IEC 60609-2:1997 serves as a basis for the formulation of guarantees on cavitation pitting on Pelton turbine runners. It also provides a basis for the measurement and evaluation of the amount of cavitation pitting on Pelton turbine runners of a given turbine, which is defined in the contract by power, specific hydraulic energy of machine (head), rotational speed, material, operation etc. Guarantees which restrict the extent of caviation pitting and drop erosion on Pelton turbies at the end of an operating period specified in the contract are necessary when the pitting is expected in all or in some operating ranges.