This International Standard specifies general requirements intended to facilitate the procurement and supply of steam turbines and gas expansion turbines primarily for industrial applications.This International Standard should serve as a basis for any application although, for special applications, supplementary specifications may also be required, for example for general and special purpose industrial steam turbines used in the petroleum and natural gas industries.This International Standard is applicable to axial- and radial-flow industrial-type turbines (steam turbines and gas expansion turbines). It specifies the basic requirements for single-stage and multi-stage impulse or reaction turbines, which are not spared or are in critical service. In addition, this International Standard also specifies some requirements for driven machines, gear units, lubrication and sealing systems, controls, instrumentation and auxiliary units for turbine plants.Exceptions to the requirements laid down in this International Standard may be agreed between the purchaser and supplier.