Pressure Equalization in Composite Pipes

Abstract

A flexible polymeric pipe for transportation of oil, gas or water, having an unbonded reinforcing intermediate layer between two polymeric layers. The pipe has a vent for the intermediate layer which allows venting of gas from the intermediate layer through to the exterior environment. The vent is generally impervious to water but pervious to air and gas.

Claims

1. A flexible polymeric pipe for transportation of oil, gas or water, comprising: (a) a polymeric inner layer surrounding a conduit for oil gas and/or water; (b) an unbonded reinforcing intermediate layer surrounding said inner layer; (c) a polymeric outer layer surrounding said intermediate layer; (d) at least one vent through the outer layer, acting as a conduit between the intermediate layer and an exterior environment; (e) said vent being generally impervious to water and generally pervious to air and gas.

2. A flexible polymeric pipe of claim 1 wherein either or both of the polymeric inner layer and the polymeric outer layer is made from a polyolefin.

3. The flexible polyolefin pipe of claim 1 wherein the vent comprises a membrane which is generally impervious to water and generally pervious to air and gas.

4. The flexible polyolefin pipe of claim 3 wherein the membrane is a Gore-Tex membrane.

5. A crimp fitting for the connection of two flexible polymeric pipes, each of said two flexible polymeric pipes having a polymeric inner layer having an inner surface surrounding a conduit for oil, gas and/or water, an unbonded reinforcing intermediate layer surrounding said inner layer, and a polymeric outer layer surrounding said intermediate layer and having an outer surface, a said crimp fitting comprising: (a) a mandrel configured to friction fit to the inside surface of a pipe; (b) A sleeve, connected to said mandrel and configured to fit overtop of the outside surface of the pipe and be crimped thereto; (c) At least one vent on said sleeve or at the interface of said mandrel and said sleeve, said vent oriented to act as a conduit between the intermediate layer and an exterior environment; (d) said vent being generally impervious to water and generally pervious to air and gas.

6. The crimp fitting of claim 5 wherein the vent comprises a membrane which is generally impervious to water and generally pervious to air and gas.

7. The crimp fitting of claim 6 wherein the membrane is a Gore-Tex membrane.

8. A lined steel pipe for transportation of oil and gas, comprising: (a) a steel pipe; (b) a polyolefin lining; (c) an annulus between said steel pipe and said polyolefin lining; (d) at least one vent through the steel pipe, acting as a conduit between the annulus and an exterior environment; (e) said vent being generally impervious to water and generally pervious to air and gas.

9. The lined steel pipe of claim 8 wherein the vent comprises a membrane which is generally impervious to water and generally pervious to air and gas.

10. The lined steel pipe of claim 9 wherein the membrane is a Gore-Tex membrane.

11. A fitting for the connection of two lined steel pipes, each of said lined steel pipes having a steel pipe, a polyolefin lining, and an annulus between said steel pipe and said polyolefin lining, said fitting comprising: (a) a steel connector having a vent acting as a conduit between the annulus and an exterior environment; (b) said vent being generally impervious to water and generally pervious to air and gas.

12. The fitting of claim 11 wherein the vent comprises a membrane which is generally impervious to water and generally pervious to air and gas.

13. The fitting of claim 12 wherein the membrane is a Gore-Tex membrane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a schematic cross-section of a prior art vented crimp fitting fitted to the end of a flexible composite pipe.

[0015] FIG. 2 is a schematic cross-section of a prior art steel pipe end fitted with a liner flange adaptor.

[0016] FIG. 3 shows a liner flange adaptor in isolation.

[0017] FIG. 4 is a schematic cross-section of a vented crimp fitting fitted to the end of a flexible composite pipe.

[0018] FIG. 5 is a close-up schematic cross-section of a crimp fitting having a vent of the present invention.

[0019] FIG. 5b is a schematic cross-section of a vented crimp fitting fitted to the end of a flexible composite pipe, having a screw-in vent seal.

[0020] FIG. 6 is a schematic cross-section of a flexible composite pipe having vents for the intermediate layer.

[0021] FIG. 7 is a schematic representation of a vent seal used to seal the vents shown in FIG. 6.

[0022] FIG. 8 is a photograph depicting an air pressure equalization testing of a vent seal on steel crimp configuration.

[0023] FIG. 9 is a photograph depicting a water testing of a vent seal.

[0024] FIG. 10 is a photograph depicting a water testing of a vent seal.

SUMMARY OF THE INVENTION

[0025] According to a certain aspect of the present invention is provided a flexible polymeric pipe for transportation of oil, gas or water, comprising: a polymeric inner layer surrounding a conduit for oil gas and/or water; an unbonded reinforcing intermediate layer surrounding said inner layer; a polymeric outer layer surrounding said intermediate layer; at least one vent through the outer layer, acting as a conduit between the intermediate layer and an exterior environment; said vent being generally impervious to water and generally pervious to air and gas.

[0026] In certain embodiments, either or both of the polymeric inner layer and the polymeric outer layer is made from a polyolefin.

[0027] In certain embodiments, the vent comprises a membrane which is generally impervious to water and generally pervious to air and gas.

[0028] In certain embodiments, the membrane is a Gore-Tex membrane.

[0029] According to another aspect of the present invention is provided a crimp fitting for the connection of two flexible polymeric pipes, each of said two flexible polymeric pipes having a polymeric inner layer having an inner surface surrounding a conduit for oil, gas and/or water, an unbonded reinforcing intermediate layer surrounding said inner layer, and a polymeric outer layer surrounding said intermediate layer and having an outer surface, a said crimp fitting comprising: a mandrel configured to friction fit to the inside surface of a pipe; A sleeve, connected to said mandrel and configured to fit overtop of the outside surface of the pipe and be crimped thereto; At least one vent on said sleeve or at the interface of said mandrel and said sleeve, said vent oriented to act as a conduit between the intermediate layer and an exterior environment; said vent being generally impervious to water and generally pervious to air and gas.

[0030] In certain embodiments, the vent comprises a membrane which is generally impervious to water and generally pervious to air and gas.

[0031] In certain embodiments, the membrane is a Gore-Tex membrane.

[0032] According to yet a further aspect of the present invention is provided a lined steel pipe for transportation of oil and gas, comprising: a steel pipe; a polyolefin lining; an annulus between said steel pipe and said polyolefin lining; at least one vent through the steel pipe, acting as a conduit between the annulus and an exterior environment; said vent being generally impervious to water and generally pervious to air and gas.

[0033] In certain embodiments, the vent comprises a membrane which is generally impervious to water and generally pervious to air and gas.

[0034] In certain embodiments, the membrane is a Gore-Tex membrane.

[0035] According to yet a further aspect of the present invention is provided a fitting for the connection of two lined steel pipes, each of said lined steel pipes having a steel pipe, a polyolefin lining, and an annulus between said steel pipe and said polyolefin lining, said fitting comprising: a steel connector having a vent acting as a conduit between the annulus and an exterior environment; said vent being generally impervious to water and generally pervious to air and gas.

[0036] In certain embodiments, the vent comprises a membrane which is generally impervious to water and generally pervious to air and gas.

[0037] In certain embodiments, the membrane is a Gore-Tex membrane.

DETAILED DESCRIPTION

[0038] Adding a vent seal to oil and gas pipeline annulus vents, said vent seal being generally impervious to water but able to vent air and organic gases, provides an advantageous improvement over the prior art. The vent seal may be in the form of a gas-permeable, water impermeable membrane such as a Gore-Tex™ membrane. The vent seal may be incorporated into vents, for example, into the vents found in crimp fittings for use with a composite pipe, or the steel flange of a lined steel pipe. Alternatively, the vent seal may be a separate component, retro-fittable onto said crimp fitting or steel flange. Composite pipe lengths may also be manufactured having vents and vent seals of the present invention incorporated within their lengths, as may steel pipeline lengths.

[0039] One example of such a vent seal is shown in FIG. 4. FIG. 4 shows the flexible composite pipe length 10 and crimp fitting 20 of FIG. 1, having vent 32 within the crimp fitting 20 as previously described. Close-up view 4A shows the same vent 32, configured with a vent seal 70 of the present invention. Vent seal 70 highlights vent conduit or vent hole 72, which is covered in vent cover 74, which is a piece of Gore-Tex™ affixed to the sides of the crimped sleeve 24 surrounding the vent hole 72. The vent cover 74 may be affixed, for example, using an adhesive “donut” around its circumference and between it and the crimp fitting 20, such that there is still a portion of vent cover 74 overtop of vent hole 72 which does not have adhesive.

[0040] An alternative configuration of the vent seal is shown in FIG. 5. Shown is a close-up of vent seal 70 having vent hole 72 through crimped sleeve 24. In this configuration, the vent seal 70 comprises a recessed area 76, which is larger in circumference than vent hole 72, and which is deep enough to allow for flush-mounting of the vent cover components (membrane 78 and mesh 80, which are described in more detail, below). In certain embodiments, the recessed area 76 is 2 cm in diameter and 1.0 mm deep.

[0041] Recessed area 74 contains a membrane 78, for example an ePTFE—based membrane, or a laminate comprising a fabric and an ePTFE—based membrane (for example a Gore-Tex™ membrane such as a 3-layer Gore-Tex™ fabric), which surrounds and covers vent hole 72. The membrane 78 may be affixed to the surface of the recessed area 76 with adhesive, or it may be free-floating. Overtop of membrane 78 is mesh 80, which provides impact resistance to membrane 78 but which is typically both water and gas pervious. Mesh 80 may be, for example, a sintered steel disk, for example, of 74 micron 2 ply sintered stainless steel. Mesh may be affixed using an adhesive, such as Loctite™, may be welded in place, and/or a porous patch or tape may be applied overtop of the entire vent area to keep the mesh 80 and membrane 78 in place.

[0042] FIG. 5B shows an alternate configuration, utilizing a Gore-Tex screw-in plug vent seal.

[0043] In an alternate configuration, the sealed vent may be within the outer surface of a flexible composite pipe. A schematic cross-section view of a flexible composite pipe length 10 is shown in FIG. 6, including inner polyolefin layer 12, fiberglass reinforcing layer 14, and outer polyolefin layer 16. FIG. 6 shows two vent holes 82, 84. The configuration of vent hole 82 is an 8 mm hole. Vent hole 84 is also an 8 mm exterior hole, however it tapers to 3 mm at the reinforcing layer 14. Both these vent holes can be covered with a Gore-Tex vent hole cover 85 having the configuration shown in FIG. 7, available from W. L Gore and Associates and bearing vent model number VE-08 14, as an example. Such a vent hole cover 85 has a Gore-Tex™ inner circumference 86, surrounded by a “donut” of adhesive 88, has an inner diameter of 8 mm (the diameter of inner circumference 86), an outer diameter of 14 mm (the diameter of outer adhesive 88), a vent area of 50 mm.sup.2 and an air flow of 575 ml/min.

[0044] As would be understood by a person of skill in the art, the adhesive vent hole covers may be replaced with Gore™ vents screw-in series (W. L. Gore and Associates), which provide rugged, screw-in construction, Gore™ vents snap-in series (W. L. Gore and Associates), which allow for rapid, snap-in installation, or other membrane configuration that allows for movement of air and hydrocarbon gas but prevents ingress of water.

Example 1: Flexpipe Gore-Tex Vent Seal

[0045] A 1.5 foot section of 4 inch Flexpipe™ flexible composite pipe crimp fitting (Flexpipe, Canada) was modified by drilling a 2 mm vent hole through its outer polyethylene layer. The bottom of the section of pipe was sealed. The top of the section of pipe was sealed but fitted with a compressed air intake. A 5 mm Gore adhesive vent seal (W. L. Gore and Associates) was affixed to the outside of the crimp fitting, surrounding the 2 mm vent hole. A photo of the apparatus can be seen in FIG. 8. The compressed air intake was calibrated to provide 1.5 psi of pressure (0.5 cubic.ft/hr) to the pipe conduit, for five days. The pipe exhibited steady state pressure equalization, with 1.5 psi of pressure released from the vent. As can seen in the photo, one end of a rubber tube was pressed against the vent and the other end was placed in the water in a beaker. The air escaping from the vent formed a steady flow of bubbles through the water.

Example 2: Gore-Tex Vent Seal Water Imperviousness Test

[0046] A water column having a 2 mm hole was sealed with a 5 mm Gore-tex vent seal. It was then filled to a level calculated to approximate 1 psi of pressure, with acidic water in order to affect a color change in the pH paper if a leak occurred. The hole was placed over pH paper to identify water leaks through the Gore-tex vent seal in a highly sensitive manner. No leaks were observed (and the pH paper remained neutral) after 6 weeks (See FIG. 9). The test was repeated with 2 psi pressure, and again no leaks were observed after 4 weeks (See FIG. 10).