The utility model described in this application has a polyethylene pipe for making piping for distributing and transporting pressurised fluids. More particularly, this pipe model is fitted with a socketed end suitable for connecting to the end of another pipe of the same diameter, in order to fit the piping in line.

As is known, the manufacture of a polyethylene pipeline for transporting liquid requires the use and the coupling of a large number of pipes, particularly when their diameter is such as to not permit their transport in rolls.

There are numerous systems for coupling the pipes, amongst which a very widespread one consists of approaching and preparing the ends of the piping to be connected by welding with a butt joint. A first method that uses this technique is performed by placing a heated metal plate between the two ends of the pipes to be connected, which is removed after melting the ends of the pipes in contact with it, so that these ends come together and are pressed, thus permitting cohesion.

A second joining method of the ends of the pipes is based on projection welding the ends by using a circular joint containing an electrical resistance inside it. By applying a suitable current, significant thermal energy is produced by the well- known Joule effect. This heats up the turn and thus welds the contact surfaces between the joint and the ends of the pipes to be joined.

After a certain time, necessary to melt and completely join the contact surfaces, the energy supply is interrupted and sufficient cooling time is given,. After this the j oint is completed.

The greater distribution of projection welding with respect to the traditional welding system is justified by a series of advantages amongst which a larger surface welded. This guarantees a longer lasting joint and an increase of the mechanical performance and the possibility of joining pipes with differing thicknesses or belonging to different classes of pressure.

The pipes joined by means of projection welding also guarantee an excellent seal which is necessary to avoid leakage during the transit of fluids and to allow cables to be fitted when they are laid using compressed air. Finally, another well-known mechanical system for on-line joining of polythene pipes consists of using compression joints, these are based on clamping the pipe by means of a toothed ring which surrounds and clamps the pipe after a clamp ring is screwed.

All the known systems which either use a butt weld of the pipes to be joined or which foresee a mechanical type of connection by using connections, present a series of problems.

Indeed, the former require long and at times laborious preliminary operations which are necessary to ensure a good weld.

Moreover, a problem of this system is represented by the fact that the presence of an expert operator with an appropriate licence is necessary, as is the presence of

ideal weather conditions, without which a good weld cannot be obtained.

The heating procedure, pressurisation and cooling of the pipe ends also requires long processing times and the use of suitable equipment.

A further problem of butt welding systems consists of the excessive time to make the connection, whereas from a technological point of view, a difficulty of

creating such a system is connected to the need for the perfect alignment of the

joint to be welded with respect to the pipe to which it is applied.

As regards the technique which foresees joining the pipes by means of projection welding, it has the problem of being particularly difficult with respect to traditional methods. Even the second ones, that is those which foresee the use of compression joints have a series of difficulties amongst which the main one is undoubtedly their cost which has a significant effect on the price of completing the whole pipeline.

This model aims at providing a pipe which is pre-fitted with a joint and thus permits a saving on the cost of purchasing the joint or alternatively of the butt welding.

Another important aim is that of providing a pipe with which it is possible to obtain a rapid positioning and alignment of the elements to be joined making the presence of specialised operators superfluous.

A final aim is that of guaranteeing greater rigidity and bending resistance at the point where the pipes are joined.

These aims are achieved with the model which is described below in a preferable implementation but not limited by further possible developments within the

model, with the aid of the two attached tables of drawings which illustrate the following figures: fig. 1 An assonometric view of a joint obtained by means of the pipe with a socketed end; fig. 2 The same view as figure 1 with the socketed end of the pipe in a

longitudinal section; fig. 3 An assonometric view of the pipe with a socketed end, longitudinal section,

in the version with a reinforcing ring;

fig. 4 An exploded display of the pipe with a socketed end. fig. 5 An assonometric view of a joint obtained with a socket containing a single internal groove.

As illustrated in the attached tables, the pipe has one swollen end 1 obtained with a socketing machine. This is a machine that creates a shape in the pipe by means of thermomechanical action performed by a mechanical stopper which creates a swelling of the head by penetrating the end of the heated pipe.

The internal surface of the socket 1 has two grooves, the first groove 5 will house a trapezoid section toothed ring 2 which surrounds and squeezes the pipe T to be connected according to the longitudinal thrusts which tend to release the same pipe T.

The second groove 6 on the other hand has the job of housing a seal 3 which increases the hydraulic seal between the connected pipes.

Grooves 5 and 6 can be of any shape and geometry. In a further version, the external surface of the socket has a groove 7 in which a ring 4, which has the job of contrasting the radial forces exerted by ring 2, is

housed.

In another version grooves 5 and 6 on the internal surface of the socket are replaced by a single groove 8 which is used to contain simultaneously both the toothed ring 2 and the seal 3