GB2425815A

GB2425815A - Lining fluid conduits

Info

Publication number: GB2425815A
Application number: GB0509001A
Authority: GB
Inventors: Graeme John Collie
Original assignee: FMC TECHNOLOGIES; FMC Technologies Inc
Current assignee: FMC TECHNOLOGIES; FMC Technologies Inc
Priority date: 2005-05-03
Filing date: 2005-05-03
Publication date: 2006-11-08
Anticipated expiration: 2025-05-03
Also published as: GB0509001D0; GB2425815B

Abstract

A method of lining a conduit 10 having a non uniform geometry, comprising the steps of: forming the conduit to the required geometry; forming a liner 30 from fabric; impregnating the fabric with an uncured polymer resin; positioning the liner within the conduit and curing the polymer resin. The liner may be pressed into contact with the conduit by pressurisation until the resin cures. Preferably, the fabric of the liner is chosen from woven, non-woven or knitted textiles, felts or fleeces. The liner may be multilayered. Preferably the liner is knitted to form the required geometry or is formed from joined fabric panels or tubular sections. Also claimed is a lined conduit of non-uniform geometry.

Description

LINING FLUID CONDUITS

Field of the Invention

This invention relates to a method of lining non-uniform fluid conduits, and to lined conduits obtainable by that method. Non-uniform fluid conduits include those having bends, branches or changes in the shape or size of the flow area, including combinations of any or all of those features. Particular examples of such non-uniform fluid conduits include christmas tree flowloops and manifolds used in oil and gas production equipment. For brevity, much of the following description is confined specifically to christmas tree flowloops, although the invention is of more general applicability.

Problem to be Solved Flowloops on christmas trees and other pieces of oilfield equipment are often in contact with highly corrosive fluids which are produced from, or injected into, oil and gas wells. Such flowloops with thick wall sections, complex three dimensional shapes and tight radii of curvature, are fabricated from short lengths of straight pipe welded to bends and flanges.

All of these components are either pre-formed form a relatively expensive corrosion resistant material such as super-duplex steel or a nickel based alloy, or are created by weld- overlaying carbon steel with a corrosion resistant alloy. Although it saves on expensive materials, weld-overlaying is itself an expensive and time consuming operation. If a cheaper method could he found of providing a corrosion resistant skin on the inside of an irregularly shaped carbon- or low cost alloy-steel outer, then the cost of producing christmas tree flowloops and other lined, non-uniform fluid conduits could be reduced. Alternative lining methods, besides being useful in providing cheaper corrosionlerosionJchemjcal attack resistant conduits of irregular form, would also be useful in lining irregular conduits for other purposes, such as to provide smooth or sanitary finishes, or electrical or thermal insulation.

Technology exists which allows inexpensive carbon steel pipe to be lined with a plastics or composite liner. Various methods of installation have been used including stretching the liner during installation or by inflating the liner following installation. In all cases currently used there are restrictions in terms of the tightness of bend radii; liners do not stay in contact with the parent pipe following installation. Substantially no variation in the flow area shape or size along the flow axis is permitted with known lining methods. Since the liners have little or no inherent strength they rely on the parent pipe and without close contact with the parent they will fail. For these reasons current lining technology is mostly used for substantially straight pipework.

Summary of the Invention

The present invention pushes forward the use of composite lining technology by allowing its use in lining pipes with tight bend radii, as well as for lining other conduits of more complex or non-uniform geometry than a straight pipe. Accordingly, the invention provides a method of lining a conduit having a specified, non-uniform geometry, comprising the steps of: a) forming the conduit to the specified geometry; b) forming a liner from fabric so as to have a geometry substantially conformable to that of the interior surface of the conduit; c) impregnating the fabric with an uncured polymer resin; d) positioning the liner within the conduit, and e) curing the polymer resin.

Thus, the fabric liner is specially manufactured so that its geometry mirrors that of the interior of the parent conduit. The liner geometry preferably conforms to the interior surface of the conduit sufficiently closely for no gaps to he left between the liner and the parent conduit that would be sufficiently large to degrade the mechanical performance of the liner in use (e.g. causing it to crack and/or break). The shape/dimensional mismatches between the liner and the conduit inner surface which can be tolerated will therefore depend not only upon service conditions, the strength of the cured lining composite and the strength of the bond between the liner and the parent conduit, but also on the deforrnability of the liner, particularly when impregnated with the uncured resin. The liner will typically (but not necessarily always) be: of the same general shape as the conduit interior surface but having outside dimensions slightly smaller than the interior dimensions of the conduit.

Preferably the impregnated liner is pressed into contact with the conduit as the polymer resin cures. For example the interior of the liner may be pressurised. Where the impregnated liner is permeable, an inflatable bladder may be used to apply the pressure.

The bladder may be disposable and at least in part may be left attached to the cured lining, or may be stripped out. The liner and/or bladder (where present) may be inflated so that full contact is achieved between the liner and the parent pipe. This pressure may be maintained until the resin is fully cured. If required, ends of the liner can be flared out over a flange lace of the conduit.

Preferably the orientation and position of the impregnated liner is adjusted SO that it sits correctly within the conduit prior to curing of the resin.

The fabric of the liner may he WOVen, non-woven or knitted textile, single or multilayered, a felt or a fleece. Steps h) to e) above may be repeated to build up a multilayered lining (with the optional variation in step b) that the interior surface of the next outer impregnated liner takes the place of the interior surface of the conduit). The resin may or may not he allowed to fully cure in step e) before the next liner is installed. It is usually more convenient to produce all the required liners before impregnating and positioning them within the conduit.

Different fabrics/textiles and/or resin fhrrnulations may be used in each layer of a inultilayer construction, to impart different physical properties according to need.

The liner may he formed to the required geometry by any suitable method known in the textile art. For example it may he knitted to shape in manner of a knitted sock or glove; or it may be "tailored" from joined fabric panels or tubular sections.

The invention correspondingly provides a lined conduit of specified nonuniform geometry, in which the liner has been formed from fabric with a geometry substantially conformable to that of the interior surface of the conduit and subsequently positioned within the conduit, the liner being impregnated with a polymer resin that has been allowed to cure with the liner positioned within the conduit.

An illustrative embodiment of the invention is described below with reference to the drawings.

Brief Description of the Drawings

Figure 1 is a perspective view of a fabricated christmas tree flowloop; Figure 2 shows a "tailored" fabric liner flir installation and use in the flowloop of' Figure 1; Figure 3 schematically indicates the liner of Figure 2 installed in the flowloop of Figure 1 and Figure 4 is a schematic cross-section through a pipe containing several bends (such as a flowloop) with a composite liner formcd according to an embodiment of the invention.

Referring to Figure I, pipework forming a christmas tree flowloop 10 is fabricated from a number of bends 12 and straight sections 14, and a pair of connector flanges 1 6, all united by circumferential welds 18 to form a specified, relatively complex geometry, with the pipework centreline C/L extending in three dimensions. Alternatively, the pipework can be fonned by induction bending or any other suitable means.

Figure 2 shows a liner 30 made from straight sections 22 of glassfibre textile (or similar) tube, and elbows 24 formed from the same material. These are joined at seams 24 by sewing, staples, fusing or the like. The finished geometry of the liner resembles that of the pipe to be lined, albeit smaller on its outside diameter than the pipe is on its inside diameter.

Other longitudinal seams (not shown) may be necessary to fabricate the elbows 20 and tubular sections 22 from a sheet of the textile concerned.

The liner 30 may be folded partly or completely flat, and is sufficiently flexible, after impregnation with a suitable polymer (e.g. epoxy) resin, and before the resin has cured significantly, to be drawn into the pipework 10, for example using a rope previously threaded through the pipework. The liner passes around the bends 12 until it is positioned in the pipework with its straight sections 22 aligned inside those 14 of the pipework 10 and the elbows 20 aligned inside the bends 12. This position is shown in Figure 3. Care must be taken to ensure that the straight sections and elbows/bends are properly aligned, without twists or kinks in the liner. Ends of the outermost liner straight sections 22 protrude beyond the connector flanges 16.

The liner 30 is then expanded into intimate contact with the entire inner surface of the pipework 10, for example by introducing hot water under pressure into the liner 30 interior.

The heat from the water will shorten the resin cure time. Alternatively, where the impregnated liner is permeable or the pressurising fluid is incompatible with the polymer resin, the fluid can be isolated from the resin by a flexible bladder (not shown). The pressure is sufficient to drive out any air trapped between the impregnated liner 30 and the pipework inner surface. The liner is expanded into contact with the pipework inner surface, without excessive strain or kinks or wrinkles in the liner. The pressure is sustained whilst the resin cures.

Figure 4 shows a longitudinal section through a piece of pipework 10 of relatively complex geometry, embodying the invention and incorporating a finished composite lining 30. The adhesive effect of the cured resin may serve to anchor the liner 30 to the inner surface of the pipework 10. Additionally or alternatively, the projecting ends 26 of the liner may be flared before the resin has cured, and flattened against the mating faces of the flanges 16, extending radially outwardly, preferably at least far enough to cover a sealing location such as a seal accommodating groove (not shown) in the mating face. Clamping the liner flared ends between the flange 16 mating faces also helps to secure the liner 30 within the pipework 10. Ensuring a continuous, close fit between the liner outside diameter and the pipework inside diameter is dependent on: * A close match between the geometries of the liner and the pipework interior * Correct positioning and orientation of the liner 30 prior to inflation * Complete liner/bladder inflation * Total impregnation of the liner 30 with the uncured resin.

Many variants of the illustrated embodiments will be apparent, within the scope of the claims. For example the conduit and pre-formed liner may comprise changes in the shape or size of the flow cross-section (e.g. convergent and/or divergent throats), and/or incorporated branches, flat sides, steps, shoulders, etc. The resin is selected to suit the particular service conditions and to allow installation of the impregnated liner. It may incorporate a variety of fillers to improve the mechanical or other properties of the finished lining, including its resistance to corrosion and/or abrasion.

Claims

1. A method of lining a conduit having a specified, non-uniform geometry, comprising the steps of: a) forming the conduit to the specified geometry; b) forming a liner from fabric so as to have a geometry substantially conformable to that of the interior surface of the conduit; c) impregnating the fabric with an uncured polymer resin; d) positioning the liner within the conduit, and e) curing the polymer resin.

2. A method of lining a conduit as defined in claim I, in which the impregnated liner is pressed into contact with the conduit as the polymer resin cures.

3. A method of lining a conduit as defined in claim I or 2, in which the interior of the liner is pressurised.

4. A method of lining a conduit as defined in claim 3, in which the pressure is maintained until the resin is cured.

5. A method of lining a conduit as defined in any preceding claim, in which ends of the liner are flared out over a flange face of the conduit.

6. A method of lining a conduit as defined in any preceding claim, in which the orientation and/or position of the impregnated liner is adjusted so that it sits correctly within the conduit prior to curing of the resin.

7. A method of lining a conduit as defined in any preceding claim, in which the fabric of the liner is selected from woven, non-woven or knitted textiles, felts or fleeces.

8. A method of lining a conduit as defined in any preceding claim, in which the liner is multilayered.

9. A method of lining a conduit as defined in any preceding claim, in which steps h) to e) are repeated to build up a multilayered lining.

10. A method of lining a conduit as defined in claim 9 with the variation in step b) that the interior surface of the next outer impregnated liner takes the place of the interior surface of the conduit.

11. A method of lining a conduit as defined in claim 9 or 10, in which the resin is not fully cured in step e) before the next liner is installed I0

12. A method of lining a conduit as defined in any preceding claim, in which the liner is knitted to form the required geometry.

13. A method of lining a conduit as defined in any preceding claim, in which the liner comprises joined fabric panels or tubular sections.

14. A lined conduit of specified non-uniform geometry, comprising a liner which has been formed from fabric with a geometry substantially conformable to that of the interior surface of the conduit and subsequently positioned within the conduit, the liner being impregnated with a polymer resin that has been allowed to cure with the liner positioned within the conduit.

15. A lined conduit as defined in claim 14, in which ends of the liner are flared out over a flange face of the conduit.

16. A lined conduit as defined in claim 14 or 15, comprising a multilayered lining.

1 7. A lined conduit as defined in any of claims 14 - 16, in which the fabric of the liner is selected from woven, non-woven or knitted textiles, felts and fleeces.

18. A lined conduit as defined in any of claims 14- 17, in which the liner comprises joined fabric panels or tubular sections.

S

19. A method of lining a conduit having a specified, non-uniform geometry, substantially as described with reference to the drawings.

20. A lined conduit having a specified, non-uniform geometry, substantially as described with reference to or as shown in the drawings.

Amendments to the claims have been filed as follows

1. A method of lining a conduit having a specified, non-uniform geometry, comprising the steps of: a) forming the conduit to the specified geometry; b) forming a liner from fabric so as to have a geometry that in an expanded but unstretched state mirrors and is substantially conformable to the geometry of the interior surface of the conduit; c) impregnating the fabric with an uncured polymer resin; rn d) positioning the liner within the conduit; e) expanding the liner, and f) curing the polymer resin.

3. A method of lining a conduit as defined in claim 1 or 2, in which the interior of the liner is pressurised.

6. A method of lining a conduit as defined in any preceding claim, in which the orientation andior position of the impregnated liner is adjusted so that it sits correctly within the conduit prior to curing of the resin.

9. A method of lining a conduit as defined in any preceding claim, in which steps b) to f) are repeated to build up a multilayered lining.

11. A method of lining a conduit as defined in claim 9 or 10, in which the resin is not fully cured in step f) before the next liner is installed 12. A method of lining a conduit as defined in any preceding claim, in which the liner is knitted to form the required geometry.

14. A lined conduit of specified non-uniform geometry, comprising a liner which has been formed from fabric with a geometry that in an expanded but unstretched state mirrors and is substantially conformable to the geometry of the interior surface of the conduit and subsequently positioned within the conduit, the liner being impregnated with a polymer resin that has been allowed to cure with the liner positioned within the conduit.

15. A lined conduit as defmed in claim 14, in which ends of the liner are flared out over a flange face of the conduit.

17. A lined conduit as defined in any of claims 14- 16, in which the fabric of the liner is selected from woven, non-woven or knitted textiles, felts and fleeces.

18. A lined conduit as defined in any of claims 14 - 17, in which the liner comprises joined fabric panels or tubular sections. It