Describes the importance of the chemical characteristics of steam supplied to steam turbines and the need to prevent corrosion and deposition in steam space, in order to minimize the risk of turbine corrosion failures or loss of efficiency or output. Is applicable to turbines of all electrical output rating and any exhaust condition, i.e. condensing or back pressure. It is designed for new plant, but may be adapted for use on existing plant. The limits described in this specification are specifically designed to protect the steam turbine. This specification is applicable to steam turbines driven from any source, except geothermal plants in which the turbine is fed direct from the geothermal sources.