GB2408550A - Compression pipe fitting bonded to fibre reinforced plastic chamber - Google Patents

Abstract

A fitting 122 for providing a fluid tight seal between an opening in a chamber wall and a pipe 130 passing through the opening has a flange 128 that surrounds the opening, and has compression means to form a seal with the pipe 130. The fitting 122 may be formed in two parts 123, 125 which have complementary screw threads 132, 135 to compress a compression ring or olive 124 which seals against the pipe 130. The fitting is particularly intended to seal between a pipe and the wall of a manhole chamber of a subterranean fuel tank, or between a pipe and the sump of a fuel dispensing pump. The chamber or sump may be made of fibre reinforced plastics material, and the flange 128 may be sealed to the wall of the chamber or sump by applying resin. The flange may further be overlayed by a reinforcing matting, and a cover 160, 161 may be provided to encapsulate the flange. The flange may be made from a material adapted to bond to a fibre reinforced plastics material, e.g. steel, aluminium, brass or bronze.

Description

CONNECTION BETWEEN A PIPE AND A WALL

Field of the Invention

This invention relates to fittings for providing a seal between a wall and a pipe passing through an opening in the wall, to a method of providing such a seal, and to an assembly comprising the combination of a pipe, a wall and a fitting providing a seal between the two. The invention is particularly applicable to the provision of a seal between a pipe and a wall of a manhole chamber as found in a subterranean fuel tank or between a pipe and the wall of sump for a dispensing pump, for example in a petroleum forecourt installation, and in particular where the wall of a chamber or sump is made of glass reinforced plastic (GRP).

Background to the Invention

Subterranean piping systems of the type that are typically installed at service stations are generally utilized to communicate fuel or chemicals between an underground storage tank and an above ground dispensing station. The underground storage tanks and associated piping pose serious potential environmental and fire hazards as the chemicals contained therein could and have in the past leaked into the earth.

Oil companies have been under considerable pressure to ensure that environmental concerns are given priority in the planning and installation of petrol station infrastructures. This has not been without significant on-cost. One important advancement has been the use of pipeline systems constructed from plastics materials which have enabled the oil companies to install cost-effective environmentally acceptable alternatives to steel pipework systems which tend to corrode over time.

Moreover, over recent years there have been major developments in fuel technology which have culminated in commercially available alternative fuels containing additives which have replaced lead-based antiknock compounds. Research also continues to centre on reducing sulphur content and hazardous emissions from fuel. In order to eliminate lead and sulphur from fuels, exotic additives and octane enhancers such as MTBE (methyl tertiary butyl ether) have been developed which are based on complex organic or heavy metal organic additives.

The presence of these additives in fuel can give rise to major environmental issues. Some such issues are described in an article entitled "MBTE - How should Europe Respond", in Petroleum Review February 2000 pages 37-38. The entire text of this article is incorporated herein by reference by way of background information. The authors conclude that lead and some other metals are the most effective octane enhancers. However, lead is in the final stages of being phased out because of environmental and health issues, and the most readily available alternative, MINT (methylcyclopentadienyl manganese tricarbonile) is currently not widely accepted. The only other octane enhancers currently available are MTBE and other ethers such as ethyl tertiary butyl ether (ETBE) and tertiary amyl methyl ether (TAME), or alcohols such as ethanol. The ethers all tend to have similar properties and drawbacks. Ethanol is already used as a gasoline-blending component in parts of the United States where it is readily available, and in Brazil. It is an effective octane booster but has a number of drawbacks: it needs a "water-free" distribution system and is not without ground water issues. It is currently not recommended by the motor industry and is not costcompetitive.

The introduction of new fuel mixtures and esoteric additives has led oil companies to question whether existing pipeline systems can cope with the new fuels with regards to mechanical performance and permeability resistance. In some instances this will result in the pipework having to be replaced by pipework made from a more resistant material, with all the disruption that entails.

In petroleum forecourt installations, pipework running between dispensing pumps and a subterranean fuel storage tank passes into a manhole chamber which is situated directly above the manhole lid of the tank. The chamber is normally defined by an upstanding wall which, when viewed from above, can be of an octagonal, square, circular or rectangular shape, and which includes apertures through which respective pipes pass.

To overcome environmental concerns this pipework is now generally constructed from plastics materials and many current designs of forecourt installation utilise secondary containment. This involves containing each fuel supply pipeline in a respective secondary containment pipeline which is optionally sealed at its ends to the fuel supply pipeline. The secondary containment pipeline prevents leaks from the fuel supply pipeline from being discharged into the environment, and also can convey leaked petrol to a remote-sensing device. Typically, the pipes forming the secondary containment pipeline are initially separate from the fuel pipes and are sleeved over the latter as the fuel pipes are installed between the fuel storage tanks and dispensing pumps.

A common material for the chamber to be constructed from is glassreinforced plastic which involves moulding a resin or other polymeric material reinforced with fibres such as glass fibres.

It is desirable to provide a seal between each of the apertures and its respective pipe to avoid ingress of water into the manhole chamber. To that end, it is known to attach a fitting to a portion of the wall around the aperture and a rubber boot" that sleeves over the pipe and is clamped to both the pipe and the fitting by, for example, jubilee (TM) clips. Some types of such fitting are bolted to the chamber wall, whilst other types of fitting provide inner and outer parts between which the wall is sandwiched, the inner and outer parts being held together by a screwthreaded connector which extends through the aperture. These connectors often incorporate a rubber seal located between a part of the connector and the chamber wall.

Neither type of fitting provides a completely effective seal.

Over time, both types of seal can allow water to leak into the manhole chamber and to accumulate in a pool in the bottom of the chamber. This in turn makes the maintenance of the chamber bottom and tank entrance extremely difficult. In addition a defective seal can allow any petroleum fluid or vapours which find their way into the chamber to escape into the environment.

It would be preferable if such a fitting could be chemically bonded or electrofusion welded both to the pipe and to the chamber wall. One type of such fittings, manufactured from a plastics material capable of electrofusion to both the pipe and the chamber wall is known from GB2332255 (PetroTechnik Ltd). However, these fittings cannot be used when the chamber is constructed from GRP, a material commonly used in construction of chambers and Bumps for this application.

In summary therefore, in the event that pipework has to be replaced, or in new build situations, there is a requirement to seal pipework made from polyethylene, polypropylene, polyamide or the like to a GRP chamber wall. Accordingly it is an object of the present invention to provide a fitting for forming a seal between pipework formed from a plastics materials and a GRP chamber which overcomes some or all of the above disadvantages.

Summary of The Invention

According to a first aspect of the invention there is provided a fitting according to Claim 1. In one embodiment this provides a fitting for providing a substantially fluid tight seal between an opening in a chamber wall and a pipe passing through said opening, said fitting having at least one radially extending flange, said flange being adapted to engage with the chamber wall around substantially the entire circumference of the flange, said fitting being further adapted to form a fluid tight seal with said pipe by a mechanical compression means.

This arrangement enables the fitting to be sealed to the chamber wall. GRP resin or other adhesive can be used in order to obtain long lasting waterproof seal between the flange and the chamber wall. A fluid tight seal can then be formed between the fitting and the pipe using the mechanical compression means which provides a complete seal between the chamber and the pipe.

Preferably the fitting comprises: i) a first portion having at least one radially extending flange, said flange being adapted to engage with a chamber wall around substantially the entire circumference of the flange; ii) a second portion; iii) securing means adapted to secure said first portion to said second portion via a mechanical compression means.

The second portion is preferably adapted to form a sliding fit with the outside of said pipe. Preferably said first and said second portions are formed from metal. Such metals include stainless steel, coated steel aluminium, coated aluminium, brass or bronze.

In a particularly preferred embodiment the mechanical compression or securing means comprises complementary screw threaded regions on the first and second portions such that the two portions screw together, whereby a compression ring, or olive, located between the first and second portions, is deformed to provide a fluid tight seal between the fitting and the pipe.

Preferably the fitting is used in a chamber whereof the chamber wall is of GRP.

Preferably the flanges are formed from a material that bonds readily to GRP.

Such flange materials include metal such as stainless steel, coated steel, aluminium, coated aluminium, brass or any suitable material which can bond to the GRP wall.

It will be appreciated that the present invention also extends to encompass underground pipe works systems including such fittings, and a garage forecourt systems incorporating them, methods for manufacturing such fittings and methods of forming fluid tight seals used in such fittings.

According to a further aspect of the invention there is provided a fitting for providing a substantially fluid tight seal between an opening in a chamber wall and a pipe passing through said opening, said fitting comprising: (i) a first tubular sleeve adapted to pass through the opening in the chamber wall and; (ii) a second tubular sleeve adapted to form a fluid tight fit with the first tubular sleeve, both the first tubular sleeve and the second tubular sleeve being adapted to allow the pipe to pass therethrough; characterized in that the material of the first tubular sleeve is formed from a fibre reinforced plastics material and that the material of the second tubular sleeve is formed from an electrofusible polymeric plastics material.

By forming a first part of the fitting from a fibre-reinforced plastic and a second part of the fitting from a plastics material electrofusible to the pipework, a strong, long- lasting fluid-tight seal can be formed between the fitting and both the chamber wall and the pipe.

Preferably the first and second tubular sleeves overlap for a proportion of their length, the fluid-tight seal between the two sleeves being formed in that overlapping region.

Preferably the first tubular sleeve further comprises a flange, extending radially outwardly from the sleeve, a first surface of the flange being configured to contact the chamber wall around substantially the whole circumference of the opening.

Preferably the fitting further comprises a sealing means located between the first tubular sleeve and the second tubular sleeve, said sealing means being adapted to form a fluid-tight seal between the two overlapping sleeves.

In a particularly preferred embodiment the sealing means takes the form of an O-ring seal seated in a circumferential channel around one or other of the sleeves.

In a further preferred embodiment the fitting further comprises a third tubular sleeve, formed from a metal, and adapted to fit tightly inside the fitting in the region in which the first and second tubular sleeves overlap.

Preferably the third tubular sleeve is formed from stainless steel, coated steel or a polymer resistant to fuel.

Brief Description of the Drawings

The present invention will now be described by way of examples only with reference to the accompany drawings wherein: Figure 1 is a partially cutaway side view of part of a petroleum forecourt installation which includes a tank having a manhole chamber, having a fitting in accordance with the invention; Figure 2 illustrates a cross-section through a fitting according to one embodiment of the present invention; Figure 3 illustrates an elevational view of the fitting shown in Figure 2; Figure 4 illustrates a cross-section through a first tubular sleeve of the fitting shown in Figure 2; Figure 5 illustrates a cross-section through a third tubular sleeve of the fitting shown in Figure 2; Figure 6 shows an end elevation of the fitting of Figure 2; Figure 6A illustrates a typical flange; Figures 7, 8 and 9 show fittings according to the present invention in use through a chamber wall; Figure 10a illustrates a cross- section through a fitting according to a further embodiment of the invention and further includes an expanded view of a portion of the fitting; Figure 1 Ob illustrates an end view or partial scrap view showing flange details; Figure 10c illustrates a fitting as shown in Figure 10a with covers applied over the flanges; Figure 11 illustrates an exploded cross-section of the olive and the two portions of the fitting of Figure 10; Figure 12 illustrates an end view of the olive and two portions of the fitting of Figure 10; Figure 13 illustrates an example of the fitting in use; Figure 14 illustrates an example of the fitting prior to assembly; and Figure 15 illustrates an example of the component parts of a fitting according to the present invention.

Description of the Preferred Embodiments

The present embodiments represent currently the best ways known to the applicant of putting the invention into practice. But they are not the only ways in which this can be achieved. They are illustrated, and they will now be described, by way of example only. By way of terminology used in this document the following definitions apply: chamber- any receptacle designed to keep a fluid in or out. This includes, but is not limited to, manhole and sump chambers as described herein. It also includes tanks in general.

enerav transfer means - a generic term describing any form of energy source.

Typically it takes the form of a resistance winding which heats up when an electrical current is passed through it. The term also encompasses other welding techniques including ultrasonic welding and induction welding.

flange - any collar suitable for attaching a fitting to a chamber wall. In the examples given the surface of the flange which contacts the chamber wall is substantially planar.

However, it will be understood that the flange must conform to the profile of the chamber wall around the pipe inlet opening. Thus the flange can adopt any suitable conformation to achieve the necessary contact with a flat or curved surface or even the corner of a container wall.

fluid - whilst the examples provided relate mainly to liquids, the term fluid refers to liquids, vapours and gases. For example, should a leak occur in a secondarily contained pipe in a garage forecourt installation then petrol or petrol vapour will collect in the manhole chamber. It is essential that this petrol vapour cannot escape through the wall of the chamber and into the surrounding ground.

pine - the examples given herein are for a generally circular crosssectioned single wall pipe. However, the invention also covers other cross-sections such as box sections, corrugated and the like and secondarily contained pipes of the "pipe-within-a- pipe" type. In this case the sealing member or boot for sealing the sleeve to the pipe will be rather more complex. However, such boots are well known in the art. The invention also encompasses pipes which are not circular in cross-section.

tubular sleeve - this term has a very broad meaning. It includes any tubular structure through which a pipe may pass. Although illustrated and described as substantially circular cylindrical in form, a sleeve according to this invention need not have a substantially circular crosssection and may confirm to the profile of the pipe to be accommodated in it. Nor need the cross-section of the sleeve be uniform along its whole length, i.e. it need not be cylindrical.

Glass reinforced plastic (GRP) - The term GRP has a very broad meaning in this context. It is intended to encompass any fibre-reinforced plastic wherein a fibre of any type is used to strengthen a thermosetting resin or other plastics material.

The petroleum forecourt installation shown in Figure 1 comprises a pair of dispensing pumps 1 and 2 connected to a subterranean tank 3 through a pipeline 4.

The pipeline 4 is formed from contiguously arranged sections of polyethylene pipe. The pipeline 4 extends from the pumps 1 and 2 into a manhole chamber 6 immediately above the tank 3. The chamber 6 is defined by a GRP member 8 having a side wall 10 and a base 12.

Figure 1 shows two lines extending from the pipeline 4 into the tank 3. These lines relate to two alternative forms of fuel supply system and are both shown for the sake of completeness. In practice, only one of the lines would extend from the pipeline 4 into the manhole chamber 6. One of those lines is a suction line 14 which is used where the dispensing pumps and 2 are fitted with suction pumps. The alternative line, reference 16, is a pressure line connected to the pipeline 4 via a pump 18 which is operable to propel fuel from the tank 3 to the pumps 1 and 2.

It can be seen from Figure 1 that the wall 10 has to be apertured in order to allow the pipeline 4 to pass into the chamber 6. In order to prevent water leaking from the surrounding ground (here denoted by reference numeral 20) into the chamber 6 through the aperture, the pipe is sealed to the cylindrical wall 10 by means of a fitting 22 shown in more detail in Figures 2 to 9 inclusive. In the event of a spillage or a leak in a supply pipe the seal also prevents fuel from escaping into the environment.

Figure 2 illustrates one example of a suitable fitting 22 in greater detail. The purpose of this fitting is to form a strong, permanent, fluidtight seal between the fitting and the chamber wall 10 and between the fitting and the pipework system 4. Fitting 22 comprises a first tubular sleeve 31 formed from GRP or a material easily bondable to GRP such as a metal such as stainless steel or a coated steel material, bronze, brass or a brass alloy, or aluminium. An important feature is that the material must form a strong, substantially fluid-tight seal to the GRP wall using known resins, adhesives or the like. Plastics materials such as polyethylene or polyamides are not generally good at bonding to GRP using conventional resins or adhesives, hence the need for a two- part fitting. The sleeve 31 is generally cylindrical in shape with a longitudinal axis through which a pipe (not shown) can pass. A second tubular sleeve 32 is moulded around one end of the first tubular sleeve, the sleeve 32 being formed from an electrofusible polymeric plastics material, compatible with the pipework system, such as polyethylene, polyamide or PVDF. Suitable materials will be discussed in more detail below.

In order to improve the fluid-tight nature of the seal between the two sleeves, a series of grooves, slots or ridges 34 are formed in the region of the first sleeve where the two sleeves overlap. When the second sleeve is formed around the first, plastics material fills these grooves, preventing the two components from separating in use.

Advantageously, part of the first tubular sleeve is encapsulated within part of the second tubular sleeve such that there is an overlapping region between the two sleeves. Encapsulating part of the first sleeve within the second sleeve creates a stronger fitting and one less prone to leakage over time.

It should be remembered that these fittings can often be used in inhospitable conditions, e.g. underground where there may be soil shrinkage, subsidence or other movement, and where fuel can escape in the case of a supply pipe failure.

Optionally, the seal between the two sleeves can be further improved by incorporating a sealing means such as an O-ring 36 or a bead of sealant. The O-ring in this example nests into a annular channel around the circumference of one or other of the sleeves. It will be appreciated that the O-ring seal can be positioned during assembly on either the first or second sleeve. For ease of construction it would normally be positioned on the outer surface of the first tubular sleeve, towards the end of that sleeve which is located within the main body of the fitting itself.

It will be appreciated that the O-ring could also be positioned in the end face 37 of the first sleeve, engaging with a shoulder 38 in the second sleeve.

Because the sealing means is internal to the fitting, and sealed within it, it is expected to have a very long life, at least the life of the fitting.

There is a further optional feature which serves to strengthen the fluidtightness for the seal between the first and second sleeves. A third tubular sleeve 33 is located on the inner surface of the fitting in the region where the first and second sleeve overlap. The purpose of this third sleeve, which is made from a metal such as stainless steel, coated steel or a polymer, is to prevent the polymeric plastics material component from withdrawing away from the first, GRP sleeve in the event it should shrink or soften when exposed to fuel or other chemicals.

Figure 3 illustrates a side elevational view of fitting 22 showing the neat, streamlined appearance and form resulting from this method of construction. A reference mark 39 enables an electrofusion coupling (see below) to be positioned and properly located over the end of the fitting made from electrofusible plastic. It also serves to identify that end of the fitting, if there were any doubt.

Figure 4 shows a cross-sectional view of the first tubular sleeve 31 and shows in more detail the slots 34. It will be apparent from Figure 4 the general simplicity of this GRP moulding. The slots 34 can take a wide variety of shapes, sizes, location and configuration. The essential feature is that they create indentations into which the liquid plastics material of the second tubular sleeve component can flow during manufacture.

In an alternative form of construction the slots 34 could take the form of screw threads such that the first and second sleeves could be formed separately and screwed together during construction. A chemical adhesive or a locking screw (not shown) could then be used to prevent the two sleeves coming apart during use.

Figure 5 shows the third tubular sleeve component in cross-section. This can be pressed into place after the second sleeve has been formed around the first, but while the material of the second sleeve is still warm and thus deformable.

In use, and referring to Figures 8 and 9, the end of the GRP portion of the fitting is passed through an aperture in the chamber wall and temporarily held in place. A GRP bandage (not shown) is then used to seal the fitting to the chamber wall on one or both sides. The advantage of this arrangement is that both the fitting and the chamber wall are made of the same or compatible materials such that a strong, permanent, fluid tight seal can be easily formed. The necessary rubber boot 55, 56, is then used in conventional fashion to form a seal inside the chamber where a secondary pipework system is used. Outside the chamber electrofusion fittings may be used, together with expanders or reducers as necessary, to accommodate secondarily contained pipe.

In Figure 8 both the primary pipe 61 and the secondary pipe are sized such that they will pass through the fitting 22. The secondary pipe 60 is therefore sealed to the outside fitting 22 by way of an electrofusion coupling 62, expander 63 and electrofusion coupler 64. The termination between the primary and secondary pipes takes place inside the chamber using rubber boot 56.

It will be appreciated from Figure 9, where the secondary pipe 50 containing the supply pipe 51 is larger than the internal diameter of the fitting, then the fitting itself becomes part of the secondary containment system. This is achieved through use of electrofusion coupling 52, reducer 53 and coupling 54 which in effect connects the secondary pipe 50 to the outside of the fitting 2. This illustrates part of the versatility of a fitting according to a first aspect of the present invention.

An alternative and preferred fitting incorporating a flange is shown in Figure 7.

Flange 40 extends radially from the GRP component of the fitting and may be formed integrally during construction of the first tubular sleeve. The flange is configured to conform to the shape of the chamber wall in the region of the aperture to be sealed. In this example it is shown as planar but other configurations are possible.

In use, resin is applied to the flange and the fiffing clamped in place against the chamber wall while the resin sets. Further assembly takes place as described above.

Preferably the second tubular sleeve component is formed from one or more plastics materials selected from the group comprising: polyethylene; polypropylene; polyvinyl chloride; polybutylene polyurethanes; polyamides, including polyamides 6, 6.6, 6.10, 6.12, 11 and 12; polyethylene terphthalate; polybutylene terephthalate; polyphenylene sulphide; polyoxymethylene (acetal); ethylene/vinyl alcohol copolymers; polyvinylidene fluoride (PVDF3 and copolymers; polyvinyl fluoride (PVF); tetrafluoroethylene-ethylene copolymer (ETFE); tetrafluoroethylenehexafluroethylene copolymers (FEP) ethylene tetrafluoroethylene hexafluropropylene terpolymers (EFEP) terpolymers of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV); polyhexafluoropropylene; polytetrafluoroethylene (PTFE); 1 0 polychlorotrifluoroethylene; polychlorotrifluoroethylene (PCTFE); fluorinated polyethylene; fluorinated polypropylene; and blends and copolymers thereof.

This selection is not intended to be limiting but rather demonstrates the flexibility and breadth of the invention. The plastics material which is most compatible to the pipe to which it will be joined and with the lowest permeability to the fluid in question will usually be chosen by the materials specialist. Furthermore, it is known to use blends of two or more polymers and this invention extends to cover known and yet to be developed blends of plastics material.

The GRP resin component can be formed from any suitable thermosetting resin as selected by the materials specialist, including but not limited to polyester or epoxy resins.

The GRP sleeve can be formed by any of the conventional techniques used to mould GRP including hand lay-up, compression moulding or injection moulding. The present invention also extends to moulding methods yet to be discovered.

The examples described above relate principally to single wall chambers. However, fittings according to the present invention can be used equally well with double-walled chambers where there is an interstitial space between the two chamber walls. In that case a seal is formed between the fitting and the outer wall and between the fitting and the inner wall. This can be done using two bandages, one outside and one inside the chamber, or by a flange and a bandage. In either case the integrity of the interstitial space between the chamber walls is maintained and can be monitored.

Figure 1 Oa illustrates a further aspect of the invention and a preferred embodiment of a fitting 122 in greater detail. The purpose of this fitting is to form a strong, permanent, fluid tight seal between the fitting and the chamber wall and between the fitting and the pipe works system. In this embodiment, fitting 122 comprises three separate components, a first portion 123, a deformable ring or olive 124, and a second portion 125. Taming first to the portion 123, a first end 126, has an internal diameter

which is a sliding fit over the outside of the secondary pipe 130. Portion 123 is thus generally cylindrical in shape with non-uniform cross-section having a longitudinal axis through which a secondary pipe may pass through the entire body of the portion. Extending radially outwards from the first portion is a flange 128, one surface of which is adapted to conform to engage with the surface of the chamber wall 129. Thus the flange may be flat if the sides of chamber are flat or curved if the chamber has curved walls.

The opposite or second end 127 of the first portion is adapted to accommodate the second portion 125. The internal diameter of the second end 127 incorporates a screw threaded region 132.

It can be seen from the enlarged area that the first end 126 extends beyond the external face of the flange 128. This helps to locate the fitting within the chamber wall and also helps provide a fluid tight seal between the fitting and the wall.

Cut outs or slots can be provided in the flange 128 to allow resin to pass through the body of the flange to increase the strength bond between the flange and the wall (see below).

With reference to Figure 6a, the indentations 272 are in effect castellations in the outer circumferential edge of the flange. These castellations, which can vary in their number, their spacing around the perimeter of the flange, and the extent to which they extend into the body of the flange, serve two purposes. Firstly, they allow a tool to engage the flange if necessary in order to rotate it and tighten it against the chamber wall. Secondly, when overlaid with resin, they significantly strengthen the bond between the fitting and the GRP chamber wall. It follows therefore that it is not essential to have apertures extending through the face of the flange, but merely castellations or indentations in the edge of the flange. This arrangement applies to all the embodiments described herein, including those described below.

First portion 128 further comprises a chamfer 133 on the inside of the first portion. This is necessary to allow the deformable ring to become embedded in the pipe during use and the angle of the chamfer on the first portion is generally matched to the corresponding chamfer 137 on the ring 124. Preferably the chamfer angle on both components is the same.

The second portion 125 has an internal diameter 134 which can accommodate the secondary pipe 130. It can either be a tight sliding fit or can alternatively have a slightly larger clearance than the outside diameter of the secondary pipe as the fluid tight seal will come from the olive 124. The outside surface of the second portion 134 is adapted to comprise a complementary screw threaded region 135 to the screw thread of the first portion 132. It can be seen from the diagram that the external diameter of the second portion need not remain uniform and in the diagram shown it is reduced at the opposite end to the first portion in order to provide a neater, slimmer fitting. It will be appreciated that the screw threads could equally well be positioned on the outside of the first portion and the inside of the second portion.

The second portion 125 further incorporates a recess 136. This is adapted to accommodate the compression ring or olive 124 during use. The advantage of this recess, is that it locates the olive 124 and holds it between the fitting and the secondary pipe such that when the ring 124 is compressed, it acts in a predictable way and deforms to a known degree by locking it in place during deformation. This ensures that a fluid tight seal is always formed and the pipe is deformed to a known degree as the compression ring 124 will always be in a known configuration and cannot ride up the face of the second portion 125.

The deformable ring or olive 124 has a chamfer 137 at one end to match the degree of incline of the fitting chamfer 133. The opposite end of the ring 124 is adapted to fit in the recess 136. The compression ring, is made from a material which is deformable under compression. Typically, it can be made of brass although other materials known to the material specialist which have similar properties could also be used. The thickness of the ring 124 should be thick enough to turn the fluid tight seal but thin enough to allow for the deformation and be wide enough to form a sufficient seal without damaging the pipe.

In use, the first portion 123 of the fitting is passed through a predrilled hole in the chamber wall 129, until the flange engages flat against the chamber wall. Before doing this however, GRP resin, glass fibre mat or other adhesive is applied to either the face of the flange, the chamber wall around the aperture, or both. When the resin sets this forms a fluid tight seal between the chamber wall and the flange. In order to increase the strength of this bond, resin may also be applied to the outside of the flange. Alternatively, the flange maybe clamped firmly against the chamber wall and resin or other suitable adhesive applied over substantially the whole exposed surface of the flange and the surrounding areas. This will also result in a strong fluid tight seal.

In a further alternative, resin/adhesive maybe applied to both faces of the flange, both between the flange and the chamber wall and over the external, exposed face of the flange.

The method of application of GRP resin or adhesive to the chamber wall and fitting can consist of several steps. In one preferred method, the resin or adhesive is applied to the chamber wall around the aperture and the face of the flange facing the chamber wall. The flange is then pressed against the chamber wall. The resin or adhesive is pushed through the holes or castellations in the flange such that, when the resin is set, further increases the strength of bond.

Resin or adhesive is then placed on the outer surface of the flange and additionally the join between the flange and the chamber wall. A reinforcing matting, which essentially comprises flexible sheeting, typically made of glass fibre although other materials known to the material specialist can be used, is then applied to the outer surface of the flange. This reinforces the seal by effectively creating a glass fibre layer on the outside of the flange and results in a strong bond with effectively a reinforced layer on the outside of the flange. In order to complete this seal, more resin or adhesive is applied to the outside of the fibre matting. The fibre matting can be pre-cut into C- sections to accommodate the flange and pipe and aid assembly.

The deformable ring 124 is then moved into position with the ring chamfer nesting against the fitting chamfer 133. This will naturally occur if the ring 124 is slid up the pipe to butt against the fitting chamfer 133. Alternatively, the ring can be placed in the recess 136 and it will naturally be pushed into position as the second portion is screwed in. The second portion of the fitting 125 is then screwed onto the threaded region of the first portion. As the second portion is screwed into place the deformable ring 124 is pushed against the chamfer 133 of the first portion. This results in the compression ring 124 deforming and being forced downwards into the surface of the secondary pipe which then forms a fluid tight seal between the fitting and the pipe. The angle of the chamfer is designed to allow the compression ring to deform into the surface of the secondary pipe forming a fluid tight seal without affecting its integrity. It has been found that an angle of between 20 and 35 can be used and more preferably an angle of 27 . This allows for the formation of the fluid tight seal without affecting the integrity of the pipework system. The recess 136 in the second portion accommodates the deformable ring 124 and holds it in position whilst the ring is deforming. This ensures that a continuous seal is formed between the first portion and the second portion which is fluid tight. This locating region means that the deforming ring 124 cannot ride up the front face of the second portion which would affect the integrity of the seal.

The width of the deforming ring 124 is important to ensure that a comprehensive seal is formed. It has been discovered that a width of between 10 and 20mm and especially around 15mm provides excellent sealing properties. Once the second portion has been sufficiently tightened, a fluid tight seal is formed and the combination of the GRP resin or adhesive sealing the face of the flange to the chamber wall and the deformed ring sealing the fitting to the pipe results in a substantially fluid tight seal. In order to confirm that the second portion has been tightened enough, the system can be pressure tested for its fluid tightness, and if the deforming ring has not formed a sufficient seal, the second portion can be tightened further and then re- pressure tested.

The angle of the chamfer and the width of the olive are crucial in order to provide a successful seal. If the angle is too steep, the deforming ring will cut too far into the secondary pipe which will adversely affect the properties of the pipe. If however, the angle is too slight, the ring will not bite in enough to the secondary pipe to form a successful seal. In addition to this, the width of the ring is essential in order to provide a successful seal. If the diameter is too small a successful seal cannot be formed.

This has a number of advantages over the prior art. The fitting is simple in its construction, cheap to manufacture, and provides a fully fluid tight seal. Because tightening of the fitting is all that is required to form the seal, the fitting does not require complicated tools or machinery to install.

It is also possible to apply resin or adhesive to the outside surface of the remainder of the fitting once the compression seal has been formed. More fibre matting can then be applied to the outer surface of the fitting followed by a further resin/adhesive layer. It is possible to extend this fibre/resin layer onto the outer surface of the pipe to give a fitting which is entirely encased in a layer of glass reinforced resin.

This improves both the strength of the fitting and also the seal formed. The fitting would be pressure tested prior to the application of this layer to ensure that a fluid tight seal had been formed.

it can be seen from Figure 10a that in use a fitting can be placed on either side of the chamber wall. This is used when the chamber is a doubled walled chamber and thus provides secondary containment. The arrangement of a fitting of this type on either side of the chamber wall allows for the integrity of the seal to be monitored via the interstitial gap of a secondary contained wall. If the chamber wall is not secondarily contained a single fitting will suffice to provide the necessary seal. However, it may still be advantageous to sandwich a single chamber wall between two such fittings.

In an alternative embodiment the fitting can be attached to the chamber wall via the flange 28 and the compression joint fitted to a section of pipe which itself contains electrofusion winding. This allows for the possibility of having an integral fitting with its own section of pipe which can then be electrofusion welded to the secondary pipe thus allowing for a tertiary level of containment. Electrofusion couplings are well known to those skilled in the art. This embodiment provides an even greater level of containment, combining a GRP adhesive seal, a compression seal and an electrofusion welded seal.

Figure 10b shows an end view of the fitting according to a first embodiment of the present invention. It shows the flange 128 which incorporates holes 139 to allow the GRP resin to flow through the flange during installation. It also shows a tightening bolt 138 on the outside of the second portion which allows a tool to be attached to the outside of the second portion to thread the second portion onto the first portion and thus deform the compression ring.

Figure 11 shows the component parts of the fitting 122 in greater detail.

Figures 12 a-c show an end view of the component parts of the fitting 122. The flange 128 can be clearly seen in Figure 12a, the compression ring 124 in Figure 12b and the second portion 125 in Figure 12c shows the tightening region 138 clearly.

Figure 13 shows a diagram of the fitting in use. It shows two fittings either side of an imaginary chamber wall with the secondary and primary pipe passing through the fittings.

Figure 14 shows a close-up view of a fitting according to the present invention in a disassembled state. It can be seen that in use the second portion is threaded onto the first portion whereby the olive is deformed there-between.

Figure 15 shows an alternative view of the separate components of the fittings.

The fitting can be made from a number of materials. The first and second portions need to be made of a material which will allow them to be screw threaded together and the first portion furthermore needs to be able to attach to a GRP wall. The compression ring needs to be made of a material which is readily deformable under pressure. The first and second portions can be made from a different, stronger material than the deforming ring but it has also been found that it is possible to make both the first portion, second portion and deforming ring from the same material provided that the diameter of the deforming ring is thin enough to permit it to deform under compression. The fitting can be made from a metal such as brass or bronze or a bronze alloy, stainless steel, coated steel or aluminium or coated aluminium.

Under compression conditions, the outside plastic surface of the pipe deforms and partially runs to help form the fluid tight seal. This flow aids the formation of the seal without affecting the integrity of the pipe itself. The pipes can be made from a variety of materials, including but not limited to those listed above.

polyvinyl fluoride (PVF); The GRP resin or adhesive component can be formed from any suitable thermo setting resin as selected by the material specialist, including but not limited to polyester or epoxy resin.

Fittings according to the present invention can be used equally well on single or double wall chambers. Because a seal can be formed on both sides of the wall, the integrity of the interstitial region between the chamber walls is maintained and can be monitored. They can be used equally well to form a seal between a pipe and a wall of a sump, such as sump 68 and 70 in Figure 1. For the purpose of this description the term pipe generally refers to a circular cross-sectioned pipe. However, this invention also covers pipes having other cross-sections such as box- sections, corrugated and the like and also single wall or secondary contained pipes. The invention is also equally applicable to use with a primary pipe.

An example of the tightening region is shown as a hexagonal nut structure in Figure 12c. However various other shapes and devices can be used to provide a turning purchase on the portion. opposing sides can contain flats such that a spanner, wrench or special tool could be used. Alternatively the portion can incorporate handles protrusions or cut outs which could be used to obtain the necessary purchase.

The material of the fitting is preferably made of brass or bronze.

In a further variant, illustrated in Figure 10c, a flange cover 60, 61 can be provided to overlay the flange on one or both sides of the fitting. The flange cover may preferably be formed from fibreglass or other GRP material and is preferably filled with a resin during assembly. By forcing the flange cover against the flange and against the chamber wall a neat, strong seal can be made encapsulating the flange and that part of the chamber wall, within a cocoon of resin. This arrangement has the advantage that the flange covers may be clamped in place whilst the resin or adhesive sets. If desired the covers could make contact with the flange at pre-determined points such that the clamping force also forces the flange into contact with the chamber wall. A further advantage of these covers is that they minimise the possibility of resin coming into contact with other parts of the fitting during the assembly process.

In order to improve the adhesion of flange to the chamber wall, the face of the flange may include slots, grooves or channels or the like which, in use, become filled with adhesive. One suitable arrangement is to provide one or more annular grooves or channels in the face of the flange which contacts the chamber wall. These endless grooves can be filled with sealant or adhesive before the parts are assembled. This arrangement can significantly improve the quality and durability of the seal and adhesion between the flange and the chamber wall.

Claims (9)

1. A fitting for providing a substantially fluid-tight seal between an opening in a chamber wall and a pipe passing through said opening, said fitting having at least one radially extending flange, said flange being adapted to engage with the chamber wall around substantially the entire circumference of the flange, said fitting being further adapted to form a fluid-tight seal with said pipe by a mechanical compression means.

2. A fitting according to Claim 1, wherein said fitting comprises: i) a first portion having at least one radially extending flange, said flange being adapted to engage with a chamber wall around substantially the entire circumference of the flange; ii) a second portion; iii) securing means adapted to secure said first portion to said second portion via a mechanical compression means.

3. A fitting according to any preceding claim, wherein said fitting further comprises a compression ring or olive.

4. A fitting according to Claim 2 or Claim 3, wherein the first portion is formed from a material adapted to bond to a fibre reinforced plastics material.

5. A fitting according to any of Claims 2 to 4 inclusive, wherein the first portion is formed from a metal such as stainless steel, coated steel, aluminium, coated aluminium, brass, bronze or bronze alloys.

6. A fitting according to any preceding claim, wherein the mechanical compression means comprises complementary screw threaded regions which in use compress a compression ring or an olive.

7. A fitting according to any of Claims 2 to 6 inclusive, wherein the mechanical compression or securing means comprises complementary screw threaded regions on the first and second portions such that the two portions screw together, whereby a compression ring, or olive, located between the first and second portions, is deformed to provide a fluidtight seal between the fitting and the pipe.

8. A fitting according to any preceding claim, wherein said fitting further comprises a cover adapted to cover said flange and to encapsulate said flange in adhesive during the assembly process.

9. A fitting substantially as herein described with reference to and as illustrated in any combination of Figures 2 to 15 inclusive.