Pipe Cap Assembly

Abstract

A monolithic pipe cap assembly, and method of production, is described. The monolithic pipe cap assembly comprising a unitary body, a connector integrally formed at a proximal end of the unitary body and a pipe cap integrally formed at a distal end of the unitary body. As no welds are required in the formation of the monolithic pipe cap assemblies there is a significant reduction in the associated production time and a reduced risk of imperfections being formed when compared with the fabricated pipe cap assemblies known in the art. This results in a reduced risk of failure of the monolithic pipe cap assembly when deployed in the field. Connecting the monolithic pipe cap assembly to the section of pipeline is also significantly quicker since this process only requires the employment of a single weld that can be fully inspected prior to operational use.

Claims

1. A monolithic subsea pipe cap assembly comprising: a unitary body, a connector integrally formed at a proximal end of the unitary body; and a pipe cap integrally formed at a distal end of the unitary body wherein the pipe cap comprises a tapered cross-sectional surface suitable for butt welding the monolithic subsea pipe cap assembly to a tubular component employed to contain high pressure fluids.

2. The monolithic subsea pipe cap assembly as claimed in claim 1 wherein the connector comprises a padeye.

3. The monolithic subsea pipe cap assembly as claimed in claim 1 wherein the connector comprises a hook.

4. The monolithic subsea pipe cap assembly as claimed in claim 1 wherein the pipe cap comprises a hemispherical pipe cap; a semi-hemispherical pipe cape; an ellipsoidal pipe cap; a torispherical pipe cap; or a flat unstayed pipe cap.

5. The monolithic subsea pipe cap assembly as claimed in claim 1 wherein the unitary body comprises a cylindrical billet.

6. The monolithic subsea pipe cap assembly as claimed in claim 5 wherein the cylindrical billet comprises a circular cross section.

7. The monolithic subsea pipe cap assembly as claimed in claim 1 wherein the unitary body comprises a forged shaped unitary body.

8. A method of producing a monolithic subsea pipe cap assembly, the method comprising: selecting a unitary body; forming an integrated pipe cap at a distal end of the unitary body; forming an integrated connector at a proximal end of the unitary body and forming a tapered cross-sectional surface on the pipe cap for butt welding the monolithic subsea pipe cap assembly to a tubular component employed to contain high pressure fluids.

9. The method of producing a monolithic subsea pipe cap assembly as claimed in claim 8 wherein forming of the integrated pipe cap at the distal end of the unitary body comprises employing a turning operation.

10. The method of producing a monolithic subsea pipe cap assembly as claimed in claim 9 wherein the turning operation is performed by a Computer Numerical Control (CNC) machine.

11. The method of producing a monolithic subsea pipe cap assembly as claimed in claim 8 wherein forming of the integrated pipe cap at the distal end of the unitary body comprises the formation of a hemispherical pipe cap; a semi-hemispherical pipe cape; an ellipsoidal pipe cap; a torispherical pipe cap; or a flat unstayed pipe cap.

12. The A method of producing a monolithic subsea pipe cap assembly as claimed in claim 8 wherein forming of the integrated connector at the proximal end of the unitary body comprises employing a milling and boring operation.

13. The method of producing a monolithic subsea pipe cap assembly as claimed in claim 12 wherein the milling and boring operation is performed by a Computer Numerical Control (CNC) machine.

14. The method of producing a monolithic subsea pipe cap assembly as claimed in claim 8 wherein forming the integrated connector at the proximal end of the unitary body comprises the formation of a padeye.

15. The method of producing a monolithic subsea pipe cap assembly as claimed in claim 8 wherein, forming the integrated connector at the proximal end of the unitary body comprises the formation of a hook.

16. The method of producing a monolithic subsea pipe cap assembly as claimed in claim 8 wherein selecting the unitary body comprises selecting a cylindrical billet.

17. The method of producing a monolithic subsea pipe cap assembly as claimed in claim 16 wherein the cylindrical billet comprises a circular cross section.

18. The method of producing a monolithic subsea pipe cap assembly as claimed in claim 8 wherein selecting the unitary body comprises selecting a forged shaped unitary body.

19. A method of attaching a pipe cap assembly to a section of pipeline, the method comprising providing a monolithic subsea pipe cap assembly comprising: a unitary body, a connector integrally formed at a proximal end of the unitary body; and a pipe cap integrally formed at a distal end of the unitary body wherein the pipe cap comprises a tapered cross-sectional surface suitable for butt welding the monolithic subsea pipe cap assembly to a tubular component employed to contain high pressure fluids; and forming a weld between the monolithic subsea pipe cap assembly and an end of the section of pipeline.

20. The method of attaching a pipe cap assembly to a section of pipeline as claimed in claim 19 wherein the method further comprises inspecting the weld for imperfections.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0041] There will now be described, by way of example only, various embodiments of the invention with reference to the drawings, of which:

[0042] FIG. 1 presents perspective view of a fabricated pipe cap assembly known in the art attached to a proximal end of a section of pipeline;

[0043] FIG. 2 presents perspective views of the method of assembly of the fabricated pipe cap assembly of FIG. 1 with the proximal end of the section of pipeline;

[0044] FIG. 3 presents a monolithic pipe cap assembly in accordance with an embodiment of the present invention;

[0045] FIG. 4 presents a monolithic pipe cap assembly in accordance with an alternative embodiment of the present invention;

[0046] FIG. 5 presents perspective views of the of the method of production of the monolithic pipe cap assembly of FIG. 3;

[0047] FIG. 6 presents perspective views of the method of attachment of the monolithic pipe cap assembly of FIG. 3 with an end of a section of pipeline; and

[0048] FIG. 7 presents perspective views of a method of production of an alternative embodiment of the monolithic pipe cap assembly.

[0049] In the description which follows, like parts are marked throughout the specification and drawings with the same reference numerals. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] An explanation of the present invention will now be described with reference to FIGS. 3 to 7.

[0051] FIG. 3 presents a monolithic pipe cap assembly in accordance with an embodiment of the present invention, depicted generally by reference numeral 14. The monolithic pipe cap assembly 14 comprises a unitary body 15 integrally formed at a proximal end of which is a connector in the form of a padeye 16, while a pipe cap 17 is integrally formed at a distal end. In the presently described embodiment, the padeye 16 has a thickness of 150 mm while the pipe cap 17 takes the form of a hemispherical pipe cap (e.g. an ASME B16.9 pipe cap) suitable for attachment to the end of a section of pipeline 2.

[0052] FIG. 4 presents a monolithic pipe cap assembly in accordance with an alternative embodiment of the present invention, depicted generally by reference numeral 18. This embodiment contains many of the same elements as the pipe cap assembly 14 of FIG. 3 which are thus marked with identical reference numerals. The main difference is that the padeye connector 16 at the proximal end of the device has been replaced be an integrated hook 19.

[0053] It will be appreciated by the skilled reader that the pipe cap 17 may take an alternative form to the above described hemispherical pipe cap. For example, the pipe cap 17 may take the form of a semi-hemispherical pipe cape; an ellipsoidal pipe cap; a torispherical pipe cap; a flat unstayed pipe cap or any other pipe cap design known to those in the art. The particular choice pipe cap will depend on the intended use of the monolithic pipe cap assembly 14 or 18, and the environment within which it is to be deployed.

[0054] A method of production the monolithic pipe cap assembly 14 will now be described with reference to FIG. 5.

[0055] The first stage, as presented in FIG. 5(a), involves the provision of a unitary body in the form of a cylindrical billet 20, having a circular cross section, made from of a suitable material for the monolithic pipe cap assembly 14. The choice of the cylindrical billet 20 depends on the required dimensions of the monolithic pipe cap assembly 14, the integrated pipe cap 17 and the integrated padeye 16. In the presently described embodiment the cylindrical billet 20 has a diameter of 10.75 inches (273 mm), a length of 20 inches (508 mm) and is made from carbon steel. Alternatively, a stainless steel cylindrical billet 20 could be employed.

[0056] FIG. 5(b) presents the second stage of the production process which involves the formation of the pipe cap 17 at the distal end of the cylindrical billet 20. In the presently described embodiment the pipe cap 17 is a hemispherical pipe cap and is formed by employing a turning operation at the distal end of the cylindrical billet 20. The turning operation is preferably performed by a Computer Numerical Control (CNC) machine.

[0057] FIG. 5(c) presents the final stage of the production process which involves the formation of the padeye 16 at the proximal end of the cylindrical billet 20. In the presently described embodiment the padeye 16 is formed by employing a milling and boring operation at the proximal end of the cylindrical billet 20. The milling and boring operation is preferably performed by a CNC machine.

[0058] It will be appreciated that the order in which the formation of the pipe cap 17 and the padeye 16 is performed is not critical to the method of production the monolithic pipe cap assembly 14 i.e. the order of stages described with reference to FIGS. 5(b) and 5(c) may be reversed. Indeed, modern CNC machines are capable of performing these two stages simultaneously.

[0059] A method of attachment of the monolithic pipe cap assembly 14 of FIG. 3 with an end of a section of a pipeline 2 will now be described with reference to FIG. 6.

[0060] The first stage, as presented in FIG. 6(a), involves the selection of the monolithic pipe cap assembly 14 for the particular section of pipeline 2.

[0061] Next, the selected monolithic pipe cap assembly 14 is positioned so that it abuts the proximal end of the section of pipeline 2, see FIG. 6(b).

[0062] The penultimate step involves a full-penetration butt weld 21 being formed between the monolithic pipe cap assembly 14 and the proximal end of the section of pipeline 2. Both the pipe cap 17 and the proximal end of the section of pipeline 2 comprise tapered cross-sectional surfaces 9, 10. Therefore, when the pipe cap 17 and the proximal end section of the pipeline 2 are aligned, the opposing tapered cross-sectional surfaces 9, 10 form a V shaped butt welding joint. It typically takes around four hours to form the full-penetration butt weld 21.

[0063] Finally, it is necessary to inspect the full-penetration butt weld 21 of the combined structure for imperfections. This can be achieved by employing one or more of the known testing techniques, namely: [0064] 1) visual inspection testing techniques; [0065] 2) radiography or ultrasonic testing techniques; and [0066] 3) magnetic particle inspection (for carbon steel components) or dye-penetrant inspection (for stainless steel components) testing techniques,

[0067] Given that only one full-penetration butt weld 21 requires to be inspected this process can take less than a day to complete.

[0068] It will be appreciated by the skilled reader that the monolithic pipe cap assembly 18 of FIG. 4 is formed in a similar manner to that described above. The main difference involves the final stage where, instead of the padeye 16 being formed at the proximal end of the cylindrical billet 20, an integrated hook 19 is formed instead.

[0069] A method of production an alternative monolithic pipe cap assembly 22. will now be described with reference to FIG. 5.

[0070] The first stage, as presented in FIG. 7(a), involves the provision of a unitary body in the form of a forged shaped unitary body 23. The choice of the forged shaped unitary body 23 again depends on the required dimensions of the monolithic pipe cap assembly 22, the integrated pipe cap 17 and the integrated padeye 16. In the presently described embodiment the forged shaped unitary body 23 is made from carbon steel. Alternatively, a stainless steel forged shaped unitary body 23 could be employed.

[0071] FIG. 7(b) presents the second stage of the production process which involves the formation of the pipe cap 17 at the distal end of the forged shaped unitary body 23. In the presently described embodiment the pipe cap 17 is again a hemispherical pipe cap and is formed by employing a turning operation at the distal end of the forged shaped unitary body 23. The turning operation is again preferably performed by a Computer Numerical Control (CNC) machine.

[0072] FIG. 5(c) presents the final stage of the production process which involves the formation of the padeye 16 at the proximal end of the forged shaped unitary body 23. In the presently described embodiment the padeye 16 is formed by employing a milling and boring operation at the proximal end of the forged shaped unitary body 23. The milling and boring operation is again preferably performed by a CNC machine.

[0073] The monolithic pipe cap assembly 22 has the advantage over the monolithic pipe cap assemblies 14 or 18 in that the CNC machining processes are easier to complete and involve the production of less waste material.

[0074] The monolithic pipe cap assemblies 14, 18 or 22 of the present invention offer a number of advantageous over the fabricated pipe cap assembly 1 known in the art.

[0075] In the first instance there are no welds required in the formation of the monolithic pipe cap assemblies 14, 18 or 22. This fact not only decreases production times but it also means there is a reduced risk of imperfections being formed, and thus a reduced risk of failure of the monolithic pipe cap assemblies 14, 18 or 22 when deployed in the field.

[0076] When it comes to deployment, there is only one component that is required to be sourced when the monolithic pipe cap assemblies 14, 18 or 22 are employed. This simplifies the selection process while again reducing construction times.

[0077] Connecting the monolithic pipe cap assemblies 14, 18 or 22 to the section of pipeline 2 is also significantly quicker since this process only requires the employment of a single weld 21. As this weld 21 can be fully inspected by one or more of the known testing techniques, imperfections can be more easily detected and thus the risk of failure of the monolithic pipe cap assemblies 14, 18 or 22 during operation can be further reduced.

[0078] The foregoing description of the invention has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The described embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, further modifications or improvements may be incorporated without departing from the scope of the invention as defined by the appended claims. [0079] 1 Fabricated Pipe Cap Assembly (Prior Art) [0080] 2 Section of Pipeline [0081] 3 Fabricated Padeye [0082] 4 Pipe Cap [0083] 5 Padeye aperture [0084] 6 Padeye Plate [0085] 7 Cheek Plates [0086] 8 Limbs (Padeye Plate) [0087] 9 Fillet Weld Between Cheek Plate and Padeye Plate [0088] 10 Full Penetration Butt Weld Between Pipe Cap and Section of Pipeline [0089] 11 Tapered Contact Surface (Pipe Cap) [0090] 12 Tapered Contact Surface (Section of a Pipe) [0091] 13 Partial Penetration Weld Between Two Limbs and Section of Pipeline [0092] 14 Monolithic Pipe Cap Assembly (Padeye) [0093] 15 Unitary Body [0094] 16 Padeye [0095] 17 Pipe Cap [0096] 18 Monolithic Pipe Cap Assembly (Hook) [0097] 19 Hook [0098] 20 Cylindrical Billet [0099] 21 Weld Between Pipe Cap and Section of Pipeline [0100] 22 Monolithic Pipe Cap Assembly (Forged) [0101] 23 Forged Shaped Unitary Body