WO2006103479A2

WO2006103479A2 - Fluid impervious lining

Info

Publication number: WO2006103479A2
Application number: PCT/GB2006/050069
Authority: WO
Inventors: Christos Sotirious Haritou; Alan Fada; Ian Gimiel Fada; John Harry Rhodes
Original assignee: Christos Sotirious Haritou; Alan Fada; Ian Gimiel Fada; John Harry Rhodes
Priority date: 2005-03-31
Filing date: 2006-03-30
Publication date: 2006-10-05
Also published as: GB0718850D0; GB2439860A; WO2006103479A3

Abstract

A wall lining apparatus comprises a wall and at least one sheet of semi-rigid impervious material, wherein the at least one sheet of semi-rigid fluid impervious material is located to one side of the wall, and an interstitial space exists between opposing faces of said wall and said sheet of semi-rigid fluid impervious material. One embodiment of the apparatus comprises at least one sheet of semi-rigid fluid impervious material and three-dimensionally shaped components of the same fluid impervious material, the or each sheet and the shaped components being attached to each other.

Description

Fluid Impervious Lining

Field of the Invention

This invention relates to a fluid impervious lining, and in particular to a fluid impervious lining comprised of planar sheets and shaped components. The lining is particularly useful for internally lining fuel storage tanks.

Background of the Invention

It is becoming increasingly common to line vessels used to store fluids that are potentially damaging to the environment. For example fuel storage tanks are often lined with a corrosion resistant layer. Such linings are commonly fabricated so as to provide an interstitial space between the inner surface of the tank hull and the corrosion resistant layer. The interstitial space facilitates monitoring of the integrity of the liner and the tank hull.

One problem associated with the lining of tanks, pipes and other enclosures with plastics materials is that the nature of the lined structures is such that areas of potential weakness might arise. In one lining system described in the present applicants' co-pending United Kingdom patent application no 0409466.0 a fuel storage tank is lined so as to form an interstitial space by sheets of corrosion resistant plastics material, adjacent sheets being welded together.

Installing the lining system described in 0409466.0 can be time consuming. Furthermore, the welding together of PVDF sheets required in at least one embodiment can result in damage to a plastics layer located between the PVDF sheet and the tank wall, that is the hot weld can melt the inner plastics layer and breach the interstitial space.

An interstitial space is a requirement of a double skinned tank. The purpose of the interstitial space allows the integrity of the tank lining to be monitored. For example, the interstitial space may be subject to a vacuum which is monitored. If the pressure increases, then the interstitial space has been breached.

Accepted wisdom suggests that the gap between the inside tank surface and the surface of the plastic lining facing the inside of the tank, i.e. the interstitial space, must be of uniform cross-section through the tank. Recent research has shown that the interstitial space may be non uniform, and that such a non-uniform space allows for satisfactory monitoring thereof, particularly where the monitoring system involves subjecting the interstitial space to a vacuum.

The invention therefore provides a method and apparatus for lining a curved wall that is far simpler than methods and apparatus known from the prior art.

It is common for fuel tanks to include elements such as man-ways, cross braces, domed or torispherically shaped ends, etc which can make the application of sheets difficult due to the requirement to weld together plastics sheets in inaccessible locations. Also, the operation of cutting to size pieces of plastics sheet is time consuming, especially if performed by a technician located in a tank.

Furthermore, the use of at least two different materials, i.e. that of the outer hull and the plastics liner material(s) can lead to relative movement of the liner with respect to the hull due to changing atmospheric conditions and changes in the quantity of fluid stored in the tank. One such problem could occur around a man-way into a fuel storage tank If the man-way is lined with a plastics material and the man-way lining and main tank lining are attached together, changes in atmospheric conditions could generate undesirable forces on the main hull lining.

An object of the invention is to avoid the problem associate with cutting and welding small pieces of plastics sheet material in inaccessible areas. Another object of the invention is to provide a means to compensate for movement between an inner lining and an outer hull.

Summary of the Invention

According to one aspect of the invention, there is provided a fluid impervious lining as specified in Claim 1.

According to another aspect of the invention, there is provided a fluid impervious lining as specified in Claim 17.

According to yet another aspect of the invention, there is provided a vessel as specified in Claim 36.

Preferably the semi-rigid fluid impervious sheet material has a thickness in the range of lmm to 6mm, and more preferably in the range 1.5mm to 4mm, and still more preferably 1.5mm to 2.5mm.

Other preferred features are described in the claims dependent on Claims 1, 17 and/or 36 and/ or in the description.

A vessel is lined with the lining of the invention by attaching sheets of semi-rigid fluid impervious material to a surface of the vessel so as create an interstitial space between the tank wall and the fluid impervious sheet material. The fluid impervious sheet material is held in place by means of magnetic force.

A vessel is lined with the lining of the invention by affixing sheets of fluid plastics material to a surface of the vessel, fixing components having shapes matching shapes of elements forming part of, or located in, the vessel and attaching sheets or shaped components together or to each other by welding.

Brief Description of the Drawings In the drawings which illustrate preferred embodiments of the invention, and are for exemplary purposes only:

Figure 1 is a schematic representation of a tank lining according to the invention;

Figure Ia is a schematic representation of a tank lining according to a second embodiment of the invention;

Figure 2 is a schematic representation of an end dome of the tank lining illustrated in Figure 1;

Figure 3 is a schematic representation of a part of a tank lining according to the invention;

Figure 3a is a plan view of the fastening means of the tank lining illustrated in Figure 3;

Figure 4 is a cross-sectional elevation illustrating the man-way of a tank having a plastics lining;

Figure 4' is an alternative expandable section for use in the man-way of a tank having a plastics lining;

Figure 5 is a schematic representation of a saddle component for use in lining the man- way,

Figure 5' is a sectional view of the saddle component illustrated in Figure 2;

Figure 6 is a schematic representation of a collar for use in lining the man-way;

Figure 6' is a cross-section of the collar illustrated in Figure 3;

Figure 7 is a cross-sectional elevation illustrating a component lining an obstruction in a tank;

Figure 8 is a schematic representation of a coving liner element;

Figure 8' is an end view of the coving liner element illustrated in Figure 5; and

Figure 9 is a schematic representation of the torispherical head of a tank. Detail Description of the Preferred Embodiments

Referring now to Figure 1, a fuel storage tank 1 comprises an outer hull 2, and a lining 3, which in the example is formed by three sheets 3a of semi-rigid fluid impervious material which in the example is a plastics material, each sheet being formed into a ring by a weld 4, and dome ends 6 (only one is shown for the sake of clarity). Adjacent plastics sheets 3a are joined to each other by circumferential welds 11.

The dome ends 6 comprise two semi-circular elements 7 joined together by a weld 8, and three elements 9, each element 9 being curved in one plane and flat in the others. The elements 9 are joined to each other by welds 10 whilst the elements 9 adjacent the sheet 3a are joined thereto by a weld 11, and to the semi-circular elements 7 by a weld 12.

The outer hull 2 is formed from steel and the plastics sheets 3a, which are impervious to liquid fuel are held in place in the tank by a plurality of earth magnets 5 which are attracted to the steel outer hull 2. Similarly, the semi-circular elements 7 are held in place with magnets 18. Whereas the sheets 3a are held in place by a plurality of magnets, in the example each semi-circular element 7 is held in place by a single magnet 18. The magnets 5 used to support a sheet 3a generate a magnetic force about two to three times the weight of the said sheet 3a. Similarly, the force generated by each magnet 18 is greater than the weight of a semi-circular element 7. The magnets 5 are illustrated holding the lower portion of the tank in place. Magnets 5 may also be distributed around the whole of the section 3a, or in the top part of the section 3a.

An interstitial space is generated between the lining 3 and the tank hull simply by virtue of slight undulations in the plastics sheets 3a, which provide a pathway for air. When the monitoring system selected is a vacuum, the application of a vacuum to the interstitial space pulls the lining 3 onto the inner surface of the tank hull 2. The lining 3 is therefore held in place by both magnets 5 and the vacuum applied between the lining and the outer hull 2. In one embodiment of the invention, the magnets are used only during construction of the lining, the force generated by the vacuum and the lining's own strength holding the said lining in place.

In Figure 1 an alternative method of joining together adjacent sheets 3a, the method comprising using a tape 23, which in the example is an adhesive tape and is attached to the inner surface of the sheets 3a. This same method may be used to join together the respective ends of a single sheet 3a.

In Figure Ia, a backing strip 15 is provided behind each weld 4. In Figure Ia, for the sake of clarity, only a part of the backing strip 15 is illustrated. In use, the backing strip 15 extends around the circumference of the liner to form a hoop. The backing strip 15 serves a number of purposes. First, it strengthens the assembled liner 3. Second, the integrity of the weld 11 is enhanced. Third, the backing strips space the liner 3 away from the inside of the outer hull 2.

Referring now to Figure 2, the knuckle angle between the dome end 16 and the cylindrical portion of the outer hull 2 is made more obtuse by the deposition of a wedge of filler 13, which in the example is an epoxy engineering filler. One of the sheets 3a terminates in close proximity to the intersection of the wedge 13 and the outer hull 2. The elements 9 lie on the surface 17 of the wedge 13. As described with reference to Figure 1, one side of each element 9 is attached to a free end of a sheet 3a and the other side of each element 9 is attached to the semi-circular elements 7. The provision of the wedge 13 reduces the levels of stress imposed on the liner. As can be seen from Figure 2, the element 9 is supported by the surface 17 of the wedge 13. If the wedge were not present, upon filling the vessel, elements 9 would be subjected to a bending force, which would stress welds 11 and 12.

The purpose of the wedge 14 is the same as that of wedge 13, and is used where a tank is divided into sections. The dome end 16 is lined, the lining comprising an element 19 which lies on the surface of wedge 14 and is attached to element 20 and the liner 18, attachment being by welding. The dome end lining elements may be formed from one or more vacuum formed section.

Referring now to Figures 3 and 3a, there is shown an alternative arrangement for joining together adjacent plastics sheets 3a. Rather than welding together adjacent sheets 3a, adjacent edges of the sheets 3 are pressed into channels 22 of a fastener 21. The width of the channels 22 is slightly less than the width of a sheet 3a to form a push fit This joining arrangement may be used to join together the respective ends of a sheet 3a.

The plastics sheets 3a may be formed from high density polyethylene (HDPE), or polyvinyl iodine fluoride (PVDF). In certain circumstances perfluorinated vinyether (FEP), or ethylene- chlorotrifluorethylen (ECTFE) may be used. These materials are much more difficult to work with, in terms of welding and fumes produced, and would therefore only be used where the nature of the product to be stored necessitated extreme resistance to chemical attack or temperature.

As mentioned above, in one embodiment of the invention, when the tank has been fully lined, the magnets are removed. The lining becomes a self-supporting structure. Where backing strips as referred to above in connection with Figure Ia are deployed, these serve to brace the lining. The force exerted on the lining by the vacuum also assists in preventing the upper part of the lining from collapsing when liquid is drawn from the tank

The invention also relates to a method of construction of a tank lining, the method comprising the steps of:

i) presenting sheets 3a of plastics material to a wall surface to be lined; ii) holding the sheets of plastics material with at least one magnet 5, 18; iii) joining edges of adjacent sheets to each other.

The method may also include the step of laying backing strips 15 onto the inner surface of the tank and laying plastics sheets on top of the said strips 15 at a joint between the said sheets. The method may include the step of joining together adjacent sheets of plastics material by welding, by applying a tape over the inner surface of the adjacent sheets of plastics material, or by the use of connectors.

The method further includes the steps of assembling end domes 6, which comprises the steps of laying out the said semi-circular elements 7 and joining them by welds 8 to form a circle, and infilling the centre with the three elements 9, and welding the said three elements to each other and to an edge of the semi-circular elements 7.

The method may included the further step of forming one or more wedges 13, 14, preferably formed from a filler such as an epoxy filler prior to the step of forming dome ends 6 in the lining.

The method of constructing a tank lining may further include the step of applying a vacuum to the interstitial space between the lining and the lined wall.

Referring now to Figure 4, a fuel storage tank 1 comprises an outer hull 2, which includes a man-way 3 in the form of a substantially cylindrical collar 4 surrounding an opening 5. The man-way 3 is closed by a tank lid 11. The collar 4 is attached to the outer hull. A lower end 5 of the collar extends into the tank with a Ep 6 extending around the outer perimeter of the upper end of the collar 4. In the example, the lining of the outer hull consists of three elements: a corrosion barrier coating 7, a first layer of plastics material 8 having a plurality of protrusions 9 extending from one surface thereof towards the inner surface of the outer hull 2, and a second layer of plastics material 10. Around the inside of the collar 4, the first plastics layer 8 is omitted, the inner surface of the collar being covered only with the plastics material 10. The omission of the plastics layer 8 is due to the absence of a requirement for an interstitial space. In order to provide corrosion protection to the whole of the inside of the tank, the plastics layer 10 extends across the tank lip 6, and when the lid 11 is put in place, is sandwiched between the lower surface of the lid 11 and the upper surface of the tank lip 6. In the example, the first layer of plastics material 8 is formed from high density polyethylene (HDPE), whilst the second layer of plastics material is formed from polyvinyl iodine fluoride

(PVDF).

In order to accommodate movement of the liner 10 within the tank, the section 12 of plastics material lining the collar 4 includes an expandable portion 13. The expandable portion 13 includes a plurality of element hinged together in a concertina manner. Section 12 is vacuum formed. The section 14 of plastics material lining the lower end 5 of the collar is also vacuum formed, and is attached to the section 12 by a weld 15. The section 14 is also attached to the main second layer of plastics lining material by a weld 16.

Figure 4' illustrates an alternative expandable section for lining the collar 4 of the man-way of a tank. The expandable section 12' comprises upper and lower conical sections having walls 13' hinged at 13". The hinge may be formed in the manufacturing of the section, such as by vacuum forming. When the position of the tank liner 10' changes slightly, the walls 13' flex at hinge 13" to accommodate the movement of the tank liner 10'.

As can be seen from Figure 5, the section 14 of plastics material is in the form of a saddle having a shape corresponding to the shape of the outer hull 2.

Figure 6 illustrates the section 12 of plastics material which lines the collar 4.

Referring now to Figure 7, there is shown a tank outer hull 20 and attached to an inner surface thereof an I beam. A vacuum formed element 22 is provided to bridge the I beam, the free ends 23 of the vacuum formed element 22 being attachable to a sheets 24 of plastics material by welding.

Referring now to Figure 8, a vacuum formed coving element 25 is useful in lining corners of tanks. For example, rather than using the torispherically shaped end section illustrated in Figure 9 and described below, a coving element 25 could be used to line the knuckle element 32 (Figure 9), with the centre of the coving element being filled with an individual plastics component or a plurality of plastics components, which may be of plastics sheet material, or may themselves be shaped components. The coving element 25 may comprise a number of sections to be welded together in situ.

Figure 9 illustrates one end of a steel tank 29 having an outer hull 30 including a torispherically shaped end section 31. The end section 31 is includes a knuckle radius 32 having a free end 32a to which the outer hull 30 is welded. For the sake of clarity, only one layer of plastics material is illustrated. However, two layers may be provided, with one layer providing an interstitial space. The layer of plastics material illustrated comprises a torispherically shaped element 33 corresponding to the shape of the end section 31. The element 33 is attached to a sheet of plastics material 34 by a weld 35. The domed element 33 may be vacuum formed, or may be heat formed. By providing the torispherically shaped element 33, small pieces of plastics material do not have to be cut and welded to fabricate a shape corresponding to the knuckle 32.

The element 33 may be cut into a number of sections, for example four, to facilitate the passing of said element 33 into the tank.

The element 33 may comprise a plurality of sheet sub-elements an edge portion of each being heat formed to generate a shaped corresponding to the knuckle radius.

In the examples, the plastics material from which the shaped elements are made is PVDF. The shape of the said shaped elements may render them substantially rigid.

In the description of the preferred embodiments the semi-rigid fluid impervious sheet material is a plastics material, which has been found to be suitable for the task, insofar as it may be bent into curved shapes, joined effectively and withstand the stresses imposed by filling and emptying the lined tank with fluid. Other suitable semi-rigid fluid impervious materials may be used instead of plastics. The provision of specifically shaped elements of plastics lining material allows the cutting to shape of intricately shaped pieces to be avoided. Furthermore, welding in inaccessible places is avoided. In many cases where the walls of an object are lined, the integrity of the lining is vital. Whilst a sound weld will be stronger than the material of the sheets being welded together, if fitters are required to weld in inaccessible locations, flawed welds may result. The invention avoids this problem by providing shaped elements which require welding only in accessible locations. Also, cutting and welding sheets of plastics material to cover oddly shaped or positioned objects is time consuming. The invention provides a solution that would save considerable amounts of time. The vacuum or heat formed expandable collar is particularly advantageous, since it accommodates simply and effectively naturally occurring changes in atmospheric pressure or fluid level in the tank The torispherically shaped end portion or a coving allows welding to be avoided in the knuckle region of the end portion.

Claims

1 A wall lining apparatus comprising a wall and at least one sheet of semi-rigid fluid impervious material, wherein the at least one sheet of semi-rigid fluid impervious material is located to one side of the wall, and an interstitial space exists between opposing faces of said wall and said semi-rigid fluid impervious sheet.

2. A wall lining apparatus as claimed in Claim 1, wherein the at least one sheet is held in place with respect to the wall by at least one magnet.

3. A wall lining apparatus as claimed in Claim 1 or 2, wherein the interstitial space is subjected to a monitoring means.

4. A wall lining apparatus as claimed in Claim 3, wherein the interstitial space is subjected to a vacuum.

5. A wall lining apparatus as claimed in any preceding claim, wherein edges of adjacent sheets of material are joined together by joining means.

6. A wall lining apparatus as claimed in Claim 5, wherein the joining means are selected from the group comprising: welding, tape, adhesive, an element engaging with the said sheets.

7. A wall lining apparatus according to Claim 5 or 6, wherein a backing strip is located behind each joint between adjacent sheets of material.

8. A wall lining apparatus according to any preceding claim, wherein free ends of each sheet of material are joined to form a hoop.

9. A wall lining apparatus according to Claim 7, wherein at least one backing strip forms a hoop around the lining apparatus.

10. A wall lining apparatus according to any preceding claim, wherein the wall includes ends, and wherein a wedge is provided at the intersection of the or each end and the wall.

11. A wall lining apparatus according to Claim 10, wherein the included angle between the wall and the wedge, and the included angle between the wedge and the wall end are obtuse.

12. A wall lining apparatus according to Claim 10 or 11, wherein the wedge is formed from an epoxy filler.

13. A wall lining apparatus as claimed in any preceding claim, wherein the lining comprises end pieces.

14. A wall lining apparatus according to any preceding claim, wherein the said at least one sheet of semi-rigid fluid impervious material is a plastics material.

15. A wall lining apparatus as claimed in Claim 14, wherein the said plastics material is a fluoropolymer or from the polyolefin family.

16. A wall lining apparatus as claimed in Claim 14 or 15, wherein the said plastics material is polyvinyl iodine fluoride (PVDF) or high density polyethylene (HDPE).

17. A tank lined with a wall lining apparatus as claimed in any of Claims 1 to 16.

18. A method of lining a wall using apparatus as claimed in comprising the steps of: i) presenting sheets of plastics material to a wall surface to be lined; ii) holding the sheets of plastics material with at least one magnet; iii) joining edges of adjacent sheets to each other.

19. A method as claimed in Claim 18, comprising the further step of removing the said at least one magnet

20. A method as claimed in Claim 18 or 19, wherein the wall is part of a tank and free ends of the sheets of plastics material are joined to each other.

21. A method as claimed in Claim 18 or 19, wherein joining is by joining means as specified in Claim 6.

22. A method as claimed in Claim 18 or 19, wherein the interstitial space between the lining and the lined wall is subjected to a vacuum.

23. A method according to any of claims 17 to 21, wherein a backing strip is placed behind each joint between adjacent sheets.

24. A wall lining according to any of Claims 1 to 16 comprising sheets of semi-rigid fluid impervious material and three dimensionally shaped components of the same fluid impervious material, wherein the or each sheet and the shaped components are attached to each other by welds.

25. A fluid impervious lining according to Claim 24, wherein the shaped components are vacuum formed.

26. A fluid impervious lining according to Claim 24, wherein the shaped components are heat formed.

27. A fluid impervious lining according to any of Claims 24 to 26, wherein one of the shaped components includes an expandable portion.

28. A fluid impervious lining according to Claim 27, wherein the expandable portion is part of a tubular shaped component.

29. A fluid impervious lining according to Claim 27 or 28, wherein the expandable portion includes a hinge, or a plurality of hinges.

30. A fluid impervious lining according to any of Claims 24 to 29, wherein one of the shaped components includes a collar.

31. A fluid impervious lining according to any of Claims 24 to 30, wherein one of the shaped components includes a saddle.

32. A fluid impervious lining according to any of Claims 24 to 31, wherein one of the shaped components is torispherical.

33. A fluid impervious lining according to any of Claims 24 to 32, wherein one the shaped components includes a U shaped element.

34. A fluid impervious lining according to any of Claims 24 to 33, wherein one of the shaped components includes an L shaped element.

35. A fluid impervious lining according to any of Claims 24 to 34, wherein one of the shaped components includes a coving element

36. A fluid impervious lining according to any of Claims 24 to 35, wherein each shaped component includes an edge for welding to another shaped component or a sheet of plastics material.

37. A vessel lined with a fluid impervious lining according to any of Claims 24 to 36, wherein the vessel includes a man-way, and the lining of the man-way is lined includes a shaped component having an expandable portion.

38. A vessel according to claim 37, wherein the lining of the man-way includes a saddle a cross-section of which corresponds to the shape of the element of the vessel immediately surrounding the man-way, and wherein the saddle extends around the man- way.

39. A vessel according to Claim 38, wherein the saddle is welded to the shaped component including the expandable portion.

40. A vessel according to Claim 39, wherein the expandable portion includes a hinge or a plurality of hinges.

41. A fluid impervious lining substantially as shown in, or as described with reference to, the drawings.