DESCRIPTION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 62/036,352 filed on August 12, 2014 which is incorporated in its entirety herein by reference and made a part hereof.

TECHNICAL FIELD

[0002] The present invention generally relates to a process or method for joining and sealing pipe assemblies in the field.

BACKGROUND OF THE INVENTION

[0003] Oil and gas exploration and development companies have improved both their exploration techniques and their production techniques to tap alternative sources, including offshore oil and gas reserves, such as in oceans, bays and gulfs. This effort has prompted the need for insulation systems for fluid conduits (i.e., carrier pipes), called flow assurance lines (horizontal flowlines and vertical steel catenary risers), which meet thermal insulation (U-value) requirements to keep the fluids from developing solid hydrate formations and waxy buildup which can reduce or block flow and which in turn are costly and disruptive to clear. Flow assurance lines also are used in onshore above-ground and underground piping systems. The more effective the thermal insulation, the less frequently the oil and gas companies have to clear buildups and blockages. "Pipe-in-Pipe" insulation systems in which a steel outer casing is used to protect the insulation from deep water pressure have been used, and will continue to be used, to meet these purposes and needs. In addition, high density polyethylene (HDPE) and other casing materials are used.

[0004] In certain applications, the fluid that flows through the carrier pipe needs to be heated to maintain proper flow within the pipe. This can be accomplished with tracer tube(s) or heat tube(s) welded over the longitudinal length of the carrier pipe. The tracer tube contains a heating element, such as an electrical heating element, and fiber optic temperature sensing cables. The carrier pipe and tracer tube are then insulated and jacketed in a pre -insulated piping assembly. The free ends of the carrier pipe and tracer tube assembly are not insulated or jacketed as part of the pre-insulated piping assembly so as to allow the carrier pipes and tubes to be joined in the field where they are to be placed and used. The pipe assembly end seal process of the present invention provides sealing of the insulation with tracer tube(s) protruding to provide improved integrity of individual pipe joints against moisture intrusion that would be detrimental to the insulation system.

SUMMARY OF THE INVENTION

[0005] The present invention provides a process for end sealing the insulating system tracer tube(s) protruding and joining pipe assemblies. The process includes the steps of providing a first carrier pipe and a second carrier pipe, and applying an adhesive material along the outer surface of the first and second carrier pipes at selected longitudinal intervals. The process also includes attaching a first tracer tube longitudinally to the first carrier pipe such that the first tracer tube contacts the adhesive material on the first carrier pipe, and attaching a second tracer tube longitudinally to the second carrier pipe such that the second tracer tube contacts the adhesive material on the second carrier pipe. There may be multiple tracer tubes on a carrier pipe. The process further includes the step of encasing the first and second carrier pipes and first and second tracer tubes in an insulating material, while leaving a portion of the free ends of each of the first and second carrier pipes and first and second tracer tubes free from insulating material. In addition, the process includes wrapping a polymeric coating around the first and second carrier pipes and first and second tracer tubes at the uninsulated free ends thereof and then jacketing the insulation encased first and second carrier pipes and first and second tracer tubes.

[0006] In the field, the free end of the first carrier pipe is joined to the second carrier pipe to form a carrier pipe joint, and the free end of the first tracer tube is joined to the second tracer tube to form a tracer tube joint. The previously uninsulated free ends of the first and second carrier pipes and first and second tracer tubes are insulated to form an insulated joint, and jacketed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:

[0008] FIG. 1 is a perspective view of a carrier pipe, adhesive material and tracer tube made in accordance with an embodiment of the present invention; [0009] FIG. 2 is a perspective view of an insulated pipe assembly made in accordance with an embodiment of the present invention;

[0010] FIG. 3 is a perspective view of a polymeric wrap made in accordance with an embodiment of the present invention;

[0011] FIG. 4 is a schematic view of pipe assembly made in accordance with an embodiment of the present invention;

[0012] FIG. 5 is a schematic view of a pipe assembly made in accordance with an embodiment of the present invention;

[0013] FIG. 6 is a schematic view of field joined and insulated pipe assemblies made in accordance with an embodiment of the present invention;

[0014] FIG. 7 is a schematic view of pipe assembly made in accordance with an embodiment of the present invention;

[0015] FIG. 8 is a perspective view of a pipe assembly made in accordance with an embodiment of the present invention, and including a wind down end seal;

[0016] FIG. 9 is an end view of a carrier pipe with four tracer tubes;

[0017] FIG. 10 is an enlarged sectional view taken from area C of FIG. 9; and

[0018] FIG. 11 is a side elevation view in cross-section of the carrier pipe and tracer tube assembly of FIG. 9.

DETAILED DESCRIPTION

[0019] While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.

[0020] Referring to the FIGS. 4-7, pipe assemblies 1 and 2 are provided. In pipe assembly 1, a first carrier pipe 10 is provided. FIG. 1 shows the first carrier pipe 10 being generally cylindrical and can be of a diameter of a range typically between four and seventy-two inches, but may be of any suitable diameter. The first carrier pipe 10 can be made from any suitable material, but is preferably made of metal such as steel. The first carrier pipe 10 has a first outer surface 12. [0021] In accord with an embodiment of the present invention, an adhesive compound 14 is placed longitudinally at desired intervals in mounds along the outer surface 12 of the first carrier pipe 10. The compound 14 is preferably an adhesive for use in harsh environments and preferably an epoxy compound. A suitable expoxy is of the type sold under the trade name Belzona 1111 (Super Metal) by Belzona Inc. of Miami, FL but other adhesives of similar performance can be used. The mounds are preferably approximately of a width of 100 millimeters, but can be of any suitable size.

[0022] The first pipe assembly 1 also includes a first tracer tube 16 that is placed on top of the mounds of compound 14 in a direction parallel to the first carrier pipe 10. The compound 14 is placed such that the first tracer tube 16 may contact each of the

longitudinally spaced mounds of compound 14. The adhesive compound 14 is cured in accordance with its manufacturer's instructions.

[0023] The first tracer tube 16 is capable of heating the carrier pipe 10 and its contents. In one preferred form, the tracer tube defines a lumen containing an electrical heating element (not shown), but alternatively can include other heating means such as a heated liquid such as water or steam and a temperature sensor and preferably a fiber optic temperature sensing cable. The first tracer tube 16 is approximately ¾ inch in diameter, but can be any suitable size depending on the diameter of the first carrier pipe 10, and the material flowing therethrough. The first tracer tube 16 is attached, for example, by tack, stich, full length, banded or taped welding to the first carrier pipe 10 after or before curing of the adhesive mounds. The first carrier pipe 10 and first tracer tube 16 are blasted to achieve SA 2.5 surface finish.

[0024] In a second pipe assembly 2, a second carrier pipe 40 is also provided. The second carrier pipe 40 is identical to the first carrier pipe 10, and has a second outer surface 42. The second carrier pipe 40 includes a second tracer tube 44 identical to the first tracer tube 16. Also like the first carrier pipe 10, the second carrier pipe 40 has adhesive compound 14 spaced longitudinally at desired intervals, but typically at ends, and the second tracer tube 44 contacts the mounds of compound 14. The adhesive compound 14 is cured in accordance with its manufacturer's instructions. The second tracer tube 44 is welded to the second carrier pipe 40 after or before curing of the adhesive compound.

[0025] In accord with an embodiment of the present invention, the first and second carrier pipes 10 and 40 and first and second tracer tubes 16 and 44 are encased in an insulating material 50 (FIG. 2). The insulating material 50 can be any suitable insulating material such as polyurethane or polyisocyanate foam or glass syntactic polyurethane foam (GSPU), and is applied using current techniques. The insulating material is typically applied as per thickness and density required, with a thickness of between one and four inches, and a density of 90 to 100 kilograms per cubic meter being typical.

[0026] Opposing free ends 60 of the first and second carrier pipes 10,40 and first and second tracer tubes 16,44 are left uninsulated as shown in FIGS. 3-4. In an embodiment, approximately six to eight inches of the opposing ends 60 are left uninsulated, however, the uninsulated length can vary depending on the application. A suitable anticorrosive material can also be applied to the opposing ends 60 of the first and second carrier pipes 10,40 or carrier pipes 10,40 or tracer tubes 16,44.

[0027] As shown in FIG. 3, a polymeric coating 70 is wrapped around the first carrier pipe 10 and first tracer tube 16, and the second carrier pipe 40 and second tracer tube 44. The polymeric coating 70 is preferably in the form of a polymeric tape and more preferably a polyvinyl chloride tape coated with a modified pressure sensitive rubber resin adhesive. Suitable PVC tapes or wrappings are sold by Stopaq BV of the Netherlands under the brand name STOPAQ® Wrappingband CZHT but other polymeric coatings with similar performance can be used. The polymeric coating 70 is wrapped approximately 25 mm from the edge of the insulation material 50. The polymeric coating 70 can be applied in multiple layers if suitable for the application (FIG. 7).

[0028] The pipe assemblies 1,2 are then jacketed using currently available techniques such as wind down end seal as shown in FIG. 8. The jacketing 80 is preferably a high density polyethylene (HDPE) or fiber optic reinforces plastics (FRP) and is applied in a layer of approximately four millimeters, but can be any suitable jacketing material and thickness.

[0029] To join the first and second carrier pipes 10,40 and first and second tracer tubes 16,44 in the field, they are welded together at their opposing free ends 60 to create a carrier pipe joint 66 and tracer tube joint 68 (FIG. 5). The carrier pipe joint 66 and tube joint 68 are insulated and jacketed in the field (FIG. 6).

[0030] FIGS. 9-11 show an alternative embodiment of a carrier pipe and tracer tube assembly 100 having a carrier pipe 101, four tracer tubes 102 substantially equally circumferentially spaced about the carrier pipe 101. The carrier pipe and tracer tube assembly 100 can be insulated and joined to a similarly configured assembly as shown above in FIGS. 4-7.

[0031] While four tracer tubes are shown, it is contemplated that a plurality of tracer tubes could be used from, for example, 2 to 10, more preferably 3 to 8 and most preferably 4 tracer tubes, or any range or combination of ranges therein. While the tracer tubes are shown to be equally spaced about the circumference of the carrier pipe, it is contemplated the spacing could be unequal. Any number of the tracer tubes can be in service of the ones provided. For example, if four tracer tubes are provided, one could be used to provide heat to the carrier pipe while the other three remain inactive. The inactive tracer tubes can be activated later should the first trace tube fail or if the conditions require a greater amount of heat to be provided. Additionally, the manner of providing heat using the tracer tubes can vary from tracer tube to tracer tube with some being provided with a heating wire while the others' being provided with a heated liquid.

[0032] While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying Claims.