This invention relates to a joining system for tubular fluid distribution elements. In particular, this invention deals with an integrated joining system in tubular elements capable of withstanding high fluid pressures.

Various types of joint systems for tubular elements for fluid distribution are known.

A first type consists of a system in which the joint between the circular section pipes takes place without the use of radial welding and without threading in which said joint occurs through a watertight cup that uses an elastomeric sealing gasket. Each single tubular element has, at one end, a socket fitting (female) and, at the opposite end, a fitting with dimensions equal to the nominal external diameter of the tubular element (male) with a tolerance such as to allow coupling between the same.

The hydraulic seal to the internal pressure (and to the vacuum) is ensured by means of a toroidal gasket (or other suitable shape) in elastomeric material.

The pipes can, therefore, be introduced one inside the other in order to create continuous piping.

This type of joint has the main drawback of absolutely not being able to guarantee the resistance to extraction between the pipes in the case of introduction of pressures of a certain force. In order to guarantee the resistance to extraction, suitable ancillary works such as concrete blocks, mechanical anchors, etc. are necessary.

These pipes are mainly used with relatively low atmospheric pressure values for the construction of aqueducts, irrigation systems, waste water, smoke evacuation, vacuum and sewerage. The materials used are many including metal, thermoplastic, ceramic and fibre cement.

They also have several drawbacks including the impossibility of a stable connection between the pipes when the fluid is under pressure, except through special processing and/or ancillary works.

Another known system consists of pipes with a continuous circular section and joint fittings, both made of the same metal material, in which the hydraulic seal to internal pressure (and vacuum) is ensured by a toroidal gasket (or other suitable shape) in elastomeric material.

The pipes can be easily inserted inside the socket of the jointing sleeve (or fitting of another shape: for example, elbow, reduction) and the anti-slip retention of the tubular element is achieved by pressing radial sectors by means of tools dedicated (mainly hydraulic clamps).

The pressure applied internally to the pipes cannot, therefore, cause the detachment (extraction) of one tubular element from the other due to the locking system consisting precisely of the deformed sections of the tubular element and fitting.

The materials used are mainly stainless steel and copper.

This system also has several drawbacks including the need to use two gaskets for as many assembly operations on a single joint, the need for specific equipment to perform the pressing, the impossibility of disassembly and reassembly in the event of errors or modifications and, finally, the possible error of “pressing” or positioning of the pipe by the operator, with the consequent risk of hydraulic system leaks and/or the need for a new execution of the joint with a significant increase in costs. Also known are joining systems by means of shell fittings, provided with radial recesses made in positive with respect to the external surface of the pipe, having the function of retaining the pipes and containing/compressing an elastomeric sleeve gasket. Each single tubular element has, near each end, a radial recess mainly with a rectangular or half-round section. This withdrawal is performed by mechanical processing or by plastic deformation (e.g., rolling). The two half shells are joined together by means of bolts, at the close ends of the two pipes and therefore perform a retaining function between the same pipes by means of the radial section protrusions able to fit into the corresponding recess of the tubular element and function hydraulic seal through containment/compression of the gasket between them contained in a seat of suitable geometry.

The pressure applied internally to the pipes cannot, therefore, cause the detachment (extraction) of the pipes due to the locking system constituted precisely by the recesses (grooves) of the tubular element that accommodate a radial tooth of similar section (without interference).

The complementary fittings use the same joining system, but the recesses (grooves) can also be obtained by forming in moulds (die casting, casting, forging, etc.). The materials mainly used are: steel, cast iron, stainless steel, and aluminium alloys.

Said system, although it allows a certain speed of installation except for the need to join together pieces of tubular element of non-standard lengths and the possibility of disassembly and reassembly, has several drawbacks including the high cost of the elastomeric gasket and the need for caulking of the tubular element at both ends. In addition to this, the elastomeric gasket, of large volume, is subjected to mechanical compression which is often not uniform, with a possible defect in the hydraulic seal (especially after installation, due to the possible elastic decay of the elastomer of which the gasket is made up).

The installation also requires a perfect alignment of the pipes due to the small depth of keying, which generates possible hydraulic sealing problems. Furthermore, there is a need for ancillary processing of one or more pipes (rolling, pressing, turning) if a different length of the tubular element is required than the standard supply. This operation of cutting to size a tubular element involves the loss of one of the two radial grooves, which must be recreated: therefore, the availability of suitable equipment on site is necessary. The grooves made by rolling cause, however, a localised narrowing (constriction) of the passage section which is repeated twice for each single pipe. Said variations in the passage section also determine turbulence and head losses as a function of the flow velocity value and the thickness of the pipes must be oversized in the event that the recessed groove is performed by removing material (e.g., turning). With this system, the maximum internal pressure values cannot normally exceed 8 - 10 bar. This is based on the safety coefficients established by international standards which may require minimum yielding pressures up to five times said operating pressures.

Another known joint system uses a radial band joint of shaped sheet metal that allows the retention of the tubular element by compression of a notched radial ring in sectors and the hydraulic seal by compression of a sleeve gasket. The band joint embraces the end sections of the two opposing pipes and is “reduced” in diameter by screwing two or more bolts in correspondence with a longitudinal opening of the band itself: the reduction in diameter causes the teeth to penetrate into the thickness of the tubes and the consequent contrast to the axial extraction and the tightening of the bolts allows the compression of the elastomeric gasket along the surfaces of the two pipes and the consequent hydraulic seal. The material mainly used for the construction of the basic elements is stainless steel.

The disadvantages of this system are the need for a perfect alignment of the piping due to the small depth of keying with consequent possible problems of hydraulic seal, the difficulty of insertion on the tubular element due to possible expansion limit of the band in some variables of the diameters of usable coupling. Furthermore, the tubular element requires caulking of the opposite end to the socket, the use of a torque wrench is mandatory for tightening the bolts and the elastomeric gasket of large volume is subject to mechanical compression which is often not uniform, with possible defect of hydraulic seal (especially after installation, due to the possible elastic decay of the elastomer of which the gasket is made). Even in this case, maximum internal operating pressure values higher than 8 - 10 bar are often not achievable. This is a function of safety factors established by international standards that may require minimum yielding pressures up to five times the operating pressures.

A last known joining system provides for the use of couplings with sleeve couplings with hydraulic seal by means of an elastomeric gasket and retention of the tubular element by means of compression half-rings acting on rings with a frusto-conical section with radial toothing and equipped with of tangential gap. The fitting is inserted axially on the pipes (and/or the pipes in the fitting) for the entire keying depth, passing the gasket (usually with toroidal section), placed in a seat of the body, up to the stop. By acting on the half-ring bolts, the diameter of the truncated cone ring is reduced, causing the radial toothing to penetrate into the thickness of the pipe. The truncated cone section improves the penetration of the teeth when the axial stress generated by the internal pressure undergoes its relative increase. The construction materials are mainly aluminium alloys, different metals and thermoplastics.

This joint system also has several drawbacks including the use of two gaskets for as many assembly operations on a single joint: the cost of the joint is quite high.

The present invention overcomes the aforementioned drawbacks by providing a stable and safe joint system for pipes that can be made in reduced installation times, using assembly equipment and accessories that are not complex, not bulky and normally supplied (Allen wrenches, fixed wrenches, battery screwdrivers of normal power).

The system also offers resistance to internal pressure of fluids up to, for example, 16 bar in operation with a safety factor of up to 4.5 times said value, in which the minimum yielding pressure substantially corresponds to 72 bar. Furthermore, it is always possible to assemble, disassemble and reassemble the pipes and use pieces of pipe of non-standard length without the need to recreate the flanges/recesses/grooves necessary for retention. Lastly, the system uses a single gasket, of relatively low cost, for each joint.

The present invention relates to an integrated joining system for tubular fluid distribution elements according to the characteristics of the attached claim 1. The invention will be described in detail in one of its embodiments, exemplary but not limiting made with reference to the attached Figures in which:

• Figure 1 illustrates a perspective longitudinal section of a tubular element according to this invention,

• Figure 2 illustrates an enlarged view of detail A of Figure 1,

• Figure 3 illustrates an enlarged view of detail B of Figure 1, • Figure 4 illustrates a perspective longitudinal section of two tubular elements joined by the system according to a first embodiment of this invention,

• Figure 5 illustrates the enlarged detail C of Figure 4,

• Figure 6 illustrates a top view of two tubular elements joined by the band fitting according to the prior art,

• Figure 7 illustrates a side view of what is shown in Figure 6,

• Figure 8 illustrates a longitudinal section according to A-A of Figure 7,

• Figure 9 illustrates the enlarged detail D of Figure 8,

• Figures 10a, 10b and 10c illustrate the assembly steps of two tubular elements joined together by means of the joining system according to the present invention,

• Figure 11 illustrates a perspective longitudinal section of two tubular elements joined together by means of the joining system according to a second embodiment of this invention,

• Figure 12 illustrates the enlarged detail E of Figure 11,

• Figure 13 illustrates a perspective longitudinal section of two tubular elements joined together by the joining system according to a third embodiment of this invention,

• Figure 14 illustrates the enlarged detail G of Figure 13,

• Figure 15 illustrates a perspective longitudinal section of two tubular elements joined together by means of the joining system according to a fourth embodiment of this invention,

• Figure 16 illustrates the enlarged detail F of Figure 15,

• Figure 17 illustrates the top view of a tightening ring according to th e present invention,

Figure 18 illustrates the side view of the tightening ring of Figure 17, • Figure 19 illustrates a further side view of the tightening ring of Figure 17,

• Figure 20 illustrates the cross section according to A-A of Figure 17,

• Figure 21 illustrates a perspective view of the tightening ring of Figure 17,

• Figure 22 illustrates the top view of a tightening ring according to a second embodiment of the ring of the present invention,

• Figure 23 illustrates the side view of the tightening ring of Figure 22,

• Figure 24 illustrates a further side view of the tightening ring of Figure 22,

• Figure 25 illustrates the cross section according to A-A of Figure 22,

• Figure 26 illustrates a perspective view of the tightening ring of Figure 22,

• Figure 27 illustrates the top view of a tightening ring according to a third embodiment of the ring of the present invention,

• Figure 28 illustrates the side view of the tightening ring of Figure 27,

• Figure 29 illustrates a further side view of the tightening ring of Figure 27,

• Figure 30 illustrates the cross section according to A-A of Figure 27,

• Figure 31 illustrates the cross section according to B-B of Figure 27,

• Figure 32 illustrates a perspective view of the tightening ring of Figure 27,

• Figure 33 illustrates a top view of the spacer according to the present invention,

• Figure 34 illustrates a side view of the spacer of Figure 33,

• Figure 35 illustrates a front view of the spacer of Figure 33,

• Figure 36 illustrates a section of the spacer according to A-A of Figure 33,

• Figure 37 illustrates a section of the spacer according to B-B of Figure 33,

• Figure 38 illustrates a perspective view of the spacer of Figure 33.

With reference to the aforementioned Figures, the tubular element 1 according to the present invention has, at a first end 2, with an enlarged cup-shape (female) equipped with a specially shaped flange 3 so as to create a concentric edge 4 external to the tubular element and respective cavity 41 turned towards the inside of said tubular element 1, suitable for receiving and retaining inside it an elastomeric gasket 11 with a circular seal or of other convenient shape. Said tubular element 1, in said end 2, comprises a radial groove 5 which is also concentric, flanked and external to said edge 4, provided with an end edge 6, protruding with respect to the external surface of the tubular element 1. The aforementioned edge 4 and the aforementioned radial groove 5 therefore form an “S”-shaped flange. A second end 7 (male) of the tubular element 1 is, on the other hand, of the same diameter as the tubular element and is equipped with a preferably continuous radial protuberance with a hump 8.

The tubes are then assembled by inserting the second male end 7 of a tubular element 1 inside the first cup end 2 of another tubular element up to the end of its axial stroke and, therefore, up to contact of a base or shoulder 9 of the cup-shaped end 2 with the edge of the second end 7, after this edge has passed the elastomeric seal 11 received in the cavity 41. In this position, said protuberance 8 of the tubular element 1 finds a nest in the end edge 6 of the tubular element .

To ensure axial retention between the tubular elements 1 and , a junction block 10 is provided consisting of two semicircles 27, 27’ which are placed radially around the tubular element 1, at said concentric edge 4 and at said end edge 6 thus clamping the two tubular elements 1, .

Said junction block comprises, at its ends, a pair of symmetrical protuberances 31, 3 , 32, 32’ with through holes 12, 12’ capable of accommodating tightening elements such as screws 13 which are locked with relative nuts 14. The two semicircles 27, 27’, on the inside, have radial cavities 15, 16 specially shaped so as to accommodate inside them the external edge 4 of the flange 3 in the cavity 15 and the end edge 6 of the said flange 3 in the cavity 16. The edge of the junction block 10 next to the cavity 16 (Figure 5) has an inclined wall 17 which rests on and covers the protuberance 8 of the tubular element 1 and is equipped with a tooth 18 which, in turn, rests on the outer edge of the tubular element 1.

The two semicircles 27, 27’ therefore geometrically copy the profile of the flange 3 of the tubular element G, the protuberance 8 and the adjacent part of the tubular element 1, thus creating a solid seaming bond when the tightening screws 13 of the junction block 10 are are screwed in.

In order to facilitate the alignment of the two locking semicircles 27, 27’, the use of a spacer 28 is provided (optional), specially shaped so as to partially accommodate the protuberances 31, 3 , 32, 32’ which must be joined together, thus acting as a fixing guide. Said spacer 28 is equipped with a bushing 29, able to fit into special holes 30, 30’ made in the protuberances 31, 3G, 32, 32’ as well as a through hole 33 to accommodate the tightening bolts 13.

In case, then, it is necessary to have a shorter tubular element due to the conformation of the network of pipes, it is possible to cut the male end 7 of the tubular element 1 that is the one with the radial protuberance 8. In this case, if the cut comprising said protuberance 8, in a second embodiment of the invention (Figure 11), the retention of the cut tubular element takes place by means of the use of a truncated cone-shaped crimping ring 19 equipped, in the internal part, with tooth 20, capable of gripping the tubular element when the screws 13 of the junction block 10 are tightened. Said ring 19 is also equipped with a notch 21 whose size is determined on the basis of the effective need for tightening the tubular element, according to its circumference and its thickness. It is inserted into the tubular element 1 and made to slide along it until it touches the upper part of the flange 3 of the tubular element ; in this position, the internal part of the junction block 10, in correspondence with the inclined wall 17, meets the external part of the ring 19 and, when the screws 13 are tightened, the inclined wall 17 presses on the inclined edge 24 of the ring 19, resulting in the crimping described above.

The particular geometry of the tooth 20 is such as to ensure the retention of the tubular element as it penetrates to an extent that varies from 0.5 to 1 or more millimetres in the tubular element 1, in relation to its thickness. The penetration must, however, be limited in order not to cause an excessive notch in the wall of the tubular element.

In further embodiments, preferably the crimping ring 19 is provided, in the internal part, with two or more teeth 22, 22’ or by a series of two or more teeth 23, 23’ parallel to each other and interspersed with free spaces so as to guarantee an even greater pressure seal.

In a third embodiment of the invention (Figure 13), the junction block 10 is composed of two locking semicircles 27, 27’ joined together, on one side, by a connecting pin 34 while, on the other side, the ends are free and can be joined by means of a fixing screw 13 with relative nut 14. In this case, should one wish to use the spacer 28, it is therefore possible to use only one.

The assembly of a pipe consisting of two or more tubular elements takes place simply by inserting one tubular element inside the other: the male part 7 of a tubular element is introduced into the socket 2 (female part) of the opposite tubular element up to end of the axial stroke in order to guarantee the overcoming of the elastomeric gasket 11 present inside it. It is therefore possible to create a network of pipes in a short time and with the help of a few simple tools.

Also in this case, should it be necessary to have a shorter tubular element for conformation needs of the piping network, it is possible to cut the male end 7 of the tubular element 1 that is the one equipped with the radial protuberance 8. In the event that the cut included said protuberance 8, according to a fourth embodiment of the invention (Figure 15), the retention of the cut tubular element takes place through the use of a truncated cone-shaped crimping ring 19 and with the methods already described in second embodiment.

The embodiments described in the present description and the configurations shown in the drawings are only the preferred embodiments of the present invention but the technical variants falling within the above expressed concept of the present invention are also to be considered protected by the patent.