Exploitation des résultats d'analyse de l'eau

Utilization of water analyse results

Service de Contrôle des Eaux de la Ville de Paris

Abstract

The corrosion of a water distribution network may originate from the characteristics of pipes, from the network structure or its use. The transported water can, by virtue of its composition, accelerate or, on the contrary, decelerate the rapidity of piping corrosion. The knowledge of the physico-chemical factors of the water can help determine the main origin of corrosion. The most important factors are : mineralisation. resistivity, nature of (the) dissolved salts, temperature and dissolved oxygen. Nevertheless, the basic feature is linked to the calco-carbonic equilibrium which controls a tight natural deposit of protecting calcium carbonate on the metal. The formation of such a deposit can be readily provided for by the agressive or calcifying character of the transported water. The many calculations necessary for such a study can be avoided by using the LEGRAND-POIRIER graph method described in this paper. The same method also allows the corrective treatments necessary to bring an agressive water to equilibrium, to be determined.