This part of ISO 3977 covers the design requirements for the procurement of all applications of gas turbines and gas turbine systems, including gas turbines for combined cycle systems and their auxiliaries, by a purchaser from a packager. It also provides assistance and technical information to be used in the procurement.

It is not intended to deal with local or national legislative requirements with which the installation may be required to conform.

This part of ISO 3977 is applicable to simple-cycle, combined-cycle and regenerative-cycle gas turbines working in open systems. It is not applicable to gas turbines used to propel aircraft, road construction and earth moving machines, agricultural and industrial types of tractors and road vehicles.

In cases of gas turbines using special heat sources (for example, chemical process, nuclear reactors, furnace for a super-charged boiler), this part of ISO 3977 provides a basis.

The relevant parts of ISO 3977 are applicable to closed and semi-closed systems.