Odata cu cresterea sensibilitatii populatiei marilor orase vis-à-vis de santierele de lucrari la suprafata, precum si cerintele de solutii ieftine pentru remedierea defectiunilor ce pot aparea la retelele de alimentare si canalizare, au condus la aparitia tehnicilor de reabilitare si modernizare a acestor retele fara a mai fi nevoie de sapaturi.
Pipe-Jacking – este o tehnologie de inlocuire a retelelor de conducte (gaz, apa, canalizare) care datorita gradului de uzura ( imbatranire) nu mai prezinta siguranta in functionare.
This technology consists of breaking the old pipe by introducing a so-called “breaking cone” and replacing it with another, of equal size or significantly larger, using the same route by pulling or pushing new pipes by the breaking cone.
Compared to the usual modernization process with HDPE pipes, this process can introduce pipes with a diameter equal to or even larger than the diameter of the host pipe, without the need to dig ditches. The pipes that can be replaced by “pipe-cracking” technology are usually made of materials such as: cast iron, steel, plain concrete, asbestos, PVC, polyethylene.
Reinforced concrete can also be successfully replaced if it is not strongly reinforced or if it is substantially damaged.
This head is coupled to a winch with a pulling power of at least 10 T, electronically controlled for the execution of a constant pull. Also, the action of the winch is coordinated with the breaking head, in order to facilitate its uniform advance and of the pipe coupled to it.
The air pressure required for percussion is provided by a compressor through a hose which is inserted through the new pipe and is connected to the rear of the breaker.
The launch pit of the bursting device and the new pipe must be dimensioned in such a way as to allow its “flow” without exceeding the maximum radius of curvature specified by the manufacturer – the optimal dimensions for the launch pit are: length – 4 m and width – 2 m.
Depending on the laying depth and the diameter of the pipe and implicitly of the allowed radius of curvature, several types of launching grooves can be chosen.
Another option is to use a pulling machine with capacity depending on the diameter of the new pipe and the material of the pipe to be replaced. The machine will be located next to the arrival pit of the rehabilitation section.
The company ULTRAJET SRL has equipment with power between 11 and 100 tf, with which “pipe jacking” works can be performed for pipes with diameters between 80 and 2000 mm. The machine is provided with metal rods that join together to form a chain the length of the section to be rehabilitated. At the proximal end of the section, at this chain of rods, the pipe breaking head will be engaged.
After attaching the burst head to the HDPE pipe and to the rods of the firing apparatus, the “pipe-jacking” operation begins.
In the case of brittle pipes (cast iron, ceramic, PVC or concrete), the advance of the firing cone causes the host pipe to break into fragments of different sizes and push them outwards. In the case of pipes made of flexible materials (PE) by advancing the firing cone, they will be cut longitudinally and dislocated so that they will form a tire around the new pipe.
As the HDPE pipe advances along the path of the old pipe, the rods are removed from the firing machine. At the end of the work, manholes or valves will be located or executed at the ends of the new pipeline. The new pipes will be connected to the manholes through fittings.
If the project does not provide manholes near the start-arrival pits, the pipe sections will be joined by inserting and welding a special pipe section between the ends of the pipe sections located by “pipe-cracking”. After the completion of the network connection works, the pipe is disinfected and put into operation.