This application is related to a pipe connecting system for providing fluid communication between pipes and, in particular, for connecting pipes that may be misaligned and/or subject to relative movement therebetween. The pipe connecting system includes a first and second pivot attachment system for attaching the pipe connecting system between the pipes and a telescopically extendable central connector pivotably engaged with the first and second pivot attachment systems to allow the central connector to be positioned at various angles and distances with respect to the pivot attachment systems.
Routinely in a large number of operational situations in the oil and gas industry, (colloquially known as the “oil patch”), it is necessary to connect different sections of piping together. Such systems may require connecting standard-size flanges of the pipe sections to permit both high and low-pressure fluids to be carried within connected pipe sections. Often, when different sections of the pipe must be connected together in the field, the relative alignment between the different sections is offset or misaligned such that significant stress is incorporated into the connection if such pipes are connected together. Moreover, if the degree of misalignment is significant enough, it simply may not be possible to connect the different sections together without a significant custom solution being developed. Further still, in various operational situations, the relative distance between the ends of the different pipe sections may be variable and may change due to a variety of factors including temperature variations and/or the support systems for the pipe sections.
As a result, there has been a need for pipe connection systems that readily allow field workers to connect different pipe sections together that may be misaligned and separated from one another and that are otherwise capable of carrying normal oil patch fluids including high-pressure and high-temperature fluids.
As an example of the complexity and hence cost of prior art methods of addressing the above problems, a method in use today is to measure the distance between the two ends of pipe that must be in sealed communication and to cut a proper length of pipe to fit there between. Thereafter, field workers position the pipe into its ultimate position, fit proper flanges and tack weld these connecting flanges to the center piece of pipe. Once measured, the pipe is put on a bench and welded together by hand. Thereafter, it is usually common practice to send this welded unit to an oven for stress relief to relieve any internal stresses which may have formed during the welding process. Furthermore, it is common practice to bathe this custom piece in an acid bath to remove slag and other types of debris which may have formed thereon, in particular from the weld. Finally, the unit may have to be pressure tested before actually connecting the custom unit to the final pipe. Pressure testing typically requires fitting the piece to a pressure testing system that applies the requisite pressures for its end use. After these processes, if the unit does not fit or fails a test for whatever reason, it must be re-fabricated and all of the above steps must be re-done. As can be readily understood, such a process involves a significant amount of skilled construction, processing and fabrication time as well as supplies of construction and fabrication materials, all of which significantly affect the costs and time involved in assembly and/or servicing a job.
Thus, the conventional process for fitting two ends of pipe together can be expensive, utilize many man-hours and require a large amount of downtime before completion of a job. Finally, it should be noted that in many oil patch jobs, the location of a job may be in a remote location that also contributes to the time and cost in completing a job.
While the prior art teaches various connecting systems that provide a solution to various aspects of the above problems, there continues to be a need for pipe connecting systems that minimize the time and complexity of effecting pipe connections in the field and in particular, for effecting pipe connections involving high pressure fluids.
In accordance with the invention, there is provided a pipe connecting assembly for providing fluid communication between pipes.
Specifically, there is provided a pipe connecting assembly for interconnecting a first pipe and a second pipe, the pipe connecting assembly having an interior surface defining a fluid passageway, the pipe connecting assembly comprising a first pivot attachment system for operative and fluid connection to the first pipe, the first pivot attachment system having a first socket; a first sleeve having a first ball operatively retained within the first socket; and a second sleeve telescopically engaged with the first sleeve, the second sleeve including a second sleeve connection system for connection to the second pipe; wherein the second sleeve includes at least one sealing element in sealing contact with the first sleeve and second sleeve, the sealing element moveable with respect to the first sleeve during telescopic extension of the first sleeve with respect to the second sleeve.
In one embodiment, the second sleeve connection system includes a second ball for operative connection to a second pivot attachment system having a second socket.
In another embodiment, the first socket includes a first socket seal adjacent the interface between the first ball and first socket. Preferably the first socket seal includes a first socket recess operatively retaining a first socket o-ring.
In yet another embodiment, the at least one sealing element includes at least one second sleeve recess operatively retaining at least one second sleeve o-ring.
In another embodiment, the first pivot attachment system includes a first housing member for connection to the first pipe and a first housing cover for connection to the first housing member, the first housing member and first housing cover having dimensions to permit insertion and sealing retention of the first ball within the first socket.
In a further embodiment, there is provided a pipe connection assembly further comprising an outer sleeve having a first end operatively connected to the first sleeve and telescopically connected to the second sleeve for exterior sealing of the second sleeve and exterior protection of the second sleeve. Preferably, the second sleeve includes a shoulder and the assembly further comprises a retaining ring operatively connected to a second end of the outer sleeve, the retaining ring having an internal diameter for operative engagement with the shoulder to prevent separation of the first sleeve with respect to the second sleeve. In one embodiment the retaining ring includes a retaining ring seal between the retaining ring and second sleeve.
In yet another embodiment, the first sleeve of the pipe connection assembly is pivotable with respect to the first pivot attachment system. Preferably, the first sleeve is pivotable to an angle up to 15° in all directions with respect to the longitudinal axis of the first pivot attachment system.
In one embodiment, the first sleeve is rotatable 360° about the longitudinal axis of the first pivot attachment system.
In another embodiment, the first socket and first ball define a ball/socket fluid passageway substantially continuous between the first sleeve and first pivot attachment system during pivotable movement of the first sleeve with respect to the first pivot attachment system. Preferably, the first ball includes a frusto-conical recess at the first ball/socket fluid passageway.
In yet another embodiment, the pipe connecting assembly passes a standard ASME hydrostatic pressure test of 22,960 kPag for 60 minutes at a temperature of 15 to 30° C.
The invention is described with reference to the accompanying figures in which:
With reference to the figures, a pipe connecting system 20 for interconnecting two pipes is described. The system is particularly intended for use in the oil and gas industry, where it may be necessary to connect two offset pipes potentially containing high pressure and high temperature fluids effectively and efficiently.
As shown in
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Referring again to
The design and functions of each component of the pipe connecting system 20 are described in greater detail below.
With reference to
Similarly, the second connecting member 80 includes a second ball head 82 and second sleeve 86. The second sleeve 86 has a first end 86a, a neck 86b, an inner surface 86c and an outer surface 86d. The inner surface 86c is slidingly engaged with the first connecting member outer surface 76b such that the first connecting member is telescopically displaceable within the second connecting member.
The outer sleeve 90 has an inner surface 92 with interior buttress threads 94, whereby the interior buttress threads 94 engage with the exterior buttress threads 77 of the first connecting member 70. The outer surface 76b of the first connecting member tube and the inner surface 92 of the outer sleeve 90 form a cavity 98 for receiving second connecting member sleeve 86. The outer sleeve adds extra strength to the connecting member and facilitates the sliding movement of the second connecting member.
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Various sealing mechanisms are in place to prevent pressurized fluid in the fluid passageway 62 from leaking from the pipe connecting system 20. The outer surface 86d and the inner surface 86c of the second sleeve 86 have annular recesses 86e, 86f. Sealing mechanisms, such as O-rings, are located within the annular recesses to create a tight hydraulic seal between the first sleeve 70, the second sleeve 80 and the outer sleeve 90. The retaining member 100 also has an annular recess 100d to accommodate a sealing mechanism, such as an O-ring, to create a hydraulic seal between the retaining member and the second connecting member 80. While not essential in all embodiments, it is preferred that redundancy in the number of o-rings at the various interfaces is provided.
The pivot attachment systems 30, 32 enable the ends of the central connector 60 to pivot spherically around the pivot attachment systems in order to align the pipe connecting system 20 with the first and second pipe 340 and 342 and to allow for movement within the pipe connecting system as further described below. The pivot attachment systems are substantially identical, and as such, the first pivot attachment system 30 will be described in detail with the understanding that the same description applies to the second pivot attachment system 32.
As shown in the figures and outlined above, the pivot attachment system 30 includes housing member 34 and the detachable cover 38. Referring to
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The pivot attachment system has been described herein as having two sections, the housing member 34 and the detachable cover 38. However, as known to those skilled in the art, the pivot attachment system may be comprised of a variety of number of sections or may be a unitary member.
The first and second ball-and-socket joints 50, 52 are substantially identical, and as such, the first ball-and-socket joint 50 will be described in detail with the understanding that the same description applies to the second ball-and-socket joint 52.
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The connection between the central connector and the pivot attachment system has been described herein as comprising a ball-and-socket joint. However, as known to those skilled in the art, a variety of joint types could be used to connect the members.
As shown in
As noted previously, the outer surface of the ball head is adapted to engage the seal 34e in order to create a fluid seal between the ball head and the pivot attachment system. The ball head has outer lips 66 that generally do not extend inwardly past the seal 34f. The ball head 72 comprises an inner surface 72a that forms part of the fluid passageway 62. In general, the distal portion of the inner surface 72a is at least partially frusto-conical, with the wider end of the frustocone being adjacent the outer lips 66 of the ball head 72. The frusto-conical inner surface, which is shown cross-sectionally in
In other words, the outer lip 66 of the ball head has a diameter that when the central connector 60 is positioned at an extreme angle (
The first pipe 340, which presumably has an interior cylindrical bore, has a central axis 350, and the second pipe fixture 342 has a central axis 352. Oftentimes when connecting pipes, the axes 350 and 352 are not co-linear. Further, the central axes may be offset from one another, or may be offset and non-intersecting. One of the pipes 340 or 342 may be attached to some form of mechanism, such as a pump or compressor, which can cause vibration. Further, depending upon the length of the material and various factors, thermal expansion/contraction can occur, changing the distance 360 between the pipes and also changing the relationship between the axes 350 and 352 of the pipes.
For example, if the first pipe 340 is attached to a series of elbows (90-degree fittings), thermal deflection can displace the axis 350 in a direction other than the alignment of the axes 350 (for example, orthogonal thereto if there is an orthogonal pipe fitting somewhere removed from the terminating end of the pipe 340). Therefore, it can be appreciated that in connecting the pipes 340 and 342, the installer must consider the immediate orientation of the central axes 350 and 352 (and, practically speaking, the installer may utilize the flange portions 344 and 346, which is the point of connection).
Further, in certain circumstances it may be desirable to allow the pipe fixtures 340 and 342 to allow for a certain amount of flexion there between, as well as attempt to isolate vibrations there between. Therefore, it can be appreciated in particular with the detailed foregoing description above, that the operation of the pivot connecting system 20 is such that the pivot attachment systems 30, 32 (such as those shown in
The telescopic central connector 60 allows for longitudinal changes in the distance between the first and second pivot attachment system 30, 32. This change in distance allows for adjustment of the length of the pipe connecting system in order to fit the pipe connecting system between the pipe fixtures 340 and 342.
The central connector also allows for a certain amount of fine displacement between the first and second connecting members 70 and 80 when the pipe connecting system is connected to the first and second pipe. For example, in the broader range the motion between the telescopic members can be approximately 0 mm-20 mm. A more preferred range is a prescribed amount of motion of about 0 mm-5 mm given the common forces that are exerted upon the unit in the field. The motion is generally high frequency low amplitude and can be oscillatory-type motion which aids in dampening vibrations. Or, the motion can be, for example, a thermal expansion of one of the pipes 340 or 342 where the central connector will absorb a certain amount of the deflection. Of course, it should further be noted that the ball and joint system can also allow for a certain amount of deflection of the pipe fixtures 340 and 342. In other words, various angles in the pipe such as right angles to the axis 350 as shown in
Further, the various sealing assemblies as described in great detail above between the ball and joint mechanisms as well as the telescopic extending members maintains a seal for transmittal of fluid (whether compressible or incompressible) there through.
The pipe connecting system preferably accommodates an internal working pressure of 1950 psig. The working fluid is preferably natural gas, however the working fluid may be other gases or liquids.
The pipe connecting member is preferably made from a high strength steel and may be coated to increase corrosion resistance.
Testing was performed on the pipe connecting system to confirm the integrity of the design under a representative set of operating conditions, which included static and dynamic forces, and to confirm that the system was absolutely free of leaks and maintained relative movements of the flange and sliding joint components. The testing was performed with the outer sleeve removed.
Three types of tests were performed: a hydrostatic test; a static maximum allowable working pressure (MAWP) test; and a vibration test. The testing fluid was kept static inside the system at the prescribed pressure.
The primary pass/fail criterion for all the test scenarios was the evidence of leakage. The second pass/fail criterion was material failure, including deformation, breakage, failure or cracking of the system.
The system was tested under three test temperatures: ambient (15-30° C.), cold (−30° C.); and hot (150° C.). For all tests, the system and the internal test fluid were maintained at the prescribed test temperature (+/−5° C.) throughout the test, with the filled unit allowed to “soak” prior to testing until it reached the specified temperature.
Six 3-direction rosette strain gauges 140a, 140b, 140c, 140d, 140e, 140f were placed on the unit to measure axial and hoop strains as shown in
For the hydrostatic test, the system was subjected to a standard ASME (American Society of Mechanical Engineers) hydrostatic pressure test of 22 960 kPag (+/−75 kPa) for a duration of 60 minutes at ambient temperature.
Following the completion of the hydrostatic test, the system was subjected to the static MAWP test where there was a succession of decreasing static pressures at various temperatures as shown in Table 1, with the strain gauges in recording mode.
For the vibration test, the system was instrumented with the addition of an externally-applied mechanical vibration having an amplitude of 10 mils peak-to-peak at a constant frequency of 20 Hz +/−2 Hz, applied in both an axial and radial direction. The system was tested with one end fixed and the other end attached to a vibration-inducing mechanism, and the system was subjected to a succession of decreasing static pressures at various temperatures as shown in Table 2.
The pipe connecting system passed all the tests in that neither leakage nor material failure was evident.
Although the present invention has been described and illustrated with respect to preferred embodiments and preferred uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope of the invention as understood by those skilled in the art.
This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Patent Application No. 61/385,220 filed Sep. 22, 2010 which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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61385220 | Sep 2010 | US |