GB2474038A

GB2474038A - Storage tank lining and jacketing

Info

Publication number: GB2474038A
Application number: GB0917234A
Authority: GB
Inventors: Stephen Robinson; Kevin Hoare
Original assignee: 1ST ADVANCE TANKS PIPEWORKS Ltd; JACQUELINE ROBINSON
Current assignee: JACQUELINE ROBINSON
Priority date: 2009-10-01
Filing date: 2009-10-01
Publication date: 2011-04-06
Anticipated expiration: 2029-10-01
Also published as: GB2474038B; GB201013515D0; GB0917234D0; GB2474096A; GB2474096B

Abstract

A method and system for lining the interior or exterior surface of a wall of a pre-existing tank is described. A first layer 12 of glass reinforced plastic (GRP) material is applied against the wall of a tank 20. The layer 12 has first and second opposed surfaces 14, 16 and is formed integrally with a plurality of spaced, non-intersecting projections 18 extending from the first surface. The lining layer 12 is applied with the first surface 14 facing the wall 20 and the projections 18 contacting the wall. The projections 18 are bonded to the tank wall to define an interstitial gap 22 between the tank wall and the first surface of the lining layer 12. At least one additional layer 24 of GRP material is bonded against the second surface 16 of the first layer 12 to form a lining with a laminated structure. The interstitial gap 22 may be filled with pressurised gas or liquid, or it may be evacuated, and status monitoring apparatus may be installed to detect a change in pressure or liquid level in the interstitial gap, in order to monitor for leaks in the tank.

Description

Method and System for Lining and Jacketing Storage Tanks The present invention relates to a method and system for lining or jacketing storage tanks to protect against leaks. The invention is described with particular reference to storage tanks for fuels such as petrol but is equally applicable to tanks for other purposes.

Leakages from tanks containing fuels or other chemicals may create safety hazards in terms of environmental pollution, fire or explosion risks, etc. Therefore, it is necessary to avoid leakages as far as possible and have early leak detection should a tank failure occur.

GB 2342430 discloses a petroleum product storage tank with a laminated interior liner formed of sheets of glass reinforced plastic material sandwiching a PVC plastic layer formed with castellations or corrugations in order to define a gap. In use, the gap may be evacuated.

In a first aspect, the present invention provides a method for lining the interior or exterior surface of a wall of a tank, comprising applying against the wall of the tank a first layer of glass reinforced plastic (GRP) material with first and second opposed surfaces, wherein a plurality of spaced, non-intersecting projections extend from the first surface, and wherein the lining layer is applied with the first surface facing the tank wall and the projections contacting the tank wall, and bonding the projections to the tank wall to define an interstitial gap between the tank wall and the first surface of the lining material, further comprising bonding at least one additional layer of GRP material against the second surface of the first layer of GRP material to form a lining with a laminated structure.

Preferably, the method further comprises applying a sealing layer to a second surface of the lining layer which is opposed to the first surface.

Conveniently, the method further comprises forming an opening in the tank wall or the lining layer in communication with the interstitial gap and securing a valve in the opening.

The method preferably also involves either evacuating the interstitial gap, filling the interstitial gap with pressurised gas or filling the interstitial gap with liquid, and installing status monitoring apparatus to detect a change in pressure or a change in liquid level in the interstitial gap.

In a second aspect the present invention provides a tank having a wall with interior and exterior surfaces and a lining applied against at least one of the interior or exterior surfaces, the lining comprising two or more layers of GRP material bonded together to form a laminate with first and second opposed surfaces and a plurality of spaced, non-intersecting projections extending from the first surface, wherein the first surface of the lining faces the tank wall and the projections are bonded to the tank wall, such that an interstitial gap is defined between the first surface of the lining and tank wall.

Preferably the interstitial gap is either evacuated, filled with pressurised gas, or filled with liquid, and the tank further comprises status monitoring apparatus operable in use to detect a change in pressure or a change in liquid level in the interstitial gap.

Preferably the status monitoring apparatus includes a visual and/or audible alarm actuable when changes in pressure or liquid level are detected.

The tank may further comprise a sealing layer applied to the second surface of the lining.

In one example the projections comprise a plurality of ribs.

In another example, the projections comprise one or more of cones, cylinders, domes, cubes or pyramids.

Preferably the tank further comprises at least one valve in the tank wall and/or the lining layer allowing selective communication with the interstitial gap.

In a third aspect the present invention provides a system for lining the interior or exterior surface of a wall of a tank comprising a first lining layer formed of GRP material and having first and second opposed surfaces, wherein a plurality of spaced, non-intersecting projections extend from the first surface, and a second layer formed of GRP material and having first and second opposed surfaces, whereby the first lining layer is appliable to a surface of a wall of a tank with the first surface facing the wall and the projections contacting the wall in order to define an interstitial gap between the tank wall and the first surface of the first lining layer, and the first surface of the second lining layer is bondable to the second surface of the first lining layer to form a laminate.

In use, the interstitial gap is preferably either evacuated, filled with pressurised gas or filled with liquid, and the system further comprises status monitoring apparatus operable to detect a change in the pressure or a change of the liquid level in the interstitial gap.

A sealing layer may be applied to the second surface of the second lining layer.

The projections may comprise a plurality of ribs.

Alternatively, the projections may comprise one or more of cones, cylinders, domes, cubes or pyramids.

Thus, the present invention provides a method and system for lining the interior surface, or jacketing the exterior surface, of an existing tank with a GRP laminate to create a double skinned structure. The GRP laminate forms a structural member. The interstitial gap between the two skins is either evacuated, pressurised or filled with liquid. The status of the interstitial gap is monitored so that any change of status, such as loss of pressure or a drop in liquid level, indicating a tank failure, actuates a warning system.

The system can be applied to new tanks, or to existing tanks in situ. For in situ underground tanks, the interior surface will be lined to form the double skinned structure.

In situ or new above ground tanks may either be lined internally or jacketed externally to form the double skin structure. For existing tanks the system may be applied to upgrade to sound or to repair and upgrade a tank which has already failed to restore its structural.integrity. The tanks themselves may be single skinned, or may already have a double skinned construction. In either case, in the following description reference to obtaining a doubled skinned structure with the present invention refers to combining whatever existing wall structure the tank may have, whether single, double or other configuration, with the lining/i acketing layer of the invention. Also in the following description, reference to lining a tank is intended to cover both lining the interior surface of a tank and lining the exterior surface (i.e. jacketing) and reference to a lining material or lining layer may refer to the layer applied either internally or externally.

The present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a cross sectional view of part of a tank wall with a lining system in accordance with one embodiment of the present invention, shown schematically and not to scale.

The present invention provides a tank lining layer 10 which is formed partially of a flexible glass reinforced plastic (GRP) layer 12 with opposed first and second surfaces 14, 16. A plurality of projections 18 are formed on the first surface of the sheet 12. Preferably, these projections 18 are in the form of a grid of ribs. The ribs do not intersect each other so the spaces between the ribs communicate with one another. The second, opposing surface 16 is substantially flat. It will be appreciated that ribs could be replaced by other configurations of projection such as cones, cylinders, domes, cubes or pyramids, or any other convenient form.

The layer 12 is formed in any appropriate manner.

Typically, this is by applying chopped strand glass fibre reinforced mat into a mould impregnated with a polyester resin and leaving the resulting sheet to cure. However, other GRP materials could be used, for example glass flake filled resin. The mould is generally flat but provided with grooves or recesses of the appropriate shape to form the projections 18 on the sheet 12.

After curing, the sheet 12 is released from the mould and is slightly flexible to allow it to be fitted to the curved shape of a tank.

In one example, the sheets 12 measure approximately 2.44m by 1.22m, with the projections approximately 18 3mm wide, 3mm deep and 50mm long. However, all these dimensions may be varied as required to suit the application.

In use, the wall 20 of a tank to be lined is prepared, e.g. cleaned, repaired if any leaks are present, etc. A primary layer of GRP lining material 12 is applied either by hand or some mechanical means, with the first surface 14 facing the tank wall 20 and the projections 18 contacting the tank wall 20. At the areas of contact the projections 18 are chemically spot bonded to the tank wall 20 e.g. with.

polyester bonding paste or a suitable grab adhesive. Thus, the projections 18 ensure that a continuous interstitial space 22 is defined between the tank wall 20 and the lining material 12.

For applications in which it is intended to pressurise the interstitial gap 22 or fill it with liquid, generally smaller lining sheets 12 will be used than if it is intended to evacuate the interstitial gap 22. The smaller sheets for pressurised/liquid filled applications are preferably individually tied to the tank wall 20 at their edges with further pieces of GRP material. Adjoining lining sheets may be butted together or overlapped. Each joint is then covered with further strips of GRP material.

A secondary layer 24 of GRP material is then applied over the entire surface of the primary layer of lining material 12 and the two are chemically bonded together to form a laminate. Further layers may be added if desired.

This laminate structure formed of two or more layers of the same material provide a very strong lining layer of greater structural integrity than linings made of a combination of different materials.

Optionally, preformed rib sections of GRP material, e.g. flanged sections of approximately 50mm to 100mm in length and rnoulded into the same profile as the tank, may be bonded to the lining layer 10 for additional strength.

Additional coats of resin 26 may then be applied to the secondary layer 24. Finally, a sealing top coat 28 is applied. For tanks which are-internally lined, this will be the layer in contact with the product stored in the tank and must therefore be impervious and resilient to it. For example, for applications in the petroleum industry ATLLAC 590 vinyl ester resin is specified as it is resistant to 85 ether alcohol EA85. For externally lined (jacketed) tanks, a weatherproof ing final top coat may be required.

Thus a double skinned construction is now created with the first skin being the pre-existing tank wall 20 and the second skin being the lining layer 10, with an interstitial gap 22 therebetween. As mentioned previously, the first skin may itself be a single walled, double walled or other construction. The second skin will be a laminate comprising at least primary and secondary layers of GRP lining material 12, 24 and various additional layers of resin and sealant 26, 28.

Subsequently, one or more openings communicating with the interstitial gap 22 are formed through the lining layer and/or the existing tank wall 20 and a valve 30 such as a high pressure ball valve is secured in the opening. This allows the interstitial gap 22 to be either evacuated, pressurised with air or other gas, or filled with liquid.

Monitoring equipment 32 is installed to monitor the status of the interstitial gap 22, i.e. whether the vacuum is maintained, the pressure is maintained or the liquid level is maintained as appropriate. The monitoring equipment 32 is connected to an appropriate alarm system 34, e.g. by a -9-.

cable or a remote signal. In this way, any change in the status of the interstitial space 22, which would indicate a tank failure and possible leak, will actuate an alarm such as an audible and/or visual alarm.

In this way, an improved tank lining/i acketing method and system is provided which can be applied to new tanks or fitted in situ to existing tanks, whether above ground or underground. It will be appreciated that the precise details of the invention can be varied to suit the application without departing from the scope of the invention as set out in the claims.

Claims

-10 -CLAIMS1. A method for lining the interior or exterior surface of a wall of a tank, comprising, applying against the wall of the tank a first layer of glass reinforced plastic (GRP) material with first and second opposed surfaces, wherein a plurality of spaced, non-intersecting projections extend from the first surface, and wherein the lining layer is applied with the first surface facing the tank wall and the projections contacting the tank wall, and bonding the projections to the tank wall to define an interstitial gap between the tank wall and the first surface of the lining material, further comprising bonding at least one additional layer of GRP material against the second surface of the first layer of GRP material to form a lining with a laminated structure.
2. A method as claimed in claim 1, further comprising applying a sealing layer to a second surface of the lining layer which is opposed to the first surface.
3. A method as claimed in claim 1 or 2, further comprising forming an opening in the tank wall or the lining in communication with the interstitial gap and securing a valve in the opening.
4. A method as claimed in claim 3, further comprising either evacuating the interstitial gap, filling the interstitial gap with pressurised gas or filling the interstitial gap with liquid, and installing status monitoring apparatus to detect a change in pressure or a change in liquid level in the interstitial gap.

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5. A tank having a wall with interior and exterior surfaces and a lining applied against at least one of the interior or exterior surfaces, the lining comprising two or more layers of GRP material bonded together to form a laminate with first and second opposed surfaces and a plurality of spaced, non-intersecting projections extending from the first surface, wherein the first surface of the lining faces the tank wall and the projections are bonded to the tank wall, such that an interstitial gap is defined between the first surface of the lining layer and tank wall.
6. A tank as claimed in claim 5, wherein the interstitial gap is either evacuated, filled with pressurised gas, or filled with liquid, and further comprising status monitoring apparatus operable in use to detect a change in pressure or a change in liquid level in the interstitial gap.
7. A tank as claimed in claim 6, wherein the status monitoring apparatus includes a visual and/or audible alarm actuable when changes in pressure or liquid level are detected.
8. A tank as claimed in any of claims 5 to 7, further comprising a sealing layer applied to the second surface of the lining.
9. A tank as claimed in any of claims 5 to 8, wherein the projections comprise a plurality of ribs.

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10. A tank as claimed in any of claims 5 to 8, wherein the projections comprise one or more of cones, cylinders, domes, cubes or pyramids.
11. A tank as claimed in any of claims 5 to 10, further comprising of at least one valve in the tank wall and/or the lining layer allowing selective communication with the interstitial gap.
12. A system for lining the interior or exterior surface of a wall of a tank comprising a first lining layer formed of GRP material and having first and second opposed surfaces, wherein a plurality of spaced, non-intersecting projections extend from the first surface, and a second lining layer formed of GRP material and having first and second surfaces, whereby the first lining layer is appliable to a surface of a wall of a tank with the first surface facing the wall and the projections contacting the wall in order to define an interstitial gap between the tank wall and the first surface of the first lining layer, and the first surface of the second lining layer is bondable to the second surface of the first lining layer to form a laminate.
13. A system as claimed in claim 12, wherein in use, the interstitial gap is either evacuated, filled with pressurised gas or filled with liquid, and the system further comprises status monitoring apparatus operable to detect a change in the pressure or a change of the liquid level in the interstitial gap.

-13 -
14. A system as claimed in claim 12 or 13, wherein a sealing layer is applied to the second surface of the second lining layer.
15. A system as claimed in any of claims 12 to 14, wherein the projections comprise a plurality of ribs.
16. A system as claimed in any of claims 12 to 14, wherein the projections comprise one or more of cones, cylinders, domes, cubes or pyramids.
17. A method for lining the interior or exterior surface of a wall of a tank substantially as hereinbefore described and with reference to the accompanying drawings.
18. A tank as substantially and hereinbefore described and with reference to the accompanying drawings.
19. A system for lining the interior or exterior surface of a wall of a tank substantially as hereinbefore described and with reference to the accompanying drawings.CLAIMS1. A method for lining the interior or exterior surface of a wall of a pre-existing tank, comprising applying against S the wall of the tank a first layer of glass reinforced plastic (GRP) material with first and second opposed surfaces, formed integrally with a plurality of spaced, non-intersecting projections extending from the first surface, and wherein the lining layer is applied with the first surface facing the tank wall and the projections contacting the tank wall, and bonding the projections to the tank wall to define an interstitial gap between the tank wall and the first surface of the lining material, further comprising bonding at least one additional layer of GRP material against the second surface of the first layer of GRP material to form a lining with a laminated structure.2. A method as claimed in claim 1, further comprising * ** **.* * applying a sealing layer to a second surface of the lining layer which is opposed to the first surface. *3. A method as claimed in claim 1 or 2, further comprising forming an opening in the tank wall or the lining in * communication with the interstitial gap an securing a valve in the opening.4. A method as claimed in claim 3, further comprising either evacuating the interstitial gap, filling the interstitial gap with pressurised gas or filling the interstitial gap with liquid, and installing status monitoring apparatus to detect a change in pressure or a change in liquid level in the interstitial gap.5. A system for lining the interior or exterior surface of a wall of a pre-existing tank comprising a first lining layer formed of GRP material and having first and second opposed surfaces, integrally formed with a plurality of spaced, non-intersecting projections extending from the first surface, and a second lining layer formed of GRP material and having first and second surfaces, whereby the first lining layer is applicable to a surface of a wall of a pre-existing tank with the first surface facing the wall and the projections contacting the wall in order to define an interstitial gap between the tank wall and the first surface of the first lining layer, and the first surface of the second lining layer is bondable to the second surface of the first lining layer to form a laminate.6. A system as claimed in claim 5, wherein in use, the interstitial gap is either evacuated, filled with pressurised gas or filled with liquid, and the system further comprises status monitoring apparatus operable to detect a change in the pressure or a change of the liquid level in the interstitial gap.7. A system as claimed in claim 5 or 6, wherein a sealing *::::* layer is applied to the second surface of the second lining layer. * .s8. A system as claimed in any of claims 5 to 7, wherein S..* the projections comprise a plurality of ribs.* : 30 9. A system as claimed in any of claims 5 to 7, wherein S.....* the projections comprise one or more of cones, cylinders, domes, cubes or pyramids.10. A method for lining the interior or exterior surface of a wall of a tank substantially as hereinbefore described and with reference to the accompanying drawings.11. A system for lining the interior or exterior surface of a wall of a tank substantially as hereinbefore described and with reference to the accompanying drawings. * * **.*..* * * * ** * * * * ** *.**** * a a * ...I* * S