NFPA 85 Boiler and Combustion Systems Hazards Code, 2015 Edition

Major changes in the 2015 edition of NFPA 85 include: New requirements to facilitate safe purging of fuel gas piping in and out of service, including requiring a designated equipment isolation valve, purging upstream piping in accordance with the applicable standard, and minimum safety requirements for purging piping and equipment downstream of the equipment isolation valve. Several provisions concerning multiple burner boilers (formerly in Chapter 6) were relocated to Chapter 4, General Requirements to indicate they apply to all equipment under the scope of NFPA 85. Relocated requirements include conducting a process hazard analysis for unattended operation, restrictions on removing interlocks from service during startup or operation, and preventing the flow of flue gases from a common stack into an idle boiler or Heat Recovery Steam Generator (HRSG). Safety-rated programmable logic controllers are recognized in the Code for use with single-burner boilers where they are certified as at least SIL 3-capable according to IEC 61508. Chapter 9, Pulverized Fuel Systems, was completely rewritten to separate requirements for direct-fired and indirect-fired systems to help users identify and apply requirements for specific equipment.