This part of IEC 60953, also called "retrofit code" (RC), establishes a supplementary retrofit code for thermal verification tests of retrofitted steam turbines. The rules given in this standard follow the guidance given in IEC 60953-2, hereinafter called the RS but contain amendments and supplements regarding guarantees and verification of the guarantees by thermal acceptance tests on retrofitted steam turbines. General principles for the preparation, performance, evaluation, comparison with guaranteed values and the determination of the measurement uncertainties of verification tests are given in this standard. This standard is applicable only when the retrofit involves some hardware change in the steam turbine equipment. Conversely, any modification on the cycle or any retrofit of other equipment of the power plant (e.g. boiler, feedwater heaters, etc.) is not covered by this standard .