Improvements in or relating to css tubing and fluid-flow fitting assembly

Abstract

A CSS (corrugated stainless steel) tubing and fluid-flow fitting assembly 1 comprises CSS tubing 10 having uniform or substantially uniform corrugation peaks 14 defining an internal peak diameter IPD, uniform or substantially uniform corrugation troughs 16 defining an internal trough diameter ITD which is less than the said internal peak diameter IPD, and a fitting-receiver end 54 including a fitting-receiver opening having an internal receiver diameter IRD which is greater than at least the internal trough diameter ITD. There is also a fluid-flow fitting 18 including a fluid-flow nipple element 22 which is located in the CSS tubing 10 and having an outer diameter which is less than the internal trough diameter ITD. A gasket sleeve 48 is interposed between the fluid-flow nipple element 22 and the CSS tubing 10 and a crimp sleeve 44 is at an exterior surface of the CSS tubing 10 by which an interior surface of the CSS tubing 10 is fluid-tightly engaged with an exterior surface of the fluid-flow nipple element 22 with the gasket sleeve 48 therebetween. Aspects include a method of minimising fluid-flow fitting size whilst preventing or limiting damage to a gasket sleeve when crimp engaging CSS tubing.

Description

The present invention relates to a corrugated stainless steel tubing and fluid-flow fitting assembly. The invention also relates to a fitting apparatus and / or to a tubing former which is / are specifically adapted for a CSS tubing and fitting assembly, and to a method of minimising fluid-flow fitting size whilst preventing or limiting damage to a gasket sleeve when crimp engaging corrugated stainless steel tubing and a fluid-flow fitting having an internally receivable fluid-flow nipple element. The use of corrugated stainless steel tubing, hereinafter referred to as CSS tubing or just CSST, has become significantly more widespread worldwide for use in various plumbing situations. There is a range of known methods for connecting plumbing fittings with CSST which include the use of plastic gaskets and / or O-rings. These attempt to seal the CSST with the fitting either around the opening of the tubing or further along the tube. A threaded nut may be used to engage the threaded part of the fitting body. This can increase the interaction between the fitting and the CSST by use of an anvil, collet or retainer ring which is deformed between the nut and CSST. During this tightening process, a problem can occur when one or more CSST corrugations may be undesirably deformed, resulting in an imperfect seal and thus a potential fluid leak path. Furthermore, the above-mentioned tightening may be difficult to perform when the installer requires a tool such as a wrench to advance the nut. In this situation, a reasonable level of work and effort is required on the part of the installer, as they must align the wrench and supply sufficient torque to the entire assembly in order for the CSST to be correctly deformed and a fluid tight seal to be achieved. This work takes time, and can also become frustrating in small, enclosed or awkward-to-reach spaces, such as in a cupboard or against a wall behind a kitchen unit, for example. It can be difficult to tighten the fitting assembly using wrenches, due to the limited angle in which to maneuver the wrench, or limited space which prohibits the use of a wrench that would deliver the desired amount of torque to achieve the desired seal. Connectors on the fittings may also have an externally threaded fitting body, which contains an internal bore to receive the CSST therein. An anvil and / or collet designed to engage with the circumferential valleys of the tubing may be provided in these devices. With the CSST received within the fitting body, if the seal is not tight enough, there may be risk of a, potentially hazardous, fluid leak. It is known to crimp engage a fitting body to an outer surface of tubing, such as CSST. However, with the tubing received within the fitting body, the crimp sleeve and thus the fitting body become overly large. Again, this causes particular issues for installation in confined or tight spaces, due not only to the over-sized fitting, but also the much larger crimp tool required to form the crimp engagement. A further problem occurs when attempting to engage the tubing, such as CSST or indeed any fluid-flow tubing, when cutting the tubing to a required length. This often leaves ragged edges, burs and the like. Such a poorly finished edge can easily snag, tear or otherwise damage a seal, such as an O-ring or sleeve, during sliding of the fitting and the tubing into engagement with each other. Any damage, again, may cause an imperfect seal and thus a potentially dangerous leak path. The present invention seeks to provide a solution to these problems. According to a first aspect of the present invention there is provided a CSS (corrugated stainless steel) tubing and fluid-flow fitting assembly comprising: a length of CSS tubing having a plurality of uniform or substantially uniform corrugation peaks defining an internal peak diameter, a plurality of uniform or substantially uniform corrugation troughs defining an internal trough diameter which is less than the said internal peak diameter, and a fitting-receiver end including a fitting-receiver opening having an internal receiver diameter which is greater than at least the internal trough diameter; a fluid-flow fitting including a fluid-flow nipple element located in the CSS tubing and having an outer diameter which is less than the internal trough diameter; a gasket sleeve which is interposed between the fluid-flow nipple element and the CSS tubing at or adjacent to the fitting-receiver end; and a crimp sleeve at an exterior surface of the CSS tubing by which an interior surface of the CSS tubing is fluid-tightly engaged with an exterior surface of the fluid-flow nipple element with the gasket sleeve therebetween. The fact that the fitting-receiver opening has the internal receiver diameter which is greater than at least the internal trough diameter is advantageous because this promotes the ease of insertion of the fluid-flow nipple element into the CSS tubing as the fluid-flow nipple element has the outer diameter which is less than the internal trough diameter of the CSS tubing. The dimension of the internal receiver diameter of the CSS tubing also prevents the fitting-receiver opening from snagging and / or tearing the gasket sleeve. The gasket sleeve being located between the fluid-flow nipple element and the CSS tubing is beneficial because the gasket sleeve provides a seal between the said fluidflow nipple element and the CSS tubing. Furthermore, the crimp sleeve is able to be fluid-tightly engaged with the fluid-flow nipple and the gasket interposed therebetween provides the means for an improved seal. Preferably, the CSS tubing and fluid-flow fitting assembly further comprises a crimpsleeve stop at or adjacent to a fitting body of the fluid-flow fitting. This is beneficial because the crimp-sleeve stop provides the crimp sleeve with an abutment portion so that when the crimp sleeve is crimped the crimp sleeve is held in a desirable position along the fluid-flow nipple element. Advantageously, the crimp-sleeve stop may overhang a proximal end of the crimp sleeve. This secures the crimp sleeve over the fluid-flow nipple element. Preferably, the fitting-receiver end abuts or substantially abuts the crimp-sleeve stop. This advantageously ensures that the CSS tubing is in the optimal position to be crimped and thus a desirable seal can be achieved. Optionally, the fluid-flow nipple element includes a nipple head at or adjacent to a free distal end thereof, the head forming a shoulder to prevent or inhibit unintentional axial displacement of the gasket sleeve. This is beneficial as the gasket sleeve remains in place if the CSS tubing is pulled away from the fluid-flow fitting assembly and thus improves the overall seal achieved. Preferably, the CSS tubing and fluid-flow fitting assembly further comprises a gasketsleeve recess along at least a majority of a longitudinal extent of the fluid-flow nipple element, the gasket sleeve being seated in the gasket-sleeve recess. This is advantageous as the gasket sleeve has a dedicated position to be seated therein and thus the gasket sleeve remains in place when the CSS tubing is slid over the gasket sleeve or if the CSS tubing is pulled away from the fluid-flow fitting assembly and thus this improves the overall seal achieved. Advantageously, the gasket sleeve is or is substantially annular. This allows the gasket sleeve to surround and / or to be placed over the fluid-flow nipple element and thus provide the fluid-flow fitting assembly with a suitable seal. Preferably, the gasket sleeve is polymeric. Beneficially, the use of a polymeric gasket sleeve means that the gasket sleeve can be easily deformed. Optionally, the CSS tubing and fluid-flow fitting assembly further comprises a second gasket sleeve of a different material to the first said gasket sleeve. Beneficially, the said second gasket sleeve may be copper. Having two gasket sleeves of different materials allows the CSS tubing and fluid-flow fitting assembly to benefit from both properties of each of the gasket sleeves and thus improve the overall seal produced. A CSS tubing and fluid-flow fitting assembly may comprise CSS tubing which includes a first inner sheathing and a second outer sheathing. There are two options in this case: the first inner sheathing may be a flexible plastics tube or layer, and the second outer sheathing may be a braided metal tube or layer; or the first inner sheathing may be a braided metal tube or layer, and the second outer sheathing may be a flexible plastics tube or layer. In these examples, the benefit of using the braided metal tube or layer enables the assembly to have or include the option of an electrical conductor Additionally or alternatively, the fluid-flow fitting and / or the crimp sleeve is / are at least in part electrically conductive. This is particularly useful in conjunction with the braided metal tube or layer, but may be an option when only the CSS tubing is provided and / or when the CSS tubing includes only a single plastics sheath. Preferably, the CSS tubing and fluid-flow fitting assembly is in the form of a kit of parts. This is advantageous because the CSS tubing and fluid-flow fitting assembly is modular and easily assembleable. Parts of the assembly may thus be supplied separately of each other or bundled in combination. According to a second aspect of the present invention there is provided a fluid-flow fitting apparatus specifically adapted for a CSS tubing and fluid-flow fitting assembly in accordance with the first aspect of the invention, the fluid-flow fitting apparatus comprising a fitting body, a fluid-flow nipple element which extends from the fitting body, and a gasket sleeve on the fluid-flow nipple element. Beneficially, the CSS tubing is able to receive the fluid-flow nipple element to provide a fluid-flow fitting apparatus which is capable of being assembled easily as well as providing a suitable seal between the said CSS tubing and the fitting body. According to a third aspect of the present invention there is provided a tubing former apparatus specifically adapted for a CSS tubing and fluid-flow fitting assembly in accordance with the first aspect of the invention, the tubing former apparatus comprising a former head having a first former condition with a first dimension receivable within an internal trough diameter of CSS tubing, and a second former condition with a second dimension which is larger than the first dimension so as to form an internal receiver diameter at a fitting-receiver end of CSS tubing. Advantageously, the tubing former apparatus is able to expand to the second dimension which, when inserted into the fitting-receiver end of the CSS tubing, forms the internal receiver diameter required to fit the CSS tube over the fluid-flow nipple element of the fluid-flow fitting apparatus. Optionally, the tubing former apparatus further comprises a former mechanism which mechanically expands at least a portion of the former head to move between the first former condition and the second former condition. This is beneficial because the former head is able to move between the first former condition to allow the former head to be inserted into the fitting-receiver end of the CSS tubing, and a second former condition to form the internal receiver diameter. Preferably, the former head of the tuber former apparatus includes a plurality of former steps to accommodate tubing with different bore diameters. This is advantageous because the steps can accommodate different CSS tubes with different diameters and thus the tubing former apparatus can be used with multiple different CSS tubes. Beneficially, a surface of each said former step of the tubing former apparatus defines an or substantially an annulus. This stepped ring formation provides the user with an apparatus with multiple diameter options for the formation of the internal receiver diameter. Optionally, the tubing former apparatus further comprises a restrictor element locatable at or adjacent to the fitting-receiver end of the CSS tubing, the restrictor element restricting expansion of the former head to or substantially to the internal receiver diameter. The restrictor element therefore advantageously preferably restricts the extent of expansion of the fitting-receiver end. Preferably, a bore of the restrictor element is or includes a frusto-conical portion. This is beneficial as the frusto-conical portion promotes ease of removal of the restrictor element from the CSS tube. Advantageously, a bore of the restrictor element is or includes a cylindrical portion. This is beneficial because the restrictor element is able to fit around the fitting-receiver end of the CSS tube, which is also cylindrical. The cylindrical portion preferably prevents the restrictor element from sliding along the length of the CSS tubing and thus keeps the restrictor element in place. According to a fourth aspect of the present invention there is provided a method of minimising fluid-flow fitting size whilst preventing or limiting damage to a gasket sleeve when crimp engaging CSS tubing and a fluid-flow fitting having an internally-receivable fluid-flow nipple element, the method comprising the steps of: a] at a fitting-receiver end of CSS tubing, forming an internal receiver diameter which is greater than an internal trough diameter of the CSS tubing; b] at a fluid-flow fitting with a fluid-flow nipple element, locating a gasket sleeve on the fluid-flow nipple element and a crimp sleeve over the gasket sleeve; c] at a fitting-receiver opening of the fitting-receiver end, inserting the fluid-flow nipple element together with the gasket sleeve into a bore of the CSS tubing, so that a wall of the CSS tubing is interposed between the gasket sleeve and the crimp sleeve; and d] crimping the crimp sleeve to fluid-tightly engage an interior surface of the CSS tubing with an exterior surface of the fluid-flow nipple element via the gasket sleeve. Beneficially, this method prevents or limits the damage to a gasket sleeve as the CSS tube is placed over the fluid-flow nipple element and thus maintains the sealing ability of the gasket sleeve. Optionally, wherein in step a] of the method, utilising tubing former apparatus to form the internal receiver diameter, the tubing former apparatus may include a former mechanism which mechanically expands at least a portion of a former head to move between a first former condition having a first dimension receivable within the internal trough diameter of the CSS tubing, and a second former condition having a second dimension which is larger than the first dimension so as to form the internal receiver diameter at the fitting-receiver end of the CSS tubing. This is beneficial because the former head is able to move between the first former condition to allow the former head to be inserted into the fitting-receiver end, and a second former condition to form the internal receiver diameter. Preferably, wherein in step a] of the method, utilising a restrictor element at or adjacent to the fitting-receiver end of the CSS tubing when forming the internal receiver diameter, the restrictor element preferably restricts expansion of the fitting-receiver end. The restrictor element therefore advantageously preferably restricts the extent of expansion of the fitting-receiver end. Beneficially, wherein in step b] of the method, first said gasket sleeve is preferably polymeric, and a second gasket sleeve of a different material axially preferably abuts the said first gasket sleeve. Having two gasket sleeves of different materials allows the CSS tubing and fluid-flow fitting assembly to benefit from both properties of each of the gasket sleeves and thus improve the overall seal produced. Advantageously, wherein in step a] of the method, the formed internal receiver diameter preferably presents a smoothly-flaring leading corrugation surface within the bore of the CSS tubing, whereby, in step c], the gasket sleeve mounted on the fluidflow nipple element preferably smoothly slides into the bore of the CSS tubing, thereby preventing or limiting rucking or snagging of the gasket sleeve. It is beneficial to prevent the rucking or snagging of the gasket sleeved because this maintains and provides a suitable seal and also improves the ease of insertion of the CSS tube around the fluidflow nipple. Preferably, wherein in step b] of the method, at least a majority of an uncrimped internal bore diameter of the crimp sleeve matches or substantially matches an outer peak diameter of the corrugations of the CSS tubing, and in step d], utilising a crimping tool having a jaw diameter which crimps the crimp sleeve such that a crimped internal bore diameter is less than the said outer peak diameter. The uncrimped internal bore diameter of the crimp sleeve having the uncrimped internal bore which matches or substantially matches the outer peak diameter of the CSS tubing is advantageous because the crimp sleeve is able to be easily slide over the CSS tube and thus position the crimp sleeve correctly. The crimped internal bore diameter being less than the outer peak diameter after the crimp sleeve is crimped is beneficial because the crimped crimp sleeve is thus able to provide a suitable seal between the CSS tubing and fluidflow fitting assembly. The fitting-receiver opening having the internal receiver diameter which is greater than at least the internal bore diameter is advantageous in order to promote ease of insertion of the fluid-flow nipple element into the fluid-flow tubing. The dimension of the internal receiver diameter also prevents the fitting-receiver opening from snagging and / or tearing the gasket sleeve. The gasket sleeve being located between the fluid-flow nipple element and the fluidflow tubing is beneficial because the gasket sleeve provides a seal between the said fluid-flow nipple element and the fluid-flow tubing. Furthermore, the crimp sleeve is able to be fluid-tightly engaged with the fluid-flow nipple and the gasket interposed therebetween provides the means for an improved seal. When the CSS tubing includes a braided metal sheathing, in step d] of the aforementioned method, a secure electrical connection may be formed by the crimp sleeve between the braided metal sheathing and at least one of the fluid-flow fitting, the crimp sleeve, and / or a crimp-sleeve stop. This therefore enables the assembly to conveniently form an electrical connection between its two ends for installation situations requiring such connectivity. For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 shows a side cross-sectional view of CSS tubing, forming part of an embodiment of a CSS tubing and fluid-flow fitting assembly according to the first aspect of the invention, a fitting-receiver opening of the CSS tubing being in an unadapted condition; Figure 2a shows a partial cross-sectional view of the CSS tubing and fluid-flow fitting assembly in an unconnected condition, a proximal end of the CSS tubing with a fitting-receiver opening in a flared adapted condition being shown spaced from a distal end of a fluid-flow nipple element of a fluid-flow fitting; Figure 2b is an enlarged view of the proximal end of the fitting-receiver opening of the CSS tubing in the flared adapted condition; Figure 3 is a partial cross-sectional view of the CSS tubing and fluid-flow fitting assembly, the CSS tubing shown being offered up to a gasket sleeve mounted on the fluid-flow fitting; Figure 4 is a partial cross-sectional view of the CSS tubing and fluid-flow fitting assembly of Figure 3, the CSS tubing shown inserted between the gasket sleeve and a crimp sleeve of the fluid-flow fitting, the crimp sleeve being in an uncrimped condition; Figure 5 is an enlarged view of a portion of the CSS tubing and fluid-flow fitting assembly of Figure 4, a distance between an internal bore diameter of the crimp sleeve and an external peak diameter of the CSS tubing being indicated by D1; Figure 6 is a partial cross-sectional view of the CSS tubing and fluid-flow fitting assembly, similar to Figure 4, where the crimp sleeve is in a crimped condition; Figure 7 is an enlarged view, similar to Figure 5, of a portion of the CSS tubing and fluid-flow fitting assembly of Figure 6, a distance between the internal bore diameter of the crimp sleeve and the external peak diameter of the CSS tubing spaced from the crimp sleeve being indicated by D2; Figure 8 is a side cross-sectional view of a first embodiment of tubing former apparatus, in accordance with the third aspect of the invention, shown together with a length of CSS tubing; Figure 9 is an enlarged view of a former head of the tubing former of Figure 8, engaged with a proximal end of the CSS tubing and with the fitting-receiver opening being in the unadapted condition; Figure 10 shows a side cross-sectional view of CSS tubing and a restrictor element, forming part of a second embodiment of a CSS tubing and fluid-flow fitting assembly according to the first aspect of the invention, the CSS tubing in this embodiment including an exterior sheath; Figure 11 shows the restrictor element of Figure 10 mounted to a proximal end of the CSS tubing, a fitting-receiver opening of the CSS tubing being in an unadapted condition and ready to be offered up to the tubing former apparatus shown in Figure 8; Figure 12 shows the CSS tubing with restrictor element thereon engaged with the former head, similarly to Figure 9 and with the former head being in a first unexpanded condition; Figure 13 is a side cross-sectional view of the tubing former apparatus, similar to Figure 12, wherein the former head of the tubing former apparatus is in a second expanded former condition; Figure 14 is another side view of the restrictor element and CSS tubing, removed from the former head and in a separated condition, the fitting-receiver opening of the CSS tubing being in a flared adapted condition; Figure 15a is an enlarged axially cross-sectional side view of the fitting-receiver opening of the CSS tubing shown in Figure 14 and in the flared adapted condition; Figure 15b is an isometric axially cross-sectional view of the CSS tubing and its fitting-receiver opening, similar to Figure 15a; Figure 16 shows an optional method of forming the fitting-receiver opening of the CSS tubing, similar to the second embodiment shown in Figures 10 to 15b, but using pliers instead of the said tubing former apparatus; Figure 17 shows a partial side cross-sectional view of a third embodiment of a CSS tubing and fluid-flow fitting assembly according to the first aspect of the invention, a crimp head being diagrammatically shown along with the assembly being in a crimp-engaged condition, and a distal end of a nipple element of the fluid-flow fitting having an axially-elongate head; Figure 18a shows an isometric axially cross-sectional slightly-modified version of the third embodiment of the CSS tubing and fluid-flow fitting assembly, shown in Figure 17, spaced apart and still in accordance with the first aspect of the invention, the fluid-flow fitting being that shown in Figure 17, but the CSS tubing including an exterior flexible sheath or cover; Figure 18b is a view similar to Figure 18a, showing the slightly-modified CSS tubing and fluid-flow fitting assembly in assembled form; Figure 18c shows the assembly of Figure 18b as an axially cross-sectional side view; Figure 18d shows an isometric view of the slightly-modified CSS tubing and fluid-flow fitting assembly; Figure 19 shows a partial side cross-sectional view of a fourth embodiment of a CSS tubing and fluid-flow fitting assembly according to the first aspect of the invention, a crimp head again being diagrammatically shown along with the assembly being in a crimp-engaged condition, and first and second gasket sleeves; Figure 20a is a portion of corrugated stainless-steel tubing, shown with a wall partially sectioned for clarity and which forms part of a fifth embodiment of a CSS tubing and fluid-flow fitting assembly according to the invention, the CSS tubing in this embodiment including a first inner sheathing being a braided metal tube or layer, and a second outer sheathing being a flexible plastics tube or layer; Figure 20b shows the fifth embodiment of the CSS tubing and fluid-flow fitting assembly with the CSS tubing shown in Figure 20a in spaced-apart relationship with the fluid-flow fitting of the third embodiment of the invention; Figure 20c is a partially-axially sectioned view of the assembly shown in Figure 20b, when assembled; Figure 20d is an enlarged view of a portion of the assembly shown in Figure 20c, showing an electrical connection of the first inner sheathing with the fluid-flow fitting; and Figure 21 is a view similar to that of Figure 20a and which shows a portion of corrugated stainless-steel tubing, with a wall partially sectioned for clarity and which forms part of a sixth embodiment of a CSS tubing and fluid-flow fitting assembly according to the invention, the CSS tubing in this embodiment including a first inner sheathing being a flexible plastics tube or layer, and a second outer sheathing being a braided metal tube or layer. Referring firstly to Figures 1 to 7 of the drawings, to form a corrugated stainless steel tubing and fluid-flow fitting assembly 1, there is shown steps of engaging a length of corrugated stainless steel tubing 10 with fluid-flow fitting apparatus 12. The corrugated stainless steel tubing 10, which as above will be herein referenced as CSS tubing 10, includes a plurality of uniform or substantially uniform corrugation peaks 14, and a plurality of uniform or substantially uniform corrugation troughs 16. As best shown in Figure 1, each said corrugation peak 14 defines an outer or exterior peak diameter EPD, and an internal peak diameter IPD which is less than the exterior peak diameter EPD by a thickness of the material of the CSS tubing 10. Each said corrugation trough 16 similarly defines an outer or exterior trough diameter ETD, and an internal trough diameter ITD which is less than the exterior trough diameter ETD also by a thickness of the material of the CSS tubing 10. The internal trough diameter ITD is also less than the internal peak diameter IPD. As best shown in Figure 2a, a fluid-flow fitting 18 of the apparatus includes a fitting body 20, and a fluid-flow nipple element 22 which in this case is unitarily formed as one-piece with the fitting body 20 to extend therefrom. The fitting body 20 and fluidflow nipple element 22 are preferably formed of metal, such as by casting. However, other materials or combinations thereof may be envisaged, such as plastics. The fitting body 20, in this embodiment, comprises an internally screw-threaded proximal body portion 24 which is configured to complimentarily engage with a peripheral device, for example a fluid inlet of an appliance or further pipework. Although an internal screw-thread is suggested, other attachment means may be envisaged, such as push-fit. Contiguously formed with the proximal body portion 24 is a distal body portion 26 which defines a projecting flange-like nut element 28. The nut element 28 includes a series of circumferentially arranged flats to enable engagement of a spanner or adjustable wrench. The nipple element 22 projects axially from a distal end surface of the distal body portion 26, and has an outer diameter which is less than the internal trough diameter ITD. The nipple element 22 includes a nipple body 30 and a nipple head 32. The nipple body 30 is preferably cylindrical or substantially cylindrical, and defines a gasketsleeve recess 34 along at least a majority of a longitudinal extent of the fluid-flow nipple element 22. A first abutment shoulder 36a is formed at or adjacent to the distal body portion 26, and a second abutment shoulder 36b is provided at or adjacent to the nipple head 32. The nipple head 32 extends radially beyond a surface of the nipple body 30, and defines a frusto-conical ramp or sloped surface 38 in between an outer cylindrical wall 38a and an axially-facing annular or substantially annular leading surface 38b. The frusto-conical ramp surface 38 preferably tapers from the outer cylindrical wall 38a to the leading surface 38b. It will be recognised that the nipple head 32 and / or nipple body 30 may have different configurations, as necessity dictates. For example, the nipple head 32 may be or include a part-spherical or part-domed surface instead of or in addition to the frusto-conical ramp surface 38. Equally, the cylindrical wall 38a and / or leading surface 38b may be dispensed with. Furthermore, the nipple body 30 in this case has a smoothly continuous or substantially smoothly continuous outer body surface. However, one or more engagement ribs, projections and / or recesses may be included to improve the grip between the nipple body 30 and the CSS tubing 10. The fitting body 20 together with the nipple element 22 defines an axial fluid-flow through-bore 40. In this embodiment, the fluid-flow through bore 40 is stepped at or adjacent to the distal body portion 26. To this end, the proximal body portion 24 of the fitting body 20 has a fluid-flow through-bore portion of a first diameter, and the nipple element 22 has a fluid-flow through-bore portion of a second diameter which is less than the said first diameter. The CSS tubing and fluid-flow fitting assembly 1 further includes a crimp-sleeve stop 42 at or adjacent to the fitting body 20 of the fluid-flow fitting 18. Although preferably a plastics annular ring-like element, it may be metal or a composite material. The crimpsleeve stop 42 includes a stepped internal bore, having a minimum bore diameter that complimentarily matches a maximum outer diameter at a base of the nipple element 22. A crimp sleeve 44 can thus be seated at or adjacent to the base of the nipple body 30 so as to abut an axial leading face of the distal body portion 26 of the fitting body 20. As best seen in Figures 5 and 7, the stepped internal bore of the crimp-sleeve stop 42 defines an axially-facing stepped surface which is radially outwardly spaced from the nipple body 30, and an outermost cylindrical sleeve-retaining wall 46 which extends from the axially-facing stepped surface. The assembly additionally includes both a gasket sleeve 48 and the crimp sleeve 44. The gasket sleeve 48 is elongate, and may beneficially be annular or substantially annular. The gasket sleeve 48, in this embodiment, is polymeric and more preferably elastomeric. A benefit of being elastomeric is that an internal gasket-sleeve bore of the gasket sleeve 48, when not in use, may match or be marginally less than the outside diameter of the gasket-sleeve recess 34 of the nipple body 30. When inserted over the nipple body 30, the gasket sleeve 48 may therefore achieve a tight fit around the nipple body 30. It is also feasible that the gasket sleeve 48 may not be elastomeric, and may instead be polymeric and thus may not have elastic properties. In this embodiment, the nipple head 32 may be disposed of or not present and thus the polymeric gasket sleeve 48 may be placed over the nipple body 30 without having to stretch or permanently deform the polymeric gasket sleeve 48. Preferably, an outer gasket-sleeve diameter, along at least a majority of its longitudinal extent, is greater than a diameter of the outer cylindrical wall 38a of the nipple head 32. As shown in Figure 2a, a leading end of the gasket sleeve 48 may include a chamfered or frusto-conical portion 52 to assist engagement with the tubing. The crimp sleeve 44 is advantageously a standard-sized crushable or compressible engagement sleeve which is commonly available. As can be best understood from Figure 2a, a crimp-sleeve body 50 is preferably cylindrical or substantially cylindrical along at least a majority of its longitudinal extent, being open at both ends and thus hollow. Furthermore, the crimp-sleeve body 50 is preferably shaped akin to a ring. A flared frusto-conical portion 52, in this case, is included at a leading crimp-sleeve edge. In an uncrimped condition, at least a majority of a crimp-sleeve through-bore of the crimp-sleeve body 50 has an internal crimp-sleeve diameter which matches or substantially matches the exterior peak diameter EPD of the corrugation peaks 14 of the CSS tubing 10. To assemble the CSS tubing and fluid-flow fitting assembly 1, a fitting-receiver end 54 of a length of the CSS tubing 10 is first selected and an internal receiver diameter I RD is formed. See Figures 1,2a and 2b. In this embodiment, the internal receiver diameter I RD is produced, for example, by use of pliers to bend a leading tube edge 56 of the CSS tubing 10 outwardly. The leading tube edge 56 of the fitting-receiver end 54 is worked with the pliers around the entire circumference of the CSS tubing 10 until the fitting-receiver end 54 has been suitably widened. As best shown in Figure 2a, the internal receiver diameter I RD of the fitting-receiver end 54 is greater than the internal trough diameter ITD of the CSS tubing 10. Preferably, the internal receiver diameter I RD is less than or equal to the internal peak diameter IPD. This therefore presents a smoothly-flaring leading corrugation surface LCS within the bore of the CSS tubing 10, best seen in Figure 2b. The gasket sleeve 48 is located on the fluid-flow nipple element 22 of the fluid-flow fitting 18. Once slid over the nipple head 32 and seated in the gasket-sleeve recess 34, the gasket sleeve 48 becomes a snug fit therein, and is axially retrained by the first and second abutment shoulders 36a, 36b. With the gasket sleeve 48 in place, the outer gasket-sleeve surface projects radially slightly or marginally beyond the nipple head 32. It is also feasible that the outer gasket-sleeve surface is flush or substantially flush with the outer body surface of the nipple body 30. It is possible that there may not be a gasket-sleeve recess 34 present, however it is preferable to have said gasket-sleeve recess 34. The crimp-sleeve stop 42 is slid onto the nipple element 22 so as to abut the axial leading face of the distal body portion 26 of the fitting body 20. The crimp sleeve 44 is selected based on the associated CSS tubing 10 to be used. The crimp-sleeve through-bore is fractionally or marginally larger than the outer peak diameter EPD of the CSS tubing 10, in the uncrimped condition. The selected crimp sleeve 44 is slid onto the nipple element 22 and engaged with the axially-facing stepped surface of the crimp-sleeve stop 42. The outermost cylindrical sleeve-retaining wall 46 of the crimp-sleeve stop 42 overhangs a proximal end of the crimp sleeve 44 as a tolerance fit, thereby maintaining axial alignment of the crimp sleeve 44 with the fluid-flow fitting 18. In this way, the crimp sleeve 44 overlies the gasket sleeve 48 in spaced-apart relationship. As shown in Figure 3, the flared fitting-receiver end 54 is presented to the nipple element 22 such that the nipple head 32 slides into the fitting-receiver opening of the CSS tubing 10. The smoothly-flaring leading corrugation surface LCS within the bore of the CSS tubing 10, in conjunction with the frusto-conical ramp surface 38 of the nipple head 32 and the chamfered leading edge of the gasket sleeve 48 allows the fluid-flow fitting 18 to be smoothly received within the CSS tubing 10, thereby preventing or limiting rucking or snagging of the gasket sleeve 48. The flared frusto-conical portion 52 of the crimp sleeve 44, as can be understood from Figures 3 and 4, guides the fitting-receiver end 54 and the following portion of the CSS tubing 10 along the nipple element 22 and snugly within the crimp-sleeve through-bore of the crimp-sleeve body 50. With the fitting-receiver end 54 of the CSS tubing 10 abutting or being close to the crimp-sleeve stop 42, the assembly is ready for crimp engagement. As can be seen in Figure 5, in the uncrimped condition, the crimp-sleeve through-bore of the crimp-sleeve body 50 is marginally spaced apart by a first distance D1 from the corrugation peaks 14 of the CSS tubing 10. A standard crimp tool with a suitably sized crimping head 258a, 358a and a suitably sized jaw diameter 258b, 358b, an example of which is shown in Figures 15 and 16, is then used to crimp the crimp sleeve 44. The jaw diameter 258b, 358b of the crimping tool crimps the crimp sleeve 44 to form a crimped condition, as shown in Figures 6 and 7, whereby the crimped internal bore diameter of the crimp sleeve 44 is a second distance D2 less than the outer peak diameter of the CSS tubing 10. In this embodiment, the first distance D1 is less than the second distance D2. In this way, an interior surface of the CSS tubing 10 is fluid-tightly engaged with an exterior surface of the nipple element 22 with the gasket sleeve 48 therebetween. More specifically, the crimping of the crimp sleeve 44 results in the crimp-sleeve body 50 being deformed such that the adjacent portion of the CSS tubing 10 is crushed down into gas-tight and / or liquid-tight engagement with the gasket sleeve 48. Referring to Figures 8 and 9, instead of using pliers as described above to form the internal receiver diameter I RD, tubing former apparatus 60 may be utilised. One embodiment of the tubing former apparatus 60 comprises a tubing former device 60a having a former body 62 and a former head 64 mounted on the former body 62. The former body 62 is conveniently in the form of a handle or grip. The former head 64, in this embodiment, includes a plurality of former steps 66 and a former mechanism to mechanically expand at least a portion of the former head 64. Although the former head 64 is shown in the drawings as having former steps 66 on each opposing side thereof, the former steps 66 may only be provided on one side. It is also feasible that instead of the former steps 66, the former head 64 may comprise a sloped and / or tapered portion. A surface of each former step 66 is or is substantially an annulus, and a diameter of each step matches or substantially matches commonly available increasing bore diameters of CSS tubing 10. To therefore form the internal receiver diameter I RD of the fitting-receiver end 54 of the CSS tubing 10 for the assembly described above, the leading tube edge 56 of the CSS tubing 10 is fitted on the corresponding step 66 of the former head 64. In this first former condition, typically, an internal trough surface or a portion adjacent thereto of the CSS tubing 10 is seated on the appropriate former step 66. The former mechanism is then activated, as will be described later with reference to Figure 13, to expand the former head 64 from a first dimension of the first former condition to a second dimension corresponding to a second former condition. The second dimension is larger than the first dimension, and thus forms the previously described internal receiver diameter I RD at the fitting-receiver end 54 of the CSS tubing 10. The assembly of the CSS tubing and fluid-flow fitting assembly 1 can then be completed, as described above. With reference now to Figures 10 to 15b, a second embodiment of tubing former apparatus 160 is envisaged. Parts which are the same as or similar to those of the previous embodiments use the same reference prefixed by T, and therefore further detailed description will be omitted. In this embodiment and in addition to the former device 60a described above, the tubing former apparatus 160 includes a, preferably metal, restrictor element 168, which as shown in Figures 10 and 11, is locatable at or adjacent to the fitting-receiver end 154 of the CSS tubing 110. The restrictor element 168 prevents or inhibits excessive expansion, flaring and / or splitting of the fittingreceiver end 154 of the CSS tubing 110. The restrictor element 168 has an annular outer surface, and a non-uniform restrictor bore. The restrictor bore includes a frusto-conical portion 170, and a cylindrical portion 172 which is contiguous with the frusto-conical portion 170. The frusto-conical portion 170 preferably promotes ease of placement and removal of the restrictor element 168 onto or from the fitting-receiver end 154 of the CSS tubing 110. The cylindrical portion 172 preferably prevents the restrictor element 168 from sliding along the length of the CSS tubing 110 and thus keeps the restrictor element 168 in place. In Figures 10 to 15b, the CSS tubing 110 is shown by way of example with an outer flexible sheath 174, such as a plastic tube. However, CSS tubing 110 which is unsheathed and as shown in Figures 1 to 9 can be utilised with the restrictor element 168. The restrictor element 168 is selected whereby the cylindrical portion 172 of the non-uniform restrictor bore matches or substantially matches the exterior peak diameter EPD of the CSS tubing 110 to be modified. The selected restrictor element 168 is slid onto the fitting-receiver end 154 of the CSS tubing 110 so that the cylindrical portion 172 aligns or substantially aligns with the leading tube edge 156 of the CSS tubing 110, as shown in Figure 11. As with the first embodiment of the tubing former apparatus 60 described above, the fitting-receiver end 154 of the CSS tubing 110 is then mounted to the correspondingly dimensioned former step 166 of the former head 164, and the former mechanism is activated, as shown in Figure 13, to expand the leading tube edge 156 to form the fitting-receiver opening with the required internal receiver diameter I RD. Once the former head 164 is moved from the first former condition to the second former condition, the expanded CSS tubing 110 is disengaged from the former head 164, and the restrictor element 168 is removed, leaving the smoothly-flaring leading corrugation surface LCS. See Figures 14 to 15b. The assembly of the CSS tubing and fluid-flow fitting assembly 1 can again be completed as described above. Figure 16 shows an optional method of forming the fitting-receiver opening at the fitting-receiver end 154 of the CSS tubing 110. As described above with reference to the first embodiment of the CSS tubing and fluid-flow fitting assembly, pliers P may be utilised instead of the tubing former apparatus, described above. The restrictor element 168 may be utilised, as shown, or as with the first embodiment above, may be dispensed with. In regard to Figure 17, a third embodiment of a CSS tubing and fluid-flow fitting assembly 21 is shown. Parts which are the same as or similar to those of the previous embodiments use the same reference prefixed by ‘2’, and therefore further detailed description will be omitted. In this embodiment, the assembly comprises the CSS tubing 210, a modified fluid-flow fitting 218, a modified gasket sleeve 248, and the crimp sleeve 244. The modified fluid-flow fitting 218 comprises the fitting body 220 and a modified fluidflow nipple element 222. The modified nipple element 222 includes the nipple body 230 and a modified nipple head 232. The modified nipple head 232 extends radially beyond the surface of the nipple body 230, and defines the frusto-conical ramp surface 238 in between an outer cylindrical wall 238a and the axially-facing annular or substantially annular leading surface 238b. In this case, a surface of the outer cylindrical wall 238a has an increased axial extent when compared to the first embodiment. In other words, the modified nipple head 232 extends further from the fitting body 220 and extends further into the CSS tubing 210. As can be seen in Figure 17, this thus allows increased support to the CSS tubing 210 in the vicinity of the crimp sleeve 244. As a consequence, an axial extent of the gasket-sleeve recess 234 and thus also the gasket sleeve 248 may be reduced to accommodate the larger nipple head 232. Figure 17, by way of example only, also shows the crimp head 258a of a crimp tool. It will be understood that the crimp head 258a is of substantially similar size to the exterior peak diameter EPD of the CSS tubing 210. The jaw diameter 258b is also indicated in Figure 15. With reference to Figures 18a to 18d of the drawings, a slightly-modified CSS tubing and fluid-flow fitting assembly 21a is shown. This assembly 21a is similar in all respects to that of the third embodiment of the assembly 21 described above, except that a CSS tubing 210a includes a flexible outer sheath, layer, coating or cover 274a. As above, like references refer to features which are the same or similar to those of the foregoing embodiments, and therefore further detailed description will be omitted. In this modification of the third embodiment, the assembly 21a therefore comprises the sheathed CSS tubing 210a, and the fluid-flow fitting 218 of the third embodiment with gasket sleeve 248 and crimp sleeve 244. With the fitting-receiver opening of the fitting-receiver end 254a of the CSS tubing 210a in the flared adapted condition, the outer sheathing 274a is removed to approximately a length from the fitting-receiver end 254a that matches or substantially matches the longitudinal extent of nipple body 230 of the fitting element 222, as best shown in Figure 18b and 18c. Assembly of the CSS tubing and fluid-flow fitting assembly 21a is then performed, as described above with reference to the third embodiment of the assembly 21. In the assembled form and as shown in Figures 18b and 18c, the outer sheathing or cover 274a of the CSS tubing 210a is preferably at least in part received beneath, within or under the crimp sleeve 244. The outer sheathing 274a may be physically or mechanically crimped by the crimp sleeve 244 at and / or adjacent to the nipple head 232. Preferably, the outer sheathing 274a does not or does not substantially overlie the gasket sleeve 248. Referring to Figure 19, a fourth embodiment of a CSS tubing and fluid-flow fitting assembly 31 is shown. Again, parts which are the same as or similar to those of the previous embodiments use the same references prefixed by ‘3’, and therefore further detailed description will be omitted.. In this embodiment, the assembly 31 comprises the CSS tubing 310, the modified fluid-flow fitting 318 of the third embodiment described above, a further modified gasket sleeve 348, and the crimp sleeve 344. The further modified gasket sleeve 348 includes a first gasket sleeve 348a and a second gasket sleeve 348b of a different material to the first gasket sleeve 348a. In this arrangement, the first gasket sleeve 348a is preferably similar to that described in the first embodiment of the assembly, and as such may be polymeric, and more preferably elastomeric. However, in order to accommodate the second gasket sleeve 348b, an axial extent, and thus overall length, of the first gasket sleeve 348a is less than that of the gasket sleeve 48 of the first embodiment. The second gasket sleeve 348b may be metal, such as copper. In this case, it may be formed as two parts, for example, two semi-cylindrical parts which can be placed into engagement within the gasket-sleeve recess 334. If formed of two parts, brazing or a similar engagement method may be used to permanently secure the two parts together. The first and second gasket sleeves 348a, 348b, when located in the gasket-sleeve recess 334 of the nipple element 322, abut each other in end-to-end fashion to thus be axially aligned. It is possible that the second gasket sleeve 348b may be placed over the first gasket sleeve 348a if the first gasket sleeve 348a has a larger axial extent and thus greater length. The reverse is also possible where the first gasket sleeve 348a may be placed over the second gasket sleeve 348b if the second gasket sleeve 348b has a larger axial extent and thus greater length. It is also feasible that the first and second gasket sleeves 348a, 348b may be separate from one another in the gasketsleeve recess 334 and thus the first and second gasket sleeves 348a, 348b may not abut one another. Similarly to the third embodiment of the assembly 21, Figure 19, again by way of example only, shows a crimp head 358a of a crimp tool. The crimp head 358a is again of substantially similar size to the exterior peak diameter EPD of the CSS tubing 310. The jaw diameter 358b is also indicated in Figure 19. Turning now to Figures 20a to 20d of the drawings, there is shown a fifth embodiment a CSS tubing and fluid-flow fitting assembly. As above, parts which are the same as or similar to those of the previous embodiments use the same references prefixed by ‘4’, and therefore further detailed description will be omitted. A CSS tubing and fluid-flow fitting assembly 41 comprises CSS tubing 410, the modified fluid-flow fitting 218 of the third embodiment described above, the modified gasket sleeve 248, and the crimp sleeve 244. The CSS tubing 410 of this embodiment is best shown in Figure 20a, and as with the first embodiment includes a flexible stainless-steel corrugated pipe or tube body 410a having a plurality of uniform or substantially uniform corrugation peaks 414, and a plurality of uniform or substantially uniform corrugation troughs 416. As with all the preceding embodiments and with reference to Figures 1 and 2a, each said corrugation peak 414 defines an outer or exterior peak diameter EPD, and an internal peak diameter IPD which is less than the exterior peak diameter EPD by a thickness of a corrugation of the CSS tubing 410. Again, as with all the preceding embodiments, each said corrugation trough 416 defines an outer or exterior trough diameter ETD, and an internal trough diameter ITD which is less than the exterior trough diameter ETD by a thickness of the stainless steel tubing material of the CSS tubing 410. The internal trough diameter ITD is also less than the internal peak diameter IPD. In this embodiment, similarly to the modified third embodiment of the assembly 21a, the CSS tubing 410 not only includes the flexible stainless-steel corrugated tube body 410a, but also a first inner sheathing 476. Additionally, however, a second outer sheathing 478 is also included. In this case, the first inner sheathing 476 is a flexible braided metal tube or layer, and the second outer sheathing 478 is a flexible plastics tube or layer. As shown in Figure 20b and with the CSS tubing 410 cut to a required length, a fittingreceiver end 454 of the CSS tubing 410 is adapted to form the smoothly-flaring leading corrugated surface LCS. The nipple element 422 is fed into the bore of the CSS tubing 410, and the smoothly-flaring leading corrugated surface LCS enables the flexible stainless-steel corrugated tube body 410a to slide unhindered over the gasket sleeve 248 until the CSS tubing 410 abuts or substantially abuts the crimp-sleeve stop 242. As best seen in Figures 20c and 20d, in this abutted condition, at least the braided metal tube or layer 476 contacts the crimp-sleeve stop 242 and / or the fitting body 220. With the crimp sleeve 244 crimped, a secure electrical connection is formed by the crimp sleeve 244 between the braided metal tube or layer 476 and one or both of the fluid-flow fitting 218 and / or the crimp-sleeve stop 242. Consequently, the fluid-flow fitting 218 and / or the crimp-sleeve stop 242 are or are in part electrically conductive, such as by being formed of or including an electrically-conductive metal. Figure 21 shows a modification to CSS tubing thereby forming a sixth embodiment of a CSS tubing and fluid-flow fitting assembly. Parts which are the same as or similar to those of the previous embodiments use the same or similar references prefixed by ‘5’, and therefore further detailed description of these features will be omitted. The CSS tubing and fluid-flow fitting assembly 51 comprises CSS tubing 510, and the fluid-flow fitting, the gasket sleeve and the crimp sleeve of any of the embodiments described above. The CSS tubing 510, similarly to the fifth embodiment, not only includes the flexible stainless-steel corrugated tube body 510a, but also a first inner sheathing 576 and a second outer sheathing 578. In this case, the first inner sheathing 576 is a flexible plastics tube or layer, and the second outer sheathing 578 is a flexible braided metal tube or layer. In all other respects, the sixth embodiment is the same as or similar to those other embodiments described above. Due to the braided metal tube or layer 578 being at the exterior of the CSS tubing 510, when the assembly 51 is assembled, the crimp sleeve directly engages the braided metal tube or layer 578. This may therefore allow the crimp sleeve to form the secure electrical connection between the CSS tubing 510 and the associated fluid-flow fitting. For example, in this case, the crimp sleeve will be formed at least in part of an electrically-conductive metal, and would be in electrical communication with the crimp-sleeve stop and / or fluid-flow fitting. It will be understood that the parts of the various embodiments described above may all be interchangeable. Therefore, by way of one example only, the fluid-flow fitting of the first embodiment may be used with the CSS tubing of the sixth embodiment. Similarly and as another example, the CSS tubing of the fifth embodiment may be used with the fluid-flow fitting of the fourth embodiment. By use of the above described assemblies and by way of illustrative example, a 20 millimetre said crimp sleeve, such as a PEX RTM crimp sleeve, has an uncrimped diameter of 22 mm, and the jaw diameter of the crimp head for such a PEX crimp sleeve has a diameter of close to 20mm when the jaws are closed. It is therefore evident that the required crimp head using the above described assemblies can be of a compact size. PEX crimp sleeves have commonly available outer diameters of 16 mm, 20 mm, and 25 mm. As such, the exterior peak diameter of the CSS tubing in the present invention can be or substantially be correspondingly 16 mm, 20 mm, and 25 mm. In the case of copper crimp sleeves, which are also a popular alternative, the same as above applies. Copper crimp sleeves are typically sold with 15 mm, 22 mm, or 28 mm internal diameters. Consequently, the present invention enables use of a corresponding crimp tool with a head and jaw diameter to fit the aforementioned copper crimp sleeve sizes whilst accommodating CSS tubing with an exterior peak diameter EPD of or substantially of 15 mm, 22 mm or 28 mm, as required. It is therefore possible to minimise a fluid-flow fitting size whilst preventing or limiting damage to a gasket sleeve when crimp engaging CSS tubing and a fluid-flow fitting having an internally-receivable fluid-flow nipple element. By having an internally-receivable fluid-flow nipple element, it is also possible to use commonly available standard crimp sleeve sizes and crimp heads associated with those crimp sleeve sizes. The assembly can be provided as a kit of parts, and / or parts of the assembly may be supplied separately of each other or bundled in combination. As such, the fluid-flow tubing, the tubing former, the fluid-flow fitting, the gasket sleeve, the gasket-sleeve stop, and / or the crimp sleeve may each be provided separately or two or more items may be bundled together for supply to an end user, installer or fitter. The words ‘comprises / comprising’ and the words ‘having / including’ when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps, or components, but do not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

1. A CSS (corrugated stainless steel) tubing and fluid-flow fitting assembly comprising:a length of CSS tubing having a plurality of uniform or substantially uniform corrugation peaks defining an internal peak diameter, a plurality of uniform or substantially uniform corrugation troughs defining an internal trough diameter which is less than the said internal peak diameter, and a fitting-receiver end including a fittingreceiver opening having an internal receiver diameter which is greater than at least the internal trough diameter;a fluid-flow fitting including a fluid-flow nipple element located in the CSS tubing and having an outer diameter which is less than the internal trough diameter;a gasket sleeve which is interposed between the fluid-flow nipple element and the CSS tubing at or adjacent to the fitting-receiver end; anda crimp sleeve at an exterior surface of the CSS tubing by which an interior surface of the CSS tubing is fluid-tightly engaged with an exterior surface of the fluidflow nipple element with the gasket sleeve therebetween.

2. A CSS tubing and fluid-flow fitting assembly as claimed in claim 1, further comprising a crimp-sleeve stop at or adjacent to a fitting body of the fluid-flow fitting.

3. A CSS tubing and fluid-flow fitting assembly as claimed in claim 2, wherein the crimp-sleeve stop overhangs a proximal end of the crimp sleeve.

4. A CSS tubing and fluid-flow fitting assembly as claimed in claim 2 or claim 3, wherein the fitting-receiver end abuts or substantially abuts the crimp-sleeve stop.

5. A CSS tubing and fluid-flow fitting assembly as claimed in any one of the preceding claims, wherein the fluid-flow nipple element includes a nipple head at or adjacent to a free distal end thereof, the head forming a shoulder to prevent or inhibit unintentional axial displacement of the gasket sleeve.

6. A CSS tubing and fluid-flow fitting assembly as claimed in any one of the preceding claims, further comprising a gasket-sleeve recess along at least a majority of a longitudinal extent of the fluid-flow nipple element, the gasket sleeve being seated in the gasket-sleeve recess.

7. A CSS tubing and fluid-flow fitting assembly as claimed in any one of the preceding claims, wherein the gasket sleeve is or is substantially annular.

8. A CSS tubing and fluid-flow fitting assembly as claimed in any one of the preceding claims, wherein the gasket sleeve is polymeric.

9. A CSS tubing and fluid-flow fitting assembly as claimed in any one of the preceding claims, further comprising a second gasket sleeve of a different material to the first said gasket sleeve.

10. A CSS tubing and fluid-flow fitting assembly as claimed in claim 9, wherein the said second gasket sleeve is copper.

11. A CSS tubing and fluid-flow fitting assembly as claimed in any one of the preceding claims, wherein the CSS tubing includes a first inner sheathing and a second outer sheathing.

12. A CSS tubing and fluid-flow fitting assembly as claimed in claim 11, whereinthe first inner sheathing is a flexible plastics tube or layer, and the second outersheathing is a braided metal tube or layer.

13. A CSS tubing and fluid-flow fitting assembly as claimed in claim 11, whereinthe first inner sheathing is a braided metal tube or layer, and the second outersheathing is a flexible plastics tube or layer.

14. A CSS tubing and fluid-flow fitting assembly as claimed in claim 12 or claim 13, when dependent on any one of claims 2 to 4, wherein the crimp-sleeve stop is at least in part electrically conductive.

15. A CSS tubing and fluid-flow fitting assembly as claimed in any one of claims 12 to 14, wherein the fluid-flow fitting and / or the crimp sleeve is / are at least in part electrically conductive.

16. A CSS tubing and fluid-flow fitting assembly as claimed in any one of the preceding claims, in the form of a kit of parts.

17. Fluid-flow fitting apparatus specifically adapted for a CSS tubing and fluid-flow fitting assembly as claimed in any one of claims 1 to 15, the fluid-flow fitting apparatus comprising a fitting body, a fluid-flow nipple element which extends from the fitting body, and a gasket sleeve on the fluid-flow nipple element.

18. Tubing former apparatus specifically adapted for a CSS tubing and fluid-flow fitting assembly as claimed in any one of claims 1 to 15, the tubing former apparatus comprising a former head having a first former condition with a first dimension receivable within an internal trough diameter of CSS tubing, and a second former condition with a second dimension which is larger than the first dimension so as to form an internal receiver diameter at a fitting-receiver end of CSS tubing.

19. Tubing former apparatus as claimed in claim 18, further comprising a former mechanism which mechanically expands at least a portion of the former head to move between the first former condition and the second former condition.

20. Tubing former apparatus as claimed in claim 18 or claim 19, wherein the former head includes a plurality of former steps to accommodate tubing with different bore diameters.

21. Tubing former apparatus as claimed in claim 20, wherein a surface of each said former step defines an or substantially an annulus.

22. Tubing former apparatus as claimed in any one of claims 18 to 21, further comprising a restrictor element locatable at or adjacent to the fitting-receiver end of the CSS tubing, the restrictor element restricting expansion of the former head to or substantially to the internal receiver diameter.

23. Tubing former apparatus as claimed in claim 22, wherein a bore of the restrictorelement is or includes a frusto-conical portion.

24. Tubing former apparatus as claimed in claim 22, wherein a bore of the restrictorelement is or includes a cylindrical portion.

25. A method of minimising fluid-flow fitting size whilst preventing or limiting damage to a gasket sleeve when crimp engaging CSS tubing and a fluid-flow fitting having an internally-receivable fluid-flow nipple element, the method comprising the steps of:a] at a fitting-receiver end of CSS tubing, forming an internal receiver diameter which is greater than an internal trough diameter of the CSS tubing;b] at a fluid-flow fitting with a fluid-flow nipple element, locating a gasket sleeve on the fluid-flow nipple element and a crimp sleeve over the gasket sleeve;c] at a fitting-receiver opening of the fitting-receiver end, inserting the fluid-flow nipple element together with the gasket sleeve into a bore of the CSS tubing, so that a wall of the CSS tubing is interposed between the gasket sleeve and the crimp sleeve; andd] crimping the crimp sleeve to fluid-tightly engage an interior surface of the CSS tubing with an exterior surface of the fluid-flow nipple element via the gasket sleeve.

26. A method as claimed in claim 25, wherein, in step a], utilising tubing former apparatus to form the internal receiver diameter, the tubing former apparatus including a former mechanism which mechanically expands at least a portion of a former head to move between a first former condition having a first dimension receivable within the internal trough diameter of the CSS tubing, and a second former condition having a second dimension which is larger than the first dimension so as to form the internal receiver diameter at the fitting-receiver end of the CSS tubing.

27. A method as claimed in claim 25 or claim 26, wherein, in step a], utilising a restrictor element at or adjacent to the fitting-receiver end of the CSS tubing when forming the internal receiver diameter, the restrictor element restricting expansion of the fittingreceiver end.

28. A method as claimed in any one of claims 25 to 27, wherein, in step b], first said gasket sleeve is polymeric, and a second gasket sleeve of a different material axially abuts the said first gasket sleeve.

29. A method as claimed in any one of claims 25 to 28, wherein, in step a], the formed internal receiver diameter presents a smoothly-flaring leading corrugation surface within the bore of the CSS tubing, whereby, in step c], the gasket sleeve mounted on the fluid-flow nipple element smoothly slides into the bore of the CSS tubing, thereby preventing or limiting rucking or snagging of the gasket sleeve.

30. A method as claimed in any one of claims 25 to 29, wherein, in step b], at least a majority of an uncrimped internal bore diameter of the crimp sleeve matches or substantially matches an outer peak diameter of the corrugations of the CSS tubing, and in step d], utilising a crimping tool having a jaw diameter which crimps the crimp sleeve such that a crimped internal bore diameter is less than the said outer peak diameter.

31. A method as claimed in any one of claims 25 to 30, wherein, when the CSS tubing includes a braided metal sheathing, in step d] a secure electrical connection is formed by the crimp sleeve between the braided metal sheathing and at least one of the fluidflow fitting, the crimp sleeve, and / or a crimp-sleeve stop.

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