Field of the Invention

The present invention relates to a compression joint security fitting, and more specifically to a security or safety device adapted to be applied to a pre-existing, in-use compression joint of conventional construction typically employed in the vast majority of domestic, commercial and industrial premises to connect the free ends of two or more fluid -carrying pipes together in mechanically and hydraulically secure fashion.

Although the following description is provided with almost exclusive reference to conventional compression joints, wherein the primary means for establishing both a sound mechanical connection and a hydraulic seal and between the joint body and the free end of pipe received therein is the combination of a compression nut and olive which act in concert as the compression nut is screwingly tightened to the joint body, the skilled reader should understand that the present invention may not be limited to the particular type of joint, compression or otherwise, by means of which the free end of a fluid-carrying pipe is connected to some other part of a fluid-carrying network. Indeed, the skilled reader should understand that the present invention is not so much concerned with the type of joint or the physical means by which that joint achieves an ostensibly mechanically and hydraulically sound connection between the pipe free end and the joint itself, but more with aspects of the exterior configuration of joint body and, if present and/or required, the mechanical means which, as part of the connection process between pipe and joint, may be screwed onto or otherwise secured to the joint body. Thus, although the term "compression joint" appears throughout the following description, the skilled reader should understand that this term is to be broadly interpreted and indeed may, where context requires, cover a multitude of different types of joints and their respective jointing means, mechanisms and arrangements, such not necessarily being of a "compression" type in the traditional sense, but which nevertheless act on both the joint and the pipe to, ostensibly at least, secure the latter to, and commonly at least partially within, the former.

Background to the Invention

The common plumbing compression joint has been in existence for decades, and their use is completely ubiquitous in all aspects of the plumbing industry, be these domestic, commercial or industrial. Naturally, over such an extended time period, both compression fittings and the pipes they connect have become standardised to a certain extent, and depending on application, compression fittings and the associated pipework they join are commonly available, in the UK at least, in a range of standard sizes, starting with 6mm diameter, and increasing to 54mm, with intervening standard sizes being 8mm, 10mm, 15mm, 22mm, 28mm, 35mm, 42mm. Compression fittings and associated pipework at the lower end of this range (8, 10, 15, and occasionally 22mm) are most commonly found in domestic environments, whereas larger pipes and joints (22mm and above) are more commonly found in larger commercial and industrial premises, where there are more often requirements to transport much larger volumes of fluid, often at significantly greater static pressures than are employed in domestic environments.

In the vast majority of circumstances, and where the correct fitting procedures have been followed, compression joints function perfectly well, often for many years, without leaking. However, particularly in commercial and/or industrial environments where compression fittings connect pipework carrying much larger volumes of fluid often at significantly higher static pressures, the fundamental issue is not that they can function perfectly well for long periods of time, but that when they fail, they fail catastrophically. In particular, a most common failure mode for larger compression joints is that the pipe carrying the pressurised fluid, typically water, works entirely and completely free from within the fitting body, resulting in the immediate unrestrained and continuous (until arrested) discharge of fluid from the said pipe. Although water itself is not toxic or damaging to human health, unrestrained discharge thereof within commercial and/or industrial premises can cause extensive and extremely costly damage, particularly from the points of view of repair, renovation and refurbishment costs, and loss of and interruption of business activities, among other things. In practically all cases, this results in large claims being made by businesses against their own and often other third party insurance policies. When it is considered there can be many hundreds if not thousands of compression joints installed in commercial premises, particularly multi-storey office blocks and the like, compression joint failure is the most common root cause of fluid-leak insurance claims made by businesses operating in such premises, and frequently the most costly.

One of the fundamental issues with compression joints generally is that, visibly at least, there is no external indication whatsoever of the state or integrity of the compression connection between pipe and fitting, and thus no indication as to whether the joint may fail imminently or whether the joint may continue to operate flawlessly for many years to come. As the skilled reader will understand, this is because the principal component of the fitting responsible for both the mechanical and hydraulic connection of the pipe thereto is the olive, which is disposed around the pipe inside the compression nut of the joint which acts upon it, and is therefore entirely concealed from view. Therefore, at least without exceedingly costly examining equipment, or very costly temporary supply disconnection and joint dismantling procedures, it is impossible for any inspection, for example as may be required by insurance companies, to determine the state and integrity of any of the compression joints present within any building. Currently therefore, premiums charged by insurance companies in respect of commercial water damage can be significant, because in general, the insurers already understand that claims for water escape as a result of compression joint failure will occur at some point or other, and are therefore somewhat inevitable. It is thus a first object of the present invention to provide a safety fitting for compression joints which are instantly and visibly recognisable, and thus provide, merely as a result of their having been fitted, a ready means of indicating to the casual observer that the compression joint to which they have been fitted is mechanically sound and thus that the risk of catastrophic failure of the type described is very low, indeed possibly vanishingly so.

To provide some greater technical detail as to why compression joints fail catastrophically in the manner described, it should be understood that this type of failure is almost always purely mechanical in nature, and results most commonly from the compression nut not having been tightened sufficiently and/or correctly to the body of the compression fitting upon being fitted to the free end of the pipe when originally installed. Current guidelines for sound mechanical connection, for all but the largest of compression joints, indicate that the compression nut should be firmly tightened by hand as far as is possible, and then further wrench- or spanner-tightened by a further three-quarter turn. For the largest compression joints, the compression nut should be wrench- or spanner-tightened by one full turn, that is by a further 360 degrees after having been firmly hand tightened. To achieve this on the larger compression joints, given the torques required to be applied to the compression nuts, the wrench or spanner required can be substantial, e.g. up from 50-100cm in length. If these guidelines are followed, or even if the compression nut is over- tightened beyond the recommendations, the effect of tightening the compression nut under the mechanical advantage provided by the spanner or wrench is two fold:

(i) to axially force the olive surrounding the pipe at least partially within the recess within which the pipe free end has been inserted prior to screwing the compression nut onto the threaded exterior of the compression joint body and then hand-tightening said nut, and

(ii) to radially and circumferentially deform not only the olive but the pipe itself, internally within either the compression nut or the recess within the joint body and within which the pipe free end is inserted and ultimately seated, or both (where the olive is or becomes axially disposed only partially within said recess), said contraction naturally occurring predominantly in that region where the pipe is surrounded by the olive.

As may be appreciated by the skilled person, it is a combination of the frictional engagement between, and the geometry of, the exterior surfaces of the olive and the interior surface of the recess into which it is urged when the compression nut is wrench- or spanner-tightened, that provide the mechanical resistance to any force which may, in use, be experienced by the pipe and which would tend to move it axially outwardly of the recess within the compression fitting within which it is received and seated. The frictional engagement in particular, and the mechanical resistance to pipe axial movement it provides, is increased and thus improved by whatever residual tendency there may be for the pipe to elastically relax back to its pre-contracted condition underneath and in the general vicinity of the olive. Most simply, if the compression nut isn't tightened, or is insufficiently tightened, the pipe can escape from the compression joint with immediate consequences, as already outlined.

To mitigate catastrophic failures of compression joints, it has of course been proposed for individuals or teams to carry out inspections, and possibly for them to manually tighten all the compression nuts on all the compression fittings present within a particular building. However, such a simple solution is impractical and potentially aggravating for a number of reasons. Firstly, the work would be largely redundant because it would generally be the case the majority of the compression joints in any building would have been initially fitted correctly, and would not therefore need any attention. Secondly, if operatives were instructed to further tighten compression nuts which had already been properly tightened, this would could jeopardise the existing integrity of the mechanical and hydraulic seals provided between the pipe and the compression joint of which the particular nut or nuts form part. A much better solution to this problem, and one which the present invention endeavours to offer, is to provide a quick, simple, inexpensive security or safety device which could be fitted to all the compression joints present within any particular building and which would immediately substantially mitigate if not actually completely eliminate any possibility that any compression joint fitted with the device could then fail in the manner described, i.e. by separation of the pipe from the fitting.

In terms of relevant prior art, at least in the field of conventional compression joints, given that the standard configuration and component parts of such joints were devised many decades ago now, there is a vast amount of potentially relevant art, not all of which can be cited here. However, perhaps most relevant, and maybe one of the earliest (circa 1930) patents for the traditional compression joint is US2029325, which clearly demonstrates the principle of using an olive of compressible material and a compression nut which is tightened against a compression joint body, and which both axially drives said olive within the compression joint and causes deformation thereof, as well as deformation of the pipe secured within the compression joint beneath the olive and in the region thereof. US4260182 is also relevant in this regard.

More recently, and particularly for domestic plumbing and gardening hoses, there have been many attempts in recent times to devise devices, systems, adapters, connectors and the like for connecting or otherwise securing the free end of a pipe to and within a fitting of some sort, and which mitigate or obviate the need for traditional compression fittings, which are, as the skilled person will appreciate, often made of brass or steel, can take time to fit, and require specific tools to do so. For example, in terms of modern plastics fittings adapted purely for low pressure domestic and gardening applications, there exists the SpeedFit™ range of products manufactured and sold by John Guest International Limited. Of particular note is EP1821021 which shows a fitting whereby a pipe, most commonly being of a plastics material but possibly of metal, e.g. copper, can be manually connected to a fitting simply by pushing and slidingly inserting the pipe free end into an annular cavity within the fitting, the pipe being retained therein by means of a component known as a grab ring.

Grab rings are well known in the industry, and generally comprise a continuous circular peripheral ring part from which project, inwardly of the ring part, a plurality of identical short (compared to the diameter of the ring part) tongues, each tongue being inclined at the same general angle to the cross-sectional plane containing the ring part. The number of individual tongues can vary depending on the diameter of the grab ring and its application, but usually they number between 6-20, and their length may range between 2-15% of the diameter of the ring itself. In most if not all cases, the grab rings are of unitary construction, so the tongues are integrally formed with the ring part, for example by punching or stamping techniques. The purpose of any grab ring is to axially retain a pipe of suitable diameter within a fitting in which the grab ring is housed and seated. For example, when a pipe, having an external surface diameter which is marginally larger than the diameter of the notional aperture defined to the interior of the grab ring by the tongue free ends thereof, is inserted therethrough, the tongues are slightly elastically deflected outwardly by the pipe exterior cylindrical surface. Once the pipe has been axially inserted through the grab ri ng to a desired extent, it is subsequently prevented from being axially withdrawn in the reverse direction because the relatively sharp tongue ends of the grab ring frictionally engage with the exterior surface of the pipe and in some cases, depending on relative hardness of the materials of grab ring and pipe exterior surface, actually bite into the pipe exterior surface. In essence therefore, the tongues of the grab ring act as barbs on the pipe exterior surface.

Returning to EP1821021, the grab ring is held in place within the fitting immediately behind the opening of the annular cavity and orientated with its circular array of short tongues directed inwardly of the fitting and away from the annular opening which they surround. A dual-ended fitting of similar construction and also utilising grab rings is illustrated and described in GB2538448 in the name of Pegler Yorkshire Group Limited. Furthermore, in conjunction with Yorkshire Fittings Limited, Pegler have, since 2007 or thereabouts, manufactured, marketed and sold a range of fittings under the brandname Tectite™, which all appear to be adapted for purely manual (that is, without any requirement for wrenches, spanners or other conventional tools) connection of pipes thereto and therein, and which utilise grab rings internally of the fittings to achieve a secure mechanical connection of the pipe therein. The Tectite™ fittings appear to be manufactured in steel, and would thus appear potentially capable of withstanding significantly greater pressures than corresponding fittings manufactured purely in plastics materials.

Notwithstanding recent advances described above, all the prior art fittings nevertheless suffer from the same inherent disadvantage as a conventional compression joint - namely it is still impossible, at least upon casual visual inspection, or without either invasively inspecting or analysing the fitting, or performing potentially structurally and physically damaging testing thereon, to determine the relative integrity, strength and likely longevity of the mechanical connection at that time being provided by the relevant mechanical components of the fitting because they are disposed entirely within the fitting and thus are, as such, un-inspectable and inaccessible. In the case of the more recent fittings described above, it is of course the grab ring which provides the mechanical connection between the pipe and fitting, but just as the olive and compression nut of conventional compression joints may be improperly fitted or may degrade naturally as a result of their being inevitably exposed to the fluid carried though the fitting, the grab rings used in more modern fittings may themselves be prone to unexpected and unpredictable wear, degradation and/or failure, and in any event are similarly inaccessible and somewhat, if not entirely concealed within the fitting.

Objects of the present invention are aimed at overcoming these and other disadvantages of compression fittings. The main object of the present invention is to mitigate if not indeed entirely overcome the problem of catastrophic mechanical failure of larger, more conventional compression joints constituted predominantly or exclusively of metal, typically brass, and to provide a ready indicator to the casual observer that the compression joint has been rendered "safe" by means of the device of the present invention being immediately instantly recognisable and clearly distinguished from the compression joint to, over and/or around which is fitted. Use of the term "larger" as it appears in this paragraph and elsewhere in this document, as applied to compression joints, should be understood as being adapted to receive pipework of 22mm diameter and above, i.e. 28mm, 35mm, 42mm, 54mm, and possibly even greater.

Summary of the Invention

According to the present invention there is provided a safety fitting for pipe jointing means having at least a body portion with at least one opening at one end thereof within which a pipe end is adapted to be at least partially inserted and retained in place by primary pipe engaging means disposed over and around said opening, such either forming an integral part of said pipe jointing means or being initially separate therefrom and subsequently secured to said body portion end, said safety fitting consisting of at least first and second sub-parts adapted, in use, to be connected to one another over and around both of:

- at least said end of the pipe jointing means and, if present, said primary pipe engaging means connected thereto, and

- an exposed region of the exterior surface of said pipe axially most proximate said pipe jointing means end, said first and second sub-parts of said fitting, when connected together, defining internally a hollow bore therethrough having at least two discrete regions, a first region generally corresponding in shape and size to said end of said pipe jointing means and any primary pipe engaging means connected thereto and thus being capable of accommodating such, and a second region substantially corresponding in shape and size to the exposed region of the exterior surface of said pipe immediately proximate said pipe jointing means end,

Characterised in that

At least one of said safety fitting sub-parts is provided with flange means which project inwardly of said hollow bore in the first region thereof and which, in use, are disposed behind one or other of: a laterally outwardly projecting surface of said primary pipe engaging means, and an exterior surface of said pipe jointing means which projects laterally outwardly therefrom so as to effectively secure said safety fitting to said pipe jointing means, and at least one of said safety fitting sub parts is provided with frictional engagement means which project inwardly of said hollow bore in the second region thereof and which, in use, engage said pipe exterior surface, the result of which, in cooperation with said flange means, is to effectively prevent axial displacement of said pipe away from said pipe jointing means.

Preferably, one, and further preferably both sub-parts of said safety fitting is/are provided with both flange means and frictional engagement means. In a most preferred embodiment, both safety fitting sub-parts are provided with both flange means and frictional engagement means. In a yet further preferred embodiment, one or both of the flange means and frictional engagement means provided in one or both sub-parts is one of intermittent, preferably angularly periodically so, and substantially continuous.

Preferably, the flange means provided on one or both sub-parts of the safety fitting are substantially continuous such that, in use when said sub-parts are, in use, disposed in overlying relationship over and around the pipe jointing means end, said flange means together define a substantially continuous restraining collar which is disposed behind the laterally projecting surface of the pipe jointing means end and/or the primary pipe engagement means provided thereon or connected thereto thus effectively preventing the safety device as a whole from sliding axially away from the pipe jointing means body and over and off the end thereof.

Preferably each of the two sub-parts of the safety device forms one half of the safety device as a whole, and most preferably, except for formations and design aspects thereof which permit the releasable connection of one sub-part to the other, said sub-parts are substantially identical in shape and configuration. Most preferably, therefore, each sub-part of said safety device is preferably substantially hemi-cylindrical in cross-section, and the hollow bore defined internally of and through the safety device when the two sub-parts thereof are, in use, brought into overlying relationship with one another, arises as a result of each sub-part being internally provided with a hemi-cylindrical channel having two distinct regions corresponding to the first and second regions of the bore which, in use, said hemi-cylindrical channels together partially define. Most preferably, the hemi-cylindrical channel provided in one or other sub-part in its first region has a larger diameter than that of the second region of said channel, the former diameter being marginally greater than the largest external diameter of the pipe jointing means end and any primary pipe engagement means connected thereto, and the diameter of the second region of the hemi- cylindrical channel being one of: marginally less than, substantially equal to, or marginally greater than the diameter of the exterior surface of the pipe which, in use, passes through the second region of the hollow bore through the safety device. Thus in this particular arrangement, when the two sub-parts of the safety device are disposed in overlying relationship over and around the pipe jointing means end and the pipe inserted therein, and connected together, the first region of the hollow bore within the safety device either loosely, comfortably or more preferably, snugly, accommodates the relevant end of the pipe jointing means and any primary pipe engagement means provided thereon or connected thereto, whereas the second region of the bore through the safety device accommodates, and most preferably engages with, the exterior surface of the pipe around which it is disposed.

The configuration of the respective first and second regions of the hemi -cylindrical channels provided in one or preferably both sub-parts of the safety fitting, that is each region being of different diameter, effectively automatically creates an intervening shoulder or surface within the hemi-cylindrical channel, preferably at an axial position 30-70%, or more preferably 40-60%, and further preferably 45-55%, along the axial length of both sub-parts where the radial dimension of the hemi-cylindrical channel changes, most preferably abruptly, between the first and second regions thereof.

Most preferably, the flange means are provided at or proximate, and substantially continuously around that end of the first region of the hemi-cylindrical channel which is remote from the intervening shoulder or surface and which effectively provides the notional demarcation between the first region of said hemi-cylindrical channel and the second. Thus, in this preferred arrangement, together the flange means and the axially remote intervening shoulder or surface together define a hemi-cylindrical cavity within one and preferably both sub-parts so that together they define a substantially complete cylindrical cavity of appropriate size to accommodate the relevant end of the pipe jointing means and any primary pipe engagement means provided thereon or connected thereto. Preferably, the innermost radial dimension of the flange means is selected so as to be marginally greater than the corresponding diameter or other dimension of the pipe jointing means body so that the latter can be accommodated without hindrance within the terminal aperture ultimately defined by the flange portions of both sub-parts when they are brought together in overlying relationship around said pipe jointing means. Thus in this preferred embodiment, and when the sub-parts are assembled around the pipe jointing means, the flange means are disposed behind a relevant laterally projecting surface of the relevant end of the pipe jointing means and any primary pipe engagement means provided thereon or connected thereto. Further particulars of this and other possible arrangements will become more readily apparent from the specific description provided below. Most preferably, the axial length of the cavity defined between and within the two sub-parts and their respective flange portions and intervening shoulders or surfaces is marginally (for which term herein the reader should understand a range of between 0.5-4.5mm, depending on the pipe diameter and overall size of the pipe jointing means) greater than the corresponding axial length dimension of the primary pipe engagement means provided on or connected to the relevant end of the pipe jointing means.

Preferably, the frictional engagement means provided in one or both sub-parts of the safety device possess some degree of resiliency, in that they are capable of being elastically deformed slightly when, in use, they are brought into engagement with the exterior surface the pipe as both said subparts are brought together in overlying relationship on either side of both the end of the pipe jointing means and the pipe inserted therein, and then connected to one another. In preferred arrangements, the frictional engagement means engage with and act upon the relevant region of the exterior surface of the pipe in any one or more of the following ways:

- purely frictionally,

- some combination of frictionally and mechanically,

- purely mechanically.

For instance, where, as in some preferred embodiments, the frictional engagement means are constituted by a plurality of resilient teeth, tongues, prongs or the like, most preferably being formed of a material which is relatively harder than the material of the pipe exterior surface with which they come into engagement. In such embodiments, said teeth may actually elastically or plastically deform the pipe exterior surface and become embedded therein and, as will become apparent from the specific description below, act as barbs which mechanically resist any subsequent tendency of the pipe to axially separate from the pipe jointing means. Most preferably, the teeth, tongues, prongs or the like of the frictional engagement means are i nclined from the transverse plane containing their roots, the angle of inclination being anywhere within the range 1 -40 degrees, and the direction of the inclination being away from the most axially proximate free end of the sub part, that is towards the first region of the hemi-cylindrical channel provided in the or each subpart, and in the direction of the more axially remote free end thereof. As the skilled reader will immediately appreciate, in this disposition and orientation, the teeth, tongues, p rongs or the like may exert their barb-like action on the pipe exterior surface, whereas if they were inclined in the opposite axial direction, they would exert little or no mechanical barb-like action or frictional resistance on the pipe exterior surface, which would merely slide and slip past their ends. In a most preferred arrangement, within the second region of the hemi -cylindrical channel provided in at least one and preferably both sub-parts, there is provided at least one slot, orientated preferably substantially laterally relative to the axis of the hemi-cylindrical channel provided in that sub-part, said slot most preferably being also hemi-cylindrical in cross-section and adapted to receive correspondingly shaped, i.e most preferably semi-annularly shaped, frictional engagement means, at least some portion of which, when said frictional engagement means are seated completely within said slot, stand proud of at least one edge of the slot and thus project inwardly into the second region of the hemi-cylindrical channel provided in that sub-part. Most preferably, lateral slots as described are provided in both of the second regions of the hemi-cylindrical channels provided in said sub-parts, most preferably at approximately the axial mid-point of said second regions of said hemi-cylindrical channels, and semi-annularly shaped frictional engagement means are provided in both said slots. Preferably both frictional engagement means so provided have portions which project above and beyond at least one edge of the slots into the respective hemi- cylindrically shaped channel of the respective sub-parts.

Thus, in the most particularly preferred embodiment, both sub-parts are provided internally with respective frictional engagement means in their respective slots such that when the two sub-parts of the safety fitting are, in use, brought together in overlying relationship over and around the respective portions of both the ends of the pipe jointing means and the immediately adjacent exposed exterior surface of the pipe inserted therein, the portions of the friction engagement means which stand proud of the slots first come into contact with the exterior surface of the pipe before other interior surfaces of the sub-parts. Thereafter, as the two sub-parts of the safety device are brought closer together as they become completely connected to one another so as to effectively become clamped around both the end of the pipe jointing means the pipe itself, said proud standing portions of the frictional engagement means engage more firmly with the exterior surface of the pipe, possibly elastically and/or plastically deforming it in the contact regions, thus at least securely frictionally if not also mechanically providing a secure grip thereon on the pipe exterior surface. It should be mentioned here that this interaction, particularly in the case where the frictional engagement means is in the form of inwardly projecting and appropriately inclined tongues which engage with and possibly bite into the exterior surface of the pipe, may actually be improved and/or strengthened in the event that the pipe tries to axially separate from the pipe jointing means, because small displacements of the pipe relative to the jointing means in this direction would only result in the tongues ends becoming further embedded in the pipe exterior surface. Thus, in this particular arrangement, the frictional engagement means can resist very significant forces, possibly one or more orders of magnitude greater than that which common fluid static pressures could potentially exert on the pipe and which might tend to axially displace the pipe away from the pipe jointing means.

In further preferred embodiments, the frictional engagement means are provided by two separate halves (or in some embodiments, slightly less than one exact half) of a known grab ring provided with a plurality of circumferentially spaced apart tongues which project inwardly of the ring (or its semi-annular equivalent when halved), and which, when received in and completely and fully seated in the appropriate slots in each sub-part, project upwardly above at least one of the edges of each of the slots and into the hemi-cylindrical channels of one or each sub-parts in which said slots are provided. Most preferably, in the case where the frictional engagement means are provided by such substantially semi-annular grab ring parts, they are constituted of material, for example steel or aluminium, which is relatively harder than the material of which the exterior surface of the pipe is constituted, which may traditionally be copper, or in some cases any one of a number of plastics materials.

In a further preferred embodiment, the one or more slots provided in the or each sub-part and which receive substantially semi-annularly shaped grab ring halves as described above is provided with a substantially continuous chamfer along one edge thereof so as to provide one or both of: a seating surface, and a clearance spacefor the inwardly projecting and usually inclined (relative to the notional cross-sectional plane of the grab ring half) tongues of the semi-annular grab ring halve which said slot is to receive. Most preferably the alternate edge of the or each of said slots is substantially straight-edged and not so chamfered, and thus the or each slot may be considered to be "handed" in that it is only capable of receiving a grab-ring halve in a particular, correct orientation as regards the action that said grab ring is to provide on the exterior surface of the pipe and with which the tongues of the grab ring come into frictional and possibly also mechanical, for example biting or barb-like engagement. Most preferably the degree of inclination of the chamfer substantially corresponds to the degree of inclination of the tongues of the particular grab -ring half the slot is adapted to receive and accommodate.

By this arrangement therefore, firstly the grab ring halves must be orientated correctly before they inserted within the or each slot, and secondly the grab ring halves can be accommodated without any pre-stress or bending, or only minimal pre-stress or bending, being applied to some or all of the tonges thereof. In the particularly preferred arrangement, where at least some of the inwardly projecting and inclined tongues of the grab ring portion contact, and are thus at least partially initially supported by and on one chamfered edge of the slot, the effective length of those tongues is effectively much reduced and therefore the resistance to bend and flex of those tongues may be correspondingly increased, and in turn , therefore, the frictional and/or mechanical action exerted by the tips of those tongues on the exterior surface of pipe may be considerably increased when each sub-part of the safety device is progressively brought into overlying and ultimately clamping relationship with the other around the pipe. It is worth mentioning here that even if, initially at least, there is some small clearance between some or all of the tongues of each grab ring half from the chamfered edges upon complete insertion into the slots adapted to receive them, it is possible that once the safety device as a whole had been fitting to and around pipe jointing means and was in use, small displacements of the pipe relative to the compression jointing means and within the safety device could result in one or more of the tongues coming into contact with one or both of the chamfered edges, which would then of course provide the support for that or those tongues at that time and with the same advantages described.

Indeed, in some cases where the depth of the slot and the grab ring halves, the length of the tongues provided thereon, and inclination of the chamfer are all appropriately selected and/or designed, it may even be possibly, under normal usage, to prevent the tips of the tongues from experiencing any significant deformation at all, the result of such an arrangement being that the projecting tongue tips are much more likely to bitingly engage and become at least partially embedded within the exterior surface of the pipe, and thus significantly more robustly prevent any subsequent axial displacement of the pipe away from the pipe jointing means to and within which it is secured.

Preferably, one or both sub-parts of the safety device are formed from a readily mouldable, for example by injection, plastics material. More preferably, the sub-parts are formed from a thermosetting or thermoplastic plastics or resin material. In some embodiments, the sub-parts may be substantially or entirely formed from polytetrafluoroethylene (PTFE), nylon, polyethylene, polyvinyl chloride (PVC) or other suitable injection or otherwise mouldable plastics material.

In embodiments where each sub-part of the safety device is an entirely separate component from the other, the manner in which one sub-part is fixedly secured to the other, preferably in releasable fashion, is by means of simple screws, preferably using one or two pairs thereof. For example, one sub-part may be provided with one or preferably two pairs of apertures, one of each pair being provided towards the lateral extremities of the relevant sub-part in a location to one or other side and outwith the hemi-cylindrical channel provided in the interior of that sub part, and each of the two apertures of both pairs (where provided) being axially spaced apart by a suitable distance, e.g. between 4-20 mm, depending on the overall dimensions of the particular sub-part and the pipe jointing means and pipe over and around which it is adapted to fit. Most preferably, the one or two pairs of apertures are disposed in that axial part of the sub-part which coincides with the second region of the hemi-cylindrical channel, because it is in this particular region that it is desired that the clamping effect provided by the screws is desired to have its greatest effect, i.e. where the frictional engagement means is provided internally of the sub part. Most preferably, where two pairs of apertures is provided, the two pairs of apertures are disposed substantially axially symmetrically and to either side, axially speaking, of the slot provided within the second region of the hemi-cylindrical channel of that sub-part.

As the skilled reader will appreciate, correspondingly shaped, sized and positioned screw-shank receiving recesses may, in some preferred embodiments, be required to be provided in the alternate sub-part, such that appropriate screws can be fed through the apertures provided in one sub-part and into the screw-shank receiving recesses of the other part, and thus the two sub-parts may be screwingly and releasably, not to mention easily and quickly, connected together and in a manner which effectively clamps the sub-parts in position around respective regions of both the end of the pipe jointing means and the pipe inserted therein. Furthermore, with the particular arrangement where two pairs of screws are used to connect the sub-parts together, the screws, and the respective apertures and recesses provided on or in the sub-parts will preferably ideally be axially separated from one another, most preferably substantially symmetrically or equidistantly on either side of the slot and the frictional engagement means it holds. In this particular arrangement, the clamping force exerted by the screws on each sub-part and in turn on said frictional engagement means, and thus on the pipe exterior surface itself, is substantially uniformly distributed and evenly applied, which the skilled reader will immediately appreciate can be most beneficial as regards the ultimate robustness of the frictional and/or mechanical connection between the frictional engagement means and the pipe exterior surface. In some most preferred arrangements, one or both of the respective pairs of apertures and recesses are provided around their, in use, most closely disposed surrounding surfaces with cooperating ribs and correspondingly sized rebates which cooperate in male-female fashion and ensure that any and preferably all of the apertures are automatically coaxially aligned with their corresponding recesses.

In a yet further preferred embodiment, the safety device may be of unitary construction in that the sub-parts thereof are integrally formed together and united by a relatively thin (e.g. 1 -2mm thickness, or possibly less), narrow (e.g. 2 -4mm) flexible web of the material from which they are formed, such that the two sub-parts are formed initially in side-by-side relationship, and may be subsequently brought into overlying relationship around a relevant end of the pipe jointing means and the pipe inserted therein simply by manually folding one sub-part over the other about the flexible web. In a most preferred embodiment, each sub-part is integrally provided, preferably on, along or proximate their respectively opposite, free substantially axially aligned edges, with cooperating mechanical engagement means, such as, for example, simple well -known cantilever snap-fit type formations. Thus, in this particularly preferred embodiment, instead of screws and the respective apertures and recesses described above, one sub-part half is capable of being completely and securely manually connected to the other, and in entirely releasable fashion, and such an arrangement naturally significantly increases the speed and ease with which the safety device as a whole can be fitted. As will be further appreciated, provided that the dimensions, particularly the width and thickness, of flexible web of material are carefully selected, each sub-part of the fitting can still be very securely connected to the other along both axial edges without requiring any screws and the attendant tools required for them, because each adjacent axial edges of each sub - part are automatically firmly connected together, on one hand by means of the flexible web of material, and on the other hand, by means of the cooperating mechanical engagement means. A further advantage of this arrangement is that the mechanical engagement means will often be of a type, particularly in the case of snap-fit formations, which provide a positive audible click or "snap" when the mechanical engagement is complete, thus automatically signifying to an installer that the connection of respective sub-parts of the safety fitting is complete and secure. A yet further advantage of such types of mechanical engagement means is that the inherently resiliency of the flexible web of material which joins the two sub-parts naturally always tends to recover elastically to its original, un-bent condition in which each sub-part is disposed essentially adjacent the other in fully open, flat condition. Therefore, it will always be immediately evident, upon inspection, to determine whether any safety device of this particular type has been completely, properly a nd securely connected because if it has not, it will be clearly visible that one sub-part lies some way distant from the other on account of the natural tendency of the flexible web of material to elastically relax and thus move the respective sub-parts joined on either side thereof away from one another.

Further advantages, embodiments and possible variations of the present invention, will become apparent from the following specific description of the invention, provided by way of example and with reference to the accompanying drawings wherein.

Brief Description of the Drawings Figure 1 shows a perspective view of a conventional (prior art) compression fitting commonly used for connecting together the free ends of first and second pipes, and to which the present invention is most ideally suited,

Figures 2A, 2B show perspective views of various types of known (prior art) grab-rings already in widespread use within various different types of pipe jointing means, and which, when cut in half, may be ideally suited to providing the frictional engagement means utilised within the safety device according to some embodiments of the present invention,

Figures 3 and 4 show perspective views of the interiors of the first and second sub-parts of the safety device according to some embodiments of the present invention,

Figures 5 and 6 show perspective views of, respectively one, and then both of the sub -parts of the safety device according to some embodiments of the present invention arranged around compression fitting of Figure 1 after having been assembled to connect two pipes together, with Figure 5A showing an enlarged view of the dotted area in Figure 5,

Figures 7A, B, and 7C, D respectively show a plan view of the interior, and an end elevation from the plane indicated in Figures 7A, 7D of each of the two sub -parts of the safety device according to some embodiments of the present invention

Figures 8A, 8B respectively show side elevations of the sub-parts depicted in Figures 7A, B, and in Figures 7C, 7D,

Figures 9A, 9B respectively show plan views of the top of the sub -parts depicted in Figures 7A, B, and in Figures 7C, 7D, and

Figure 10 shows a perspective view of a safety device of unitary construction comprising two integrally formed sub-parts provided with cooperating snap-fit means, according to a modified aspect of the present invention, particularly adapted for entirely manual attachment to a suitable compression fitting or other pipe jointing means.

Detailed Description Referring firstly to Figure 1 , there is shown a conventional compression fitting indicated generally at 2 which comprises an essentially completely and continuously hollow compression fitting body 4 at either end of which is provided an exteriorly threaded hollow shank 6, 8 into which the free ends of first and second pipes 10, 12 respectively can be slid before abutting an interior shoulder (not shown) within the interior of the fitting. The dimensions are both generally standardised (e.g. a "British Standard Pipe" or BSP size, for example anywhere between 8mm and 54mm as previously mentioned), and important because the clearance between the exterior diameter of the pipes 10, 12 and the interior diameters of the hollow shanks 6, 8 must be less than the thickness of essentially annular olives 14, 16 which have interior diameters which are marginally larger than the pipe diameters, and exterior diameters which are marginally larger than the interior diameters of the hollow shanks. Thus the olives can easily slide over the pipes, but a pipe with an olive in place over its free end cannot, at least initially, be received within hollow shank of the compression fitting body. In order that this latter configuration can be achieved, and in sealing manner, compression nuts 18, 20 with annular end flanges 22, 24 (seen inside nut 20) are first slid over the pipes, said compression nuts not only providing the means for connecting the pipes to the compression fitting body and thus together but also providing the means for exerting significant axial compression against the olive within the nut as its interior threads 26 (for nut 20) are brought into engagement with the corresponding threads of a respective hollow shank 8 and tightened thereon. The reason that compressive force on the olive, and thus in turn on the pipe around which the olive is disposed is that the annular end flanges have an internal diameter which, although of course necessarily being greater than the pipe external diameter, is less than at least the diameter of the exteriormost surface of the olive. Thus, as the nut is tightened, the olive is forced and possibly also swaged into and forced within the hollow shank of the fitting, andas it is so swaged, it creates both a seal between the outer surface of the pipe it surrounds and the shank 6, 8, and a mechanical connection between the fitting and the exterior surface of the pipe and thus the pipe itself, as is well known in the art.

As previously mentioned, one of the primary disadvantages of compression fittings of this type is that if the nut is improperly or insufficiently tightened to the body of the compression fitting, the frictional connection between the olive and the interior of the hollow shanks 6, 8, or the predominantly mechanical connection achieved between the interior of the olive and exterior surface, of the pipe is prone to fail, with potentially disastrous consequences, particularly when the compression joint is one of the larger sizes and the fluid static pressures and potential volumetric flow rates within and through the pipes it connects can be significant. Referring briefly to Figures 2A, 2B, there are shown two different types of known grab rings indicated generally at 30, 40. Grab ring 30 is of unitary construction and will usually be formed by simple pressing, stamping or punching operations carried out on sheets of stainless steel or aluminium or other suitable metal or alloy. As can be seen, the ring comprises a continuous exterior annular periphery 32 from which project, inwardly and also slightly vertically upwardly of said periphery, a plurality of tongues 34, each of equal length, width, thickness, inclination and orientation, and which thus together effectively define a notional circular aperture indicated by dotted line 36 about the axial centre of the grab ring, and axially displaced from the plane of the periphery 32 by an amount equal to the axial component of the length "I" of each tongue dimension, i.e. I sin 9, where 0 is the angle of inclination of each tongue from the cross-sectional plane containing the periphery 32. As will be immediately understood by persons skilled in the art, a pipe having a marginally larger diameter than notional aperture may quite easily be slid through the grab ring in the same general direction as the inclination of the tongues as they can easily deflect outwardly to accommodate the pipe, but sliding a pipe already having been partially slid through the grab ring in the reverse direction would be significantly more difficult, particularly if the grab ring were surrounded by and disposed within a suitable cylindrical retaining device which provided a reaction surface for the gab ring periphery, because the tongues of the grab ring would tend more to bite into the surface of the pipe than they would tend to deflect, at least not without applying excessive force to the extent that the tongues buckled and were effectively crushedor otherwise destructively compromised.

In Figure 2B, an alternate type of grab ring 40 is shown having a similar general construction a nd principle of operation to that of grab ring 30, but for grab ring 40, the tongues are slightly more resilient, and the manufacturing method is slightly different. Specifically, ring 40 is formed from an initially tubular cylindrical metal workpiece at one end of which a rotary cutter removes intermittent portions of material from between the tongue portions 42 which thus remain. Once formed, and optionally further worked by being cylindrically pressed into desired shaped and with stiffening ribs if desired, the tongue portions are all forcibly bent back on themselves through an angle of ( 180°- 9), where 9 is the required angle of inclination of the tongue with the cylindrical axis of the ring. It has been suggested that this latter type of grab ring can significantly more robustly resist pipe extractions from within the grab ring after partial insertion therethrou gh.

Referring now to Figures 3 and 4 (and Figures 7A, B, C, D, 8A, 8B, 9A, 9B where required) there are shown first and second sub-parts generally indicated at 50 and 70 respectively, according to one embodiment of the present invention. In this particular embodiment, sub-parts 50, 70 are broadly identical in shape and configuration and form two halves of the safety device as a whole and which, in use, is adapted to be disposed completely over and around at least one end of the compression fitting of Figure 1 as will become apparent from the following description. Both sub -parts 50, 70 are essentially hemi-cylindrical in cross-section so that when brought together in overlying relationship to complete the safety device, which is thus, in this embodiment at least, essentially cylindrical. As can be seen in both figures, each sub-part can be notionally divided into two axially distinct regions, a first region 50A, 70A and a second region 50B, 70B. Within first region 50A, 70A, there is provided firstly a relatively deep hemi-cylindrical cavity 50A-1 , 70A-1 defined axially at either end firstly by inwardly projecting flange means in the form of a semi -annular collar 50A-2, 70A-2, and secondly, at the alternate axial end of the hemi -cylindrical cavity, an inwardly projecting shoulder 50A-3, 70A-3. Both of these surfaces, disposed substantially perpendicularly to the cylindrical axis of each sub-part, are important in the context of the present invention, particularly the collars 50A-2, 70A-2, as will become apparent. In particular embodiment illustrated, although cavities 50A-1, 70A-1 are essentially hemi-cylindrical, the first region 70A of sub-part 70 is provided with a pair of axial aligned locating ribs 70A-4, 70A-5, which stand proud above the diametral plane of the generally hemi-cylindrical sub-part 70, whereas sub-part 50 is provided with a pair correspondingly sized and shaped rebates on either side of the hemi -cylindrical cavity, one of which 50A-4 can clearly be seen in Figure 3. In use, the ribs are received in the rebates and advantageously provide the safety device as a whole, particularly in the first regions of the respective sub -parts with improved mechanical resistance to hoop stress and any other forces which may tend to circumferentially expand the safety device in use.

Furthermore, the cooperating, interlocking nature of the ribs and rebates facilitates easy and assured location of one sub-part on and over the other, and ensures the correct juxtaposition, both axially and laterally, of both sub-parts, and when said features are properly engaged, ensures that the remainder of the sub-parts can be brought together such that their planar axial surfaces can assume their desired mating relationship with one another. The skilled reader should appreciate that any combination of ribs and rebates which cooperate in this manner is within the contemplation of the present invention. For example, only a single rib and rebate combination may be required, or one rib and one corresponding rebate may be provided on each sub-part, and such locating and interlocking features may equally be provided in the second region of each sub part as opposed to the first.

Turning now to the second hemi-cylindrical region 50B, 70B of each sub-part 50, 70, sub-part 50 is provided with two pairs of screw receiving recesses, 50B-1, 50B-2, whereas sub-part 70 is provided with two pairs of corresponding apertures 70B-1 , 70B-2, to which access from the underside (as illustrated in Figure 4) is facilitate by means of rebates, one pair of which are referenced at 70B -1A, 70B-2A, provided in the exterior cylindrical surface of that sub -part. Similar rebates are of course provided for apertures 70B-1 , 70B-2. As can be seen in each of Figures 3, 4, the second regions 50B, 70B, of the sub-parts 50, 70 are also essentially hemi-cylindrical in cross-section, and internally include hemi-cylindrical inner surfaces 50B-3, 70B-3 which are essentially identical and shape and size, and discontinuous in that they are both interrupted at the same positions along their axial length by hemi-cylindrical slots 50B-4, 70B-4 adapted to receive frictional engaging means as will be later described. Each slot is defined by axially spaced apart end walls 50B -5, 50B-6, 70B-5, 70B- 6 respectively, and as can be seen from the figures, end walls 50B-6, 70B-6 are radially shorter in length than oppositely disposed end walls 50B-5, 70B-5, and arejoined to the inner hemi-cylindrical surfaces 50B-3, 70B-3 along inwardly chamfered surfaces 50B-7, 70B-7, the reasons for which will become apparent. The direction of the chamfer is also important, and considered to be "inward" because it is directed away from the axially most proximate free end of each sub -part and towards the more axially remote free end, that the chamfered surface is disposed within the second regions of each sub-part but directed towards the first regions thereof.

Figures 3 and 4 thus illustrate all the relevant features of the two sub -part halves of the safety device of the present invention, with the exception of the frictional engagement means which are adapted to be received in at least one, and most preferably both slots. As the skilled reader will immediately understand, the frictional engagement means may be provided in a wide variety of different forms. In the particular embodiment of the present invention illustrated and presently described, the frictional engagement means are ideally provided by semi -, or more preferably slightly less (e.g. subtending an angle between the notional radii at their ends of about 160-175 degrees) than semi-annular grab-ring halves. Naturally, a truly semi-annular grab-ring half would subtend an angle of 180 degrees between its notional end radii. Thus, in the most preferred arrangement, the frictional engagement means adapted to be received by and fully inserted and seated within slots 50B-4, 70B-4 could be provided by either style of grab ring illustrated in Figures 2A, 2B and having a diameter equal to the twice the radial depth of the said slots, and very simply cut in half, or having segments cut therefrom having a radial angle of between 160-175 degrees such that that segment would substantially occupy the majority of the hemi -cylindrical slot into which it was subsequently inserted.

The skilled reader will now understand how the chamfered surfaces 50B-7, 70B-7 may provide their possible functions. Firstly, such surfaces allow for the grab-ring portion to be inserted only, or at least most easily, in the correct orientation, where the tongues are disposed above or, in some embodiments on, the inclined surfaces and in broadly parallel relationship thereto. In the case where there is some small clearance between the tongues and respective adjacent inclined surface, it will be appreciated by the skilled person that allows for some movement of the tongue, for example as the tongue bends about its root, towards the inclined surface, which thus effectively acts to limit such movement, if or when the tongue comes into contact therewith, for example during use. Thus, in one embodiment, the inclined surfaces permit for easy insertion of the grab ring portions with sufficient clearance for the tongues thereof.

In other embodiments, some length of the inclined tongues of the grab ring may rest upon and thus be supported by said inclined surfaces upon insertion . Again, of course, each grab-ring portion must be inserted into a respective slot of either or both sub -part in the correction orientation. As will also be understood by the skilled person, in order for the grab ring portions to be effective, in particular for the ends 50B-9 of the tongues thereof to have perform their frictional ly and/or mechanically resisting effect on the exterior surface of the pipe 10 they ultimately engage with, the length and inclination of the tongues of the grab rings must be selected such that some portion of the tongues project beyond the slot in which the grab ring portions are provided, and into the hemi-cylindrical channel defined by the surfaces 50B-3, 70B-3 of the first regions of each sub-part.

The skilled reader should of course understand that although grab rings such as described provide a ready, simple and inexpensive frictional engagement means, such may be provided in a variety of different ways. For example, an elastically compressible composition or material may be considered, such as a rubber or rubberised polymer composition, possibly having its frictional and/or abrasive quality enhanced by some additive, such as sand or other quartz or silicate-based granules. Again, substantially semi-annular inserts of such a material of appropriate size could be inserted within and fully seated within the slots, and provided that some portion of the insert stood proud of the slot edges, the inserts would engage with and successfully restrain the pipe with which they came into contact when the sub-parts of the fitting were brought together in position to complete the safety fitting. In such embodiments, there would of course be no need to provide slots with chamfered surfaces 50B-7, 70B-7 as previously described. A further possibility is that, instead of providing slots 50B-4, 70B-4, the frictional engaging means could be integrally formed with the sub-parts, and be constituted of a small raised semi-annular rib in place of the or each slot. The raised rib would of course only be required to project inwardly of the hemi -cylindrical channel of the second region of the or each sub part by a very small amount, e.g. 0.2-3mm, and would naturally be elastically compressible on account of being formed of the plastics material of which the remainder of the sub-part would also be formed. Furthermore, such a raised semi -annular rib may additionally be integrally formed, for example by moulding, with its innermost cylindrical contact surface, i.e. that surface adapted to come into contact with the pipe exterior surface, frictionally enhanced, for example with a frictionally enhancing surface pattern or by some form of stippling.

Notwithstanding the above possibilities as regard the frictional engagement means, it is nevertheless fundamental to the present invention that such frictional engagement means are provided, and in the most preferred embodiment, they are provided by one and most preferably two substantially semi-annular grab ring portions inserted into and fully seated within the slots. 50B-4, 70B-4 as previously described, and whose functionality can more readily be understood with reference to Figure 5.

In this Figure, sub-part 50 is shown in position over and around one end of the compression joint of Figure 1 in assembled condition, prior to the alternate sub-part 70 being brought into overlying relationship thereon and clamped thereto, such latter actions effectively completing the safety device of the present invention. Thus, from the figure it can be seen that the cavity 50A-1 of the sub-part is of a sufficient length and radial depth to be able to receive and accommodate substantially the entire lower half of the compression nut 18 and its annular flange, and critically, this is achieved with the collar 50A-2 being disposed behind at least laterally projecting rear surface of the nut 18. Although in this particular embodiment said collar is disposed behind some rear laterally projecting surface of the nut 18, it is to be mentioned that the sub -part may be designed such that the collar 50A-2, or some functionally equivalent aspect of the sub-part, is disposed behind some other similarly laterally projecting surface of the compression fitting. For example, the collar could be designed such that some portion of it engaged with and behind one or more of the laterally projecting surfaces of one or more of the threads 6, or even behind the nut 20, provided of course it was not desired to attach any similar safety fitting to this end of the compression joint.

In general, the skilled reader should understand that the present invention only really requires that one or both sub-parts of the safety device have some means which can be disposed behind some laterally projecting surface of the compression fitting which thereby effectively anchors the safety device as a whole to the compression fitting, once completely assembled with both sub-parts in overlying relationship and connected to one another, and effectively prevents it from sliding away from and off the relevant end of the compression fitting over which it is provided and within which a pipe 10 is inserted and connected. Also, the skilled reader should understand that the term "laterally projecting" in this context should be understood to means that whatever surface is being described in this manner extends at least to some extent in the plane which is substantially orthogonal to a relevant longitudinal axis of both the compression fitting and the relevant pipe inserted therein and connected thereto, and outwardly away from those components.

Returning again to Figure 5, and also to Figure 5A, what may also be seen is that the second region 50B of the sub-part 50, in particular the hemi-cylindrical channel thereof, forms a very snug fit around pipe 10, and furthermore that the slot 50B-4 is now illustrated with a substantially semiannular grab ring portion 50B-8 inserted and fully seated therein. As mentioned previously, depending on the particular embodiment of the invention, the majority of the length of the tongues of said grab-ring portion may either be disposed generally parallel to but separated from the chamfered surface 50B-7 (Figure 5A in particular), or they may both rest on and be supported by the chamfered surface 50B-7 of the slot. In either arrangement, the tips of said tongues project beyond the end of that surface and, as illustrated, directly engage with the exterior surface of the pipe 10. Thus, not only is the sub-part, and in turn the safety device as a whole when fully assembled, securely anchored to the compression fitting, but also the pipe is relatively securely anchored within the safety fitting as a result of the frictional and/or mechanical biting engagement of the tongue ends with the exterior surface of the pipe. Therefore, should the pipe experience any fluid shock or other force tending to separate it from the compression joint, such motion is substantially prevented if not rendered largely impossible because of the combined action of both the barb-like engagement of the tongue ends with the pipe exterior surface, and the firm anchoring of the sub-part halves of the safety device to the compression fitting itself.

To complete the assembly of the safety fitting, and as can be seen in Figure 6, the corresponding sub-part 70 is simply disposed, in identical orientation to that of sub-part 50, over and around the end of the compression fitting 4, and the two sub-part halves may then be simply screwed together by means of screws, one of each of the two pairs used being referenced at 80, so that the two sub - parts of the safety device are effectively clamped together over and around the relevant end of the compression fitting and the pipe 10 connected therein and thereto.

Naturally, the majority of compressing fittings are made in brass, and the majority of pipework is of copper, so if the sub-parts of the safety device are manufactured in a white plastics material, it will be advantageously immediately evident to anyone inspecting a compression fitting to see that one or more safety devices has been fitted thereto. The sub-parts could of course be made in any desired colour of plastics or other material. For example, the sub-parts could be colour coded according to fluid or the temperature thereof being carried in the pipes they secure. For instance, a red safety fitting could being indicative of pipework carrying hot fluids, blue indicative of cold fluids, and yellow indicative of gas.

Referring finally to Figure 10, there is shown a safety fitting 90 according to a modified aspect of the invention. As can be seen in the Figure, safety fitting 90 comprises two sub -part halves 92, 94 of broadly identical interior and exterior shape, design and configuration to corresponding aspects of sub-parts 50, 70 described above, except that in this embodiment, both sub-parts 92, 94 are integrally formed with one another and effectively form a one-piece safety device of unitary construction, as each sub-part is joined to the other along a thin narrow flexible resilient web of (ideally) plastics material, 96 (shown hatched in the figure for clarity), and against the resilience of which, one sub part can be folded so as to automatically brought into the correct axial and lateral overlying relationship with the other sub-part. As can also be seen in the Figure, sub part 92 is provided with a snap-fit tongue and hook formation 98, whereas opposing sub-part 94 is provided with a corresponding rebate and underlying ledge (not shown) formation at an axial position along that edge of sub-part 94 corresponding to the position of formation 98 provided along the opposite axially parallel edge of sub -part 92. Other types of similar snap -fit formations are of course possible, and the skilled person will immediately recognise that any such type of mutually cooperating, manually connectable and in preferred embodiments, also manually releasable formations allow for the safety device as a whole to be very quickly, simply and manually connected to a compression or other pipe fitting without the need for a screwdriver or other tool. Most simply, the safety device of Figure 10 can easily be slid behind any compression fitting when in the "lay -flat" condition illustrated in which each sub-part half is disposed laterally adjacent one another, and then when one or other of the sub-parts is appropriately positioned underneath a relevant end of the compression fitting (See for example Figure 5), the other sub-part half can simply be rotated about the flexible resilient web 96 and into position over the first sub-part, and then connected manually thereto by pressing the two sub-parts together such that the formation 98 successfully and in snapfitting manner engages completely and underneath corresponding formation 100.

It should also be mentioned that although the specific description above has focussed on the provision of a safety device for one end of a standard, essentially straight compression fitting as illustrated in Figure 1 , the same safety device could equally be used on both ends of such a fitting. Alternatively, in a further modified aspect of the invention, the safety device could be enlarged to cover both ends of the fitting. In such an embodiment, the safety device would again comprise two sub-parts, but each sub-part would then possess one or more first regions which would include one or more cavities to receive and accommodate the compression fitting and its various parts, and a pair of secondary regions, disposed towards the ends of each sub-part and which would be configured almost identically to the second region of the sub-parts of the primary embodiment described above. Within the first regions of the sub-parts of such an enlarged safety fitting, inwardly projecting flange means would of course be still be required to be provided so that the safety device as a whole would still be firmly anchored to, over and around the compression fitting, or more accurately certain aspects of it which projected laterally outwardly therefrom and thus provided a surface behind which the flange means could be disposed and which could thus act as a reaction surface therefor. As the skilled reader will appreciate, many other different shapes and configurations of sub-parts may be possible, particularly for compression or other pipe-receiving fittings which are occasionally and unpredictably prone to fail. For example, given the essential elements of the invention, the skilled person could easily design suitable cooperating sub-parts of a safety device to accommodate almost any type of pipe fitting, for example the common T-shaped or elbow joints.

In summary therefore: A safety fitting for commercial, industrial and large scale domestic compression joints is disclosed. The safety fitting comprises first and second parts which are adapted to be brought together around, firstly, one end of any type and shape of compression joint, and secondly around the exterior surface of one pipe retained by within said compression joint. The respective parts of the safety fitting are substantially identical in that both are p rovided internally with hemi-cylindrical cavities of differing diameters so that when the two parts are brought together two adjacent cylindrical cavities of different diameters are defined within the safety device. The first, larger cylindrical cavity is sized according to the compression joint and the retaining nut thereon which retains the pipe in place, whereas the second cylindrical cavity is sized according to the pipe diameter. Within each half-part of the safety fitting, in the region thereof which is diametrically sized to the pipe, there is provided a shallow transverse, relative to the cylindrical axis of the safety fitting, slot which receives therein a semi -annular metallic grab ring portion, orientated such that the plurality of tongues provided thereon and which protrude therefrom are inclined and directed towards the more remote free end of the respective part of the safety fitting in which it is provided, such that, in use, the free ends of the grab ring tongues not only firmly, resiliently engage with the exterior surface of the pipe, but also are directed towards the body of the compression joint such that they act as restraining barbs on the pipe in the event that said pipe tries to work loose, and thus away from the compression joint. In the event that the pipe does attempt to work loose from the compression joint, the restraining barb action of the tongues of the grab ring portions on the pipe are counteracted by the fact that the safety fitting as a whole is snugly clamped around the pipe retaining nut on the compression fitting. The resulting arrangement is that the safety device provides an incredibly robust mechanical contingency connection between the pipe and compression joint.