Walter von Baeckmann spent 35 years with Ruhrgas AG, in the field of electrotechnical engineering, corrosion and corrosion protection and 23 years as manager of the corrosion protection department. Since retirement in 1985 he has been a consultant and a member of the editorial staff of the technical journal 3R International. He is the author of diverse text books and technical and scientific publications.Wilhelm Schwenk, Ph.D., was with the Research Institute of Mannesmann AG in Duisburg and was engaged in the field of corrosion and corrosion protection. Since retiring in 1994, he has been a consultant and member of numerous technical associations and committees. He has been a lecturer at the Technical University in Aachen since 1970. Professor Schwenk is the author of several text books and many scientific and technical papers.Werner Prinz (dec.) joined Siemens AG, Mülheim, and from 1961 to 1994 worked at Ruhrgas AG, Essen, where he was engaged in the field of electrotechnical engineering and corrosion protection as an assistant engineer in the corrosion protection department. In the field of electrotechnical and corrosion protection engineering he has been a member of many national and international technical associations including standardization and a chairman of many technical committees.