GB2255818A

GB2255818A - Inspection system for insulated components

Info

Publication number: GB2255818A
Application number: GB9206944A
Authority: GB
Inventors: Gordon Renney
Original assignee: Insulation & Buoyancy Services
Current assignee: Insulation & Buoyancy Services
Priority date: 1991-04-17
Filing date: 1992-03-31
Publication date: 1992-11-18
Anticipated expiration: 2012-03-31
Also published as: GB9206944D0; GB2255818B

Abstract

A method of enabling repeated access to a region of a component (2) such as a pipeline encapsulated in an inner layer of insulating material (4) and an outer metal cladding (6) comprises removing a volume of the encapsulating material overlying the region to be accessed and providing a selectively removable replacement cover member (10) releasably lockable in, to seal, the recess (12) formed by the removed volume. The cover member (10) includes an inner layer of insulating material (14) for location in the recess (12) and a cap of metal cladding (16), said cladding (16) carrying sealing means (16) and locking means (20) so arranged that, on location of the insulating material (14) within the recess (12) and an actuation of the locking means (20), the cover member (10) is secured to the component with the sealing means (18) compressed between the cladding (16) of the cover member (10) and the cladding (6) of the component to seal the recess (12). To access a weld (8) the cover member (36) may be of two part annular form. <IMAGE>

Description

INSPECTION SYSTEM FOR INSULATED COMPONENTS This invention relates to a system for enabling the inspection of insulation enshrouded components, such as pipelines and the like, and more particularly of components to which are applied a layer of thermally insulating material and an outer cladding of metal.

Fluid-transporting pipelines, such as those carrying gas or oil, are commonly encased with an inner layer of insulation, such as expanded rigid pvc, cellular glass, urethane or phenolic foam, or mineral wool, and an outer metal cladding which may be, for example, stainless steel or aluminium.

All such pipelines that are subject to possible corrosion require, either by law or for insurance purposes, periodic inspection to check the condition, in particular the thickness, of the pipeline and/or the condition of welds interconnecting extents of the pipeline.

Heretofore such inspection has been achieved by stripping away a section of the insulation and the outer cladding, carrying out the necessary inspection, replacing the stripped-away section of insulating material and rivetting and sealing a replacement section of metal cladding in position on the pipeline. Clearly this is a time consuming and expensive exercise.

It would be desirable to be able to provide a system which permitted easier and simpler access to an insulated component for inspection purposes, and in particular which provided for repeated access to the region of the component to be inspected.

According to present invention there is provided a method of enabling repeated access to a region of a component encased in an inner layer of insulating material and an outer metal cladding, the method comprising the steps of: removing a volume of insulating material and the associated portion of metal cladding overlying the region of the component to be accessed; providing a replacement cover member including an inner layer of insulating material and an outer layer of metal cladding the periphery of which is adapted to overlie the cladding of the component bounding said removed portion, with sealing means reacting between the underside of said periphery of the cladding of the cover member and the outer surface of the cladding of the component bounding said removed portion, the metal cladding of the cover member having releasable locking means thereon;; locating the cover member in place of the removed volume of insulating material and associated portion of metal cladding with the sealing means located between the cladding of the cover member and the component, and actuating said locking means to secure the cover member in an operative position on the component and to effect a seal between the cladding of the cover member and the underlying cladding of the component.

It will thus be appreciated that, once the replacement cover member is located in its operative position on the component, the integrity of the bounding insulation and cladding is reinstated, while the cover member can be repeatedly removed and replaced as and when access to the associated region of the component is required by appropriate actuation of the locking means.

The component to be accessed may be any one of a variety of configurations, but the preferred application of the invention is to provide access to insulated pipelines, in particular to enable ultrasonic testing of the accessed regions of the pipeline to determine the thickness of the material thereof and thereby to check for corrosion of the pipeline, and to enable the inspection of circumferential welds in the pipeline. The accessed regions may be located in the main linear extent of the pipeline, at bends, at Tjunctions, in reducer lengths or the like.

A cover member for effecting the method of the invention comprises an inner layer of insulating material, which preferably conforms substantially in volume and configuration with that of the removed insulating material, an outer layer of metal cladding the size and shape of which slightly exceeds that of the removed portion of cladding, sealing means mounted on the underside of the periphery of the layer of metal cladding, and releasable locking means mounted on the outer layer of metal cladding and so arranged that, on location of the cover member on the component in place of the removed volume of insulating material and associated portion of metal cladding, actuation of the locking means secures the cover member in an operative position on the component and effects a seal between the cladding of the cover member and the underlying cladding of the component.

When it is required to provide access to a relatively small surface area of the component, the cover member conveniently comprises a plug of insulating material for location in a correspondingly-shaped recess in the insulation bounding the component, the plug being capped by a layer of cladding the periphery of which projects beyond the lateral edges of the plug of insulating material, locking means on the cap of cladding reacting between said cap and the underside of the cladding of the component bounding said recess.

Preferably the locking means comprise a plurality of cam levers disposed about the periphery of the cover member, for example a pair of opposed cam levers one to each side of the cover member, each movable between an inoperative position disengaged from the component and an operative position engaging the underside of the cladding of the component bounding said recess in such a manner that the cladding of the cover member is urged towards the component to compress the sealing means between the cladding of the cover member and the underlying cladding of the component.

When it is desired to provide access to a circumferential extent of the component, for example a circumferential seal between two sub-lengths of the component, whether on a linear extent of the component, at a bend therein or at a T-junction or the like, the cover member is adapted to replace a portion of the insulating material and associated portion of cladding encasing the component and overlying said seal, said portions being of annular transverse section and having a predetermined axial extent, said cover member conveniently comprising first and second portions each of semi-circular shape in transverse section, and each including an inner layer of insulating material the axial extent of which conforms with that of the removed portion of insulating material, an outer cap of cladding the opposed semi-circular edge extents of which overlie the edges of the cladding of the component bounding said removed portion, sealing means mounted on the underside of said semi-circular edge extents of the cladding, and locking means actuation of which secures the two portions of the cover member together on the component and effects a seal between the cover member and said component.

The locking means may react between the first and second portions of the cover member to effect said seal.

Alternatively or additionally said locking means may react between the portions of the cover member and the cladding of the component to effect said seal, conveniently being in the form of a plurality of rotatable cam levers mounted on the underside of the cladding of the portions of the cover member and each movable between an inoperative position disengaged from the component and an operative position engaging the underside of the cladding of the component to urge the first and second portions of the cover member towards the component.

In one embodiment of the invention, the first and second portions of the cover member are hinged together along adjacent, axially-extending edge regions thereof, the locking means reacting between the other opposed axiallyextending edge regions of said portions.

Alternatively, said first and second components of the cover member may be separate from one another and may be interconnected with each other and to the component by the locking means.

By way of example only, embodiments of the invention will now be described in greater detail with reference to the accompanying drawings of which: Figs. 1 to 3 show various pipelines together with cover members being fitted thereto in accordance with the method of the invention, and Fig. 4 is a detail of a cover member of Fig. 1.

Referring to Fig. 1, there is shown a metal pipeline 2 for conveying, for example, gas or oil and encapsulated in an inner layer 4 of thermally insulating material such as rigid foam pvc, and an outer metal cladding 6 for example of stainless steel. A circumferential weld 8 interconnects two sub-lengths of the pipeline 2.

As previously mentioned, it is necessary to check for corrosion of the pipeline 2 within the encapsulating material and to check the condition of welds such as that shown at 8.

Corrosion is determined by measuring the thickness of the metal of the pipeline 2 utilising ultrasonic testing techniques.

It is therefore necessary to gain access to the surface of the pipeline, and, where small area access is required, a method utilising cover members or plugs such as those indicated generally at 10 is used.

More particularly, a small substantially oval portion of the cladding 6 is removed from the pipeline, as is the underlying plug of insulating material to provide access to the pipeline through the recess 12 formed in the encapsulating material.

The replacement cover member 10 for location in the recess 12 comprises a plug 14 of insulating material conforming in size, shape and nature with that of the removed portion, said plug 14 being capped by a portion of metal cladding 16 secured thereto and of a size just greater than that of the removed portion whereby the periphery thereof projects radially beyond that of the plug 14.

A sealing strip 18 is provided around the undersurface of said periphery of the cladding 16 for reasons which will became apparent.

A pair of opposed cam levers 20 one of which is shown in Figs. 1 and 4 underlie the edge regions of the cladding 16 to be rotatable relative to the cover member by means of associated screws 22 extending through the cladding 16 between inoperative positions recessed within the confines of the plug 14, and operative positions projecting radially outwardly of the plug 14 immediately below the sealing strip 18 on the undersurface of the cladding 16 as best seen in Fig. 4.

Thus it will be appreciated that, with the levers 20 in their inoperative positions, the plug 14 of the cover member 10 can be located in, to fill, the recess 12, the peripheral region of the cladding 16 of the member 10 overlying the bounding edge of the cladding 6 defining said recess 12 with the sealing strip 18 between the cladding of the cover member 10 and the pipeline 2.

On subsequent rotation of the two opposed levers 20 by means of their associated screws 22 through 900 into their operative positions, said levers 20 engage the underside of said bounding edge of the cladding 6, the curved nature of said cladding 6 resulting in a cam action by the levers 20 which draws down the cladding 16 whereby the sealing strip 18 is compressed between the undersurface of the peripheral region of the cladding 16 and the outer surface of the cladding 6 of the pipeline. Thus the cover member is locked in position in the encapsulating material of the pipeline, the recess 12 is completely sealed and the integrity of the encapsulating material is reinstated.

Such a cover member provides for safe, simple and economic checking for corrosion of the pipeline 2, removal of the cover member 10 subsequent to actuation of the cam levers 20 giving instant access to the metal surface of the pipeline. Thereby regular inspection and monitoring programmes can be carried out to measure the thickness of all metal extents at high or medium risk of corrosion, the cover members, when in position, being sealed to prevent the ingress of water or other substances that might damage the insulating material or the pipeline.

Removal of the cover members 10 merely requires the turning of two screws which is a simple task even in the most difficult of locations.

Thus huge savings in labour and materials are effected with every inspection because there is no need to strip off and replace insulation, while, with the cover members in position, there is no break in insulation, thus minimising energy loss.

Clearly the cover members are located at cardinal points along the pipeline or at predetermined points on other vessels, the insulating material 14 and the metal cladding 16 being contoured to conform with that of the removed material.

Although a pair of opposed cam levers 20 are described and illustrated, each cover member or plug 10 may incorporate more than two such levers disposed about the periphery of the cladding 16.

When it is desired to access a circumferential region of the pipeline, such as the weld 8 in Fig. 1, a circumferential cover member or collar indicated generally at 30 can be used, this cover member 30 being adapted to replace an annular removed portion of the insulating material 4 and cladding 6 bounding the weld 8.

More particularly, the cover member 30 comprises two elements 32 each of semi-circular shape in transverse section, each element 32 including an inner layer of insulating material 34 of an axial extent equal to that of the removed material 4 and an outer layer of metal cladding 36 the axial extent of which just exceeds that of the removed cladding 6, sealing strips 38 being provided on the underside of the semi-circular peripheral edge regions of the cladding 36.

The free, axially-extending edge extents of the two elements 32 are each provided with co-operating components 40,42 of over-centre clasp-type fasteners by which the two elements can be interconnected.

On location of the cover member 30 on the pipeline 2, the insulating material 34 of each element 32 seats in the recess in the material 4 to file said recess, with the peripheral edge regions of the cladding 36 and the sealing strips 38 thereon overlying the bounding edges of the cladding 6.

The components 40,42 of the fasteners are then interconnected and the over-centre actuation of the fasteners is effected whereby the elements 32 are drawn towards one another and locked together and to the pipeline 2 with the sealing strips 38 compressed between the cladding 36 and the cladding 6.

Thereby, as with the cover members 10, the recess in the material encapsulating the pipeline 2 is completely filled and sealed and the integrity of the encapsulating material is reinstated.

Removal of the cover member 30 is achieved by opening of the fasteners 40,42 which is again a simple task.

Instead of, or in addition to, the fasteners comprising the components 40,42, the elements 32 of the cover member 30 may each be provided with axially opposed cam levers similar to those on the cover member 10 located under the peripheral edge regions of the cladding 36, and rotatable to co-operate with the undersides of the circular bounding edges of the cladding 6 to effect the locking and sealing of the member 30 on the pipeline 2.

In an alternative cover member 30, two adjacent axially-extending edges of the elements 32 are permanently hinged together with the opposed free edges of the two elements being provided with co-operating fastening means for effecting the locking together of the elements 32 and the sealing of the cover member 30 on the pipeline.

Clearly the axial extent of the cover member 30 can be chosen to suit particular requirements as may the number and the nature of the fasteners between the elements 32.

Bends in pipelines are particularly prone to corrosion, and Fig. 2 shows a cover member for enabling access to a bend and to circumferential welds to each side of the bend.

The illustrated cover member is shown generally at 40 and is similar in principle to cover member 30, comprising opposed elements 42 each of semi-circular shape in transverse section but of axial shape conforming with that of the associated bent region of the pipeline. Sealing strips 44 are provided on the underside of the cladding 46, while components 48,50 of fasteners on the cladding 46 enable the cover member 40 to be locked and sealed to the pipeline with the insulating material 52 underlying the cladding 46 completely filling the recess in the removed encapsulating material.

Fig 3 illustrates a pipeline 2 incorporating a Tjunction therein and to which is fitted a further cover member indicated generally at 54. The cover member 54 is basically an axially extended version of the cover member 30 but with the two elements 56 equivalent to the elements 32 hinged together as detailed above, each element 56 further including a radially-extending arm portion 58 of semi-circular transverse section, said arm portions 58, on locking of the cover member 54 about the T-junction by means of the fasteners 60, sealingly encasing the branch 62 of the junction.

Although described and illustrated in connection with pipelines, it is to be emphasised that the method and cover members of the invention have application to other components or vessels of varying configurations encapsulated in layers of insulating material and cladding, providing the cover members themselves can be releasably locked and sealed in place of the removed encapsulating material.

In the case of pipelines, the cover members may be provided as individual components for location in preformed recesses in the material encapsulating the pipeline, or alternatively a length of encapsulating material incorporating one or more removable cover members may be provided for location on an associated extent of the pipeline to form a continuation of the insulating material to either side thereof.

Other modifications and variations from the described arrangements will be apparent to those skilled in the art.

Claims

1. A method of enabling repeated access to a region of a component encased in an inner layer of insulating material and an outer metal cladding, the method comprising the steps of: removing a volume of insulating material and the associated portion of metal cladding overlying the region of the component to be accessed; providing a replacement cover member including an inner layer of insulating material and an outer layer of metal cladding the periphery of which is adapted to overlie the cladding of the component bounding said removed portion, with sealing means reacting between the underside of said periphery of the cladding of the cover member and the outer surface of the cladding of the component bounding said removed portion, the metal cladding of the cover member having releasable locking means thereon;; locating the cover member in place of the removed volume of insulating material and associated portion of metal cladding with the sealing means located between the cladding of the cover member and the component, and actuating said locking means to secure the cover member in an operative position on the component and to effect a seal between the cladding of the cover member and the underlying cladding of the component.

2. A cover member for use in the method of claim 1 comprises an inner layer of insulating material, an outer layer of metal cladding the size and shape of which slightly exceeds that of the removed portion of cladding, sealing means mounted on the underside of the periphery of the layer of metal cladding, and releasable locking means mounted on the outer layer of metal cladding and so arranged that, on location of the cover member on the component in place of the removed volume of insulating material and associated portion of metal cladding, actuation of the locking means secures the cover member in an operative position on the component and effects a seal between the cladding of the cover member and the underlying cladding of the component.

3. A cover member as claimed in claim 2 and comprising a plug of insulating material for location in a correspondingly-shaped recess in the insulation bounding the component, the plug being capped by a layer of cladding the periphery of which projects beyond the lateral edges of the plug of insulating material, locking means on the cap of cladding reacting between said cap and the underside of the cladding of the component bounding said recess.

4. A cover member as claimed in claim 3 in which the locking means comprise a plurality of cam levers disposed about the periphery of the cover member and movable between an inoperative position disengaged from the component and an operative position engaging the underside of the cladding of the component bounding said recess in such a manner that the cladding of the cover member is urged towards the component to compress the sealing means between the cladding of the cover member and the underlying cladding of the component.

5. A cover member as claimed in claim 2 and adapted to replace a portion of the insulating material and associated portion of cladding encasing the component and overlying said seal, said portions being of annular transverse section and having a predetermined axial extent, first and second portions each of semi-circular shape in transverse section, and each including an inner layer of insulating material the axial extent of which conforms with that of the removed portion of insulating material, an outer cap of cladding the opposed semicircular edge extents of which overlie the edges of the cladding of the component bounding said removed portion, sealing means mounted on the underside of said semicircular edge extents of the cladding, and locking means actuation of which secures the two portions of the cover member together on the component and effects a seal between the cover member and said component.

6. A cover member as claimed in claim 5 in which the locking means react between the first and second portions of the cover member to effect said seal.

7. A cover member as claimed in claim 5 in which the locking means react between the portions of the cover member and the cladding of the component to effect said seal.

8. A cover member as claimed in claim 7 in which the locking means are in the form of a plurality of rotatable cam levers mounted on the underside of the cladding of the portions of the cover member and each movable between an inoperative position disengaged from the component and an operative position engaging the underside of the cladding of the component to urge the first and second portions of the cover member towards the component.

9. A cover member as claimed in any one of claims 5 to 8 in which the first and second portions of the cover member are hinged together along adjacent, axiallyextending edge regions thereof, the locking means reacting between the other opposed axially-extending edge regions of said portions.

10. A cover member as claimed in any one of claims 5 to 8 in which the first and second components of the cover member are separate from one another and are interconnected with each other and to the component by the locking means.

11. A cover member as claimed in any one of claims 5 to 10 and adapted to replace a portion of the insulating material and associated portion of cladding encasing a Tjunction of the component, each portion of the cover member being of generally T-shape each arm of which is semicircular in transverse section.

12. A cover member as claimed in any one of claims 1 to 11 in which the layer of insulating material conforms substantially in volume and configuration with that of the removed insulating material.

13. A method of enabling repeated access to a region of an insulated component substantially as described with reference to the accompanying drawings.

14. A cover member for use in the method of claim 13 substantially as described with reference to and as illustrated by the accompanying drawings.