Lined pipeline vent

1. A pipeline assembly for the transportation of fluid, the pipeline assembly comprising a pipeline, a corrosion resistance plastic liner, and a micro-annulus located between said pipeline and liner, wherein the pipeline assembly also comprises a venting means extending through the corrosion resistance plastic liner, wherein, during transportation of fluid in the center of the pipeline assembly, the venting means allows gas to flow from the micro-annulus into the centre of the pipeline assembly by a flow path wholly internal of the pipeline.

2. A pipeline assembly as claimed in claim 1 wherein the venting means is inserted through an aperture in the plastic liner.

3. A pipeline assembly as claimed in claim 2 wherein the venting means is retained by a shoulder in the wall of the plastic liner.

4. A pipeline assembly as claimed in any one of the preceding claims wherein the venting means is a prefabricated assembly.

5. A pipeline assembly as claimed in claim 1 wherein the venting means is retained in the plastic liner by threading, gluing or fusing.

6. A pipeline assembly as claimed in claim 1 wherein the venting means has check means for regulating fluid flow.

7. A pipeline assembly as claimed in claim 6 wherein said check means is of a construction selected from a group comprising a sintered metal, a sintered wire mesh, a ceramic material, a stainless steel wire mesh, a plastics material and composite materials such as PEEK (Poly Ether Ether Ketone) alloyed with Teflon®.

8. A pipeline assembly as claimed in claim 1 wherein the venting means includes non-return valve means.

9. A pipeline assembly as claimed in claim 8 wherein the non-return valve means comprises a spring biased ball valve assembly.

10. A pipeline assembly as claimed in claim 8 wherein the valve means comprises a moveable member which is moveable between a first and second position, wherein the moveable member is in the first position when the pressure within the pipeline exceeds a set level, and wherein the moveable member is in the second position when the pressure within the pipeline falls below said set level, wherein in the first position the moveable member prevents the pipeline contents from exiting the pipeline and wherein in the second position the moveable member permits the flow of gas into the pipeline.

11. A pipeline assembly as claimed in claim 1 wherein the venting means comprises a reed valve arrangement formed directly in the liner.

12. A pipeline assembly as claimed in claim 1 wherein a sleeve member extends circumferentially around the liner and longitudinally on either side of the venting means so as to define a lengthened venting path between the micro annulus and the centre of the pipeline assembly.

13. A pipeline assembly as claimed in claim 1 wherein the fluid is a hydrocarbon.

14. A pipeline assembly as claimed in claim 13 wherein the hydrocarbon comprises a liquid phase and a gas phase.

15. A pipeline assembly as claimed in claim 14 wherein the venting means is adapted for transporting the gas phase by the flow path.

16. A method of forming a pipeline assembly from a pipeline and a corrosion resistant plastic liner, the method comprising the sequential steps of:

providing a through hole in the corrosion resistant plastic liner;

inserting a pre-fabricated venting means into the through hole in the corrosion resistant plastic liner; and

inserting the corrosion resistant plastic liner into a pipeline such that, during transportation of fluid in the center of the pipeline assembly, the venting means allows gas to flow from a micro-annulus located between said pipeline and corrosion resistant liner into the centre of the pipeline assembly.

17. The method as claimed in claim 16 , comprising the additional step of threading the venting means in a pre-drilled hole.

18. The method as claimed in claim 16 , comprising the additional step of gluing the venting means in a pre-drilled hole.

19. The method as claimed in claim 16 , comprising the additional step of fusing the venting means in a pre-drilled hole.

20. A pipeline assembly formed by the method of claim 16 .