CN222045685U - A continuous tubing connection joint - Google Patents

Abstract

The utility model belongs to the technical field of petroleum and natural gas engineering, and discloses a continuous oil pipe connecting joint capable of improving connection tensile strength, pressure bearing tightness and rotation flexibility. Including last pit joint, first ball cover, first bulb, adapter, second ball cover, second bulb and lower pit joint, the upper end that goes up the pit joint links to each other with first coiled tubing, the lower extreme links to each other with the upper end seal of first ball cover, the lower extreme of first ball cover is articulated with the upper end seal of first bulb, the lower extreme of first bulb links to each other with the upper end seal of adapter, the lower extreme of adapter links to each other with the upper end seal of second ball cover, the lower extreme of second ball cover is articulated with the upper end seal of second bulb, the lower extreme of second bulb links to each other with the upper end seal of lower pit joint, the lower extreme of lower pit joint links to each other with second coiled tubing. The upper pit joint and the lower pit joint are respectively provided with a plurality of first pits and second pits which are used for being connected with the first continuous oil pipe and the second continuous oil pipe in a pressing mode.

Description

Continuous oil pipe connecting joint

Technical Field

The utility model relates to the technical field of petroleum and natural gas engineering, in particular to a continuous oil pipe connecting joint.

Background

The coiled tubing is widely applied to the operations of workover, drilling, completion, logging and the like of oil and gas fields, and penetrates through the whole process of oil and gas exploitation, and is known as a universal working machine.

A coiled tubing connector is a connection tool that connects a coiled tubing to a coiled tubing or to a downhole tool quickly at the surface. Currently, coiled tubing connectors are largely classified into screw-type and slip-type according to the manner of locking. The screw type coiled tubing connector is generally a connection mode for locking the outer wall of the coiled tubing by adding screws to the outer wall of the coiled tubing, so that torque and tension are transmitted, most of the screw type coiled tubing connector belongs to single outer wall compaction, the single outer wall compaction is limited by considering that the coiled tubing can shrink and deform when being compacted, the transmitted torque and tension are smaller, and the screw type coiled tubing connector is only suitable for connection between the coiled tubing and a downhole tool in logging, gas lifting and other operations with small downhole tubular column acting force, and is not suitable for coiled tubing operation with large acting force and good pressure-bearing sealing capability; meanwhile, most screw type connectors can be connected in a buckling mode only by rotating around the axial direction in the connecting process, when the continuous oil pipe is connected with the continuous oil pipe, the two continuous oil pipes cannot rotate, and therefore the screw type connectors are not suitable for connection operation of the continuous oil pipe and the continuous oil pipe. The slip type coiled tubing connector is generally in a connection mode that the outer wall of the coiled tubing is locked by adding slips to the outer wall of the coiled tubing, and the slip locking force is limited due to shrinkage deformation caused by compaction of the coiled tubing, so that the slip type coiled tubing connector is only suitable for connection between the coiled tubing and a downhole tool in logging, gas lifting and other operations with small downhole tubular column acting force, and is not suitable for coiled tubing operation with large acting force and good pressure-bearing sealing capability; meanwhile, most slip-type continuous oil pipe connectors can realize slip tightening connection by rotating around the axial direction in the connection process, and when continuous oil pipes are connected with the continuous oil pipes, the two continuous oil pipes cannot rotate, so that the slip-type connectors are not suitable for connection operation of the continuous oil pipes and the continuous oil pipes.

Disclosure of utility model

In order to solve the problems of tensile strength, pressure bearing tightness and flexible rotation after the continuous oil pipe continuous joint is connected with the continuous oil pipe, the novel continuous oil pipe connecting joint is provided.

The coiled tubing connection joint according to the present utility model comprises: the upper end of the upper pit joint is used for being connected with a first continuous oil pipe, the lower end of the upper pit joint is connected with the upper end of the first ball joint in a sealing mode, the lower end of the first ball joint is connected with the upper end of the adapter in a sealing mode, the lower end of the adapter is connected with the upper end of the second ball joint in a sealing mode, the lower end of the second ball joint is connected with the upper end of the lower pit joint in a sealing mode, the lower end of the lower pit joint is used for being connected with a second continuous oil pipe in a sealing mode, a plurality of first pits used for being connected with the first continuous oil pipe in a pressing mode are formed on the outer surface of the upper pit joint, and a plurality of second pits used for being connected with the second continuous oil pipe in a pressing mode are formed on the outer surface of the lower pit joint.

Further, the upper pit joint comprises a first small-diameter section and a first large-diameter section coaxially connected with the first small-diameter section, the first small-diameter section is connected with the first continuous oil pipe, the first large-diameter section is connected with the first ball head sleeve, and a plurality of first pits are formed on the peripheral wall of the first small-diameter section; the lower pit joint comprises a second small-diameter section and a second large-diameter section coaxially connected with the second small-diameter section, the second small-diameter section is connected with the second continuous oil pipe, the second large-diameter section is connected with the second ball head, and a plurality of second pits are formed on the peripheral wall of the second small-diameter section.

Further, a plurality of first dimples are alternately formed on the outer peripheral wall of the first small-diameter section, and a plurality of second dimples are alternately formed on the outer peripheral wall of the second small-diameter section.

Further, the first continuous oil pipe is sleeved on the first small-diameter section, and the outer peripheral surface of the first continuous oil pipe is flush with the outer peripheral surface of the first large-diameter section; the second continuous oil pipe is sleeved on the second small-diameter section, and the outer peripheral surface of the second continuous oil pipe is flush with the outer peripheral surface of the second large-diameter section.

Further, the lower end of the upper pit joint is in threaded sealing connection with the upper end of the first ball head, the lower end of the first ball head is in threaded sealing connection with the upper end of the adapter, the lower end of the adapter is in threaded sealing connection with the upper end of the second ball head, and the lower end of the second ball head is in threaded sealing connection with the upper end of the lower pit joint.

Further, external threads and a sealing groove formed on the external threads and used for installing a sealing ring are formed on the outer peripheral wall of the lower end of the upper pit joint, the outer peripheral wall of the lower end of the first ball head, the outer peripheral wall of the lower end of the adapter and the outer peripheral wall of the lower end of the second ball head; internal threads matched with the external threads are formed on the inner peripheral wall of the upper end of the first ball sleeve, the inner peripheral wall of the upper end of the adapter, the inner peripheral wall of the upper end of the second ball sleeve and the inner peripheral wall of the upper end of the lower pit joint.

Further, the first ball head comprises a first ball head section and a first rod section connected with the first ball head section, the first rod section is connected with the adapter, the outer diameter of the first ball head section is larger than that of the first rod section, and a first ball groove for rotationally fitting with the spherical surface of the first ball head section is formed in the inner peripheral wall of the lower end of the first ball head sleeve; the second ball head comprises a second ball head section and a second rod section connected with the second ball head section, the second rod section is connected with the lower pit joint, the outer diameter of the second ball head section is larger than that of the second rod section, and a second ball groove used for rotating and jointing with the spherical surface of the second ball head section is formed in the inner peripheral wall of the lower end of the second ball head sleeve.

Further, a first conical surface with the inner diameter gradually decreasing inwards is formed on the lower end surface of the first ball sleeve, the small-diameter end of the first conical surface is connected with the first spherical groove, and a first included angle is formed between the first conical surface and the outer peripheral wall of the first rod section; the lower end face of the second ball sleeve is provided with a second conical surface with the inner diameter gradually decreasing inwards in the axial direction, the small diameter end of the second conical surface is connected with the second spherical groove, and a second included angle is formed between the second conical surface and the outer peripheral wall of the second rod section.

Further, the joint of the small diameter end of the first conical surface and the first ball groove is always attached to the outer surface of the first ball head section; the junction of the small diameter end of the second conical surface and the second ball groove is always attached to the outer surface of the second ball head section.

Further, a sealing groove for installing a sealing ring is formed on the outer wall of the first ball head section, which is attached to the first ball groove, and the outer wall of the second ball head section, which is attached to the second ball groove.

The pits are connected through the upper pit joint and the lower pit joint, so that the tensile capacity is high, the outer diameter of the connected pits is equal to that of the coiled tubing, the coiled tubing can smoothly pass through the coiled tubing equipment, and the coiled tubing can be coiled on the coiled tubing roller; the universal joint structure formed by the ball head, the ball head sleeve and the conversion head increases the flexibility after connection, and can realize 15-degree included angle bending and flexible rotation of 360 degrees; the built-in O rings enhance the sealing capacity of the inside and outside of the connected pipe, so that the sealing is not invalid when the pipe is bent and rotated; the loose joint combined connection structure can be freely selected according to the number of loose joints.

Drawings

Fig. 1 is a schematic structural view of a coiled tubing connection joint according to an embodiment of the present utility model.

Detailed Description

The present utility model will be described in further detail with reference to the accompanying drawings for a better understanding of the objects, structures and functions of the present utility model.

Fig. 1 shows the structure of a coiled tubing connection sub 100 according to an embodiment of the present utility model. As shown in fig. 1, the coiled tubing connection sub 100 may include: the upper pit joint 1, the first ball head sleeve 2, the first ball head 3, the adapter 4, the second ball head sleeve 5, the second ball head 6 and the lower pit joint 7 that link to each other in proper order, the upper end of upper pit joint 1 is used for connecting first coiled tubing (not shown in the figure), the lower extreme of upper pit joint 1 links to each other with the upper end of first ball head sleeve 2 is sealed, the lower extreme of first ball head sleeve 2 links to each other with the upper end of first ball head 3 is sealed, the lower extreme of first ball head 3 links to each other with the upper end of adapter 4 is sealed, the lower extreme of adapter 4 links to each other with the upper end of second ball head sleeve 5 is sealed, the lower extreme of second ball head sleeve 5 links to each other with the upper end of second ball head 6 is sealed, the lower extreme of second ball head 6 links to each other with the upper end of lower pit joint 7 is used for connecting second coiled tubing (not shown in the figure) is lower extreme of lower pit joint 7. Wherein a plurality of first dimples 13 for press-connection with the first continuous oil pipe are formed on the outer surface of the upper dimple joint 1, and a plurality of second dimples 73 for press-connection with the second continuous oil pipe are formed on the outer surface of the lower dimple joint 7.

When the coiled tubing connecting joint 100 of the embodiment of the utility model is used, the first coiled tubing and the upper pit joint 1 are connected together through the pressing of the first pit 13, the second coiled tubing and the lower pit joint 7 are connected together through the pressing of the second pit 73, and the plurality of pits are connected in a pressing way, so that the tensile resistance and the anti-rotation capacity of the coiled tubing connecting joint 100 and the first coiled tubing and the coiled tubing connecting joint 100 and the second coiled tubing after being connected are stronger, and the coiled tubing connecting joint 100 of the embodiment of the utility model can be better suitable for the connection of the coiled tubing with downhole tools in logging, gas lifting and other operations with larger downhole tubular column acting force; the upper pit joint 1 is in sealing connection with the first ball joint 2, the first ball joint 2 is in sealing connection with the first ball joint 3, the first ball joint 3 is in sealing connection with the adapter 4, the adapter 4 is in sealing connection with the second ball joint 5, the second ball joint 5 is in sealing connection with the second ball joint 6 and the lower pit joint 7, so that the continuous oil pipe connecting joint 100 is higher in pressure bearing sealing performance, and the continuous oil pipe connecting joint 100 can be better suitable for continuous oil pipe operation with good pressure bearing sealing capability; through setting up the lower extreme of first ball cover 2 and the upper end seal hinge of first bulb 3 to and the lower extreme of second ball cover 5 and the upper end seal hinge of second bulb 6, not only increased the flexibility after coiled tubing attach fitting 100 is connected with coiled tubing, thereby coiled tubing attach fitting 100 can rotate around the axial in the course of connection in order to realize its respectively quick butt joint with coiled tubing, seal hinge's mode still makes coiled tubing attach fitting 100 crooked rotatory while seal inefficacy not, has also realized in addition that coiled tubing attach fitting 100 can be coiled to the coiled tubing cylinder.

It should be noted that, in the coiled tubing connection joint 100 of the embodiment of the present utility model, the first ball socket 2 and the first ball head 3 form one loose joint combination, the second ball socket 5 and the second ball head 6 form another loose joint combination, the two loose joint combinations are connected through one adapter 4, and according to actual needs, the number of the loose joint combinations is not limited to two in the present utility model, and a plurality of adjacent loose joint combinations can be connected through the adapter 4.

In a preferred embodiment as shown in fig. 1, the upper dimple joint 1 may include a first small-diameter section 11 and a first large-diameter section 12 coaxially connected to the first small-diameter section 11, the first small-diameter section 11 being connected to the first continuous oil pipe, the first large-diameter section 12 being connected to the first ball socket 2, a plurality of first dimples 13 being formed on an outer peripheral wall of the first small-diameter section 11; the lower dimple joint 7 may include a second small-diameter section 71 and a second large-diameter section 72 coaxially connected to the second small-diameter section 71, the second small-diameter section 71 being connected to the second coiled tubing, the second large-diameter section 72 being connected to the second ball head 6, and a plurality of second dimples 73 being formed on the outer peripheral wall of the second small-diameter section 71. In this embodiment, the first small diameter section 11 and the second small diameter section 71 may facilitate insertion into the first coiled tubing and the second coiled tubing, respectively, thereby facilitating subsequent rapid compression of the connection pit.

Preferably, as shown in fig. 1, a plurality of first pits 13 may be formed alternately on the outer circumferential wall of the first small-diameter section 11, and a plurality of second pits 73 may be formed alternately on the outer circumferential wall of the second small-diameter section 71. By arranging the plurality of first dimples 13 and the plurality of second dimples 73 alternately, respectively, the tensile and anti-rotation capabilities of the coiled tubing connection joint 100 and the first coiled tubing and the coiled tubing connection joint 100 and the second coiled tubing after connection can be further improved.

Further preferably, as shown in fig. 1, the first continuous oil pipe is sleeved on the first small-diameter section 11, and the outer peripheral surface of the first continuous oil pipe is level with the outer peripheral surface of the first large-diameter section 12; the second coiled tubing is sleeved on the second small-diameter section 71, and the outer peripheral surface of the second coiled tubing is flush with the outer peripheral surface of the second large-diameter section 72. The arrangement is such that the first and second connecting tubing are respectively sleeved on the first and second minor diameter sections 11, 71 and then are equivalent to the respective coiled tubing outer diameters so that they can pass smoothly through the coiled tubing apparatus.

In the preferred embodiment shown in fig. 1, the lower end of the upper dimple joint 1 may be screw-tightly connected to the upper end of the first ball joint 2, the lower end of the first ball joint 3 may be screw-tightly connected to the upper end of the adapter 4, the lower end of the adapter 4 may be screw-tightly connected to the upper end of the second ball joint 5, and the lower end of the second ball joint 6 may be screw-tightly connected to the upper end of the lower dimple joint 7. The threaded sealing connection mode in the embodiment not only can improve the convenience of connection and disassembly among the components, but also can further improve the connection and pressure bearing sealing performance among the components.

Preferably, as shown in fig. 1, an external thread 8 and a sealing groove 9 formed on the external thread 8 for installing a sealing ring are formed on the outer circumferential wall of the lower end of the upper pit joint 1, the outer circumferential wall of the lower end of the first ball head 3, the outer circumferential wall of the lower end of the adapter 4, and the outer circumferential wall of the lower end of the second ball head 6; internal threads which are matched with the external threads 8 are formed on the inner peripheral wall of the upper end of the first ball cover 2, the inner peripheral wall of the upper end of the adapter 4, the inner peripheral wall of the upper end of the second ball cover 5 and the inner peripheral wall of the upper end of the lower pit joint 7. Through the arrangement, under the combined action of the threaded connection and the sealing ring, the connection and pressure bearing tightness between the components can be further improved.

In the preferred embodiment shown in fig. 1, the first ball head 3 may include a first ball head segment 31 and a first shaft segment 32 connected to the first ball head segment 31, the first shaft segment 32 is connected to the adapter 4, the outer diameter of the first ball head segment 31 is larger than the outer diameter of the first shaft segment 32, and a first ball groove 22 for rotationally fitting the first ball head segment 31 is formed on the inner peripheral wall of the lower end of the first ball head sleeve 2; the second ball head 6 may include a second ball head section 61 and a second shaft section 62 connected to the second ball head section 61, the second shaft section 62 being connected to the lower pit joint 7, an outer diameter of the second ball head section 61 being larger than an outer diameter of the second shaft section 62, and a second ball groove 51 for spherical rotation fit with the second ball head section 61 being formed on an inner peripheral wall of a lower end of the second ball head cover 5. This embodiment enables the first ball head 3, the first ball socket 2, and the transition head to form a gimbal structure, thereby increasing flexibility after the coiled tubing connection joint 100 is connected with the coiled tubing.

Preferably, as shown in fig. 1, the lower end surface of the first club head cover 2 may be formed with a first tapered surface 21 with an inner diameter gradually decreasing inward in the axial direction, the small diameter end of the first tapered surface 21 is connected with the first ball groove 22, and a first included angle is formed between the first tapered surface 21 and the outer peripheral wall of the first shaft section 32; the lower end surface of the second ball sleeve 5 is formed with a second conical surface 52 with an inner diameter gradually decreasing inwards in the axial direction, the small diameter end of the second conical surface 52 is connected with the second ball groove 51, and a second included angle is formed between the second conical surface 52 and the outer peripheral wall of the second rod section 62. This arrangement enables the first ball head 3 to be bent at a first angle relative to the first ball head cover 2 and the second ball head 6 to be bent at a second angle relative to the second ball head cover 5. Further preferably, the first angle and the second angle may each preferably be 15 °.

In the preferred embodiment shown in fig. 1, the junction of the small diameter end of the first conical surface 21 and the first spherical groove 22 is always in contact with the outer surface of the first ball segment 31; the junction of the small diameter end of the second conical surface 52 and the second spherical groove 51 is always attached to the outer surface of the second ball head section 61. This arrangement enables the first ball segment 31 to be more stably snap-fitted in the first ball groove 22, while the second ball segment 61 can be more stably snap-fitted in the second ball groove 51.

Further, as shown in fig. 1, the outer wall of the first ball head segment 31, which is attached to the first ball groove 22, and the outer wall of the second ball head segment 61, which is attached to the second ball groove 51, are provided with sealing grooves 9 for installing sealing rings, so as to improve the pressure-bearing hinged tightness between the first ball head 3 and the first ball head sleeve 2, and between the second ball head 6 and the second ball head sleeve 5.

In addition, as shown in fig. 1, sealing grooves 9 for installing sealing rings may also be provided on the first small diameter section 11 of the upper pit joint 1 and the second small diameter section 71 of the lower pit joint 7 to improve the sealing property of the pressure-bearing connection between the upper pit joint 1 and the first coiled tubing and between the lower pit joint 7 and the second coiled tubing.

It is noted that unless otherwise indicated, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this utility model belongs.

In the description of the present utility model, it should be understood that the terms "axial," "upper," "lower," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, and are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element in question must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present utility model, and not for limiting the same; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the utility model, and are intended to be included within the scope of the appended claims and description. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present utility model is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims (10)

1. A coiled tubing connection joint, comprising: the device comprises an upper pit joint, a first ball head sleeve, a first ball head, an adapter, a second ball head sleeve, a second ball head and a lower pit joint which are connected in sequence, wherein the upper end of the upper pit joint is used for being connected with a first continuous oil pipe, the lower end of the upper pit joint is connected with the upper end of the first ball head in a sealing mode, the lower end of the first ball head is connected with the upper end of the adapter in a sealing mode, the lower end of the adapter is connected with the upper end of the second ball head in a sealing mode, the lower end of the second ball head is connected with the upper end of the lower pit joint in a sealing mode, the lower end of the lower pit joint is used for being connected with a second continuous oil pipe, a plurality of first pits are formed in the outer surface of the upper pit joint in a sealing mode, and a plurality of second pits are formed in the outer surface of the lower pit joint in a sealing mode and used for being connected with the second continuous oil pipe in a pressing mode.

2. The coiled tubing connection sub of claim 1, wherein the upper dimple joint comprises a first small diameter section and a first large diameter section coaxially connected to the first small diameter section, the first small diameter section being connected to the first coiled tubing, the first large diameter section being connected to the first ball sleeve, the plurality of first dimples being formed on an outer peripheral wall of the first small diameter section; the lower pit joint comprises a second small-diameter section and a second large-diameter section coaxially connected with the second small-diameter section, the second small-diameter section is connected with the second continuous oil pipe, the second large-diameter section is connected with the second ball head, and a plurality of second pits are formed on the peripheral wall of the second small-diameter section.

3. The coiled tubing connection sub of claim 2, wherein a plurality of the first dimples are formed in staggered fashion on the outer peripheral wall of the first minor diameter section and a plurality of the second dimples are formed in staggered fashion on the outer peripheral wall of the second minor diameter section.

4. A coiled tubing connection sub according to claim 2 or 3, wherein the first coiled tubing is sleeved on the first small diameter section, and the outer peripheral surface of the first coiled tubing is flush with the outer peripheral surface of the first large diameter section; the second continuous oil pipe is sleeved on the second small-diameter section, and the outer peripheral surface of the second continuous oil pipe is flush with the outer peripheral surface of the second large-diameter section.

5. A coiled tubing connection sub according to any of claims 1 to 3, wherein the lower end of the upper dimple joint is in threaded sealing engagement with the upper end of the first ball head, the lower end of the first ball head is in threaded sealing engagement with the upper end of the adapter, the lower end of the adapter is in threaded sealing engagement with the upper end of the second ball head, and the lower end of the second ball head is in threaded sealing engagement with the upper end of the lower dimple joint.

6. The coiled tubing connection sub of claim 5, wherein the outer peripheral wall of the lower end of the upper dimple joint, the outer peripheral wall of the lower end of the first ball head, the outer peripheral wall of the lower end of the adapter, and the outer peripheral wall of the lower end of the second ball head are provided with external threads and a sealing groove formed on the external threads for installing a sealing ring; internal threads matched with the external threads are formed on the inner peripheral wall of the upper end of the first ball sleeve, the inner peripheral wall of the upper end of the adapter, the inner peripheral wall of the upper end of the second ball sleeve and the inner peripheral wall of the upper end of the lower pit joint.

7. A coiled tubing connection sub according to any of claims 1 to 3, wherein the first ball head comprises a first ball head section and a first rod section connected with the first ball head section, the first rod section is connected with the adapter, the outer diameter of the first ball head section is larger than that of the first rod section, and a first spherical groove for rotationally fitting with the first ball head section is formed on the inner peripheral wall of the lower end of the first ball head sleeve; the second ball head comprises a second ball head section and a second rod section connected with the second ball head section, the second rod section is connected with the lower concave pit joint, the outer diameter of the second ball head section is larger than that of the second rod section, and a second ball groove used for being rotationally attached to the spherical surface of the second ball head section is formed in the inner peripheral wall of the lower end of the second ball head sleeve.

8. The coiled tubing connection sub of claim 7, wherein a lower end surface of the first ball socket is formed with a first tapered surface having an inner diameter that tapers axially inward, a small diameter end of the first tapered surface being connected to the first spherical groove, a first included angle being formed between the first tapered surface and an outer peripheral wall of the first rod segment; the lower end face of the second ball sleeve is provided with a second conical surface with the inner diameter gradually decreasing inwards in the axial direction, the small-diameter end of the second conical surface is connected with the second spherical groove, and a second included angle is formed between the second conical surface and the peripheral wall of the second rod section.

9. The coiled tubing connection sub of claim 8, wherein the junction of the small diameter end of the first tapered surface and the first spherical groove is always in engagement with the outer surface of the first ball segment; and the joint of the small diameter end of the second conical surface and the second spherical groove is always attached to the outer surface of the second ball head section.

10. The coiled tubing connection sub of claim 7, wherein the outer wall of the first ball segment that mates with the first ball groove and the outer wall of the second ball segment that mates with the second ball groove are each provided with a seal groove for mounting a seal ring.