Corrosion of Copper in Cold-Water Plumbing Systems

Abstract

In 1985 about half of the pipework for cold water in a large public building in Clausthal was replaced. Within one year copper solubility increased. The first pipe perforations occurred in 1989. The characteristics of this corrosion differed considerably from the previously known types of corrosion. Water analyses indicated that the drinking water was normal. Microorganisms were detected on R2A-Agar, and microorganisms identified as a subspecies of the genus Sphingomonas were found on a special agar containing Cu(II) ions. Some of these copper-resistant microorganisms accumulated Cu(II) ions in the cell walls on their surfaces. The microbiologically induced corrosion could be detected with the following experiments. One meter of a tap line in the plumbing system was heated for 8 d from 6.5 to 33.9°C. Copper corrosion peaked at 20°C. In a second experiment, the pipe was heated to 70°C for 2 h. The pipe was flushed daily, and a measurable copper solubility was not detected again until ten days later. The microbiological experiments were carried out in cooperation with Dipl.-Biol. P. Arens and Priv. Doz. Dr. G.-J. Tuschewitzki of the Hygiene-Institut des Ruhrgebiets in Gelsenkirchen.

Inhibition effect of newly synthesised piperidine derivatives on the corrosion of brass in natural seawater

“…The studies show that copper surface is normally covered with a layer of cuprous oxide CuO and these inhibitors form protective barriers of inert, insoluble and long lasting polymeric Cu (I) complex coatings on the CuO substrate. These polymeric complex coatings are thermally stable, thereby inhibiting the corrosion process [9][10][11]. Cu (I) is formally bonded to N or S or O atoms of the inhibitor molecules.…”