Mechanical connection

Abstract

The present invention provides a mechanical coupling for connecting pipes or for securing a pipe, a method of assembling such a coupling and a pipe, and a tool for assembling a coupling and a pipe. The mechanical coupling comprises a main body (10) extending axially from an open end (11) and defining an insertion space for a pipe, a clip ring (30) adapted to close over a pipe, and a nut (40) movably mounted at least partly in the main body for tightening the clip ring. The clip ring (30) is arranged inside the main body for being contactable by the nut (40) and has an internal circumferential projection or boss, to be clipped into a corresponding external circumferential groove (4) of the pipe (2). Figure for abstract: Fig. 1

Description

Title of the invention: Mechanical connection Technical field

[0001] The present invention relates to a mechanical fitting for connecting a pipe, a method of assembling such a mechanical fitting and a pipe, and a tool usable in such a method. PREVIOUS ART

[0002] Compression or press fittings are used to connect not only metal pipes, but also plastic pipes or metal-plastic composite pipes. They are used to connect or connect suitably arranged pipe sections, their connecting parts being inserted into the ends of the pipes to be connected, where they are then deformed, crimped or pressed. They are fixed in certain areas, for example with the help of pressure sleeves on the parts, using so-called system compression tools which usually have interchangeable pressure jaws.

[0003] Pipe, tube or conduit systems are assembled in several steps: the pipes are first inserted into a fitting, then the fitting is crimped to ensure good mechanical strength and a watertight installation. Compression is essentially pressure exerted on the fitting sleeve - also called a crimping or pressure sleeve - which causes the fitting to deform or shape relative to the pipe inserted into it. Pressure is usually applied to the fitting using a pressure jaw acting as a friction tool. These pressure jaws exert radial pressure on the fitting material to create an interaction with the surface of the pipe(s) to be connected, resulting in a reliable connection and seal.

[0004] Other fittings, such as those used for example for gardening equipment type hoses, use a threaded engagement to ensure the crimping of the hose and rely on a portion of the fitting engaging the hose.

[0005] In both cases, the connection is based on a deformation of the pipe to be connected, most of the time using an insert placed inside the tube to be connected.

[0006] For different pipe configurations, press fittings can be designed as curved, angular or T-shaped pieces, usually with one, two or three connecting pieces.

[0007] The pipe or conduit may be mono-material and made of thermoplastic materials, including but not limited to PE, PB, PEX, PERT, PER ... or composite (multi-material pipe structure) with different layers of functional materials (PEX, PERT, PVDF, aluminum, etc.).

[0008] It is known to use press fittings made entirely of plastic, or press fittings with a metal fitting body (brass, stainless steel, etc.), or thermoplastic (PVC, PPSU, PVDF, PPS), which can also be reinforced with glass fiber reinforcements.

[0009] However, with the introduction of c-PVC pipes, compression fittings that rely on deformation of the pipe material for connection do not give good results. This is because c-PVC has different properties and is more brittle than other materials.

[0010] One solution that has been proposed is a solvent-based bonding connection. However, regulations are evolving and it will be necessary to avoid adding solvents.

[0011] It is therefore necessary to find another solution for compression fittings, in order to avoid the use of solvents.

[0012] An object of the present disclosure is to provide a mechanical fitting for connecting CPVC, PVC and PVC-U piping systems for hot and cold water installations, particularly pressure installations.

[0013] An object of the present invention is to provide a mechanical connection, for a threaded metal or polymer connection or pipe. Summary of the invention

[0014] These and other objects of the present invention are achieved by a mechanical coupling for connecting a pipe, comprising: a main body extending axially from an open end and defining an insertion space for a pipe, a clip ring adapted to close over a pipe, and a nut movably mounted at least partially within the main body for tightening the clip ring. The clip ring is disposed within the main body for contacting by the nut and has an internal circumferential projection or boss, for clipping into a corresponding external circumferential groove of the pipe.

[0015] In one aspect, the boss has an insertion surface extending from a pipe insertion end to an inner radial boss surface followed by a tear-off surface, the insertion surface forming an insertion angle with the inner radial boss surface greater than a tear-off angle formed by the tear-off surface with the inner boss surface. The geometry of the boss allows the tear-off force to be redistributed into axial and horizontal force, while facilitating insertion of the pipe into the clip ring.

[0016] The insertion surface and / or the tear-off surface may be provided with internal grooves. In one aspect, the clip ring comprises at least one surface of support extending axially from the tear-off surface and / or the insertion surface, forming at least one shoulder adapted to bear on the external surface of the pipe when the latter is inserted. This design allows the stresses or load on the pipe at the groove to be reduced and the stresses to be transmitted to the clip ring via the boss inserted in the groove.

[0017] The clip ring may be an open ring, with an inner diameter of the clip ring, when open, being greater than an outer diameter of the groove, preferably substantially corresponding to an outer diameter of the pipe, and with an inner diameter of the clip ring, when closed, equivalent to the outer diameter of the groove. This ensures that the clip ring closes and transmits force to the pipe.

[0018] In one aspect, the clip ring has an outer conical shape, with an outer conical surface, with a decrease in diameter from the pipe insertion end to the fitting side, and wherein the clip ring is housed in a clip receiving portion of the main body, the clip receiving portion having a corresponding conical shape. A conical shape facilitates both pipe insertion and force transmission when closing the clip ring when the nut is moved into the fitting.

[0019] According to one aspect, the nut comprises a first nut portion for mounting within a nut receiving portion of the main body and a nut head, the first nut portion having nut threads for screwing into internal threads of the nut receiving portion, and a nut head portion extending from the first nut portion, the head portion being adapted to abut the open end of the main body.

[0020] A seal may be provided within a seal housing portion in the main body located adjacent the clip receiving portion.

[0021] At least one of these features is achieved: the nut is made of fiber-reinforced polymer, polymer matrix or composite, the main body is made of fiber-reinforced polymer, polymer matrix or composite, the ring is made of polymer, fiber-reinforced polymer, polymer matrix or composite.

[0022] The present invention also provides a method of assembling such a mechanical coupling and a pipe provided with an external circumferential groove. The method comprises inserting the pipe into the coupling main body and the clip ring or inserting both the pipe and the clip ring mounted thereon into the coupling main body, preferably up to an internal radial rib, and moving the nut into the main body, by sliding and / or screwing the nut into the main body to close the clip ring around the pipe. The method comprises inserting the boss of the clip ring into the groove of the pipe.

[0023] In one aspect, the groove is made by a step of cutting the pipe to form the groove, preferably an external circular groove on the pipe, preferably comprising the steps of simultaneously forming the external circular circumferential groove on the pipe and chamfering the insertion end of the pipe and / or correcting the insertion end. A circular groove can be made before assembly, even if the pipe has some ovality. In other words, the groove is an ovality compensation tool. This is particularly advantageous when using PVC pipes which are brittle and do not tolerate deformation.

[0024] It should be noted that the closure of the nut is a visual indication of the quality and tightness of the connection.

[0025] In addition, after tightening, the clip ring is completely closed, and there is no dirt accumulation gap between the seal, the rubber and the pipe, which prevents the growth of microorganisms, biological films and the accumulation of dirt.

[0026] It should be noted that the clip ring is designed to fit the ovalizing pipe. The dimension of the clip ring is equivalent to the dimension of the groove, which allows for compensation for ovalization or removal of pipe material. In addition, the clip ring has an angled outer surface that allows for reduction of the clip ring diameter when inserting into the fitting or when tightening the nut. The clip ring fills the groove space in the pipe and supports the pipe under radial load.

[0027] The present invention also provides a tool usable in the above method, wherein the tool has a main hollow body to be mounted on the pipe, with a pipe stop for stopping the pipe end, the tool having a grooving knife, at an axial distance from the pipe stop, wherein the axial distance between the pipe stop and the grooving knife can be adjusted to correspond to an axial distance between the pipe stop and the boss of the clip ring of the mechanical fitting.

[0028] In one aspect, the tool has at least one chamfering blade extending from the pipe stop for chamfering the pipe insertion end, and a correcting blade at the pipe stop for correcting the pipe end, a pair of arms, preferably opposing arms, extending outwardly from the main body. DESCRIPTION OF THE DRAWINGS

[0029] Other features and advantages of the invention will become more clearly apparent upon reading the description of several presently preferred embodiments, provided by way of example only, with reference to the attached drawings, among which:

[0030] [Fig. 1] shows a mechanical connection according to a first aspect of the present disclosure,

[0031] [Fig.2] shows the mechanical connection of [Fig.l], in exploded view,

[0032] [Fig.3] shows the mechanical connection of [Fig.l],

[0033] [Fig.4] shows the mechanical connection of [Fig.l] assembled with a pipe,

[0034] [Fig.5] shows a main body of the mechanical connection according to the present,

[0035] [Fig.6] shows a clip ring usable in a mechanical connection according to one aspect of the present disclosure,

[0036] [Fig.7] shows a clip ring usable in a mechanical connection according to one aspect of the present disclosure with a pipe,

[0037] [Fig.8] shows details of the clip ring of [Fig.7] according to one aspect of the present disclosure,

[0038] [Fig.9] shows a sectional view of the clip ring of [Fig.7],

[0039] [Fig. 10] shows a clip ring usable in a mechanical connection according to another aspect of the present disclosure with a pipe,

[0040] [Fig.11] shows details of the clip ring of [Fig.10],

[0041] [Fig. 12] shows a tool according to the present disclosure,

[0042] [Fig. 13] shows a tool according to another aspect of the present disclosure,

[0043] [Fig. 14] shows a tool according to another aspect of the present disclosure,

[0044] [Fig. 15] shows a method of assembling a pipe with a mechanical coupling according to one aspect of the present disclosure. DETAILED DESCRIPTION

[0045] The description below refers to union fittings, but is not limiting, and the following description applies to elbow, T or reducing fittings which can be manufactured based on the same teachings.

[0046] In the figures, identical parts or elements are identified by the same reference numbers.

[0047] Figures 1 to 3 show a mechanical coupling 1 for connecting a pipe 2 according to one aspect of the present disclosure, and [Fig.2] shows the mechanical coupling 1 with the pipe 2 after assembly.

[0048] The pipe 2 may be, for example, a pipe intended for / in a piping system for fluid installations inside or outside buildings. The pipe may be made of CPVC, PVC and PVC-U for hot and cold water installations.

[0049] The connector 1 may form one side of a connector having a similar or other type of connector at its other end or side. The connector may also be provided at a port of a fluidic device for connecting a hose thereto.

[0050] The mechanical coupling 1 comprises a main body 10 for receiving the pipe. The main body 10 has an inner body surface 15 and defines a pipe insertion space extending in an axial direction, between an open end 11, where the pipe 2 is inserted, and an inner radial rib 12 extending radially inside the inner body surface 15. The inner radial rib 12 is intended to stop the pipe inserted in the main body 10.

[0051] Where the pipe is a multi-layer pipe, a seal may be provided at the internal radial rib to protect the multi-layer pipe.

[0052] A nut 40 is provided to be moved within the main body 10 into an assembly position when the pipe is inserted into the main body, in order to secure and hold the pipe in place.

[0053] As can be seen, the nut 40 is not provided in the entire main body 10, but only in a nut receiving portion 18 of the main body 10 extending axially between the open end 11 and a clip receiving portion 19. The clip receiving portion 19 houses a clip ring 30 in abutment against an O-ring 50 in a seal housing 58 defined by an internal radial projection 16 on the internal body surface 15. During assembly, the nut 40 pushes the clip ring 30 to press the O-ring 50 against the internal radial projection 16.

[0054] As can be seen in the figure, the internal radial projection 16 is axially spaced from the internal radial projection 12. In other words, the entire length of the pipe inserted into the fitting 1 will not be below the nut 40 and the free end of the pipe abutting against the internal radial projection 12 is not provided below the nut 40. This allows for taking into account possible variations during the installation of the pipe, which may not be completely inserted or which may have a slightly inclined cross-section. Indeed, it may happen that during the installation of a piping system, the user cuts the pipe and the cut is not perfectly straight. This free space between the internal radial projection 12 and the internal radial projection 16 ensures that the entire end of the pipe is compressed, even if the end of the pipe is not straight.

[0055] The nut 40 has a first nut portion 42 for being screwed into the nut receiving portion 18 of the main body 10. To this end, the nut receiving portion 18 has internal threads 17 extending from the open end 11. The internal threads 17 are provided for screwing the nut 40 into the main body 10 when the pipe is inserted and positioned in the main body 10. The nut 40 therefore has corresponding nut threads 47. However, the thread is only an example, and the nut could slide into the main body.

[0056] The nut 40 also includes a nut head portion 44 which extends axially between the first nut portion 42 and a free nut end 48. The head portion 44 is provided to abut against the open end 11 of the main body.

[0057] The clip ring 30 is illustrated in Figures 6-9 in a first aspect, and another example of a clip ring 130 is illustrated in Figures 10 and 11 in another aspect.

[0058] The clip rings 30 and 130 are designed to hold the pipe against a pull-out force due to internal pressure or external load.

[0059] The clip rings 30, 130 have an internal circumferential protrusion or boss 32, 132, respectively, to be clipped into a corresponding groove 4 of the pipe 2.

[0060] As can be seen in the figures, the boss 32 defines an insertion surface 33, 133 which extends from a pipe insertion end to an inner radial boss surface 34, 134, followed by a tear-off surface 35, 135 on the tear-off or extraction side. The geometry of the clip ring differs in the first aspect illustrated in Figures 7 to 9, and in the other aspect illustrated in Figures 10 and 11.

[0061] In the first aspect illustrated in Figures 7 to 9, the insertion surface 33 forms an insertion angle with the internal boss surface 34 at an angle that is greater than a tear-off angle formed by the tear-off surface 35 with the internal boss surface 34.

[0062] The dimensions of the groove and the boss depend on the diameter and operating pressure of the pipe, as well as the thickness of the pipe and the pipe material. For example, the groove may have a depth in a range between 2 and 4%, preferably between 2.5 and 4.0% of the pipe diameter, and / or in a range between 10 and 30% of the pipe thickness.

[0063] It should be noted that the groove may have other shapes, such as circular, square or rectangular.

[0064] Finally, the clip ring 30 has a support surface 36 extending axially from the tear-off surface 34, such that the support surface 36 defines a shoulder which bears against the pipe and serves to reinforce the pipe at the groove area.

[0065] The clip ring 130 of Figures 10 and 11 differs from the clip ring 30 primarily in that the clip ring 130 has two support surfaces 136a, 136b. A first support surface 136a extends axially from the insertion surface 133 and a second support surface extends axially from the tear-off surface 134. With this geometry, the boss 132 is located between two shoulders 136a, 136b designed to bear on the outer surface of the pipe 2 and to reinforce the pipe at the groove area.

[0066] The clip ring 30, 130 is an open ring which makes it possible to redistribute the axial tear-off load into axial load and radial load on the body.

[0067] The internal diameter of the clip ring 30, when open, is greater than the external diameter of the pipe, in order to facilitate assembly and disassembly with the external groove 4 of the pipe.

[0068] The clip ring 30 is intended to deform and close when the nut 40 is screwed into the main body 10. When closed, under the effect of the load, the internal diameter of the clip ring 30 is reduced and becomes equivalent to the external diameter of the groove 4.

[0069] It should be noted that in addition to holding the pipe against the tear-out force, the clip ring 30 also provides support to reinforce the groove area under operating pressure. When the nut is fully closed and reaches the body, this indicates a good assembly.

[0070] Finally, the clip ring has an external conical shape, with an external conical surface 37, 137, the diameter of which decreases from the pipe insertion end to the fitting side. The clip receiving portion 19 has a corresponding conical shape, with a decreasing diameter from the threads 47 to the seal housing 58, designed to cooperate with the ring conical surface 37, 137.

[0071] The conical shape facilitates the closure of the fitting on the pipe. When the nut slides or is screwed onto the nut receiving portion 18, the clip ring 30, under the effect of the load, closes around the pipe.

[0072] To distribute the load evenly along the pipe and avoid local concentration of the load, the clip ring 30 may not be a complete closed ring and may be an open ring instead. The clip ring 30 may be made as a one-piece open ring, as shown in [Fig. 6], with an open channel, or it may be made in several parts. An open ring allows for a reduction in diameter of the clip ring. Preferably, the clip ring is completely closed in the assembled fitting.

[0073] As indicated above, the clip ring 30, 130 is designed to cooperate with a groove 4 on the pipe. The person skilled in the art understands that the groove 4 must be made on the pipe 2 at a correct position.

[0074] It should be understood that the groove can be made in the pipe, preferably on site or just before assembly. The groove 4 is circular, even if the pipe has some ovality. In other words, the groove is an ovality compensation tool. This is particularly advantageous when using PVC pipes which are brittle and cannot withstand deformation. Instead of trying to reshape the PVC pipe to be circular again, the fitting of the present invention allows the use of a circular groove, made on site in the pipe.

[0075] Finally, the pipe 2, as it appears in the figures, is preferably chamfered to facilitate insertion onto the fitting 1.

[0076] A method of assembling a fitting and a pipe is illustrated in [Fig. 15].

[0077] First, the pipe is inserted into the main fitting body and into the ring at clip, preferably up to the internal radial rib 12, at step S1. The pipe pushes the clip ring against the seal, and when the clip ring can no longer move axially, the pipe groove and the clip ring can engage each other.

[0078] It is possible to clip the clip ring onto the pipe before insertion, and then insert both the pipe and the clip ring into the fitting. In both cases, the boss of the clip ring is inserted into the groove of the pipe.

[0079] Then, the nut is moved inside the main body, by sliding and / or screwing the nut into the main body to close the clip ring 30 around the pipe, in step S2, until the connection is completed (step S3).

[0080] The groove is preferably made on site, and it is possible to simultaneously form the external circular groove on the pipe and chamfer, and possibly correct, the pipe end to be inserted.

[0081] It is advantageous to carry out the groove and the chamfering of the tube with the same tool.

[0082] Figures 12 to 14 show different examples of tools.

[0083] [Fig. 12] shows a tool 80 with a tool body 81 which can be mounted on the pipe end, the tool body extending axially between a pipe insertion end and a pipe stop 82 for stopping the pipe end. The pipe stop 82 provides a radial / radial contact surface for the pipe end and is adapted to contact the cross-section of the pipe end. The pipe stop 82 is therefore perpendicular to the tool body 81.

[0084] The tool 80 is provided with chamfering blades 83 for chamfering the pipe end. The chamfering blades 83 extend axially from the pipe stop 82. The tool 80 also has a grooving knife 84, at an axial distance from the pipe stop 82. The axial distance between the pipe stop 82 and the grooving knife 84 corresponds to an axial distance between the pipe stop 12 and the boss of the clip ring 30, 130 of the mechanical connection.

[0085] As can be seen in [Fig. 12], corrective blades 85 are provided on the pipe stop 82 to adjust the cross-section of the pipe end. This is because, during installation, the user may cut the pipe and, once cut, the pipe end may have a slightly inclined cross-section, not perfectly straight, or have marks resulting from the cutting. This is particularly the case for large diameters when the pipe is cut manually. The corrective blades 85 can correct the cross-section of the pipe end abutting against the pipe stop, as well as the end surface of the pipe end. It is also advantageous to realize in the same tool a pipe chamfering tool and a tool for correcting the tube end to be inserted.

[0086] Figures 13 and 14 show two further examples of tools 180 and 280, respectively. The tools of Figures 13 and 14 can accommodate different ranges of pipe diameters. In the examples shown, the tools 180, 280 have a tool body 181, 281 that can be mounted on the pipe end, the tool body 181, 281 extending axially between a pipe insertion end and pipe stops. The tools have a first pipe stop 182a, 282a providing a first stop surface for a first diameter, and a second pipe stop 182b, 282b providing a second stop surface for a second, smaller diameter. The tools 180, 280 can therefore accommodate two pipe diameters, by way of example only.

[0087] Chamfering blades 183, 283 and correction blades 185, 285 are provided. In [Fig. 13], there is only one chamfering blade and one correction blade (not visible). In contrast, the tool in [Fig. 14] has four chamfering blades and four correction blades, for each diameter. Increasing the number of blades avoids rotating the tool 360° to perform a complete chamfer. For example, with four chamfering blades, a 90° rotation allows a complete chamfer. The number of chamfering blades and correction blades, as well as the number of grooving knives, can be adapted according to requirements.

[0088] The chamfering blades and / or the corrective blades may be symmetrical to allow rotation of the tool in both directions, depending on the user's preferences.

[0089] The tool 180 of [Fig. 13] and the tool 280 of [Fig. 14] are further provided with several grooving knives 184, 284 on the main body 181, 281 of the tool. It is possible to produce and adapt the dimensions of the groove for different pipe diameters, by using different grooving knives, as in [Fig. 13] which shows two grooving knives.

[0090] The blades of the grooving knives can be moved radially to adjust to the depth of the groove to be made.

[0091] It should be noted that, in [Fig. 13] and the tool 280 of the figure, the groove for small diameter pipes can be made by a smaller groover installed on the tool, because the groove dimension is different. It is also possible to use the same groove dimension for more than one diameter, for close diameters.

[0092] The tool 180 of [Fig. 13] and the tool 280 of [Fig. 14] have handles 187, 287 to facilitate rotation of the tool. This is useful for large diameter pipes.

[0093] In one embodiment, the position of the grooving knife 84 may be adjusted to accommodate the mechanical fittings and pipes used.

[0094] The clip ring 30 is designed to push the O-ring 50 to provide a seal. The inner surface features of the clip ring stack into the reshaped groove of the pipe and the tapered outer surface of the clip ring helps the pipe adjust the pipe retention and redistribute the axial pull-out load into axial and radial load on the body.

[0095] Due to the interface between the seal 50 and the pipe, the seal 50 deforms against the main body on one side and against the rigid pipe on the other, thus ensuring the clamping function.

[0096] The seal 50 may have an internal triangle shape to facilitate pipe insertion.

[0097] The seal is a rubber seal, preferably made of reinforced polymer.

[0098] The nut 40 is preferably made of polymer.

[0099] This technology has a significant impact for the replacement of solvent-based glue fittings for CPVC, PVC and PVC-U pipes.

[0100] The advantage of the friction mechanical connection is that it is easy to connect and the network system becomes quickly operational.

[0101] The foregoing description of preferred embodiments of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired by practice of the invention. The embodiment has been selected and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to use the invention in various embodiments suited to the particular use contemplated. The scope of the invention is defined by the claims appended hereto and their equivalents.

Claims

Claims

1. Mechanical fitting for connecting pipes or for attaching a pipe, comprising: a main body (10) extending axially from an open end (11) and defining an insertion space for a pipe, a clip ring (30, 130) adapted to close on a pipe, a nut (40) movably mounted at least partly in the main body for tightening the clip ring, wherein the clip ring (30; 130) is arranged inside the main body to be contactable by the nut (40) and has an internal circumferential projection or boss (32; 132), to be clipped into a corresponding external circumferential groove (4) of the pipe (2).

2. A mechanical coupling according to claim 1, wherein the boss (32) has an insertion surface (33) extending from a pipe insertion end to an inner radial boss surface (34) followed by a tear-off surface (35), wherein the insertion surface (33) forms an insertion angle with the inner radial boss surface (34) greater than the tear-off angle formed by the tear-off surface (35) with the inner boss surface (34).

3. Mechanical connection according to claim 2, wherein the insertion surface (33) and / or the tear-off surface (35) are provided with internal grooves.

4. A mechanical coupling according to any one of claims 2 to 3, wherein the clip ring (30) has at least one support surface (36) extending axially from the tear-off surface (35) and / or the insertion surface (33), forming at least one shoulder adapted to bear against the outer pipe surface of the pipe (2) when the pipe is inserted.

5. A mechanical connection according to any preceding claim, wherein the clip ring (30; 130) is an open ring, wherein an inner diameter of the clip ring when open is greater than an outer diameter of the groove (4), preferably substantially corresponding to an outer diameter of the pipe, and wherein an inner diameter of the clip ring when closed is equivalent to the outer diameter of the groove (4).

6. A mechanical fitting according to any preceding claim, wherein the clip ring has an external conical shape, with an external conical surface (37, 137), with a decrease in diameter from the pipe insertion end to the fitting side, and wherein the clip ring is housed in a clip receiving portion (19) of the main body, the clip receiving portion (19) having a corresponding conical shape.

7. A mechanical connection according to any preceding claim, wherein the nut (40) has a first nut portion (42) for mounting within a nut receiving portion of the main body (10) and a nut head (44), the first nut portion (42) having nut threads (47) for screwing into internal threads (17) of the nut receiving portion, and a nut head portion (44) extending from the first nut portion (42), the head portion (44) being arranged to abut the open end (11) of the main body

8. A mechanical connection according to any preceding claim, wherein a seal (50) is provided within a seal housing portion (58) in the main body adjacent the clip receiving portion (18).

9. A mechanical connection according to any one of claims 1 to 8, wherein at least one of these characteristics is fulfilled: a. the nut (40) is made of fiber-reinforced polymer, polymer matrix or composite, b. the main body is made of fiber-reinforced polymer, polymer matrix or composite, c. the ring is made of polymer, fiber-reinforced polymer, polymer matrix or composite.

10. A method of assembling a fitting according to any one of claims 1 to 9 and a pipe provided with an external circumferential groove (4), comprising: inserting the pipe into the main fitting body and into the clip ring or inserting both the pipe and the clip ring mounted thereon into the main fitting body, preferably up to an internal radial rib (12), moving the nut into the main body, by sliding and / or screwing the nut into the main body to close the clip ring (30) around the pipe, including inserting the boss of the clip ring into the groove of the pipe.

11. A method of assembling a fitting according to claim 10, wherein the groove is obtained by a step of cutting the pipe to form the groove, preferably an external circular groove, preferably comprising the steps of simultaneously forming the external circular groove on the pipe and chamfering the pipe insertion end and / or correcting the insertion end.

12. A tool (80) for use in the method of claim 10 or 11, wherein the tool (80) has a hollow main body (81) for mounting on the pipe, with a pipe stop (82) for stopping the pipe end, the tool (80) having a grooving knife (84), at an axial distance from the pipe stop (82), wherein the axial distance between the pipe stop and the grooving knife (84) is adjustable to correspond to an axial distance between the pipe stop (12) and the boss of the clip ring (30, 130) of the mechanical fitting.

13. A tool according to claim 12, comprising at least one chamfering blade (83) extending from the pipe stop for chamfering the pipe insertion end, and a correcting blade (85) at the pipe stop for correcting a cross-section of the pipe end, and a pair of arms, preferably opposing arms, extending outwardly from the main body.

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