HK40004875A - Independently hydraulically clamped and sealed fitting - Google Patents

Description

Independent hydraulic clamping and sealing fitting

Technical Field

The present invention relates to fittings for repairing and/or connecting pipes.

Background

Mechanically connected repair fittings, such as those used for riser repair of subsea pipelines, are useful in situations where actual welding is not possible. Prior art pipe repair and maintenance fittings include mechanical clamping and sealing types as well as hydraulic clamping and sealing types. Mechanical types may require many bolt tightening steps, making installation complex and time consuming, particularly when the steps are done underwater. The hydraulic profile is expensive to produce, complex in design and difficult or impossible to lock in place in a reliable and accurate manner. There remains a need for a simplified, compact, self-contained, hydraulically clamped and sealed pipe fitting.

Disclosure of Invention

The present invention provides a pipe fitting that can be independently hydraulically clamped and sealed to a pipe using independent hydraulic systems to provide a high level of control for these operations. The hydraulic actuation of each of the clamping and sealing systems is connected through a single port, greatly simplifying the effort required by the installer. If desired, hydraulic actuation may be performed by a line from a location remote from the fitting itself.

In the disclosed arrangement, each of the hydraulic clamp actuator and the hydraulic seal actuator is a single annular piston. The pistons can be mechanically locked in their respective extended clamping and sealing positions with infinite adjustment accuracy and no retraction movement. Thus, the clamping and sealing functions are not dependent on a long-term pressurization of the respective hydraulic circuit.

Drawings

FIG. 1 is a perspective view of a pipe fitting constructed in accordance with the present invention;

FIG. 2 is a longitudinal cross-sectional view of a fitting of the present invention installed on a pipe; and

FIG. 3 is a perspective view of an annular array of grip segments.

Detailed Description

Referring now to the drawings, a pipe fitting 10 comprises an axially extending annular housing formed by annular clamping, intermediate and sealing sections 11-13, respectively. These and various other components described below, except for the seal, are typically made of steel and are annular, except for some accessories or small components. The segments 11-13 are coaxial and each preferably has an inner diameter surface 16-18 adapted to receive the outer diameter of a steel pipe 19 with a loose slide or sliding fit.

A cylindrical skirt 21 on the inside or inner end of the clamping section 11 has an internal thread 22 which engages with an external thread 23 of a cylindrical extension 24 of the intermediate section 12. This enables the clamping section 11 to be rigidly fixed to the intermediate section 12 with the ends of the skirt 21 abutting the radial shoulders 25 of the intermediate section. The clamp section 11 has a plurality of continuous counterbores 26-28 on the inside of the internal skirt threads 22 for receiving a locking ring 31, an outer clamp ring 32 and a seal 33, respectively. The seal 33 is a ring of semi-rigid material (e.g. elastomer) that fits over the exterior of the pipe 19 to prevent material from freely entering the housing or fitting 10 along the outside of the pipe.

The gripper ring 34, shown in perspective view in fig. 3, is partially grooved along the length of the ring from alternate ends of the ring to form grippers or gripper segments 36. The groove 35 enables the gripping ring 34 to be radially contracted onto the exterior of the pipe 19, as will be discussed below. The inner surface of the segment 36 may be serrated or otherwise treated to enhance its gripping ability on the pipe 19.

The segment 36 has a double tapered outer surface with one portion complementary to the tapered bore of the outer clamping ring 32 and the opposite portion complementary to the tapered bore of a clamping thrust ring in the form of an annular piston (hereinafter referred to as a clamping piston). A clamping piston 38 is arranged in the fitting 10 between the intermediate section 12 and the clamping section 11. The gripping piston 38 is biased away from the gripping ring 34 by a plurality of compression springs 39 distributed around the axis of the mating piece and extending from associated recesses (pockets) in the gripping section body. The outer diameter of the clamping piston 38 is threaded along a long section 41 extending away from the intermediate section 12. An internally threaded locking ring 31 engages the threads of the gripping piston on the long section 41.

The skirt 43 of the clamping piston 38 telescopes in an annular blind area 44 formed in the intermediate section 12 and serving as a piston chamber. The end faces of the skirt 43 are fitted with annular seals 46, 47 which seal against the radially outer and inner walls of the piston chamber 44 respectively. The chamber 44 is in fluid communication with the hydraulic coupling 48 through a passage 49.

The seal section 13, similar to the clamp section 11, is a hollow circular body having a series of counterbores 51-53 for an annular seal 56, a seal thrust ring or annular piston (hereinafter seal piston 57), and an annular extension 58 of the intermediate section 12, respectively.

The sealing section 13 is rigidly fixed to the intermediate section 12 by engagement of corresponding internal threads on the counterbore 53 with external threads on the annular extension 58 of the intermediate section, with an end face 59 of the sealing section 13 abutting a radial shoulder surface 61 of the intermediate section 12. Seal 56 is a suitable semi-rigid elastomer known in the industry. The seals 56 are separated by metal spacer rings 62. A groove 63 on the outer circumference of the spacer ring 62 communicates with a test port in the wall of the seal section 13. The sealing piston 57 receives the pipe 19 through its central hole. The reduced diameter end section 67 of the sealing piston 57 extends into the counterbore 51. The sealing piston 57 slides proportionally over the tube 19 and the counterbore 51. At the opposite end, the sealing piston 57 has an annular extension 68 of increased internal diameter which is received in an annular groove 69 formed in the adjacent face of the intermediate section 12. The annular groove 69 serves as a piston chamber for sealing the extension 68 of the piston. A pair of concentric seals 71, 72 on the extension 68 of the sealing piston seal the piston chamber 69. A hydraulic coupling 73 at the exterior of fitting 10 communicates with piston chamber 69 through a passage 74. The mechanical lock ring 76 is internally threaded and is received by mating external threads on the outer surface of the seal piston 57.

A rotating lifting ring 77 is mounted in an external groove on the gripping section 11. The lifting eye 78 is bolted to the sealing section and the rotating lifting ring 77. The outboard end of the seal segment 13 includes a flange 79 with bolt holes for connection to a complementary flange of a pipe or other vessel. Other known connection or coupling structures may be used with the disclosed fitting, in addition to the flange 79 shown.

Fitting 10 is installed by inserting the end of pipe 19 into the fitting so that it passes over seal 56 and is supported by surface 18 of sealing section 13. For example, hydraulic fluid pressurized to 3000psi is introduced into the piston chamber 44 through the coupling 48. The hydraulic pressure on the piston skirt 43 causes the clamping piston 38 to move axially in the fitting 10. The camming action between the tapered surface of the gripping piston 38 and the complementary tapered surface of the gripping section 36 causes the gripping section to contract radially outward of the tube 19. The limited axial movement of the gripping segments 36 causes the distal or outer long segments of the gripping segments to radially contract due to the camming action between the outer tapered surfaces of the gripping segments and the inner tapered surfaces of the outer gripping ring 32. By tightening the locking ring 31 screwed on the piston towards the end face of the intermediate section 12, the clamping piston 38 can be mechanically locked in the hydraulically extended position without the clamping piston being withdrawn. The threaded engagement between the locking ring 31 and the clamp piston provides stepless adjustment. The locking ring 31 has a series of spaced blind wrenching holes 82 distributed on its outer circumference, as shown in figure 1. The locking ring 31 is manually rotated onto the piston threads 41 by engaging the bore 82 with the trigger lever through a slot 83 in the wall of the gripping section 11. When deployed as described above, the locking ring 31 holds the clamp piston 38 in an extended position against the clamp ring 34 without sliding back as the pressurized fluid in chamber 44 is exhausted. If it is desired to remove the fitting 10 from the pipe 19, the ring 31 can be re-unscrewed from the intermediate section 12 and the spring 39 will retract the gripping piston 38 to release the gripping members 36.

Pressurized hydraulic fluid, e.g., up to 3000psi, applied to the coupler 73, expands the seal piston 57 to axially compress and radially inwardly expand the seal 56 onto the exterior of the pipe 19. The spacer ring 62 is able to slide in the counterbore 51, thereby enabling it to transmit compressive forces to the axially outer seal.

The sealing effect of the seal 56 on the exterior of the pipe 19 may be tested by introducing pressurized fluid into the test port 64 and observing whether leakage of that fluid past the seal occurs. When the seal is determined to be adequate, the locking ring 76 threaded on the sealing piston 57 is rotated to tightly abut the respective end of the middle section 12, mechanically locking the sealing piston in place. The blind bore 84 in the periphery of the locking ring 76 is accessible through an arcuate slot 86 in the wall of the sealing section 13 and, effectively with infinite adjustability provided by the interengaging threads, can be engaged by a manually operated pin or wrench from the exterior of the fitting 10 to manually tighten the locking ring towards the intermediate section 21. By retracting the locking ring 76 away from the middle section, the axial compression on the seal may be released. Both access slots 83, 86 may be closed with a suitable elastomeric plug or the like.

The piston area of the clamping piston 38 is larger than the piston area of the sealing piston 57 so that the compressive strength of the seal 56 is not exceeded using the same pressure source for each piston.

It will be apparent that the present disclosure is to be considered as an example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teachings contained in this disclosure. Therefore, the invention is not to be limited to the specific details of the disclosure unless the following claims are necessarily so limited. For example, threaded holes 41 or their equivalents may extend through the wall of section 12, thereby eliminating reduced diameter holes 43.

Claims (9)

1. A pipe fitting, comprising: an annular housing; an annular array of arcuate clamping segments within the housing; a first annular piston and associated hydraulic chamber; an annular semi-rigid seal within the housing, the seal being axially spaced from the gripping section; a second annular piston and associated hydraulic chamber mechanically and hydraulically isolated from the first annular piston and associated hydraulic chamber; separate first and second hydraulic circuits extending from the exterior of the housing to the hydraulic chambers of the first and second annular pistons, respectively, pressurized fluid introduced into the first hydraulic circuit effective to force the first annular piston axially toward the gripping section, a wedging surface arranged to radially retract the gripping section onto a conduit extending into the housing, whereby the conduit is axially restrained in response to axial movement of said first annular piston toward said gripping section, pressurized fluid introduced into the hydraulic chamber of the second annular piston effective to forcibly move said second annular piston axially toward said semi-rigid seal, so as to axially compress the seal, causing the seal to radially contract in the housing and seal against the exterior of the pipe.

2. The pipe fitting of claim 1, wherein the annular semi-rigid seal comprises two annular rings separated by a rigid ring, the axial space between the annular rings being connected to the exterior of the housing by a return circuit to enable testing of the sealing effect of the annular rings on the pipe.

3. The pipe fitting of claim 1, wherein the first and second annular pistons are oriented in opposite axial directions.

4. The pipe fitting of claim 1, wherein the exterior of the first annular piston is threaded and an internally threaded locking ring is mounted on the threads of the first annular piston, the locking ring being rotatable on the first annular piston to lock the first annular piston in an extended position to mechanically retain the gripping segments in engagement with the exterior of the pipe.

5. The pipe fitting of claim 1, wherein the second annular piston is externally threaded and an internally threaded locking ring is mounted on the second annular piston threads, the locking ring being rotatable on the second annular piston to lock the second annular piston in an extended position to mechanically maintain axial compression of the annular semi-rigid seal.

6. The pipe fitting of claim 1, wherein the annular array of gripping segments comprises segments having double tapered outer surfaces, whereby the segments collectively form a minimum outer diameter of the annular array at opposite axial ends of the array and a maximum outer diameter at a mid-section of the array, an outer gripping ring being located in the housing on a side of the array opposite the annular piston, the outer gripping ring and the annular piston having tapered bores, the outer surfaces of the gripping segments being complementary to both the tapered bores of the outer gripping ring and the annular piston.

7. A pipe fitting, comprising: three annular coaxial sections including a clamping section, an intermediate section, and a sealing section, the clamping section and the sealing section being respectively secured to the intermediate section; an annular array of grippers in the gripper section; an annular semi-rigid seal in the seal section; a hydraulic gripper actuator in the housing for radially contracting the gripper into gripping engagement with the exterior of a tubular extending into the housing; a hydraulic seal actuator hydraulically and mechanically independent of the hydraulic clamp actuator for radially forcing the seal into engagement with the exterior of the pipe; a first mechanical lock for holding the clamp in contact with the pipe; and a second mechanical lock that holds the seal in contact with the pipe.

8. The pipe fitting of claim 7, wherein the hydraulic clamp actuator and the hydraulic seal actuator comprise respective annular pistons, the first and second mechanical locks being arranged to maintain the annular pistons in the extended deployed positions independent of hydraulic pressurization of the actuators.

9. The pipe fitting of claim 8, wherein the first and second mechanical locks are each internally threaded rings that are threaded onto external threads of a respective annular piston.