1. Damage due to the pipes corrosion.

It is common knowledge that, all the steel underground conduits conveying gas, water, mineral oil, and so on as well as the big tanks and their connected big metal masses, are cheap and environmental. Their corrosion is generally due to electric currents coming from the ground, called "stray currents". The phenomena of corrosion of methane pipe-line, aqueducts, oil pipe-line systems, etc., caused by stray currents are particularly important and happen very quickly nearby electric railways, tram-ways, undergrounds, industrial settlements, stations supplying electricity, etc. The simple shrewdnesses of covering the pipes with insulating sheets, plastic sheathings, bituminizes, etc. or rather of setting them with particularly careful modalities, don't guarantee at all the indemnity of the pipes from the attack of the electric corrosion.

 

2. The active cathodic protection.

The tecnique of the active protection on this system of pipes by means of dispersors has been applied profitably for ages. Till some years ago they were of the "horizantal" type, that's to say placed on the surface at a distance of about 100 metres from the pipe to protect. such a technique is today surpassed by the fulfiment of dispersors of the "vertical" type, because this technique shows the following advantages: - Possibility to carry out the dispersors also nearby the pipes that must be protected (3 + 5m), with a smaller occupation of the ground, and without interfering on grounds belonging to a third party. - Better reliability with the passing of time, for a term at an average of 12-15 years of steady protection. - Better dispersion and yield, because the grounds where the anode is placed don't feel the effects of the variations of dampness and resistance, because of their depth (from 100 to 40 metres under the countryside ground). This technique of "cathodic protection" is practised now all over the world by the greatest Conveyance Companies of gas, mineral oil and water. In Italy the greatest users of such a technique are: SNAM, AGIP, ITALGAS, ENEL RETEGAS, TOSCANA ENERGIA, ITALCOGIM, TELECOM ITALIA and MUNICIPALIZED COMPANIES etc. There are some of the references of the company group FOREX-SONDITALIA, that are specialized in the application of system of cathodic protection "turnkey" since 1970.

 

3. Economic evaluations.

Americans ARGENT and SHILTON estimated that the cost of corrosion prevention on new pipes are to be between 5% and 12% of total construction costs. You should keep in mind that if at first glance seems high cost of cathodic protection, are well above the damage to unprotected water pipes, for: - Lost the product and its failure to sell. - The environmental damages and civil and criminal liability. - Repairs carried out and the surface area to be restored. Finally, it is worth remembering that a pipeline well protected cathodically maintain over time its commercial value.