CA2200289A1

CA2200289A1 - Pipeline coupling

Info

Publication number: CA2200289A1
Application number: CA002200289A
Authority: CA
Inventors: Robert P. Badrak; Joseph R. Roche
Original assignee: Individual
Current assignee: Hydril LLC
Priority date: 1996-03-20
Filing date: 1997-03-18
Publication date: 1997-09-20
Also published as: AU2216297A; ID16376A; WO1997035137A1

Abstract

A coupling for making a pressure tight, threaded connection with two axially aligned plain end pipe joints is disclosed. The coupling comprises a tubular member having internal screw threads adjacent opposite ends of the tubular member. The threads form a spiral groove in the outer surface of each of two aligned plain end pipe joints upon relative rotation between the pipe and the coupling to form threaded connections with the pipe joints when the coupling is rotated relative to the pipe joints. The coupling configured as a swivel union can also be used to connect a new section in a pipeline in place of a damaged section.

Description

2 ~ ~ 0 ~ 8 ~

PATENT

PIPELINE COUPLING
This invention relates to threaded pipeline couplings generally. In one aspect of the invention, the coupling of this invention is used to connect two axially aligned plain end pipe joints. In another aspect of this invention, the coupling is used to connect a replacement section of a submerged pipeline to replace a damaged section of the pipeline.
A major cost of a pipeline is preparing and connecting the ends of the pipe. Usually, one of three types of connections are used: welds, screw threads, or clamps. By using pipe as received from the mill, the cost of preparing the ends of the pipe for one of these connections is avoided.
One type of pipe connection that avoids the cost of pipe end preparation is described in U.S. Patents Nos. 4,328,983 and 4,527,820 to Jack E. Gibson. The patents describe a coupling that holds the ends of two axially aligned pipe joints in the coupling by friction. The friction holding the ends of the pipe is created by forcing the ends of the pipe into sockets in the coupling having an inside diameter equal to or less than the outside diameter of the pipe and by providing internal annular "cutter blades" that engage the -PATENT

outer surface of the pipe. "Cutter blades" is a misnomer since they do little if any "cutting" of the pipe they engage.
For example, in the '983 patent, the blades are said to "extend outwardly into the pipe surface . . . 10,000 to 30,000ths of an inch . . .". Such a small indentation, between .0001 and .0003 inches, probably would not cause the metal of the pipe to yield, i.e., the blades do not remove or permanently deform the metal, but the force required to pull the pipe out of the coupling may be increased. Such jamming together of mating members may form an adhesively bonded friction fit, but does not constitute a machined interlocked engagement. Such a connection does not lend itself to conventional engineering methods of stress analysis and would be relatively weak in tension and torsion.
It is an object and feature of this invention to provide a threaded coupling that, when rotated relative to two axially aligned plain end pipe joints, forms a spiral groove in the outer surface of the pipe joints to make threaded connections simultaneously with the two pipe joints. Alternatively, the coupling can make such a threaded connection with one axially aligned plain end pipe joint by rotating the coupling relatively to the pipe and then make such a threaded connection with another axially aligned plain end pipe joint by rotating the pipe relative to the coupling.

It is a further object and feature of this invention to provide a coupling having internal screw threads for forming ~00~89 PATENT

a spiral groove in the outer surface of two axially aligned plain end pipe joints and make a pressure tight, threaded connection with the two axially aligned plain end pipe joints.
For the coupling of this invention to form a threaded connection with two axially aligned pipe joints simultaneously as the coupling is rotated relative to the pipe, the threads have to be of opposite hand. This is the preferred embodiment of the invention. Nevertheless, the inventive concept includes a coupling having threads of the same hand since such a coupling can also connect the ends of two axially aligned pipe joints by forming spiral grooves in the ends of the pipe joints and connect the coupling to the pipe sequentially and wherever "threads" are referred to without specifying whether they are the same or different hand, it will be understood that they can be either the same hand or the opposite hand.
It is a further object and feature of this invention to provide a coupling for simultaneously making a pressure tight, threaded connection with two axially aligned plain end pipe joints comprising a tubular member having internal screw threads adjacent opposite ends of the tubular member for cutting simultaneously a spiral groove in the outer surfaces of two aligned plain end pipe joints to form threaded connections with the pipe joints when the coupling is rotated relative to the pipe joints. Alternatively, a threaded connection can be made with the coupling of this invention by first rotating a first joint of pipe relative to the coupling ~OO ~8 PATENT

to connect the pipe joint to the coupling and then rotating the first joint of pipe and the coupling to connect the coupling to a second joint of pipe.
It is a further object and feature of this invention to provide a coupling for connecting the ends of two axially aligned plain end pipe joints comprising a tubular coupling having internal threads of opposite hand, the threads having a diameter such that the threads will form spiral grooves in the outer surface of the pipe joints to receive at least a portion of the threads on the coupling to hold the pipe joints from axial movement relative to the coupling.
It is a further object and feature of this invention to provide such a coupling with a sealing means that seals the connection between the coupling and the pipe joints.
It is a further object and feature of this invention to seal the connection between the coupling of this invention and the pipe joints with a thread compound, such as a cross-link polymer, that lubricates the threads in the coupling as the threads form a mating thread in the ends of the pipe joints and that cures to form a seal that prevents fluids under pressure from leaking out of the connection between the threads on the coupling and the pipe joint.
It is a further object and feature of this invention to provide a coupling having separate internal metal cutting elements, such as a hardened helical coil insert, to cut or form spiral grooves on the ends of plain end line pipe that ~o~9 PATENT

combine with the insert to form a threaded connection between the coupling and the pipe.
It is a further object and feature of this invention to provide a coupling that can be rotated by conventional power tongs to form spiral grooves on the ends of aligned plain end line pipe joints and connect the coupling to the ends of the joints to form a pipeline.
It is a further object and feature of this invention to include the step of locating a circumferential scribe line on the pipe joints to indicate when the connection is fully made up .
United States Patent No. 4,572,549 that issued February 25, 1986 describes apparatus for replacing a damaged section of a pipeline laying on the bottom of a deep body of water. Patent No. 4,572,549 is included herein by reference.
Four steps are involved. First, using a remotely controlled vehicle (RCV), the damaged section is inspected. Second, a RCV attaches guide modules that raise the pipeline above the seabed. Third, the damaged section is removed, the ends of the pipe are prepared to receive collets, and the length required for the replacement section is determined. Fourth, the replacement section is connected between the ends of the pipe using collets.
Collets have a plurality of resilient fingers with lugs.
The fingers bend outwardly to allow the lugs to pass over a flange then move inwardly into engagement with the flange or PATENT

groove and hold the collet from moving in the other direction.
In accordance with the '549 patent, "connector/buckle arrestors" are used to connect the pipeline sections and "Each connector portion 10, 11 is formed with an annular flange 20.
The flange 20 constitutes a means of attachment for a collet type connector in the event that damaged pipeline sections have to be repaired."
Thus, in anticipation of having to replace sections of a pipeline, special connectors are used to connect each joint of pipe in the pipeline. Buckle arrestors are important to have in the line to prevent collapse in deep water as the line is being lowered to the bottom and is full of air, but one for every connection having extra thick walls and mating flanges in anticipation of connecting replacement sections using collets would be an expensive luxury.
Therefore, it is a further object and feature of this invention to repair a damaged underwater pipeline by replacing the damaged section with a pipe section that is connected into the pipeline using the coupling of this invention.
Specifically, a replacement section is provided that is equipped with swivel unions at each end. The union portion of each swivel union is the coupling of this invention. The swivel portion of the swivel union allows the coupling portion to be rotated to make a threaded, sealed, connection with the ends of the pipeline and thereby restore the integrity of the -PATENT

line without the use of collets and without the need for special connectors/buckle arrestors in the line.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this application including the attached drawings and appended claims.
In the Drawings:
FIG. 1 is a sectional view, taken along line 1--1 of FIG.
2, partly in elevation and partly in vertical section, of the coupling of this invention positioned between the ends of two pipe joints preparatory to forming a connection with the two joints.
FIG. 2 is a view taken along line 2--2 of FIG. 1.
FIG. 3 is a vertical sectional view, on an enlarged scale, taken along line 3--3 of FIG. 2 of the threaded connection formed between the coupling and the two axially aligned pipe joints with seal rings positioned between the ends of the pipe joints, a stop shoulder integral with the coupling, and thread compound sealing the flutes of the connection.
FIG. 4 is a view on an enlarged scale of the portion of the connection in FIG. 3 within the circle showing the thread compound that lubricates the threads on the coupling as they cut threads on the pipe joint and that cures to form a cross-linked polymer seal that prevents fluid under pressure from 2 ~ 9 PATENT

leaking out of the pipeline through the threaded connection between the coupling and the pipe.
FIG. 5 is a sectional view of the coupling of this invention installed on the end of a plain end pipe joint with the end of the pipe joint in engagement with an internal stop shoulder on the coupling to limit the distance the pipe extends into the coupling.
FIG. 6 is a view of a portion of a coupling of this invention that uses a hardened helical coil insert as the die for cutting spiral grooves in the plain end pipe joint and also serving as the female threads.
FIG. 7 is a view partly in section and partly in elevation of the coupling of this invention having flutes extending only partway through the threads.
FIG. 8 is a view partly in section and partly in elevation of the coupling of this invention provided with straight threads.
FIG. 9 is a view partly in section and partly in elevation of the coupling of this invention provided with both tapered and straight threads.
FIG. 10 shows an underwater pipeline that has been repaired by replacing a damaged section of the pipeline using the coupling of this invention to connect a replacement section in the pipeline.

2 ~ O O ~ ~ 9 PATENT

FIG. 11 is a view, partly in section and partly in elevation, of swivel union 44 of FIG. 7 connected to end 48 of underwater pipeline 52.
FIG. 12 is a view, partly in section and partly in elevation, of a telescoping joint in the pipeline replacement section.
In FIG. 1, coupling 10 is in axial alignment with and abutting the ends of pipe joints 12 and 14. Coupling 10 is provided with tapered threads 16 and 18 of opposite hand so that when coupling 10 is rotated relative to the pipe joints, with the pipe joints being moved toward the center of the coupling, threads 16 and 18 will form a spiral groove in the outer surface of the ends of the pipe joints, as shown in FIG.

3, to simultaneously form threaded connections between the adjacent ends of the two joints of line pipe and the coupling.
Flutes 20 are provided to receive metal that is removed or displaced as the threads on the coupling form spiral grooves in the outer surface of the line pipe as the connection is made up. In the embodiment shown, four such flutes are provided. Alternatively, the thread profile can be dimensioned based on the outside diameter of the line pipe so that the metal that is removed or displaced by the threads in the coupling is accommodated in the female thread groove.
Between the ends of threads 16 and 18 and the end of coupling 10, the inner ID of the coupling is cylindrical and provided with o-ring grooves 22 and 24 where O-rings 26 and 28 2 ~ Q

PATENT

are located. These O-rings engage the cylindrical outer surface of pipe joints 12 and 14 and seal the threaded connection formed between the coupling and the pipe joints.
Circumferential scribe lines 31 indicate when the pipe joint has been drawn into the coupling the proper distance to energize the seals.
As stated above, threads 16 and 18 in FIGS. 1, 2, and 3, that act as threading dies, are tapered and also are sharp V-threads in form so that they can more readily penetrate the metal in the outer surface of the two pipe joints and form spiral grooves on the threaded connection between the threads on the coupling and the threads that are formed in the outer surface of the pipe joints.
FIG. 3 is an alternate embodiment of the connection of FIGS. 1 and 2. The threads are formed in the same way. The difference is the addition of U-shaped ring seals 30 and 32 that are compressed between the ends of pipe joints 12 and 14 and integral stop shoulder 34 on the coupling. Threads 16 and 18 on the coupling are coated and flutes 20 are filled with thread compound 36. FIG. 3 is taken along line 3--3 of FIG.
2 to show how the flutes are filled with thread compound.
Preferably, the lubricant supplies the lubricity desired for reducing friction between the coupling and the pipe joints while the connection is being made up and then cures to form a cross-linked polymer seal that blocks the leak paths between the threads and through the flutes. One such thread compound PATENT

is manufactured by EQUIVALENT, S.A. Fribourg, Switzerland and sold under the trademark CATTS~ 101.
FIG. 4 is a view, on an enlarged scale of a portion of the connection shown in FIG. 3.
In FIG. 5, the distance that coupling 10 can move onto pipe joint 14 is limited by the engagement of the end of the pipe joint with internal stop shoulder 34. Alternatively, cutting element 20 is threaded or formed in coupling 10.
In FIG. 6, hardened helical coil 40 with cutting edges 41 form a spiral groove in pipe joint 14 as the coupling 10 is rotated relative to the pipe or vice versa resulting in the coil being in engagement with spiral grooves in both the coupling and the pipe joint to hold the two together. Using a centrifugal casting process, for example, a more hardenable cutting surface can be cast in the I.D. surface, which would be integral to the structure. Alternatively, a hardened cast or wrought insert that can be threaded or formed in the coupling can be used.
In FIG. 7, one end of an alternate embodiment of the coupling of this invention is shown. Thread 18a is provided with flutes 2Oa that extend only through the section of the threads having the smallest diameter and would, therefore, displace the most metal from pipe joint 14a.
The internal threads of the coupling can be straight, tapered, or both depending on the situation. In FIGS. 1-7, the threads are tapered. In FIG. 8, threads 18b in coupling PATENT

lOb are straight. O-ring 28b seals the connection and scribe line 3lb indicates when the coupling is made upon pipe joint 14b. The engagement of the end of pipe joint 14b with shoulder 34b limits the distance the coupling can be made up on the pipe joint.
In FIG. 9, threads 18c are divided into two portions A
and B. Portion A are straight threads that are designed to form relatively shallow spiral grooves in the outside surface of pipe joint 14c. Portion B are tapered threads that form much deeper spiral grooves in the pipe joint. This coupling has the advantage of forming a long stable connection between the coupling and the pipe joint with less torque.
The use of this invention to connect a replacement section in an underwater pipeline is shown in FIGS. 10-12.
Replacement section 40 is suspended from strongback 41, that includes hydraulically actuated end positioning assemblies 42 and 43, and is used to lower replacement section into position to be connected in the pipeline. The replacement section includes two swivel unions 44 and 46 that are constructed as shown in FIG. 11 in which swivel union 44 is shown in section. Swivel union 44 includes threaded section 44a and swivel section 44b. The swivel section includes cylindrical section 44c and locking ring 44d that is connected to the inner surface of cylindrical section 44c to engage lug 44e on the end of section 48 of the replacement section. This arrangement allows threaded section 44a to be PATENT

rotated relative to the replacement section and form a threaded connection with end 48 of pipeline 52. Seals 44f prevent fluid from escaping from the repaired pipeline.
The ends of the pipeline need no special treatment except that the damaged section should be cut from the pipeline so that the ends of the pipeline to be connected to the couplings are not damaged. Further, all burrs resulting from the cutting process should be removed.
Telescoping joint 58 is connected in replacement section 52 by couplings 45 and 47. Male sleeve 58a extends into female sleeve 58b to allow relative longitudinal movement of the sleeves to accommodate the longitudinal movement of the swivel unions away from each other as they are connected to the ends of the pipeline.
From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus and structure.
It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.
Because many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the PATENT

accompanying drawings is to be interpreted as illustrative and not ln a llmltlng sense.

Claims

1. A coupling for making a pressure tight, threaded connection with two axially aligned plain end pipe joints comprising a tubular member having internal screw threads of opposite hand adjacent opposite ends of the tubular member for cutting a spiral groove in the outer surfaces of two aligned plain end pipe joints upon relative rotation between the pipe and the coupling to form threaded connections with the pipe joints when the coupling is rotated relative to the pipe joints.

2. The coupling of claim 1 further provided with annular grooves between the threads and the ends of the coupling and seal rings in the grooves to engage the outer surfaces of the pipe joints and form a pressure seal between the coupling and the pipe joints.

3. The coupling of claim 1 in which the threads are sharp V-threads.

4. The coupling of claim 1 in which the threads are American National form.

5. The coupling of claims 1, 2, 3, or 4 in which the threads are provided with flutes.

6. The coupling of claim 1 further provided with an internal stop shoulder to limit the distance the pipe joints extend into the coupling.

7. The coupling of claim 6 further provided with resilient seal rings on each side of the stop shoulder to engage the ends of the pipe joints and seal the connection.

8. The coupling of claims 1, 2, 3, 4, 6 or 7 further provided with a thread compound coating the threads to lubricate the threads as the connection is made up.

9. The coupling of claims 1, 2, 3, 4, 6 or 7 further provided with a thread compound coating the threads to lubricate the threads as the threads are made up and that cures to form a seal that prevents fluid under pressure in the pipe joints from leaking out of the connection between the threads.

10. The coupling of claims 1, 2, 3, 4, 6 or 7 further provided with a thread compound coating the threads to lubricate the threads as the threads are made up and that cures to form a cross-link polymer seal that prevents fluid under pressure from leaking out of the connection between the threads.

11. The coupling of claim 1 in which the screw threads are cast.

12. The coupling of claim 1 in which the screw threads are formed in the tubular member.

13. The coupling of claim 1 in which the screw threads are machined in the tubular member.

14. The coupling of claims 1, 2, 3, 4, 6, 7, 11, 12 or 13 in which part of the threads are straight and part of the threads are tapered.

15. The coupling of claims 1, 2, 3, 4, 6, 7, 11, 12 or 13 in which the threads are straight.

16. The coupling of claims 1, 2, 3, 4, 6, 7, 11 or 12 in which the threads are tapered.

17. A coupling for connecting the ends of two axially aligned plain end pipe joints comprising a tubular member having internal threads of opposite hand, the threads having a diameter such that the threads will simultaneously machine spiral grooves in the outer surface of the pipe joints to receive at least a portion of the threads on the coupling to hold the pipe joints from axial movement relative to the coupling.

18. A method of connecting the ends of two axially aligned plain end pipe joints comprising the steps of positioning a coupling having female threads of opposite hand adjacent each end of the coupling between the aligned ends of the pipe joints, moving the plain end pipe joints and the threads of the coupling into engagement, and rotating one of the coupling and pipe joints relative to each other to cause the threads in the coupling to cut spiral grooves in the pipe joints that engage the threads and connect the pipe joints to the coupling.

19. The method of claim 18 in which the coupling is rotated relative to both pipe joints to connect the pipe joints to the coupling simultaneously.

20. The method of claim 18 in which the coupling is rotated relative to one pipe joint to connect the coupling to one pipe joint after which the other pipe joint is rotated relative to the coupling to connect the other pipe joint to the coupling.

21. A method of replacing a damaged section of a pipeline comprising the steps of removing the damaged section from the pipeline leaving spaced ends of the pipeline, lowering a replacement section of pipe having swivel unions connected to each end of the replacement section, moving the swivel union into engagement with the spaced ends of the pipeline, and rotating the swivel union to cause the threads in the swivel unions to form spiral grooves in the ends of the pipeline and connect the replacement section in the pipeline.

22. The method of claim 21 in which the replacement section includes a telescoping section to allow the distance between the ends of the replacement section to be increased by a distance equal to or greater than the distance the swivel unions move over the ends of the pipeline.

23. A coupling for making a pressure tight, threaded connection with two axially aligned plain end pipe joints comprising a tubular member having internal screw threads of opposite hand adjacent opposite ends of the tubular member for cutting a spiral groove in the outer surfaces of two aligned plain end pipe joints upon relative rotation between the pipe and the coupling to form threaded connections with the pipe joints when the coupling is rotated relative to the pipe joints.

24. The coupling of claim 23 further provided with annular grooves between the threads and the ends of the coupling and seal rings in the grooves to engage the outer surfaces of the pipe joints and form a pressure seal between the coupling and the pipe joints.

25. The coupling of claims 23 and 24 in which the threads are sharp V-threads.

26. The coupling of claims 23 and 24 in which the threads are American National form.

27. The coupling of claims 23 and 24 in which the threads are provided with flutes.

28. The coupling of claim 23 further provided with an internal stop shoulder to limit the distance the pipe joints extend into the coupling.

29. The coupling of claim 28 further provided with resilient seal rings on each side of the stop shoulder to engage the ends of the pipe joints and seal the connection.

30. The coupling of claims 23, 24, 28 or 29 further provided with a thread compound coating the threads to lubricate the threads as the connection is made up and to cure and form a seal that prevents fluid under pressure in the pipe joints from leaking out of the coupling between the threads.

31. The coupling of claims 23, 24, 28, or 29 in which the thread compound cures to form a cross-link polymer seal.

32. The coupling of claims 23, 24, 28 or 29 in which part of the threads are straight and part are tapered.

33. The coupling of claims 23, 24, 28 or 29 in which the threads are straight.

34. The coupling of claims 23, 24, 28 or 29 in which the threads are tapered.

35. A coupling for connecting the ends of two axially aligned plain end pipe joints comprising a tubular member having internal threads, the threads having a diameter such that the threads will simultaneously form spiral grooves in the outer surface of the pipe joints to receive at least a portion of the threads on the coupling to hold the pipe joints from axial movement relative to the coupling.

36. A method of connecting the ends of two axially aligned plain end pipe joints comprising the steps of positioning a coupling having female threads adjacent each end of the coupling between the aligned ends of the pipe joints, moving the plain end pipe joints and the threads of the coupling into engagement, and rotating one of the coupling and pipe joints relative to each other to cause the threads in the coupling to cut spiral grooves in the pipe joints that engage the threads and connect the pipe joints to the coupling.

37. The method of claim 36 in which the coupling is rotated relative to both pipe joints to connect the pipe joints to the coupling simultaneously.

38. The method of claim 36 in which the coupling is rotated relative to one pipe joint to connect the coupling to one pipe joint after which the other pipe joint is rotated relative to the coupling to connect the other pipe joint to the coupling.

39. A method of replacing a damaged section of an underwater pipeline comprising the steps of removing the damaged section from the pipeline leaving spaced ends of the pipeline, lowering a telescopic replacement section of pipe having swivel unions connected to each end of the replacement section, each swivel union having threads of opposite hand, moving the swivel unions into engagement with the spaced ends of the pipeline, and rotating the swivel unions to cause the threads in the swivel unions to form spiral grooves in the ends of the pipeline and connect the replacement section in the pipeline.

40. The method of claim 39 in which the replacement section is longer than the distance between the ends of the pipeline to which the replacement section is to be connected by a distance equal to or greater than the distance the swivel unions move over the ends of the pipeline.