The Evergreen PHA: An Essential Next Step

The evergreen process hazard analysis (PHA) is an essential next step in hazard identification, risk analysis, and process safety risk management. The evergreen PHA addresses weaknesses in PHA practices that allow the facility PHA to degrade and become out-of-date during the periods between five-year revalidations. This degradation in the PHA has the potential to elevate safety risk in the facility.

The origin of this problem may be traced to an original understanding of the PHA as being a study reflecting a point in time rather than a living component of facility process safety information and documentation. Regulatory language also tends to reinforce the notion that the PHA is a static set of information that requires refreshing. The requirement for five-year update and revalidation tacitly accepts the degradation of the PHA and the process safety information contained within the study during the interim periods. This allowance conflicts with the expectation that the PHA and process safety information must remain accurate and current.

This paper outlines pre-requisites that must be in place and initial steps that must be taken before moving to evergreen PHA. Initial steps include developing the document flow process, establishing triggering events, and defining PHA protocol for interim PHA studies. A phased approach for implementing evergreen PHA is outlined. Challenges and barriers, real and perceived, are discussed along with solutions.

The implementation of a well-designed and maintained evergreen PHA process not only supports better awareness of hazards within the facility, but also allows for continual improvement of the PHA. Five-year revalidation efforts may be reimagined and refocused to be more effective and to use resource time more efficiently. These benefits can ultimately contribute to safer and more reliable operations.

Keywords: process hazard analysis, PHA, evergreen, hazard identification, risk analysis, HIRA, management of change (MoC), root cause analysis, incident investigation, safeguards