External Corrosion in Modern Large Boiler Plant—Part 2

The first part of this article, which appeared last month, listed the conditions which influence the occurrence and rate of boiler corrosion, and described the mechanisms of high‐temperature corrosion arising from various causes. In this, the second part, the problems of low‐temperature corrosion are discussed. The conditions affecting this phenomenon are given, and the causes of acid attack and blockage are discussed, the main problem being the formation of sulphur trioxide. Plant trials and counter‐measures in various countries are also described.