API RP 538 (R2021)

This recommended practice (RP) specifies requirements and gives recommendations for design, operation, maintenance, and troubleshooting considerations for industrial fired boilers used in refineries and chemical plants. It covers waterside control, combustion control, burner management systems (BMSs), feedwater preparation, steam purity, emissions, etc.

This RP does not apply to fire tube boilers, gas turbine exhaust boilers, or fluidized bed boilers.

This RP does not cover boiler mechanical construction. Purchaser or owner shall specify codes such as ASME, ISO, etc. This RP does not cover forced circulation boilers.