| Abstract: | The galvanic corrosion potentials of thirty-eight different waters were measured on site, using 'Oliphant' corrosion cells, for lead-tin solder coupled to copper. A wide range in corrosion potential was found, and the chloride-sulphate ratio had the most significant effect on corrosion potential. Tests to reduce corrosion potentials by dosing sulphate, silicate, zinc and orthophosphate were carried out. Zinc dosing, especially in combination with ortho-phosphate, was the most effective treatment for all waters, but posed problems.
Contamination of tapwater by galvanic corrosion of lead solder occurs early in the life of new plumbing, and risk of exposure to contamination can be reduced by flushing before drawing dietetic water. Best-of-all, lead-tin solder should not be used. |
