API RP 669

This recommended practice (RP) provides guidelines for heat transfer equipment used in waste heat recovery systems in the petroleum, petrochemical and natural gas industries. Details of related equipment designs are included only where these are necessary to ensure proper design and operation and safe interaction with the heat recovery system. It indicates areas that need attention and offers information and descriptions of various types of heat transfer equipment available to aid in the selection of the appropriate heat recovery system.

This RP does not include detailed requirements for:
- process to process heat recovery systems,
- gas turbine exhaust heat recovery,
- CO boilers, or
- convection sections used within fired heaters.

The waste heat recovery systems included in this RP are typical of those currently in use and should not limit the use of alternate systems.

Instrumentation and controls for waste heat recovery systems are sometimes mentioned but is not meant to completely define all requirements. Other standards and documents, such as API RP 556, Instrumentation, Control, and Protective Systems for Fired Heaters, should be used to fully define the needed instruments and controls.