IL295849A

IL295849A - Electro-weldable system with saddle and on-pipe support facility that is multi-diameter with electrofusion pads

Info

Publication number: IL295849A
Application number: IL295849A
Authority: IL
Original assignee: Sainte Lizaigne
Priority date: 2020-03-02
Filing date: 2021-03-01
Publication date: 2022-10-01
Also published as: FR3107666B1; FR3107666A1; EP4114646A1; WO2021175794A1

Description

1 DESCRIPTION TITLE: Electro-weldable system with saddle and on-pipe support facility that is multi-diameter with electrofusion pads Technical field The present invention generally relates to the field of fluid distribution networks, and in particular for water or city gas. It more particularly relates to an electro- weldable saddle system for wet connection to a pipe/duct made of polyethylene, in particular HDPE (High Density Polyethylene) or LDPE (Low Density Polyethylene), from PE50 to PE100, or also PE-X (crosslinked polyethylene). The saddle of the system allows the use thereof on several pipe diameters as well as the potential insertion of an electro-welding pad into the saddle, on site, at the moment when the saddle is to be installed. It has applications in particular in the field of connection of subscribers to a fluid network, said fluid being liquid or gaseous.

Technological background Saddle systems with tightening straps for wet connection to water pipes are known. Generally, the saddles are metallic and designed to be installed and tightened against the pipe with interposition of a gasket on hard pipes. The pipe is pierced through a nipple or boss in the saddle and through a valve installed on the nipple or boss.

Today, water distribution networks use more and more pipes made of plastic material, typically HDPE, which is a hot-melt material. It has been proposed to use saddle systems heat-welded on these pipes thanks to electrofusion devices.

The following documents are known in the field of electro-weldable saddles: EP 1231045, but the tightening means are not detailed, EP 0088703, but the tightening means seem complex to implement, GB 0088703, DE 19935424, JP 2008025704, JP 2002174390, JP 2018105371 in which the saddle has a smaller diameter than the pipe, JP H10185068 implementing a metal layer.

Due to a standardization of the pipes, these latter have determined nominal diameters (ND) and the diameter difference between two successive NDs is relatively significant. In the known systems, up to ND 225 mm included, a given saddle cannot in practice be adapted to a range of several nominal diameters: the saddles are single-diameter. It results therefrom that a great number of different models is required to operate on the different NDs met. Stock management is complex and different quantities have to be provided for each model depending on the frequency of use of the corresponding ND.

The present invention proposes a saddle system whose particular structure makes it possible to adapt it to a wide range of pipe ND.

Disclosure of the invention It is first proposed according to the invention, a system for wet connection to a fluid 40 distribution pipe, in particular for water, the longitudinally elongated and cylindrical pipe being made of a heat-weldable plastic material, the system comprising a saddle made of a heat-weldable plastic material, an electrofusion pad and a tightening strap, the saddle having an upper face with a central boss and a lower face intended to come against the pipe, the saddle being longitudinally elongated 45 and transversely rounded, the electrofusion pad including two connection lugs and being added in a housing in the lower face of the saddle, the two connection lugs passing through the thickness of the saddle in two lug passages and arriving at the upper face of the saddle, the two lug passages and the boss being aligned with each other along a longitudinal inter-lug axis of the saddle, the saddle having 50 laterally, on either side of the longitudinal inter-lug axis, two lateral flanges, the 2 lower face of the saddle being concave downward and having the shape of a cylindrical surface of determined radius, the two flanges of the saddle having two lateral attachment ends for attachment to the tightening strap, the tightening of the tightening strap allowing the application of the lower face of the saddle with its two flanges against the pipe.

According to the invention, a same saddle is configured to be attached by electrofusion to pipes of nominal diameters between a minimum nominal diameter, NDmin, and a maximum nominal diameter, NDmax, with a NDmax/NDmin ratio between 1.1 and 3.0 without mechanical deterioration or leakage during the tightening and after electrofusion, and the flanges have a gradient of flexibility from the boss towards the lateral attachment ends, the flexibility being maximum near the lateral attachment ends and minimum near the boss.

Other non-limiting and advantageous features of the system according to the invention, taken individually or according to all the technically possible combinations, are the following: - the flexibility is measured by a stiffness coefficient, the stiffness coefficient being smaller near the lateral attachment end than near the boss, - the stiffness coefficient being measured along longitudinal sections of the flange, - the gradient of flexibility is obtained by at least one of the following arrangements: the presence of a plastic material whose composition varies from the boss towards the lateral attachment ends, the presence at the upper face of the flanges, on each lateral side of the longitudinal inter-lug axis, of longitudinal grooves parallel to each other and to the longitudinal inter-lug axis, the thicknesses of material between the bottom of the grooves and the lower face of the flanges decreasing in the transverse direction, from groove to groove, from the boss towards the lateral end of the flange, the thickness of material of the flanges decreases from the boss to the lateral attachment ends, the length of the flanges, as measured parallel to the longitudinal inter-lug axis, decreases from the boss to the lateral attachment ends, - the plastic material whose composition varies is a plastic material consisted of at least two components, with a homogeneous local mixing of the components and the relative proportions of the components varying from the boss towards the lateral attachment ends, - the plastic material whose composition varies is a plastic material consisted of at least two components, said at least two components forming a laminated flange structure, that is to say without mixing of the components, and the relative thicknesses of the component laminations varying from the boss towards the lateral attachment ends, - the thickness of material of the flanges decreases from the boss towards the 40 lateral attachment ends and the length of the flanges, as measured parallel to the longitudinal inter-lug axis, decreases from the boss to the lateral attachment ends, - the plastic material of the saddle and the plastic material of the pipe are identical, - the upper face of the flanges has, on each lateral side of the longitudinal inter-lug axis, longitudinal grooves that are parallel to each other and to the longitudinal 45 inter-lug axis, - the thicknesses of material between the bottom of the grooves and the lower face decreases in the transverse direction, from groove to groove, from the boss to the lateral end of the flange, - the grooves are longitudinally elongated on the upper face of the saddle and they 50 are parallel to the main axis of the pipe on which the saddle is to be installed,3 - grooves are interrupted by the boss, - grooves interrupted by the boss are lateral to the lug passages, - grooves are lateral to the boss, - grooves are continuous from a longitudinal edge of the saddle to the other, - grooves are discontinuous from a longitudinal edge of the saddle to the other, - grooves do not reach the longitudinal edges of the saddle, - the depth of the grooves increases from the boss towards the lateral ends of the flanges, - the thickness of material between the bottom of the groove and the lower face is longitudinally constant, - in the case of a saddle with a preinstalled electrofusion pad, in particular by overmoulding, the lower face of the saddle is of uniform cylindrical shape, concave downward, so that it can be applied uniformly against the pipe after tightening of the tightening strap, - in the case of a saddle with a preinstalled electrofusion pad, an overthickness of material protruding downward from the lower face may be present opposite the preinstalled electrofusion pad, said overthickness being limited to a few tenths of mm, - in the case of a saddle having no preinstalled electrofusion pad, the lower face of the saddle, apart from the housing intended to receive an electrofusion pad, which forms a recess in said lower face, is of uniform cylindrical shape, concave downwards, - a same saddle is configured to be attached by electrofusion to pipes of nominal diameters between a minimum nominal diameter, NDmin, and a maximum nominal diameter, NDmax, of NDmax/NDmin ratio between 1.1 and 2.5, - a same saddle is configured to be attached by electrofusion to pipes of nominal diameters between a minimum nominal diameter, NDmin, and a maximum nominal diameter, NDmax, of NDmax/NDmin ratio preferentially between 2 and 2.1, - the system is configured to allow a tightening force up to 5 kN to be applied without mechanical deterioration or leakage during the tightening and after electrofusion, - the system is configured to allow a tightening force of at least 5 kN to be applied without mechanical deterioration or leakage during the tightening and after electrofusion, - preferably, the saddle is chosen in such a way as to respect the relation (Dn - NDmin) / (NDmax - NDmin) = 0.34 to 0.40, where Dn is the diameter of the lower face of the saddle before tightening, - the saddle is configured in such a way that the thickness of material of the flanges of the saddle, without the grooves, is longitudinally constant, 40 - the saddle is configured in such a way that the thickness of material of the flanges, without the grooves, decreases from the boss towards the lateral ends, - the lateral end of the flange is a lateral attachment end of the strap that includes a strap hitching device, - the lateral attachment ends of the flanges each comprise a tightening strap 45 hitching device that forms upward an overthickness of material with respect to the thickness of the flange, - the downwardly concave lower face of the saddle has the shape of a cylindrical surface of determined radius, - the upper face of the saddle, apart from the boss and the two lug passages, has 50 a transverse rounding and is generally convex upward,4 - the bottoms of the adjacent grooves of the saddle are separated from each other by longitudinal elevations parallel to the grooves and ending upward with ridges, said ridges being carried by the transverse rounding of the upper face, - the ridges of the elevations are flattened, - the ridges of the elevations are rounded, - the ridges of the elevations are angular, - the elevations, seen in cross-section of the saddle, are not symmetrical with respect to the radius defining the cylindrical curve of the lower face of the saddle, - the elevations, seen in cross-section of the saddle, are symmetrical with respect to the radius defining the cylindrical curve of the lower face of the saddle, - the grooves, seen in cross-section of the saddle, are not symmetrical with respect to the radius defining the cylindrical curve of the lower face of the saddle, - the elevations, seen in cross-section of the saddle, are symmetrical with respect to the radius defining the cylindrical curve of the lower face of the saddle, - the upper face in the circular junction part between the central boss and the upper face includes at least two semi-circular areas of reduced thickness of the saddle material between the upper and lower faces, said two semi-circular areas of reduced thickness being arranged towards the two lateral sides of the boss, - at the upper face of the saddle, each of the two lug passages has an upward overthickness of material, - the upper face along the longitudinal inter-lug axis includes an upward overthickness of material between the boss and each of the two lug passages, - the saddle is longer at the longitudinal inter-lug axis than towards the two lateral ends of the two flanges, - the saddle is as long at the longitudinal inter-lug axis as towards the two lateral ends of the two flanges, - the saddle is symmetrical with respect to a vertical plane passing through the longitudinal inter-lug axis, - the saddle is generally symmetrical with respect to a vertical plane passing through the centre of the boss, - the bottom of the grooves is rounded, - the bottom of the grooves is angular, - the bottom of the grooves is flattened, - the electrofusion pad installed in the housing flushes with the lower face of the saddle, - the electrofusion pad is overmoulded in the saddle, - the electrofusion pad overmoulded in the saddle is embedded in the saddle material, - the electrofusion pad is of square or rectangular or circular shape, 40 - the tightening strap is made of metal, - the metal tightening strap includes a stainless-steel band with a toggle latch at each of its two ends, - the tightening strap is made of plastic material, - the tightening strap is made of plastic material and includes catches, 45 - the plastic tightening strap is consisted of a band having catches at its surface, - the plastic tightening strap is consisted of a band having at its surface series of traction holes through which a tightening traction tool may be inserted, - the traction tool is a tightening clamp, - the tightening clamp has two ends that can be moved apart or closer together, 50 one of the ends including a claw intended to be inserted into one of the traction 5 holes and the other end including a two-finger tab intended to bear on the lateral attachment end of the saddle flange provided with a hitching device, - the tightening strap is left in place once the saddle electro-welded on the pipe, - the tightening strap is a removable element intended to be removed once the saddle electro-welded on the pipe, - the boss is intended to receive internally a metal insert, - the system comprises a saddle with a metal insert in the boss, - the saddle is obtained by moulding of a plastic material, - the insert is overmoulded in the boss of the saddle.

The invention also relates to a facility for wet connection to a fluid distribution pipe, in particular for water or city gas, including the system of the invention.

The invention also relates to an assembly for tightening a saddle made of thermo- weldable plastic material of a system according to the invention, the assembly including, on the one hand, for use with a saddle, a tightening strap made of plastic material, having catches and at least one ball joint with two locking plates arranged inside the ball joint, the locking plates having spring tabs and locking fingers, and on the other hand, reusable, a tool of the clamp type including a toothed plate for driving the tightening catch strap.

The tightening assembly may be declined according to any structural arrangement and modality of use of the elements and tools of the system.

The invention finally relates to a method for installing a system according to the invention for wet connection to a fluid distribution pipe, in particular for water, of determined nominal diameter, ND, in which a saddle adaptable to a range of pipe diameters is chosen, the ND being included in said range, the surface of the pipe is prepared in the area in which the saddle of the system will be installed, an electrofusion pad is installed in a housing of the saddle in the case where said electrofusion pad is not preinstalled, the saddle and its electrofusion pad are placed on the prepared surface of the pipe, a tightening strap is installed at the lateral ends of the saddle flanges and said strap is tightened in such a way that the lower face of the saddle is applied against the pipe surface and the electrofusion pad is power supplied. Advantageously, the preparation of the pipe surface consists of abrasion and cleaning of the pipe surface.

Brief description of the drawings [Fig. 1] is a perspective view of the system of the invention with a saddle and its tightening strap, both made of plastic material, as well as a metal insert in the boss of the saddle, [Fig. 2] is a diagram of trigonometric modelling of the adaptation of a same saddle to pipes of minimum and maximum nominal diameters of a range, [Fig. 3] is a diagram of geometric modelling of the adaptation of a same saddle to 40 pipes of minimum and maximum nominal diameters of a range, [Fig. 4] is a perspective view of an alternative embodiment of the saddle of the system of Fig. 1, [Fig. 5] is a perspective view of the saddle of the system of Fig. 1, [Fig. 6] is a cross-sectional view of the saddle of the system of Fig. 1, 45 [Fig. 7] is a bottom view, on the lower face side, of the saddle of the system of Fig. 1, [Fig. 8] is a perspective view of a catch strap on which have been slid two ball joints having internally locking plates made of stainless steel, [Fig. 9] is a perspective view of a ball joint showing the locking plate thereof, 50 which is arranged inside the ball joint, in a through-notch of the latter,6 [Fig. 10] is a perspective view of a strap tightening tool, [Fig. 11] is a perspective and partial cross-sectional view showing the mounting of a ball joint on the catch strap and of the locking plate thereof for immobilizing the ball joint along the strap, [Fig. 12] is a cross-sectional view of a ball joint being slid along the catch strap, the locking plate thereof being retracted during the passage over the catches, [Fig. 13] is a cross-sectional view of a ball joint locked along the catch strap, the locking plate thereof abutting against a catch, [Fig. 14] shows the locking plate, [Fig. 15] is a cross-sectional view of an enhanced ball joint showing the two locking plates which are arranged inside the ball joint, [Fig. 16] is a cross-sectional view of an enhanced ball joint sliding along the catch strap, the locking plates thereof being retracted during the passage of the catches, [Fig. 17] is a cross-sectional view of a ball joint locked along the catch strap, the locking plates thereof abutting against the catches, [Fig. 18] is a perspective view of the system of the invention during the tightening of a catch strap with an enhanced ball joint thanks to a suitable enhanced strap tightening tool, [Fig. 19] is a partial cross-sectional view of a detail of the system of Fig. 18 at a flange end, with its enhanced ball joint and the catch strap, the enhanced strap tightening tool being used during a recovery phase of strap tightening, and [Fig. 20] is a partial cross-sectional view of a detail of the system of Fig. 18 at a flange end, with its enhanced ball joint and the catch strap, the enhanced strap tightening tool being used during a driving phase of strap tightening.

Detailed description of an exemplary embodiment The following description in relation with the appended drawings, given by way of non-limiting examples, will allow a good understanding of what the invention consist of and of how it can be implemented.

In its principle, the invention relates to a system of multi-diameter electro-weldable saddles and tightening straps for HDPE (High Density Polyethylene) pipes. Each saddle can be fastened by electro-welding to pipes of different diameters thanks to the particular structure of the saddle that may be adapted and applied on pipes of different diameters.

The saddle system is optimized in particular in terms of: - gradient of material thickness (i.e. between the lower and upper faces) between the longitudinal inter-lug axis (axis passing through the centres of the boss and of the connection lugs for connection to an electrofusion machine) and the lateral ends of the saddle flanges, - structure by the presence of grooves at the upper face of the flanges, 40 - shape of reduced thickness (i.e. between the lower and upper faces) of at least the lateral portions of the connection area between the boss and the upper face of the saddle.

Contrary to the known saddles, the electro-weldable saddle of the invention can thus be adapted to a wide range of pipe diameters thanks to its thickness gradient 45 between the longitudinal inter-lug axis and the two lateral ends for attachment to the strap for the tightening to the pipes and to the advantageous combination of the thickness gradient, the mean thickness, the saddle size, the notches and the potential semi-circular areas of reduced thickness of material at the basis of the wet connection boss, in such a way as to conciliate flexibility, traction/bending 50 strength and propagation of heat during the electrofusion. The longitudinal inter7 lug axis is the axis passing through the centres of the lug passages and of the boss, which are thus aligned. The solution proposed makes it possible to provide electro-welding pads that are not overmoulded in the saddles before use on site and, also, removable clamping means.

The proposed system is in particular configured to allow the application of a tightening force up to 5 kN without mechanical deterioration or leakage during the tightening and after electrofusion, and that with a saddle that is chosen so as to respect the relation (Dn - NDmin) / (NDmax - NDmin) = 0.34 to 0.40, where Dn is the diameter of the lower face of the saddle before tightening.

The system of the invention makes it possible to avoid potential errors on ND planned for interventions on site due to the fact that the saddle can be adapted to a wide range of pipe nominal diameters. Moreover, it results therefrom a limited number of saddle references, which provides gains in terms of weight and volume for the storage, transport and assembly.

Such a system 1 of a saddle 2 with its tightening strap 3 is shown in Fig. 1. The HDPE saddle 2 includes centrally a central boss 21 forming an open passage between the upper face and the lower face of the saddle. A metal insert 4 is installed in the boss 21 and includes a screw 40 for rotationally locking the wet connection valve to be mounted thereto. The metal insert is typically made of brass. The metal insert is overmoulded in the saddle and the screw is used for the installation of the wet connection valve. The saddle 2 further includes, on either side of the boss 21, two lug passages 22 for connection of an electrofusion pad to a pad power supply electrofusion machine. The boss 21 and the lug passages 22 are aligned on a longitudinal inter-lug axis that is parallel to the main axis of the pipe on which the saddle 2 may be installed. The lug passages 22 and the boss 21 correspond to overthicknesses of material with respect to the upper face of the saddle 2. In this example of Fig. 1, no overheight of material is implemented along the longitudinal inter-lug axis between the lug passage 22 and the boss 21. On the other hand, in Figs. 4 and 5, overheight of material is implemented along the longitudinal inter-lug axis between the lug passage 22 and the boss 21.

Laterally, on either side of the boss 21 and the lug passages 22, two flanges 20a, 20b extend laterally up to two lateral attachment ends each including a device 28 for hitching the tightening strap 3. In this example, the tightening strap 3 is made of plastic material and is a catch strap.

The upper face of the saddle includes at the junction with the boss 21 at least two semi-circulation areas 27 of reduced thickness of saddle material between the upper and lower faces. These semi-circular areas 27 of reduced thickness being arranged towards the two lateral sides of the boss and are intended to facilitate the deformation of the saddle during the tightening thereof on the pipe. These semi 40 circular areas 27 of reduced thickness are thus directed substantially vertically because they are made in the thickness of the saddle.

In an alternative embodiment (not shown), these semi-circular areas of reduced thickness are made in the thickness of the boss and are hence directed substantially perpendicular to the vertical at the junction between the sleeve and 45 the saddle, that is to say at the basis of the sleeve, on the upper face side of the saddle.

The upper face of the saddle 2 includes, essentially on the flanges 20a, 20b, series of grooves 25 parallel to each other. Between the grooves 25 are located crests 24 of elevations between grooves. It can be noted that, in this example, the 50 grooves 25, on the side of the longitudinal inter-lug axis, are interrupted by the 8 boss 21. In alternative embodiments, the grooves 25 do not interfere with the boss 21.

The saddle 2 is generally symmetrical with respect to a sagittal vertical plane carried by the longitudinal inter-lug. The saddle 2 is also generally symmetrical with respect to a transverse plane perpendicular to the sagittal vertical plane and passing through the centre of the boss 21.

Fig. 4 shows alternative embodiments regarding in particular the structure of the boss 21 and the structure of the hitching devices 28 of the lateral attachment ends on the flanges 20a, 20b, and used to hitch the tightening strap for tightening straps of different types. Moreover, in the alternative embodiment of Fig. 5, overheights of material 29 have been provided along the longitudinal inter-lug axis between the overthicknesses corresponding to the lug passage 22 and the boss 21.

Figs. 6 and 7 show in particular the housing 5 dug in the lower face of the saddle 2 and intended to receive an electrofusion pad. The depth of this housing 5 is of about 1.2 mm but a depth between 0.5 mm and 2 mm, or even between 0.8 mm and 1.5 mm or, preferentially, between 1 mm and 1.3 mm may be provided, in particular depending on the pad provided. This housing of substantially square shape includes longitudinal appendices for the passage of electric connections towards the lugs. The electrofusion pad includes an electric conductor intended to heat, due to its ohmic resistance, wound as a spiral coil, flat, with a very small thickness or another shape, for example, helical with flush coils.

The reported optimizations are intended to provide bendability to the saddle and in particular the flanges thereof by tightening to the pipe, before electrofusion, while withstanding the thermomechanical and hydraulic stresses characteristic of the application, once the electrofusion made. Due to this ability, a given saddle may be installed on pipes of a wide range of diameters. This installation with electrofusion is made without visible cracks or crackles appear on the saddle, and the latter cannot be torn out from the pipe unless destructuring the pipe and the saddle.

In practice, different saddle references are provided, more particularly adapted to different ranges of pipe diameters. Generally, for the water pipes usually met, 2 to 4 saddle references and 1 to 3 models of electrofusion pads are provided.

Typically, it may be provided 2 to 4 saddle references and 1 or 2 pads for exit bosses "X" (see hereinafter) and 2 to 3 saddle references and 1 to 3 pads for exit bosses "Y".

For example, three saddle references may be provided, a first reference for pipes of ND between 50 and 90, a second reference for ND between 90 and 180, a third reference for ND between 180 and 400, the diameters being in mm and ND being the Nominal Diameter of the pipe/duct and that corresponds to the outer diameter 40 for the plastic material pipes.

Generally, the multi-diameter wet connection system can be applied to pipes of very different nominal diameters, ND, and typically between 40 mm and 500 mm, different saddle references applying to different ranges of NDs between these values. 45 These different references mainly differ in their initial/unstressed bending radii and their dimensions, essentially the dimensions of their lateral flanges which must cover larger or smaller surface areas as a function of the NDs. It is understood that the longitudinal sizes may be different as a function of the references, and also, more generally, that all the dimensions may be adapted as a function of the 50 diameter of the boss intended to the wet connection derivation. Indeed, typically, 9 two types of exit bosses, a first one, called "X", of 40 x 3 mm and a second, called "Y", of 55 x 3 mm. It is to be noted that, generally and preferably, exit bosses "Y" 55 x 3 mm are provided only for NDs higher than or equal to 90 mm.

Exit bosses with gas-internal thread are also provided for drinking water.

Finally, the size of the electro-weldable pad is adapted in such a way that the pad surface is greater for saddle references having a greater surface of contact with the pipes, as it is the case with significant NDs. However, in order to further optimize the system, it is possible to use a single pad size for the saddles "X" and a single, greater, other pad size for the saddles "Y".

We will now describe size examples in the exemplary case of three references of electro-weldable saddles provided for NDs between 40 mm and 400 mm. These saddle sizes relate to non-stressed saddles. It is considered here a saddle that is configured to be tightened on the pipe thanks to a catch strap.

The RADIUS of the lower face of the saddle is the following in the following example of a range of 3 saddles "X" and 2 saddles "Y": [TABLE 1] Pipe, ND range (mm) RADIUS for X-type boss RADIUS for Y-type (mm) boss (mm) typical: 40 - 90 typical: 22.5 - 37.5 (not applicable) preferably: 50 - 90 preferably: 27.5 - 37.5 typical: 75 - 180 typical: 45 - 70 preferably: 90 - 180 preferably: 55 - 70 typical: 140 - 400 typical: 90 - 140 preferably: 180 - 400 preferably: 100 - 140 The typical minimum NDs, lower than the preferred minimum NDs, are pipe diameters for which the installation of the saddle must be particularly careful and the result well controlled due to the extreme stresses applied to the saddle and in particular to the flanges thereof but also to the pipe.

For the transverse dimension, TD, of the saddle, between the lateral ends of the two flanges, more precisely between the middles of the two opposite housings for receiving the catches of the tightening strap in the case of a catch strap, the dimension considered is along the arc of circle between the middles of the two opposite housings for the catches of the tightening strap: [TABLE 2] Pipe, ND range (mm) TD for X-type (mm) TD for Y-type (mm) typical: 40 - 90 typical: 100 - 145 (not applicable) preferably: 50 - 90 preferably: 105 - 145 typical: 75 - 180 typical: 105 - 155 typical: 120 - 185 preferably: 90 - 180 preferably: 110 - 155 preferably: 125 - 185 typical: 140 - 400 typical: 110 - 165 typical: 125 - 195 preferably: 180 - 400 preferably: 115 - 165 preferably: 130 - 195 It is to be noted that the tightening strap may be of another type and in particular a ratchet or toggle strap.10 For the LENGTH of the saddle, measured along the longitudinal inter-lug axis passing through the two lug passages and the centre of the boss, the following dimensions are given by way of example: [TABLE 3] Pipe, ND range (mm) LENGTH for X-type LENGTH for Y-type (mm) (mm) typical: 40 - 90 (not applicable) preferably: 50 - 90 typical: 75 - 180 typical: 105 - 135 typical: 120 - 185 preferably: 90 - 180 preferably: 110 - 130 preferably: 125 - 175 typical: 140 - 400 typical: 120 - 200 preferably: 180 - 400 preferably: 125 - 190 The reduction of the saddle length in the lateral direction, that is to say towards the flange ends, the flanges thus having wide bases on the boss side and narrow apex on the side of their lateral ends for attachment to the strap, is another feature (in addition to the thickness reduction but also the minimization of the lateral extend TD/transverse dimension with respect to the conventional saddles) making it possible to reduce the quantity of material away from the axis passing through the lugs. This provide the required flexibility for a multi-diameter application of the saddle, without deterioration or breakage of the latter.

The system is all the more adaptable to different nominal diameters since the quantity of material of the saddle having to be stressed by tightening to the pipe is reduced. This material reduction may be obtained in several manners, including: by reducing the flange thickness towards their lateral ends, by reducing the flange length towards their lateral ends, by reducing the saddle length between the two lateral ends of the flanges (reduction of TD/transverse dimension). These ways to do may be advantageously combined and even combined with other ways, such as, for example, using the grooves. Therefore, more flexibility/deformability is obtained, and that without applying excessive tightening efforts, while being capable of housing an electrofusion pad, and without becoming too fragile.

More generally, the adaptability is due to the existence of a gradient of flexibility in the flanges from the boss towards the lateral attachment ends, the flexibility being maximum towards the lateral attachment ends and minimum towards the boss.

The presence of this gradient of flexibility may be determined by measurements of the stiffness coefficient. It may be noted that the inverse of the stiffness is the flexibility or the suppleness, which is defined by its amplitude, i.e. the deflection, and force required for this deflection movement. Thus, both stiffness and flexibility/softness can be considered.

In the concrete case of the saddle shape and of its flanges and the usage thereof, the stiffness to be considered is angular, in N.m/rad: kθ = M / θ where M is the force moment.

Therefore, the more supple the saddle with its lateral flanges, the smaller kθ and the smaller M required for a targeted deflection θ or the greater θ for a given effort M.

The energy applied to stick a saddle is translated by the bending thereof, moving closer together (towards the small pipe diameters) or away from each other (towards the great pipe diameters) the lateral flanges thereof. This energy is 11 proportional to the product of the moving R Δθ and of the tangential component of the force required for this moving.

By way of simplified example, the saddle may be modelled on the basis of a cylindrical hollow tube of external diameter D and internal diameter d. In such a simplified case, the moment of inertia is n־ (D4 - d4) / 64 and the modulus of inertia is n־ (D4 - d4) / 32 d. Therefore, if the thickness decreases, preferentially on the outer side of the flange, D decreases and hence the force moment, the modulus and the stiffness decrease.

Finally, at a point out of the neutral fibre of a saddle, the stress is proportional to the product of the modulus of the saddle material and of the deflection, the risk of breaking being on the face in extension (the upper face towards the small diameters, and the lower face towards the great diameters). The bending moment is proportional to E I / R, where E is the modulus of elasticity of the material, I is the moment of inertia and R is the radius of the effective bending of the saddle.

Thus, if the modulus of the saddle material decreases, the maximum stress thus decreases in the same way as if the deflection was reduced.

This gradient of flexibility may be obtained in various ways, each being sufficient in itself, but being able to be combined together: by reducing the thickness of material of the flanges towards the ends, by reducing the length of the flanges (i.e. longitudinally) towards the ends, by the presence of deeper and deeper longitudinal grooves towards the ends (the thickness of the flanges being uniform or decreasing), by chemical formulation of the plastic material with mechanical properties varying transversely in the saddle. In this last case, a plastic material having at least two components, one of which is suppler than the other (or less stiff than the other), can be implemented, the proportions of the two components varying laterally, in the flanges, the supplest (or the less stiff) being proportionally in higher quantity towards the ends. These two components may be mixed together, the flanges being structurally homogeneous, or these two components may remain individualized, the flanges being structurally laminated.

The multi-component plastic material can thus form a material with a composition gradient, also called FGM ("Functional Gradient Material"). Their simple structure consists of a gradual evolution from one part of a piece to another through a continuous change in the composition. Their transition profile is defined in such a way as to obtain the desired function.

As regards the geometric parameters of the boss, the following dimensions, given by way of example, can be used: [TABLE 4] Geometric parameter of the For X-type boss For Y-type boss boss typical: 20 - 50 Height in the axis (mm) preferably: 25 - 45 Internal vertical dimension typical: 10 - 40 (mm) preferably: 15 - 35 typical: 46 - 56 typical: 59 - 73 External diameter (mm) preferably: 48 - 54 preferably: 62 - 7012 As regards the geometric parameters of the flange end area receiving the catches of the tightening strap, and which are the dug length, the recess length, the centre/edge distance and the radius for the catches, it is proposed: [TABLE 5] Pipe, ND range (mm) For X-type boss For Y-type boss (mm) (mm) typical: 40 - 90 (not applicable) preferably: 50 - 90 Dug length typical: 80 - 145 preferably: 100 - 125 Recess length typical: 60 - 125 Dug length preferably: 80 - 105 typical: 45 - 95 typical: 75 - 180 Centre/edge preferably: 60 - 80 preferably: 90 - 180 distances(idem) typical: 6 - 20 Recess length preferably: 8 - 18 typical: 25 - 75 preferably: 40 - 60 Radius for catch(idem) typical: 2 - 14 Centre/edge preferably: 4 - 8 distances Dug length typical: 6 - 20 typical: 95 - 160 preferably: 8 - 18 preferably: 115 - 140 Recess length Radius for catch typical: 75 - 140 typical: 2 - 14 preferably: 95 - 120 typical: 140 - 400 preferably: 4 - 8 Centre/edge preferably: 180 - 400 distances(idem) typical: 6 - 20 preferably: 8 - 18 Radius for catch(idem) typical: 2 - 14 preferably: 4 - 8 As regards the electrofusion pad, which is added/embedded into a housing of the lower face of the saddle, the dimensions thereof are adapted in particular as a function of the considered boss. By way of example, a square pad of 77 x 77 mm side is considered. In practice, only the winding and the lug connections, with or without a "bridge", are different. In alternative embodiments in which the pad is originally incorporated in the saddle, the pad may be plane or not, it may be 13 overmoulded in the saddle and it may be a pad that may be identical to those which are usable on site without previous overmoulding.

For bosses "X" of 40 x 3 mm, the housing has the following dimensions (the thickness corresponds to the depth of the housing): [TABLE 6] Type Thickness Diameter of External Length (in the of (mm) the central hole dimension longitudinal pad (mm) of the square direction) (mm) 1 typical: typical: 0.8 - 2 60 - 95 Square ranges preferably: preferably: + 26 mm typical: 1.0 - 1.8 65 - 90 - 45 2 typical: preferably: typical: 0.7 - 2.4 25 - 30 65 - 100 Square ranges preferably: preferably: + 26 mm 1.0 - 2.1 70 - 95 For bosses "Y" of 55 x 3 mm, the housing has the following dimensions: [TABLE 7] Type Thickness Diameter of External Length (in the of (mm) the central hole dimension longitudinal pad (mm) of the square direction) (mm) 1 typical: typical: 0.8 - 2 85 - 160 Square ranges preferably: typical: preferably: + 26 mm 1.0 - 1.8 40 - 60 95 - 145 preferably: 2 typical: typical: 40 - 45 0.7 - 2.4 90 - 165 Square ranges preferably: preferably: + 26 mm 1.0 - 2.1 100 - 150 It is understood that it is possible to make electro-weldable saddles adaptable to ND ranges with other dimensions and number of references than those presented hereinabove. This will be better understood thanks to the following explanations, which give more general indications about the modes of selection and calculation of the saddle dimensions.

In the following trigonometric modelling, Fig. 2 shows the non-stressed saddles (continuous arc of circle) and the stressed saddles (discontinuous arc of circle), that is to say tightened against PE100 (polyethylene) pipes at NDmin (i.e. minimum diameter, left diagram in Fig. 2) and NDmax (maximum diameter, right diagram in Fig. 2), the pipes being represented as circles. In one case, the saddle is tightened against the pipe (its diameter is reduced by the tightening stress) and in the other14 case, it is widened (its diameter is increased by the tightening stress).

The saddle dimensions can also be determined according to another modelling, this time a geometric one, in relation with Fig. 3. The latter shows on a single diagram the non-stressed saddle (continuous arc of circle) and the stressed saddle (discontinuous arc of circle), that is to say tightened against PE100 pipes at NDmin (i.e. minimum diameter) and NDmax (maximum diameter), the pipes being circles.

In this modelling, it is considered that the end of the saddle to be stuck on HDPE pipes of different diameters moves along a portion of ellipse in this range of deformation. This portion of ellipse is characterized by a great axis 2a equal to its internal arc (that which is intended to be put on pipes of different diameters) and a small axis 2b = (2/π) x 2a and has an eccentricity e, equal to 0.771 in the present case.

One of the essential characteristics of the saddles of the invention is their minimized lateral extent. Indeed, the arc of ellipse travelled by the lateral ends of the saddle during the deformations between NDmin and NDmax is equal to a times the integral from βmin to βmax of √(1 - (e sin(β))²) dβ. There thus exists a relation of proportionality between the arc travelled from NDmin to NDmax and a Ap. Now Ap = Aa’ / 2 and Aa’ = (B = a = e Rn) x ((1 / NRmin) - (1 / NRmax)): the maximum arc that can be travelled in terms of deformability and mechanical resistance of the saddle is hence mathematically and physically linked to ((1 / NRmin) - (1 / NRmax)).

To enlarge the multi-diameter range, i.e. (1/NRmax - 1/NRmin) increased, the half arc a (= B) of the saddle, which is one of the characteristics of their design, may be minimized.

In the case of two examples of saddle, we can have the following values: [TABLE 8] Saddle X Dn 68 Dn 125 θ (°) 89.6 64.6 Chord B’ (mm) 47.9 66.8 Arc B (mm) 53.2 70.5 NDmin (mm) 50 90 ^a ’max (°) 121.9 89.8 effective d1 (mm) 13.5 14.6 B’/2 (a’max - θ) 13.49 14.65 B/2 (a’max - θ) 14.97 15.46 NDmin (mm) 90 180 a’min (°) 67.7 44.9 effective d2 (mm) 9.6 11.8 9.16 11.51 B’/2 (θ - a’min) B/2 (θ - a’min) 10.16 12.15 Thus, B’/2 or B/2 multiplied by the angle variation with respect to the native reference angle e (before saddle deformation on a possibly different pipe diameter) is a good estimation of the effective deformation (with a maximum not to be exceeded).15 Based on these results, it is possible to select for the given examples a maximum value close to 15 mm for effective d1 and effective d2.

The thickness range and gradient, as well as the arc length of the saddles, can be chosen so as to respect the relation (Dn - NDmin) / (NDmax - NDmin) = 0.34 to 0.40, these limits being advantageous, and that, whatever the safety coefficient applied to avoid a breakage of the saddle or of the tightening strap on the extreme NDs. In this description, Dn (which is equal to 2 Rn) is the "native" diameter, that is to say before potential deformation of the saddle object of the invention.

Considering the values of the ratio (Rn - NRmin) / (NRmax - NRmin), a value considered as optimum can be taken, which is 0.363 = 1 - b/a = 1 - 2/π.

A ratio of the extreme ND (min and max) can also be considered, by the following relation: NDmax = 2.05 NDmin, wherein the coefficient 2.05 is advantageous but may preferentially be chosen from 2.0 to 2.1. Another coefficient of value between 1.1 and 3.0 may potentially be chosen to maximize the multi-ND applicability of the system. Therefore, a ratio NDmax to NDmin of 1.1 with NDmax = 200 mm and NDmin = 180 mm up to a ratio of 2.5, or even 3, for example from DN 75 to DN 225, can for example be provided.

Then: (Rn - NRmin) / (NRmax - NRmin) = R’ = 0.37 NRmax / NRmin = R’’ = 2.05 (or less) Rn / NRmin = 1 + R’ ((NRmax / NRmin) - 1) = 1 + R’ (R’’ - 1) = 1.3885 if R’’ = 2.05 (or less: 1.259 if R’’ = 1.7 for ex.) Rn / NRmax = (Rn / NRmin) / R’’ It is to be noted that the minimum of θ, B and B’ (i.e. the geometric characteristics of the saddle) are imposed by the smallest electrofusion pads liable to ensure a sufficient adhesion to the considered PE100 pipes, to which must be added a peripheral area of about 10 mm as well as the area corresponding to the device 28 for hitching the lateral strap attachment end at the lateral end of the flanges 20a, 20b. The hitching device 28 includes housings for receiving the catches of the tightening catch strap or any other hitching means for other types of straps, in particular ratchet or toggle straps.

Based on the obtained relations, the following saddle references may be made, by way of example, the listed values being nominal diameters in mm: For an "X"-type exit boss: * With R’’ = 2.05: - choice of two references with 2 ranges that do not overlap each other: 63-125; 140-280, - choice of three references with 3 ranges that do not overlap each other: 40-75; 90-180; 200-400, 40 - choice of three references with 3 ranges joining each other: 50- 90; 90-180; 180 355.

* With R’’ = 1.7: - choice of three references with 3 ranges that do not overlap each other: 63-90; 125-180; 200-340, 45 - choice of three references with 3 ranges joining each other: 63-90; 90-140; 140 250, - choice of four references with 4 ranges joining each other: 63- 90; 90-140; 140 250; 250-400.

For a "Y"-type exit boss: 50 * With R’’ = 2.05:16 - choice of two references with 2 ranges that do not overlap each other: 90-180; 200-400, - choice of two references with 2 ranges joining each other: 90-180; 180-355.

* With R’’ = 1.7: - choice of two references with 2 ranges that do not overlap each other: 90-140; 160-280, - choice of three references with 3 ranges that do not overlap each other: 90-140; 160-280; 315-500, - choice of three references with 3 ranges joining each other: 90-140; 140-225; 225-355.

As regards the feature of material thickness reduction towards the lateral ends of the saddle flanges, it may be expressed by a percentage of thickness reduction per mm of arc with respect to the thickness present towards the longitudinal inter lug axis (apart from the overheights and overthicknesses dues to the lug passages and to the boss).

This thickness reduction may for example correspond to a thickness of the flange on the boss side of 7.5 mm before the first groove and decreasing down to a flange thickness of 4.5 mm after the last groove, on the side of the lateral end of the flange. More generally, the flanges, on the boss side and apart from a groove, may have thicknesses between 6 mm and 9 mm and, on the lateral end side and apart from a groove, have thicknesses between 3 mm and 6 mm. The flange height difference between the boss side and the lateral end, and apart from the grooves and the hitching device, may be between 2 and 6 mm. It is also possible to implement saddles without flange thickness gradient, i.e. there is no flange height difference between the boss side and the lateral end, and apart from the grooves and the hitching device. Therefore, the saddle may have flanges of constant thickness that is, for example, between 8 and 9 mm. These heights, apart from the grooves, are measured at the highest point and apart from the boss itself or the semi-circular areas of reduced thickness lining the boss or the overheights or overthicknesses of the longitudinal inter-lug axis or of the device 28 for hitching the strap 3 at the lateral end of the flange 20a, 20b.

It is to be noted that this thickness reduction between the lower face and the upper face of the saddle towards the lateral ends of the flanges can preferably relate only the bottom of the grooves. Therefore, for example, a constant flange thickness of 8.5 mm is provided at the crests between the grooves and a height of material at the bottom of the grooves (height of material defined by the shortest distance between the lower face and the groove bottom) from 7.5 mm (towards the boss) to .4 mm (towards the ends of the flanges) in the case of five grooves per lateral flange for a saddle of half-arc B = 70.5 mm. 40 More generally, the depth of the grooves may be between 0.5 mm and 4 mm. The number of grooves may be between 3 and 11 per flange and in preferably between five and seven. Preferably, the depth of a groove is longitudinally constant but, in alternative embodiments, it may be different along the length and, in particular, decrease towards the longitudinal ends of the groove, or even the 45 groove may not go up to the longitudinal edges of the flange. Therefore, the grooves are preferably extended longitudinally from a longitudinal edge to the other of each flange and are hence lateral to the boss. Grooves may however be provided, which are lateral to the lug passages that are interrupted by the boss due to the fact that they are close to the longitudinal inter-lug axis. 50 Preferably, the grooves are in a regular angular arrangement, for example every17 .5° along the flange.

Preferably, the two lateral edges of each groove are two flat faces and the bottom of the groove is rounded with a small radius of about 0.5 mm, in order to limit the risks of crack initiation at the bottom of the grooves.

It is ensured that the shape of the grooves and their lateral sides allow an easy unmoulding of the saddle during the manufacturing thereof after an injection of HDPE in a saddle mould. For that purpose, it may be ensured that the faces that are the closest to the vertical of the lateral sides of the grooves are directed towards the centre of the saddle, which may be obtained for example with an opening of 98° applied to all the grooves.

The flanges hence have a quantity of material that decreases towards their lateral ends of attachment to the strap, and that, according to two modes: on the one hand, by reducing the thickness/height of material between the lower face and the upper face of the saddle towards the lateral ends of the flanges and, on the other hand, by reduction of the length (measured parallel to the longitudinal inter-lug axis) of the flanges towards the lateral ends of the flanges.

It is understood that the given indication may serve as a method for determining the dimensions of the saddles adaptable to different pipe NDs.

Other numbers of saddle references can thus be determined for the pipe DNs met.

Therefore, instead of the three references of the example given hereinabove and for HDPE pipes for drinking water, typically from 63 mm or even 50 mm to 315 mm or even 400 mm, it is provided as an alternative a number of references limited to: - 2 to 4 types of saddles and 1 to 2 electrofusion pads for "X" exit bosses of 40 x 3 mm, which may give up to 8 references; - 2 to 3 types of saddles and 1 to 3 electrofusion pads for "Y" exit bosses of 55 x 3 mm, which may give up to 9 references.

Moreover, given that the electrofusion pad is passed through at the centre thereof by a passage hole corresponding to the passage hole of the boss, the pad is preferably adapted to the dimensions of the boss.

Up to now, consideration was about a wet connection on a water pipe, but it is understood that the wet connection system of the invention can be applied to other fluids than water and, for example, gas.

For the inserts, the following dimensions may, for example, be used: [TABLE 9] Type of Internal thread Lower internal Upper external boss (mm) diameter (mm) diameter (mm) X 40 x 3 Typical: 28 - 38 Typical: 43 - 49 Pref. : 30 - 36 Pref. : 44 - 48 Y 55 x 3 Typical: 43 - 53 Typical: 58 - 64 Pref. : 45 - 51 Pref. : 59 - 63 It is also possible to provide wet connection systems for bosses adapted to gas pitch exits G 3/4’’, 1’’, 1’’1/4 and 1’’1/2.

In this case, the ranges to be covered may be distributed according to the number of references given by the following table: [TABLE 10]18 Type of Internal Lower internal Upper internal Upper external boss thread diameter of the diameter of the diameter of the (mm) boss (mm) boss (mm) boss (mm) G3/4’’ ∅e 40 Typical: 14 – 38 Typical: 29 - 49 Typical: 32 - 56 26.44 Pref. : 16 - 22 Pref. : 30 - 34 Pref. : 34 - 40 G1’’ ∅e 40 Typical: 21 - 38 Typical: 36 - 49 Typical: 39 - 56 33.25 Pref. : 23 - 29 Pref. : 37 - 41 Pref. : 41 - 47 G1’’ 1/ 4 ∅e 55 Typical: 30 - 53 Typical: 45 - 64 Typical: 46 - 73 41.91 Pref. : 32 - 38 Pref. : 46 - 52 Pref. : 49 - 57 G1’’ 1/ 2 ∅e 55 Typical: 36 - 53 Typical: 51 - 64 Typical: 52 - 73 47.80 Pref. : 38 - 44 Pref. : 52 - 56 Pref. : 55 - 63 Different types of grooves and potential sealing lips may be implemented on or in the central channel of the brass insert to ensure the leak-free screwing of a valve once the system in operation. Moreover, in order to improve the mechanical grip at the interfaces and the tightness, the presence of crenelations or relief on the faces of the brass insert may advantageously be used, just as the addition of holes to be filled with polyethylene during the step of injection.

It can be noted, on the cross-sectional view of Fig. 6 of a saddle intended to receive a metal insert, that a circular groove 26 formed into the boss is provided around the internal passage channel of the nipple. This circular groove is intended to receive a circular crown protruding downward the metal insert. In an alternative embodiment, a metal ring independent of an insert is installed, preferably overmoulded, into said circular groove 26.

As regards the electrofusion pads, the saddles may be provided with overmoulded pads, hence preinstalled, or with pads to be embedded into the saddle by the fitter, during the installation of the saddle, just before the electrofusion. In this latter case, the saddles and electrofusion pads so available as dissociated/separated parts may in particular allow avoiding errors of pipe or exit diameter ranges (40 or 55 mm) on which the connection is to be made. The electrofusion pads generally have a thickness of 1.1 mm and the housing depth is designed accordingly.

Integration of the electrofusion pads by overmoulding during the manufacturing of the saddles by PE injection (preferentially HDPE) into a mould initially ensures the grip and tightness between the rear of the pads (face of the pad that won't be in contact with the (HD)PE pipe and the inside of the saddle housings. In the case where the electrofusion pad is installed by embedding into the saddle housing by the final user on site, this is the step of electrofusion that allows ensuring the grip and tightness between the rear of the pads and the inside of the saddle housing.

Installation of a saddle system according to the invention for a wet connection to a pipe, for example a PE100 pipe, DN125, starts with a scratching of the pipe surface using the manual tool, in order in particular to eliminate the oxide layer usually present. This pipe surface is then cleaned with alcohol.

Then, if the electrofusion pad is not preinstalled, an electrofusion pad is placed on the pipe and the saddle in such a way that the pad is in the housing thereof and the two connection lugs of the pad pass through the two lug passages of the saddle. A tightening strap placed between the two lateral ends of the flanges and allowing the system to encircle the pipe is then tightened in order for the saddle with its electrofusion pad to be applied on the pipe surface through its whole lower19 face.

The tightening strap may be a toggle strap. The straps are bands made of plastic material, for example HDPE, PP, NYLON®, metal or woven, or a combination of the preceding. The tightening straps have a suitable width and, for example, 50 mm for the "X"-type saddles. The strap length is adapted to the diameter ranges provided for the different saddle references. It may be provided to cut strap length surplus once the latter tightened.

In Figs. 8 to 13 is shown an example of tightening catch strap 3 with its ball joints 32, usable with the saddles of the invention as well as a tightening tool 39.

In Fig. 8, the strap 3 is made of flexible plastic material so that it can be wound about the pipe. The strap 3 includes on its width three main areas, a central area including circular holes 31, in particular traction holes, and laterally two lateral catch areas 30. The catch areas 30 are here discontinuous along the strap 3, but in alternative embodiments, the areas may be continuous. Indeed, discontinuities in the lateral catch areas 30 allow for error proofing in the choice of the saddle reference with respect to the nominal diameter of the pipe on which it must be installed. The catch areas 30 are arranged in such a way as to allow a tightening and locking of the strap if the good saddle reference is used for the pipe on which said saddle is installed.

Typically, the catch strap 3 shown may be used for pipes of ND between 90 mm and 180 mm.

The ball joint 32, which is like a roll, is substantially cylindrical, just as the seat or cradle intended to receive it in the hitching device 28.

Two plastic material ball joints 32 have been slid/slipped along the strap 3, Fig. 8.

These ball joints will be hitched into the adapted hitching devices 28, which are at the two lateral ends of the flanges 20a, 20b of the saddle 2. The ball joint includes a through-notch 37 allowing the strap insertion and the sliding along the strap.

The ball joint 32 includes internally, in the through-notch 37, a locking plate 33 made of stainless steel, visible in the ball joint in Fig. 9, and whose relations with the catches are visible in Figs. 11 to 13. This locking plate 33, Fig. 14, includes two lateral locking fingers 35 that are intended to interfere with the catches 30 of the strap 3 and, in median position, a spring tab 34 that is inclined by about 30° with respect to the general plane of the locking plate 33 in the absence of stress exerted on the locking plate 33. The spring tab 34 bears against the material of the ball joint and is hence not inclined towards the inside of the through-notch 37 but towards the opposite. The spring tab 34 allows the locking plate to take two main positions in the ball joint, a retracted position when the spring tab is stressed and allowing the ball joint 32 to slide along the strap in a tightening direction and non retracted position locking the ball joint 32 along the strap in an untightening 40 direction. Therefore, the sliding of the ball joints can only occur in a tightening direction corresponding to a moving closer together of the two ball joints along the strap. The locking plate 33 thus forms a non-return ratchet within the ball joint.

Fig. 11 shows in more detail the relations between the strap 3 with catches 30, the ball joint 32 and its internal plate, a lateral locking finger of which has been made 45 visible. It may be provided on the surface of the ball joint, as shown in Fig. 11, a recess 36 intended to receive the end of a flat-head screwdriver which may serve to tilt a ball joint tightened on a saddle in order to unlock it from the catches of the strap and untight and remove the strap if desired.

The catch strap tightening system is centrable, possibly reusable. The tightening 50 system is ergonomic because it requires moderate efforts and may be tightened 20 using a non-disproportionate tightening tool, in particular the clamp 39 of Fig. 10.

Instead of the tool, a rod or a screwdriver may be used, to lever up a part of the saddle to pull the strap upward.

The tightening clamp 39 of Fig. 10 has two ends that can be moved apart or closer together, one of the ends including a claw 38 intended to be inserted into one of the traction holes 31 and the other end including a two-finger tab intended to bear on the lateral attachment end of the flange with a hitching device of the saddle.

It can be noted in Fig. 8, along the central area including the traction holes 31, which are circular, the presence of an elongated opening 31', which corresponds to an area where there can be no fastening by the ball joints 32. More generally, the ball joints can be held along the strap and allow a stable tightening of the saddle only in the areas in which catches are present.

Once the saddle 2 installed on the pipe and the strap 3 tightened in such a way that the lateral flanges 20a, 20b are applied against the pipe surface, the electrofusion is performed. After the electrofusion, the assembly is left to cool for at least 30 minutes and the tightening strap can then be removed, if desired, in the case it would be removable, as can be a toggle strap or the catch strap with its ball joints, which may be tilted thanks to the recess 36.

During the piercing of the pipe for wet connection, the connection equipment with the piercing tool is installed on the boss of the saddle. It may be preferable that the tightening strap is left in place during the piercing operation and removed only after, if the strap has to be removed.

An enhanced version of the system will now be described, in which the means for tightening the saddle to the pipe are enhanced.

Fig. 15 shows in a cross-sectional view an enhanced ball joint 32 with two locking plates 33 arranged inside the ball joint. The two locking plates 33 with spring tabs 34 and lateral locking fingers 35 operate similarly to the plate of the single-plate ball joint presented hereinabove. With this enhanced ball joint, the holding and tightening of the strap 3 are also improved both dynamically, during installation, and statically, after installation and tightening. It can be seen in the figures, during the sliding (Fig. 16), the passage of the locking fingers 35 over the catches, and after the final tightening, the locking finger 35 locked in the catches (Fig. 17). The use of two locking plates 33 allows a better distribution of the tightening stresses and reduces the risks of slipping and untightening between catches and locking fingers.

An enhanced tightening clamp 39 is implemented in Fig. 18. Figs. 19 and 20 allow a better visualisation of the structure of this enhanced tightening clamp 39 that includes a toothed plate 41 for driving the catch strap 3. In Fig. 20, the superposed teeth of the toothed plate 41 drives the catches of the strap 3, to pull the strap 40 upward, during the tightening of the enhanced tightening clamp 39 handles, a tightening that drives the toothed plate 41 upward. Therefore, the enhance tightening clamp 39 is positioned from the top of the flange end of the saddle, to allow tensioning the strap and the saddle on the pipe by traction on the strap and tightening thereof. 45 In Fig. 19, the enhanced tightening clamp 39 is back to the state in which it will latter be able to pull again the strap, the toothed plate 41 being moved down, the teethed thereof slipping over the catches of the strap 3. The enhanced ball joint 32 with its two locking plates 33 and the catch strap 3 operate like a ratchet. 50

Claims

21 Claims

1. A system (1) for wet connection to a fluid distribution pipe, the longitudinally elongated and cylindrical pipe being made of heat-weldable plastic material, the 5 system (1) comprising a saddle (2) made of heat-weldable plastic material, an electrofusion pad and a tightening strap (3), the saddle (2) having an upper face on which is formed a central boss (21) and a lower face intended to come against the pipe, the saddle (2) being longitudinally elongated and transversely rounded, the electrofusion pad including two connection lugs and being added in a housing 10 (5) of the lower face of the saddle (2), the two connection lugs passing through the thickness of the saddle in two lug passages (22) and arriving at the upper face of the saddle (2), the two lug passages (22) and the boss (21) being aligned with each other along a longitudinal inter-lug axis of the saddle (2), the saddle (2) having laterally, on either side of the longitudinal inter-lug axis, two lateral flanges 15 (20a, 20b), the lower face of the saddle being concave downward and having the shape of a cylindrical surface of determined radius, the two flanges (20a, 20b) of the saddle (2) having two lateral attachment ends (28) for attachment to the tightening strap (3), the tightening of the tightening strap (3) allowing the application of the lower face of the saddle (2) with its two flanges (20a, 20b) 20 against the pipe, wherein: a same saddle (2) is configured to be fastened by electrofusion to pipes of nominal diameters between a minimum nominal diameter, NDmin, and a maximum nominal diameter, NDmax, of NDmax/NDmin ratio between 1.1 and 3.0, without mechanical deterioration or leakage during the tightening and after electrofusion, and wherein 25 the flanges (20a, 20b) have a gradient of flexibility from the boss (21) towards the lateral attachment ends, the flexibility being maximum towards the lateral attachment ends and minimum towards the boss (21).

2. The system (1) according to claim 1, wherein the gradient of flexibility is 30 obtained by at least one of the following arrangements: - the presence of a plastic material whose composition varies from the boss (21) towards the lateral attachment ends, - the presence at the upper face of the flanges (20a, 20b), on each lateral side of the longitudinal inter-lug axis, of longitudinal grooves (25) parallel to each other 35 and to the longitudinal inter-lug axis, the thicknesses of material between the bottom of the grooves (25) and the lower face of the flanges decreasing in the transverse direction, from groove to groove, from the boss (21) towards the lateral end of the flange (20a, 20b), - the thickness of material of the flanges (20a, 20b) decreases from the boss (21) 40 to the lateral attachment ends, - the length of the flanges, as measured parallel to the longitudinal inter-lug axis, decreases from the boss (21) to the lateral attachment ends.

3. The system (1) according to claim 2, wherein the thickness of material of the 45 flanges (20a, 20b) decreases from the boss (21) to the lateral attachment ends, and the length of the flanges, as measured parallel to the longitudinal inter-lug axis, decreases from the boss (21) to the lateral attachment ends. 50 4. The system (1) according to any one of claims 1 to 3, wherein the system is 22 configured to allow the application of a tightening force up to 5 kN without mechanical deterioration or leakage during the tightening and after electrofusion, and in that the saddle is chosen so as to respect the relation (Dn - NDmin) / (NDmax -

4.NDmin) = 0.34 to 0.40, where Dn is the diameter of the lower face of the saddle 5 before tightening.

5. The system (1) according to any one of claims 1 to 4, wherein the upper face of the flanges (20a, 20b) has, on each lateral side of the longitudinal inter-lug axis, longitudinal grooves (25) that are parallel to each other and to the longitudinal 10 inter-lug axis.

6. The system (1) according to claim 5, wherein the thicknesses of material between the bottom of the grooves (25) and the lower face decrease in the transverse direction, from groove to groove, from the boss (21) to the lateral end of 15 the flange (20a, 20b).

7. The system (1) according to any one of claims 5 and 6, wherein the bottom of the grooves (25) s rounded. 20

8. The system (1) according to any one of claims 1 to 7, wherein the upper face in the circular junction part between the central boss (21) and the upper face includes at least two semi-circular areas (27) of reduced thickness of material of the saddle (2) between the upper and lower faces, said two semi-circular areas (27) of reduced thickness being arranged towards the two lateral sides of the boss 25 (21).

9. The system (1) according to any one of claims 1 to 8, wherein the electrofusion pad is overmoulded in the saddle (2). 30

10. The system (1) according to any one of claims 1 to 9, wherein the tightening strap (3) is a removable element intended to be removed once the saddle (2) electro-welded on the pipe.

11. The system (1) according to any one of claims 1 to 10, wherein the tightening 35 strap (3) is made of plastic material and includes catches (30).

12. The system (1) according to any one of claims 1 to 11, wherein, at the upper face of the saddle (2), each of the two lug passages (22) has an upward overthickness of material, and in that the upper face along the longitudinal inter-lug 40 axis includes an upward overthickness of material between the boss (21) and each of the two lug passages (22).

13. A facility for wet connection to a fluid distribution pipe, in particular for water, including the system (1) according to any one of claims 1 to 12, electro-welded on 45 said pipe.

14. An assembly for tightening a saddle made of thermo-weldable plastic material of a system (1) according to any one of claims 1 to 12, the assembly including, on the one hand, for use with a saddle, a tightening strap (3) made of plastic material, 50 having catches (30) and at least one ball joint (32) with two locking plates (33) 23 arranged inside the ball joint (32), the locking plates (33) having spring tabs (34) and locking fingers (35), and on the other hand, reusable, a tool (39) of the clamp type including a toothed plate (41) for driving the tightening catch strap (3).