FffiLD OF THE INVENTION

The present invention relates to methods of construction of hot water tanks for water heater use. More particularly the present invention relates to the joining of tank ends when the tank is constructed from a structural wall and a plastics liner and the insertion of inlet and connection ports through the side wall of such hot water tanks.

BACKGROUND OF THE INVENTION

Patent application PCT/AU93/0O013 discloses a lined tank assembly for a water heater which enables a tubular plastics liner to be removably inserted inside a pressure resisting tubular body and sealed using circular ends, which may be curved, either inwardly or outwardly, to resist internal pressure in the tank. The circular ends, which may be plastics lined, have peripheral sealing means that develop increasing seal compression with increasing internal tank pressure. The ends are retained by releasable retaining means, without which the ends would be free to slide axially within the tubular body in the manner of a piston inside a cylinder. The above sealing arrangement sometimes shows a disadvantage insofar as, whilst it becomes leak tight upon filling with water and applying positive internal pressure, some small number of manufactured specimens may leak in a minor manner during first filling with water after installation and this can be unacceptable in some locations even though the leakage is transient.

In PCT/AU93/0O013 end connections for water inlet and outlet, safety valves or heating elements are constructed in conjunction with moulded plastics end members and not penetrating the tubular liner which is made as an extrusion rather than an injection, blow or rotational moulding. End connections whilst relatively simple in construction, have the disadvantage that they do not facilitate installation and servicing, but to date, connections through the tubular wall of a liner to facilitate installation and servicing have been difficult to make in a leak free manner.

SUMMARY OF THE INVENTION

The invention provides a method of sealing a hot water tank wall which includes an inner plastics liner and a tank end which is also plastics lined, said method including the steps of:

(a) mounting a shaped sealing ring onto a tank end, said sealing ring having means to be attached to a portion of said tank end, said sealing attachment also including a seal receiving means;

(b) placing a liner over the tank end and over the sealing ring, said liner also overlying the seal receiving means;

(c) placing a seal over the liner and into the seal receiving means thereby holding the liner in place relative to the ring and the tank end, thereby forming an assembled tank end;

(d) pushing the assembled tank end into the tank wall so that the seal makes contact with the liner on the cylindrical wall;

(e) securing the tank end to the tank (fig 1).

The invention provides a method of sealing a tank wall which includes an inner plastics liner to a tank end which is also plastics lined, said method including the steps of:

(a) mounting a shaped sealing attachment onto a tank end, said sealing attachment having means to be attached to a portion of said tank end, said sealing attachment and/or said tank end also including a seal receiving means;

(b) placing a liner over the tank end and over the sealing ring, said liner being adjacent to or overlying the seal receiving means;

(c) placing a seal over the liner and into the seal receiving means thereby forming an assembled tank end;

(1) pushing the assembled tank end into the tank wall so that the seal makes contact with the liner on the cylindrical wall; (d) securing the tank end to the tank (fig 2).

The seal is preferably an O-ring type seal. It is preferable for the seal to hold the liner in place relative to the seal attachment and the tank end, if the liner overlies the seal receiving means.

Preferably the sealing ring is rigid and of plastics material however it could be made of steel, fibreglass reinforced polyester, aluminium or a composite of these materials. The plastics liner is preferably PVDF (polyvinylidene fluoride).

The liner can be vacuum formed directly onto the cap and rigid ring to encapsulate it however, could also be adhered thereto.

The invention further provides a method of assembling a tank and a tank end, said tank and said tank end being internally lined, said method including the steps of: (a) forming of a recess in a portion of the side wall of said tank;

(b) placing a gasket material in the recess;

(c) placing a surface of said tank end adjacent said recess;

(d) swaging the tank end into the recess to compress the gasket material thereby sealing the tank end relative to the outer wall (figs 3, 4, 5 and 6). It is preferable that a step (e) be added whereby the tank end and the outer wall at their termini can be riveted or welded.

It is further preferable that the gasket material is selected from an O-ring, a flat or ribbon material, or a liquid or semi-liquid material which sets, or is a solid material which liquefies under pressure and then re-sets preferably permanently.

Ln this embodiment the recess can be first formed in the tank end with the tank wall then being swaged into the recess.

The invention further provides a method of constructing a wall and a tank end of a water holding tank, both the wall and the tank end including an internal plastics liner, said method comprising the steps of:

(a) providing an attachment region on the rim of said wall; (b) forming a co-operating attachment portion on a rim of said tank end;

(c) providing a sealing means between the liners of said tank end and said wall;

(d) applying a seaming means to the rims of said tank end and said wall to thereby seal said tank ends and compress said seal means between said wall and said tank end to thereby seal the tank end relative to the wall (figs 7, 8 and 9). Steps (a) and (b) may be the provision ofthe termini on the wall and the tank end so that later processes can be performed. Steps (a) and (b) can also be the taking of special steps such as bending, cutting or otherwise to prepare for a seaming process.

Preferably the seaming means is selected from a rolled metal forming process such as swaging or metal bending process, a welding process, a radially actuating clamping means, or a longitudinally actuated clamping means.

Preferably the seam means can be situated at the extremities of the wall and the tank end and compressed by the seaming process or prior thereto, to seal the liner materials on the wall and tank end, with respect to each other.

Step (c) can be supplemented after the joint is made by providing the joint or filling the joint with a joint compound.

The invention also further provides a method of forming and sealing a port on a wall or tank end of a plastics lined hot water tank, said method including the following steps:

(a) shaping the wall and associated plastics liner;

(b) forming an aperture in the wall and associated plastics liner; (c) inserting a fitting having a seal member thereon, said fitting passing through said aperture in said wall;

(d) securing said fitting relative to the wall by a fastening means;

(e) tightening the fastening means to thereby seal the fitting relative to the plastics liner adjacent said wall, by means of a sealing member (figs 10, 11 and 12).

Preferably the shaping of step (a) includes a coining process, a drawing process, or other appropriate process.

Preferably the aperture of step (b) is a shaped aperture adapted to hold the fitting to prevent the fitting from rotating during step (d). Preferably the fittings are manufactured from heat resistant plastics materials such as PPS (poly phenylene sulphide).

It is preferred that the fitting is a male threaded member and is secured to the wall by means of a female nut or alternatively the fitting is a female threaded member and a hollow male threaded member is screwed into the plastics fitting, with the underneath face of the head of the hollow male threaded member providing a sealing surface with which to seal the liner relative to the wall and the tightening of the hollow male thread member further engaging the seal member.

The invention also provides a method of forming and sealing a fitting to the side wall of a container, said side wall also including an internal plastics liner, said method including the steps of:

(a) forming an aperture through the wall and liner;

(b) positioning a hollow thread formation in the aperture;

(c) securing said hollow thread formation to the wall in the aperture;

(d) passing through said aperture a sealing means to also pass through the middle of said hollow threaded formation and having a sealing mechanism attached thereto;

(e) engaging said liner with said sealing mechanism, said sealing mechanism having a securing means formed thereon or associated therewith;

(f) fastening the fitting by the securing means to thereby exert pressure between the sealing means and said wall to thereby sandwich the liner and produce a seal (figs 13 and 14). Preferably the lining passes around the aperture in the wall and lies on both sides of the wall, and a compressible fitting is placed thereover, and a female threaded fitting placed around same and secured thereto. A hollow bolt is screwed through the female threaded fitting to compress the compressible fitting and the liner on the outside of the wall.

The invention also further provides a method of forming a sealed port in the side of a plastics internally lined tank, said method including the following steps:

(a) piercing the wall only;

(b) securing a fitting to the outside of the wall;

(c) piercing the plastics liner with a smaller dimension than that which was pierced through the wall;

(d) positioning a seal means on a male member or adjacent the wall or said liner;

(e) passing through the fitting a male member having the seal means at one portion to engage the liner, or a flange to provide a sealing surface, said male portion also having a receiving portion to receive a locking cover to be attached onto said male portion and thereby force the liner, the seal and the male member together to seal same (figs 15, 16 and 17).

Preferably the male member is a male threaded flanged member passing through said female fitting and the securing means is a nut, which has the effect of sandwiching the liner and seal means to provide the necessary sealing. Preferably the fitting is a female threaded fitting, however it may be a combination male/ female fitting.

Preferably the seal means is an O-ring which can be mounted on the male member or on the liner or wall, or it may be a PVDF washer, or a gasketing compound which is settable.

If the male member is not a threaded fitting the sealing arrangement may be produced by the female portion of the fitting receiving a bored male threaded member to seal the male member, the seal means, the liner, and the wall, together.

The above methods can be performed with the steps out of sequence or in an order different to mat mentioned above and still be within the scope of the present invention.

The invention also provides hot water tanks when produced by any of the above mentioned methods.

The invention further provides a hot water tank for holding water, said hot water tank comprising a wall and as plastics liner, the tank being sealed at least at one portion by a tank end which is also lined, said tank also including a seal forming apparatus, said apparatus adapted to receive or engage a seal means to make contact with said liner, said seal forming apparatus being adapted to form a seal between said tank end, said wall and the respective liners (figs 1, 2, 3, 4, 5, 6, 7, 8, 9).

Preferably the seal forming apparatus includes a recess for a seal means which is adapted to hold in place a liner if the liner is placed over the tank end and seal forming apparatus (figs 1 and 2). Preferably the tank end and the wall are secured together, thus forming and holding the seal between said tank end, said wall and the respective liners (figs 3 to 5).

Preferably the seal forming apparatus is a recess formed in the wall (the recess also includes the liner passing through it), with the tank end having a substantially unaltered surface and liner which engages the seal forming apparatus (fig 6).

Alternatively, preferably the seal forming apparatus is a circumferential recess in the tank end and the wall has an unaltered surface to compress a seal means contained in said recess.

Preferably this seal forming apparatus is formed with the tank end. The seal forming apparatus can also be fabricated and attached to the tank end at a later time and can be attached either by adhesive or other connection means such as metal interlocking, welding, or other mechanical connecting mechanism. The seal forming apparatus can also be provided on the outer wall of the tank.

If the seal forming apparatus is provided on the outside of the tank preferably the seal forming apparatus is a clamping means which forces the rim of the tank end and the wall together thereby forming a seal between a sealing means and the respective liners (figs 6, 7 and 8).

Preferably the clamping means functions in a radial manner (figure 8). Alternatively the clamping means preferably functions in an axial or longitudinal manner relative to the wall of the tank (fig 7).

The seal forming apparatus can be a hot wire seal mechanism which is positioned after a tank end and a wall have been welded or otherwise joined, said hot wire seal mechanism then being energised to cause sealant in position around the wire to melt and form a seal between the liners of the tank end and wall. If a hot wire seal mechanism is not used the seal mechanism may be a mechanical means used to create a seal after the weld or other joint has occurred (fig 9).

One advantage of the present invention relating to sealing means and methods where, as here, liners are used to protect the tubular wall and tank ends, is that the liners will not separate from the respective tank parts under negative pressure applied to the interior of the tank. Furthermore, embodiments of hot water tanks constructed with the above inventions will be better able to reduce leakage at negative, small or large positive pressures.

Another advantage of the present invention is that a thinner liner can be utilised in this sealing arrangement. Currently liners as described under PCT/AU93/00013 are of up to 10 millimetres in thickness which adds significantly to the weight and cost of the unit.

The present invention also provides a tank for holding a fluid, said tank being characterised by a fitting which is adapted to seal the wall or a tank end of said tank when said wall or said tank end also include a liner adjacent them, said fitting being adapted to pass through said wall or said tank end and allow communicable passage there through, said fitting being characterised by including a sealing means associated with said fitting, and at least one engagement means and one securing means, said fitting being adapted, by the securing of said securing means to apply force to said engagement means and said seal means to thereby seal said liner, said engagement means and said seal means and said tank end or said wall together, without disrupting the integrity of said liner (figures 10 to 20).

Preferably said fitting passes through an aperture in said wall or said tank end. It is further preferable that the aperture is a shaped aperture which prevents the rotation of said fitting relative to the aperture when the securing means is secured (figures 10, 11 and 12).

It is further preferable that the aperture is associated with a surface which is displaced from the surface of the wall or tank end in which it is formed. It is further preferable that, when the wall is of metal, the displacement is caused by means of drawing or coining of the area around the aperture.

Preferably the fitting is complementarily shaped with the drawn or coined portion, as well as the aperture. Preferably the sealing means is an O-ring, or a shaped flat gasket, or a gasket compound. Preferably the engagement means include a seal receiving means.

Preferably the securing means is an interference fitting assembly but it is most preferably a threaded portion. If the threaded portion is male, a nut is used to sandwich the engagement means, the seal means, the liner and the wall together to produce a sealed assembly. If the threaded portion is female, a bored or hollow bolt with a head or flange is used to produce this sandwiching of components for producing a seal.

Preferably the fitting is also passed through a male, female, or male and female fitting, which is secured to the wall or tank end in the vicinity of the aperture. This securing can be done by welding or other bonding or attachment techniques (fig 13). Preferably the fitting is secured in such a manner so as to place the fitting in tension (figs 10 to 13, 15 to 20).

Preferably the fitting is secured in such a manner as to place the fitting under compression (fig 14).

Preferably the liner is folded around the aperture so that there is liner on both the inside and outside of said tank. The folded liner may be used as the point of engagement with the fitting to provide sealing with the fitting, the engagement means and the wall.

Preferably the securing means on the fitting includes a slide on arrangement, which also may be in association with a ratchet mechanism. Preferably the slide arrangement either forces the liner into contact with the sealing means on the fitting and/or it forces the liner into contact with the wall and thus seals the fitting relative to the wall, the sealing means and the securing and engagement means, (figs 15 to 17)

Preferably in the majority of instances the liner will be between the seal means and the surface of the tank end of the wall, however the seal means can be located between the liner and the wall if required or advantageous, (fig 18)

PVDF is preferably used for plastics fittings and the plastics liner. PVDF is particularly suitable for prolonged hot water contact under pressure (mains pressure) as it does not break down under the heat and pressure of the majority of water systems currently available. Other hot water resistant plastics materials are also suitable.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, each drawing being a section through the components illustrated:

Figure 1 Illustrates a first tank end/liner to wall/liner sealing mechanism;

Figure 2 Illustrates a second tank end/liner to wall/liner sealing mechanism;

Figure 3 Illustrates the first stage of a third wall/liner to tank end/liner sealing mechanism;

Figure 4 Illustrates stage 2 of the sealing mechanism of fig 3;

Figure 5 Illustrates stage 3 of the sealing mechanism of figs 3 and 4;

Figure 6 Dlustrates a fourth wall/liner to tank end/liner sealing mechanism;

Figure 7 Illustrates a fifth wall/liner to tank end/liner sealing mechanism;

Figure 8 Illustrates a sixth wall liner to tank end/liner sealing mechanism;

Figure 9 Illustrates a seventh wall/liner to tank end/liner sealing mechanism;

Figure 10 Illustrates a first through the wall/liner sealed fitting;

Figure 1 1 Illustrates a second through the wall/liner sealed fitting;

Figure 12 Illustrates a third through the wall/liner sealed fitting;

Figure 13 Dlustrates a fourth through the wall/liner sealed fitting;

Figure 14 Dlustrates a fifth through the wall/liner or tank end sealed fitting;

Figures 15, 16 & 17 Illustrates the stages through a sixth through the wall/liner sealed fitting;

Figure 18 Dlustrates a seventh through the wa Vliner sealed fitting;

Figure 19 Dlustrates a eighth through the wall/liner sealed fitting; and

Figure 20 Dlustrates a tenth through the wall/liner sealed fitting.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Figure 1 shows a tank end 2 of a hot water system. The tank end 2 is preferably made of steel and can be pressed or spun or formed in any appropriate fashion. The tank end 2 has attached to it a ring 4 which is preferably rigid or semi-rigid at temperatures of 60° to 90°C and is constructed from plastics materials such as fibreglass reinforced polyester or other similar composite plastics materials. Alternatively, aluminium would be suitable.

The ring 4 has an interface portion 6 which provides a smooth surface transition between the tank end 2 and the ring 4 and also properly supports the liner 8 at the interface of the tank end 2 and ring 4. The ring 4 has a curved end 10 and a seal recess 12. The ring 4 is shown here in cross section and the recess 12 is situated around the circumference of the ring 4. The ring 4 has a shoulder 14 which engages a rim 16 on tank end 2.

The plastics liner 8 is manufactured from PVDF (polyvinylidene fluoride) and is adhered to tank end 2 and wraps around curved end 10 of ring 4 across the seal recess 12 and overlies the tank end 2 on flange portion 18. When the liner 8 is in position, an O-ring 20 is stretched over the outside circumference of the ring 4. When in position in the recess 12 the O-ring 20 holds the liner 8 in place.

A suitable method for forming a sub-assembly of the tank end 2, the ring 4 and liner 8 is to hold and heat the liner in flat form until it is plastic (e.g. 140°C for PVDF) and to advance the tank end 2 and ring 4 against the softened liner until the outer periphery of the ring 4 and end 2 are encapsulated by the softened liner. Then, vacuum is applied through small holes (not shown) that are close to the centre of the end 2 and lead to the O-ring recess or groove 12. The end and/or the liner 8 and the ring 4 may have been pre-treated with a suitable adhesive to enhance the bond formed between the liner and the respective part it contacts when formed as a sub-assembly. The sub-assembly is next cooled to ambient temperature by removing the source of heat and the peripheral edges of the liner 8 trimmed off.

The O-ring 20 is then inserted in the groove 12 and finally the holes (that enabled vacuum forming) are sealed with a settable adhesive such as a silicone based elastomer.

The attachment of the tubular liner 8 to the steel or metal tube which forms the tank wall 28 may also be made more secure by a process of softening the tube with heat and applying vacuum to the space between the material and plastics tubes, through small air bleed holes in the metal tube which are preferably subsequently sealed with a settable adhesive. As with the end liner, an interfacial adhesive (applied initially to the metal tube or applied to or co-extruded as the outermost layer of the plastics tubular liner) may be used and, dependant on the form of adhesive, may be heat set or hardened by cooling, being such as to remain set or hardened at the maximum expected service temperature of the water heater.

The material of the liner 8 for either the ends or tubular part, can be multilayer co-extruded to provide (i) a PVDF layer adapted to become the hot water contact layer; (ii) an oxygen barrier layer internally such as EVAL (ethylene vinyl alcohol); (iii) an outer adhesive layer for bonding to the metal members of the tank which provide strength. Other hot water contact layer materials may be adequate. Polyethelene is suitable for shorter lifetime service and other polyolefins such as polypropylene or polybutylene may give adequate service. PVDF has very good structural and chemical stability in prolonged hot water immersion but may have the disadvantage of higher cost and water vapour transmissibility. Therefore an additional layer in a multilayer structure may include a polyolefin or nylon layer to reduce the water vapour transmissibility of the composite material.

The co-extruded liner material can include internal compatibility layers to assist the component layers to bond to one another.

When the tank end 2 is assembled, the O-ring 20 protrudes beyond the outside diameter of the ring 4. The assembled tank end 2, as illustrated in figure 1, is then interference fitted into a steel walled cylinder having a plastics liner on the interior portion. Once the assembled tank end 2 is in position, the O-ring 20 seals the ring 4 relative to the inside liner 8 of the cylindrical wall. The flange portion 18 is secured to the rim portion of the cylindrical wall by welding, riveting, bolting or spot welding. Other joining means, such as double seaming, as practised in metal drum container manufacture (not shown), is possible also. In operation, should a storage tank having a tank end 2 as illustrated in figure 1 ever be subjected to a negative pressure, the liner 8, because it is adhered to tank end 2, will not readily move inwardly. If, in abnormal circumstances, it should do so, it will not break connection with the ring 4 by virtue of the arrangement of the O-ring 20, recess 12 and the pressure associated therewith. Dlustrated in fig 2 is another arrangement similar to that of fig 1 except that the recess 12 is provided in the tank end 2 and the periphery is inwardly directed with respect to the tank.

The O-ring 20 seals against liner 30 which has been folded over rim 32 of tank end 2 and the wall 28. A weld 26 prevents the end 2 from moving relative to the body 28.

The tank end 2 in the embodiment of fig 2 is pre-coated with PVDF on all the inside and a peripheral portion of the outside surface of the tank end 2 as shown.

Dlustrated in figures 3, 4 and 5 is a further method of sealing a tank end to a tank wall. In this method the wall 28 and liner 34 are roll formed to form a recess 38 for the positioning of an O- ring 20 or other gasket material such as a band of gasket material or a liquid or settable gasket material. Illustrated in figure 4 the tank end 2, which is a minus end, has attached to it a liner 8. This is positioned adjacent the cylinder body 28. Once in position, cylinder body 28 and tank end 2 are

swaged together as illustrated in figure 5 with the O-ring 20 (or other gasket material) being compressed through the mechanical joint 40.

The tank end 2 is a minus tank end and generally the minus tank end is connected last if a minus and a plus end both have to be connected to a tank wall. A plus tank end, if any, might be done first so that access can be gained to the rim of the tank end 2 from the inside of the tank wall 28. This process can be reversed whereby the recess 38 is first formed on the tank end 2 and then the body 28 is swaged into the mechanical joint 40 from the outside in. This arrangement is not illustrated.

Dlustrated in figure 6, the negatively curved or minus tank end 2 and liner 8 have a recess 38 (similar to the Fig 2 embodiment) with an O-ring 20 in that recess to provide a seal. Tank wall rim 42 and minus tank end rim 44, can be welded together, (not shown) or joined by other means, such as riveting or bolting (not shown).

Dlustrated in figure 7, the cylinder wall 28 and liner 34 at rim 42 terminate by providing a gripping flange or attachment rim 43. The rim 42 and gripping flange 43 are approximately at right angles to the longitudinal direction of the wall 28. The tank end 2 with liner 8 has a co¬ operating rim 44. Before joining the two rims 42 and 44 together, an O-ring 20 or alternatively a jointing compound can be placed in the region 46 or alternatively, an O-ring 20' can be placed close to the radially outward extremity of the rims 42 and 44.

In either case, a locking seam or clamp 48 (shown here in section) applies an axially directed pressure, forcing rim 42 and 44 together thereby compressing axially the O-ring against the liners 8 and 34. Depending upon the shape of clamp 48 and rims 42 and 44, the O-ring 20 can also seal by being compressed radially as is needed for O-ring 20.

Dlustrated in fig 8 the tank end 2 and liner 8 sandwich O-ring 20 between liner 34 and cylinder 28. The retainer 50 is welded inside the cylinder 28 before assembling the end 2 to the tank. The cylinder 28 is then deformed elastically at its end(s) to an oval shape and the lined end 2 carrying O-ring 20 is inserted into the temporarily deformed cylinder such that its diameter fits into the oval. The end is then rotated 90° while simultaneously releasing the end of cylinder 28 so as to revert, at its end, to a circular cross-section. At this stage, the end liner 8 faces inwardly into the tank. Gripping means (not shown) on the outside of tank end 2 then enables the end to be pulled axially outwardly about retainer 50. Multiple releasable clip means (not shown) then are joined between end 2 and retainer 50 to prevent inward movement of the end.

Dlustrated in fig 9 is a further method of joining a tank end 2. The tank end 2 and associated liner 8 and cylindrical wall 28 and liner 34 are first clamped together and then joined by welding at 58. The weld 58 for some distance around it, may melt the plastics liner 8 and 34 and thus no seal will be produced here. However there is a portion of the liner 8 and 34 along wall 28 and tank end 2, where the temperature is sufficient to fuse the liners 8 and 34 together to form a seal.

However if desired, to ensure the integrity of the seal into the region 60, a joint filling compound can be applied either before or after welding, to effect the seal.

With respect of all of the embodiments described above, it is possible to utilise a sealing material in the form of a sealant coated hot wire sealer, whereby the wires have electricity passed through them and this melts the sealant surrounding the wire and flows into position until it resolidifies. The sealant may be PVDF.

Dlustrated in figure 10 to 20 are arrangements of a sealed fitting through a wall 28 and a plastic liner 34. Generally these following embodiments will be discussed relative to the cylindrical wall 28 and liner 34 however they are equally applicable to tank end 2 and liner 8. Dlustrated in figure 10, wall 28 has a punched hole 62 and a drawn or coined portion 64. The liner 34 follows the contour of portion 64. A plastics fitting 66 has a circumferential recess 68 in which is situated an O-ring 70. The fitting 66 has a male thread portion 72 and a bore 74 through it, to allow the inside of the tank to communicate with its exterior.

The hole 62 is hexagonal in shape, as is the neck 76 of the fitting 66 which passes through the hole 62. The hexagonal hole 62 and hexagonal shaped neck 76 prevent the fitting 66 from rotating and thus damaging the liner 34 where the seal 68 makes contact. A nut is placed onto the male thread 72 to effect the seal between the O-ring 70 and the liner 34.

Alternatively the O-ring 70 can be repositioned (not illustrated) into region 78 in order to be directly compressed when the nut (not illustrated) is tightened onto the male thread 72. The coined portion 64 provides a greater sealing surface area for the fitting 66 and thus provides a more effective seal.

Dlustrated in figure 1 1 is an embodiment similar to that of figure 10 where an O-ring seal 70 is positioned in region 78. In this figure a nut 80 is shown in position on the threaded portion 72.

Dlustrated in figure 12 the fitting 66 has a divergent shape 82 which corresponds to the divergent shape of the drawn or coined portion 64 and terminates in the hole 62. The liner 34 is overlapped at the rim 84 to provide a sealing surface 85.

To the coined or drawn portion 64 is welded a male thread portion 72 which receives a gland type nut (not illustrated). A sealing surface (not illustrated) on the nut (not illustrated) co¬ operates with seal face 85 and rim 62 of the wall 28. The fitting 66 can be manufactured from heat resistant plastics such as polyphenylene sulphide or polybutylene. A bore 74 allows communicable passage between the inside and outside of the tank.

The O-ring 70 provides a seal with the recess 68 and the liner 34 in the drawn portion or coined portion 64. The bore 74 can also have a female thread 73 formed thereon which can receive a bored through bolt 87, which allows the undersurface 83 of the head of the bolt 87 (next adjacent the thread) to be tightened and to clamp the fitting 66 into position between the rim 62 and the wall 28. The undersurface 83 of the bolt 87 can seal against rim 84 and the sealing

surface provided. The outer diameter of head of the bolt 87 need not project past the thread 72 which allows a gland nut and fitting to be placed over it.

Dlustrated in fig 13 is a wall 28 punched to provide hole 62 with the liner 34 being punched to the same diameter. A bored through male fitting 86 having male thread 88 on the outside thereof, is welded circumferentially around corner 90. Once secured, the plastics fitting 92 is put into position. The plastics fitting 92 has a recess 93 containing an O-ring 94' (or it could be a sealing projection jutting passed the surface 92' of fitting 92). The O-ring 94' engages the liner 34. The fitting 92 passes through the hole 62 and through the bore 96 of male fitting 86. Once through, a back nut 98 secures the fitting 92 relative to the male fitting 86 and wall 28 and liner 34. By tightening the back nut 98 the O-ring 94' creates a tighter seal with the liner 34. In this embodiment the plastics fitting 92 is in tension.

Dlustrated in figure 14 is an arrangement similar to that of fig 13 except that a female fitting 100 having a bore 96 and female thread 102 is welded to the wall 28 at corner 90. A PVDF fitting 104 is encapsulated by the female fitting 100 before it is welded and passed through the hole 62. Prior to this welding the liner 34 is wrapped around the hole 62 onto the outside surface so that a tail 106 of the liner 34 is on either side ofthe wall 28 around hole 62. The flange portions 108 around the PVDF fitting 104 seal against tail 106. The PVDF fitting 104 has a hole diameter 110 which is smaller than the diameter of the bore 96. When a bored through male bolt (not illustrated) is threaded into thread 102, the end of the bolt will push against the surface of flange 108 and thereby compress the flange against the tail 106 or line 34 and provide a sealing mechanism.

Dlustrated in figures 15, 16 and 17 is an alternative way to construct a fitting/liner port through a wall or tank end of a lined water storage unit. Firstly, similar to the embodiments of figures 13 and 14 a hole is punched through the wall 28 to produce a hole 62, however the hole through the liner 34 is significantly smaller than the hole 62. A female fitting 100 is welded into position on wall 28. A plastics connector 112 has a flange portion 114 and a recess 116 to hold an O-ring 70. The connector 112 has a taper 118 at the end opposite the flange 114 and has a series of shaUow recesses or barbs 120 surrounding the tapered portion 118, extending toward the O-ring seal 70. The connector 112 is placed through the bore 96 of female fitting 100. The bore 122 through connector 112 can be a shaped bore to allow a tool to rotate the connector 112 through the female fitting 100 into the position illustrated in fig 17. Once in this position or possibly further down, so that the flange 114 engages the wall 28 the liner 34 is caused to protrude or pout and makes contact with the O-ring seal 70. Once connector 112 is in position, a cover locking cap 124 is placed over the tapered end 118 with the internal diameter 126 of locking cap 124 engaging the shallow recesses or barbs 120. The cap 124 is pushed down sufficiently so that the ends 128 can compress liner 34 against the

wall 28 as well as compress the liner 34 between the cap 124 and the O-ring seal 70. It is envisaged that the taper 118 can be replaced with a male threaded portion and a threaded cap 124 utilised to replace the push on cap 124 illustrated in figure 17.

Dlustrated in figure 18 is an arrangement similar to that of figures 15 to 17. In this arrangement the hole 62 is formed in the wall 28 however the liner 34 is not holed to the same diameter. A male and female fitting 130 is welded into position. The male/female fitting 130 has a curbed portion 132 to seat an O-ring seal 70. The liner 34 by tail 106 is wrapped around the O-ring seal 70. A bored threaded bolt 134, by the underneath surface 136 of the head 138, sandwiches the liner tail 106 between the O-ring 70 when the bored threaded bolt 134 is secured in position when the nut 123 is tightened, against washer 125. The male thread 140 allows other fittings such as plumbing and other services to be secured and sealed thereto.

Dlustrated in figure 19 is an embodiment similar to that of figure 18 and figure 14. In this embodiment the PVDF fitting 104 has a flange 142 at one end. The flange 142 has a male thread 144 thereon. A hole 162 is first punched into the wall 28 and a smaller hole is punched through the liner 34. A female fitting 146 is welded into position on wall 28.

Once the female fitting 146 is in position the liner 34 is bent around the hole 62 so that the tail 106 is on the outside surface of the wall 28 in which position an O-ring seal 70 is placed and then the tapered fitting 104 is screwed into position whereby the flange 142 sandwiches the O- ring 70 and tail 106 of liner 34 between wall 28. Ln figure 20 this embodiment is very similar to that of fig 19 except that the fitting 104 is interference fitted into the hole 62 until such time as the flange 142 also sandwiches the liner tail 106, the O-ring 70 and wall 28 together. This embodiment differs from that of fig 19 in that the O-ring 70 is in contact with the outside of the wall 28 and the tail 106 is sandwiched between the O-ring and the flange 142 whereas the opposite is the case in the embodiment of figure 19.

The foregoing describes some embodiments of the present invention and modifications by those skilled in the art can be made thereto without departing from the scope of the invention.