 and a bottom opening 170 to the first bore 168. The first outer surface 164 has a plurality of outwardly facing gripping teeth 172. The outer surface 164 or the lower one end of the pipe 156 at the pin 151 has a first primary tapered portion 174 and a first secondary tapered portion 176. The outer surface of the pin 151 has a downwardly facing annular surface or shoulder 175 between the gripping teeth 172 and the first tapered portion 176.

The coupling box 152 has a second inner surface 178 and a second bore 180 and a top opening 184 to the bore 180 at the upper end 182 of the coupling box. The inner surface 178 of the coupling box has internal threads 190 at the upper end 182 of the coupling box adjacent the top opening 184. The lower end of the second inner surface 178 has a profile which is complementary with the outer profile of the pin 151 and comprises a second primary tapered portion 186 and a second secondary tapered portion 188. The second inner surface 178 also has a plurality of vertically spaced inwardly facing cam surfaces 183, 185, and 187 located between the internal threads 190 and the tapered surface portions 186 and 188. The coupling box 152 has an annular upper edge surface 191. The nut 154 has a third inner surface 192 which defines a third circular bore 194 having an opening 196 at the upper end of the bore and a lower opening 198 at the lower end of the bore. The nut 154 also has a third outer surface 200 which contains outer threads 202 at the lower end of the nut for engaging the internal threads 190 of the coupling box 152. The nut 154 has a downwardly facing annular surface or shoulder 201 just above the threads 202. The inner surface 192 has an annular groove 203 near the top opening 196 for receiving an elastomeric sealing ring 205.

Referring to FIGS. 23-26, the split ring 160 has a vertical slot 204 which extends entirely through the split ring and a plurality of vertically spaced outwardly facing cam surfaces 206, 207, and 208 which are complimentary with the cam surfaces 183, 185, and 187, respectively of the coupling box 152. The inner surface of the split ring has a plurality of inwardly facing gripping teeth 210 which are complimentary with the outwardly facing gripping teeth 172 of the lower portion of the pipe 156 or pin 151. The lower end of the split ring 160 has an annular flange 211 which extends inwardly beyond the gripping teeth 210.

The flow line coupling 150 is assembled by first positioning the split ring 160 within the bore 180 of the coupling box so that the outwardly facing cam surfaces 206, 207, and 208 are engaged with the inwardly facing cam surfaces 183, 185, and 187, respectively. The

lower end of the nut 154 is inserted into the second bore 180 through the top opening 184 so that the outer threads 202 of the nut engage the inner threads 190 of the coupling box. The lower "pin" end 151 of the pipe 156 is inserted through the bore 194 of the nut 154 and through the split ring 160 until the annular downwardly facing surface 177 of the pin 151 engages the inwardly facing annular flange 211 of the split ring 160. When the surface 177 rests on the flange 211, the gripping teeth 172 and 183 are spaced but horizontally aligned as shown in FIG. 23. Also, the first primary and secondary tapered surface portions 174 and 176 of the pipe 156 are spaced from and located above the second primary and secondary tapered portions 186 and 188 of the inner surface of the coupling box. The nut 154 is rotated so that it advanced toward the coupling box 152 until the lower edge of the nut engages the upper edge of the split ring 160. Additional turning of the nut 154 causes the lower end of the nut to force the split ring 160 downwardly. Downward movement of the split ring 160 causes the split ring to contract due to the engagement of its cam surfaces 206, 207, and 208 against the cam surfaces 183, 185, and 187 respectively. The constriction of the split ring 160 causes the ripping teeth 210 of the split ring to engage the gripping teeth 172 of the pipe

156. Additional tightening of the nut 154 toward the coupling box 152 forces the pipe 156 downwardly. When the annular surface 201 of the nut 154 is at or near the annular upper end surface 191 of the coupling box, the first and secondary tapered portions 174, and 176, respectively, of the outer surface of the pipe 156 engage the second primary and secondary tapered portions 186 and 188, respectively of the coupling box 152. This forms a tight metal to metal double seal between the pin portion 151 of the pipe 156 and the coupling box 152 which is an integral upper portion of the pipe 158. The flow line coupling 150 is uncoupled by reversing the assembling procedure described above. As in the case of previous embodiments, the coupling box 152 is provided with upper and lower ports 209 and 212, respectively, for receiving pressure fittings for testing the effectiveness of the metal to metal seal between the pin 151 and the coupling box 152. The first secondary tapered portion 176 of the pin 151 has an annular groove which contains an elastomeric sealing ring 213 which is located between the upper and lower ports 209 and 212, respectively. An elastomeric sealing ring 214 is located in an annular groove 216 in the inner surface of the coupling box 152 below the threads 190.

Clearly minor changes may be made in the form and construction of this invention

without departing from the material spirit thereof. Therefore, it is not desired to confine the invention to the exact form shown herein and described, but it is desired to include all subject matter that properly comes within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is: