ITMI20102085A1 - "ELECTRIC GASKET FOR WELDED JOINTS OF EXHAUST PIPES" - Google Patents

Description

Description of the industrial invention entitled: ELECTRIC GASKET FOR WELDED JOINTS OF EXHAUST PIPES;

The present invention relates to the sector of pipes for the disposal of black, gray and rainwater sewage from civil or industrial buildings. In particular, it has as its object an electric seal for the hydraulic and mechanical seal connection of pipes or fittings in low pressure hydraulic drainage systems.

Currently, different types of drain pipes are commercially available for use inside buildings, ships and buildings in general.

These pipes can be classified according to the type of thermoplastic resin with which they are made and the type of connection between the elements of the pipe: polyvinyl chloride or PVC (UNIEN 1329) pipes, polyethylene or PE (UNIEN 1519) pipes, polypropylene pipes or PP (UNIEN 1451).

PE pipes require butt welding. Butt welding must be carried out by means of reciprocal positioning devices of the parts to be welded and must be carried out on the bench. When welding on site, welding by means of an electric sleeve is used as an alternative to normal butt welding (see for example patent US4493985). Butt welding of pipes, even with the aid of the coupling, requires the use of suitably trained and certified personnel.

The PVC or PP pipes, on the other hand, are joined by means of a male / female coupling which is made by providing, at one end of one of the two elements of the pipeline to be joined, a seat in which the section is inserted. end of the other element. The gasket, generally made of natural or synthetic rubber, is also housed in this seat, commonly called the "cup", and is responsible for implementing the hydraulic seal between the two elements.

PVC pipes are sealed with rubber gaskets or by gluing, while PP pipes are mounted exclusively with rubber gaskets.

It should be noted that in the polypropylene drain pipes market there is also a special product where pipes and fittings are provided with a specific socket (not according to UNIEN 1451), in which the internal surface of the socket is equipped with a metal spiral which , when it is crossed by an electric current, it is able to produce the welding with the external surface of the pipe which is placed inside the aforementioned special socket.

This known system, however, can only be used by tube-socket welding and is not compatible with UNIEN 1451 type gasketed cups.

This special product can use, instead of the metal spiral, a layer of conductive plastic compound (see US 2006/016552).

The main limitations of this commercial product are the high cost (non-standard product), the impossibility of verifying the successful welding by visual inspection and the impossibility of setting up pipes with mixed, gasketed or welded joints.

A first object of the present invention is to provide a gasket that can be used in normal pipes with UNIEN 1451 gasketed cups (commercially available), as an alternative to the normal gaskets currently used, without any modification to the pipes themselves.

A second object of the invention is to provide a gasket which allows to make joints with hydraulic and mechanical seal only in the pipe sections where this is required, thus being able to realize "mixed" systems, that is with simply hydraulic sealing sections of pipe and pipe sections. watertight and pressure piping.

This has been achieved, according to the invention, by providing an annular gasket replaceable to the gaskets for the hydraulic seal of pipes with socket joints type UNIEN 1451, which is equipped with electrical means to cause the melting of the gasket material in order to achieve the welding of the surfaces in contact with the gasket itself, to obtain a mechanical pressure seal of the coupling between two adjacent sections of pipe.

A better understanding of the invention will be obtained with the following description and with reference to the attached figures which illustrate, purely by way of non-limiting example, some preferred embodiments.

In the drawings:

Figure 1 is a 3D view of the electric gasket according to the invention, ready to be inserted into the socket of the pipe for the junction;

figure 2 is a partial sectional view showing a first embodiment of the gasket of fig. 1, which provides for an axial winding of the wire, ie disposed circumferentially with respect to the axis of the pipe, already positioned in the male / female junction of two pipes;

Figure 3, similar to the previous one, shows the areas where the fusion welding of the gasket materials takes place;

figure 4, corresponding to figs. 2 and 3, shows the electrical contacts for connection to the source of electrical energy for welding;

figure 5 is a partially sectioned 3D view, which schematically shows the main parts of a joint made with the gasket according to the present invention, in which said gasket is correctly positioned in the male / female joint of two pipes;

figure 6 shows the internal support ring of the electric coil with axial winding according to the first embodiment;

figure 7, corresponding to the previous one, shows the same internal support ring with the reel already wound;

figures 8 and 9, similar to figs. 7 and 8, relate to the radially wound coil of the second embodiment;

Figures 10 and 11 are respectively a side and top view of the electrical gasket according to the invention;

figure 13 is an enlarged detail of a section along an axial plane of line B-B indicated in fig. 11; And

figure 13 is a section on a diametrical plane corresponding to fig. 5.

The drain pipes 1 of the UNI EN 1451 standard (and similar) allow the discharge by gravity at ambient pressure of black, gray and rainwater. Current rubber / plastic gaskets, such as the one described in patent IT1365724, guarantee the hydraulic seal. In this case, the pipe-socket coupling allows quick and easy installation, but does not allow to withstand accidental internal pressures, even if modest.

On the other hand, by replacing the normal rubber / plastic gasket with the electric gasket G according to the present invention, a coupling joint is obtained which, in addition to providing said hydraulic seal, also provides a resistance to pressure which is even equal to the natural limit of the pipe !.

In other words, the innovative electric gasket G that is described allows to transform a gravity discharge system into a pressure discharge system and furthermore this electric gasket G is advantageously interchangeable with the normal gaskets having a simple hydraulic seal.

A first embodiment of the invention provides an electric gasket G substantially constituted by an annular body made of plastic material, inside which an electric resistance is arranged and uses a principle substantially similar to that used by the electric sleeves (Fig. 1).

By applying voltage to the ends of the electrical resistance G, the plastic material melts in proximity to the conductive wire coil 2 embedded in the annular body of the gasket itself. The fusion carries out the welding of the areas adjacent to the gasket, respectively inside the socket 3 and outside the tube 1 inserted therein (fig. 5).

The welding described above according to the invention guarantees the hydraulic and mechanical seal of the joint.

During welding, the molten material emerges from suitable holes 4 suitably positioned in the part of the annular body which is purposely provided externally to the cup 3, visually signaling that the operation has taken place (figs. 2 and 3).

Alternatively, during welding, the molten material covers a suitable disposable coil positioned in view in the part of the ring external to the socket 3, signaling that welding has taken place.

The annular body of the electric gasket G according to the invention preferably consists of a polypropylene ring that can be used for sealing the pipe / socket coupling of elements of drain pipes of the type according to the UNI EN 1451 standard.

According to the present invention, the gasket G is equipped with wire windings 2 which are arranged both on its outer surface and on its inner surface and are connected in series. When the electric winding 2 is crossed by current, due to the Joule effect, heat is developed which melts the plastic of the adjacent areas. The melting of the material and the pressures that are generated as a result of heating produce the welding of the following surfaces in contact:

A) internal cup 3 - external gasket G;

B) internal gasket G - external tube 1.

As already mentioned, the welding has taken place is adequately displayed in the specific portion of the electric gasket G which conveniently protrudes from the cup 3.

The electric gasket G object of the present invention replaces the current rubber / plastic gaskets (for example patent IT1365724) and is advantageously interchangeable with them.

In view of the foregoing, it is clear that by installing electrical gaskets G along the entire pipe, a plug-in pipe is obtained which, however, is resistant to a static pressure equal to the natural limit of the pipe for the application of forced drains (e.g. rainwater drains, naval - scuppers, gray water discharges from ships: P = 1.0 bar, etc.)

Otherwise, by installing electrical gaskets G only in some parts of the pipeline and using the normal (known) watertight gaskets in the remaining parts, it is advantageously possible to solve the problem of local overpressures typical of some installations such as rainwater drains of industrial buildings in conditions full section drainage due to torrential rain, horizontal collectors at the foot of columns of towers and skyscrapers in case of accidental obstruction, etc.).

A first advantage of the invention is that the electric gasket G described up to now allows to install a drain pipe in PP by exploiting its well-known ease of positioning offered by the male / female coupling, allowing then, after welding, to withstand high pressures of exercise.

A second advantage consists in the fact that the electric gasket G is visible and can be easily inspected: the visual inspection makes it possible to verify that the welding has taken place correctly.

A third advantage is that the present electric gasket G allows the creation of a low-cost pressure discharge pipe starting from a standard pipe (for example, but not exclusively, according to UNI EN 1451) by replacing the normal rubber gasket with the gasket electric G where it is needed.

A fourth advantage of the invention is that it requires no particular preparation of the personnel who carry out the assembly.

According to the invention, a suitably designed inner ring 5 is provided in the annular body of the gasket, preferably in PP, which acts as a support on which the electric wire 2 is wound to make the electric coil (figs.

6, 7 and 8, 9).

In the first embodiment that is described, said coil is wound in an axial direction, that is circumferentially with respect to the axis of the pipe (figs. 2, 3 and 4).

In a second embodiment, the electric coil is wound in a radial direction (figs. 8 and 9).

The electric coil 2 with axial winding allows the execution of a turning with mechanical deposition of the wire on the support ring.

The metal wire 2 can be either bare or coated with the same plastic of which the gasket is formed.

In both cases (axial or radial coil) after having made the winding the electric coil 2 is inserted in an overmoulding mold to obtain the final shape (fig. 1).

It is interesting to note how both the radial electric coil and the axial electric coil can function correctly even with the electric coils 2 in sight, eliminating the need for over-molding.

In this regard, in order to avoid that the winding turns are short-circuited in the case of uncoated wire 2, it is envisaged to make grooves in the support ring 5 within which the wire 2 is housed: both on the external side and on the inner side of the ring 5 itself.

In the event that the wire 2 is coated, said grooves are necessary at least on the internal side to keep the turns of the winding in position.

In light of the foregoing, it is clear that the present invention provides a cup jointing system 3, which allows to use indifferently rubber lip seals and electrical seals G.

According to a peculiar characteristic of the invention, outside the cup 3 it is advisable to provide a containment ring 6 adapted to balance the thrusts generated by the thermal expansion of the materials during welding.

Said external containment ring 6 is made of metallic material or of other material with a low coefficient of thermal expansion, such as for example a composite material of a known type.

Furthermore, said external containment ring 6 can be disposable or removable, such as for example a metal clamp with screw fastening of a known type, able to be disassembled after welding.

From the experiments, it has been verified that after welding there is no loss or mechanical failure by subjecting the joint to a pressure of 4 bar.

Finally, a third embodiment of the invention (not shown) provides that the support ring 5 in PP described above, on which in the previous embodiments the metal coils 2 are wound, is made with a compound formed by a matrix of PP with mineral charges (metallic, carbonaceous, etc.) such as to make it conductive, thus eliminating the need to wind the electric coils 2.

The concept of electric gasket G according to the present invention, described heretofore for PP pipes, can obviously be extended without modifications to any plastic pipe that can be welded by electro-fusion.

For example, the invention can be applied to plastic pipes for underground drainage, similar to those for drainage inside the building but with a larger diameter.

To make the welded joint according to the invention, it is envisaged to fit the gasket G into the seat of the socket 3, by hand or with the aid of a light mallet.

Welding takes place by connecting, to suitable pins 7 connected to the ends of the metal wire spirals 2 or to the conductive compound, an electricity supply which supplies a suitably predetermined quantity of energy.

Claims (17)

CLAIMS: 1. Electric gasket for the realization of welded joints of exhaust pipes (1) of the type with male / female end coupling with female cup (3), characterized by the fact of comprising an annular gasket (G) replaceable to the known gaskets for the hydraulic seal of pipes (1) with socket joints (3), which is equipped with electrical means (2) to cause the melting of the plastic material of the gasket in order to weld the surfaces of the pipe that are in contact with the gasket itself; thus obtaining - in addition to the hydraulic seal - also a mechanical pressure seal of the coupling between two adjacent pipe sections, transforming a gravity discharge system into a pressure discharge system. 2. Gasket according to the preceding claim, characterized in that it comprises an annular body (G) in plastic material inside which an electrical resistance (2) is arranged and uses a principle substantially similar to that used by the electric sleeves, so that by applying voltage to the ends of the electrical resistance, the material is melted near the coil of conductive wire (2) embedded in the annular body (G) itself; said molten material by welding the areas adjacent to the gasket: respectively inside the socket (3) and outside the tube (1) inserted therein. 3. Gasket according to the preceding claim, characterized in that, in order to signal that the welding operation has taken place, it provides holes (4) suitably positioned in view, from which the molten material emerges during welding, or it provides at least one turn disposable positioned on sight that is covered with molten material during welding. 4. Gasket according to claim 2, characterized in that said annular body (G) is made of polypropylene which can be used for sealing the pipe / socket coupling of elements of drain pipes of the type according to the UNI EN 1451 standard. 5. Gasket according to claim 1, characterized in that it is provided with wire windings (2) both at the outer surface and at the inner surface connected in series. 6. Gasket according to claim 1, characterized in that it provides an inner ring (5) preferably in PP suitably designed, which acts as a support for the winding, on which the electric coil (2) is wound. 7. Gasket according to the preceding claim, characterized in that the electric coil (2) is wound in the radial direction. 8. Gasket according to claim 6, characterized in that said coil (2) is wound in an axial direction, ie circumferentially with respect to the axis of the pipe (1). 9. Gasket according to the preceding claim, characterized in that the wire (2) which constitutes the electric coil with axial winding, is able to be mechanically deposited on the support ring (5) in a seat obtained by turning. 10. Gasket according to one of claims 6 onwards, characterized in that in order to obtain its final shape, a suitable over-molding mold is provided in which the electric coil (2) wound on the support ring (5) is inserted ). 11. Gasket according to claims 8 and 10, characterized in that to eliminate the need for overmoulding, the axial electric coil (2) is made with visible turns. 12. Gasket according to claim 1 or 2, characterized in that a containment ring (6) is provided on the outside of the socket (3) to balance the thrusts generated by thermal expansion during the melting of the material to prevent enlargement radial section of the socket (3) and obtain the welding. 13. Gasket according to the preceding claim, characterized in that said external containment ring (6) is made of metallic material or of other material with a low coefficient of thermal expansion, such as for example a composite material of a known type. 14. Gasket according to the preceding claim, characterized in that said external containment ring (6) is disposable or removable, such as for example a metal clamp with screw fastening of a known type, suitable for being disassembled after welding. 15. Gasket according to claim 1, characterized in that the PP ring which constitutes the support (6) of the metal coils (2), is made with a compound formed by a matrix of PP with mineral fillers, for example metal, carbonaceous, etc., such as to make it conductive; thereby eliminating the need to wind electric coils. 16. Gasket according to the preceding claim, characterized in that it provides suitable pins (7) connected to the ends of the electrical resistance or of the electrical winding (2) suitable for being connected to a power supply that supplies a defined quantity of electrical energy to carry out welding. 17. Gasket according to claim 11, characterized in that said metal wire (2) is bare or is coated with the same plastic of which the gasket (G) is formed.