ON FORMATION OF CORROSION PRODUCTS IN SANITARY PIPES

In copper pipework, at work for about four years, blue coloured striat ions or areas, mainly composed of posnjakite (Cu4(OH)6SO4.H2O), were f ound (water chemistry (room temperature): pH = 8.1; SO4 = 24 mg/l; Cl = 16 mg/l; O2 = 10 mg/l). Moreover cuprite, tenorite and malachite wer e detected on the internal surfaces of copper pipeworks. After the pip ework had been in operation for five years, an NaHCO3-dosing apparatus was installed to treat water in all but one branch of the system. In the section with treated water, sulphate formation decreased while mal achite formation (Cu2CO3(OH)2) increased. Layer formation can be simul ated in electroysis experiments. Normal tap water alone or mixed with bicarbonate is used as an electrolyte.