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Linking PSM, NFPA, and ISA/IEC 61511 for Fired Equipment: The Wynnewood Refining Co. Case

PSM NFPA IEC 61511 Wynnewood boiler case
Refinery plant in Wynnewood, Oklahoma.

In 2012, one of the steam boilers at the Wynnewood Refinery in Oklahoma exploded during a turnaround, resulting in the death of two workers. It was discovered that the boiler in

question had a history of “hard starts.” As a result of this avoidable tragedy, the Occupational Safety and Health Administration (OSHA) cited Wynnewood Refining Company with multiple violations related to the Process Safety Management (PSM) standard under 29 CFR 1910.119.

The incident at Wynnewood impacted the families of those harmed, the corporation’s reputation, and the bottom line. It also set a precedent for how facilities should implement PSM applicability, interconnectivity, and proximity for fired equipment.

Interconnected boiler illustration

OSHA contended that the boiler was interconnected to a covered process through the refinery fuel gas system and steam header. The 10th Circuit Court of Appeals agreed and ruled on behalf of OSHA that the boundary of a PSM process can extend beyond vessels and piping that contain hazardous chemicals. This ruling determined that utilities and fired equipment posing the risk of a catastrophic release, independent of their connection to hazardous materials, may be drawn into a site’s PSM covered processes.

Many facilities rely on prescriptive applications, such as codes provided by the National Fire Prevention Association (NFPA), to manage fired equipment. While facilities have incorporated fired equipment, such as boilers, into their risk assessment process, the focus has historically been on the steam or process side of the equipment. Often the default for the Burner Management System (BMS) is the application of NFPA. Compliance with NFPA does not ensure compliance with OSHA PSM. In light of the Wynnewood ruling, PSM covered facilities must reevaluate their approach to fired equipment.

Per NFPA 85*, utilizing the equivalency provision, an alternative design to meet the requirements of the code can be accomplished where all the following are provided: (1) Approval of the authority having jurisdiction. (2) A documented hazard analysis that addresses all the requirements of the code. (3) A documented life-cycle system safety analysis that addresses all requirements of the code and incorporates the appropriate application-based safety integrity level (SIL) for safety instrumented systems (SIS). The NFPA codes (85, 86, and 87) all reference ISA/IEC 61511 as a recognized methodology for achieving equivalency. Likewise, OSHA also recognizes ISA/IEC 61511 as Recognized and Generally Acceptable Good Engineering Practice (RAGAGEP) for PSM covered processes.

The Wynnewood ruling points to one distinct conclusion: PSM covered facilities should evaluate the applicability of their PSM and NFPA management systems for their fired equipment to determine if they are in conformance with OSHA’s declared expectations.

* Reference Added to clarify equivalency: NFPA 85 Boiler and Combustion System Hazard Code 2019 Annex A, A4.11.


Keywords: Process Analysis, Process Safety Management, Combustion, Boilers, Fire Alarm Interconnected Systems, Fired Equipment, Safety Instrumented Systems, ISA/IEC 61511, NPFA 85, NFPA 86, NFPA 87, ISA 84, OSHA,


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