Limitations and Economics of Cathodic Protection

Abstract

It can be safely said that the technique of cathodic protection has already overcome the initial resistance to its acceptance which is normally encountered by any new concept or a new development. The resistance to the use of cathodic protector had been on the following basis:- (a) Everybody thought that corrosion of steel when buried in ground or immersed in water must be accepted as inevitable, and nothing could be done to prevent the losses due to corrosion except by keeping more spares or standby capacity, and by regular maintenance and repl-acement programme. (b) It was accepted that the application of paints or coating to steel buried in ground or immersed in water was all that one could do to prevent corrosion as painting or coating was the only practice known to many for preventing corrosion. (C) The claim that cathodic protection would prevent all further corrosion and give the structure almost indefinite life appeared to the customer that he is being sold some-thing which is not as good as is spoken of. But since its first application about 20 years ago in this country, cathodic protection has been found very useful, and technically a feasible proposition. Everybody familiar with it would agree that it does work, it prev-ents leaks and minimises repair cost. What was, a few years back, termed as a sales talk or a gimmick, has been found to be a sound engineering practice. On the other hand, many who have been associated with cathodic prot-ection one way or the other believe that cathodic prot-ection can prevent corrosion of all underground and under-water structures. But this is also not true. The purpose of this paper is therefore to discuss some of the technical limitations of applying cathodic prot-ection and then explain the economics of cathodic prot-ection when it has been successfully applied.