(46g) On What Do You Base the Safety of Your Process

Process Plants often require certain safeguards to satisfy management that the risk of operating the plant is sufficiently low.  The required safeguards are based upon the credible consequences of a process incident, and the events that cause them.  Safeguards can be preventative (preventing the incident from occurring), protective (e.g. safety relief valves) or mitigative (controlling and minimizing damage after the incident has occurred.  In each category, the safeguards might be split into those that are “have to have,” (i.e. the process will not be operated without this safeguard or a suitable replacement), and “nice to have,” (i.e. those without which the process could run for defined periods of time).  When the number of safeguards becomes large, it is difficult for the process operator to know them all, understand why they exist and what they do.  It can be difficult to prioritize the safeguards when developing Asset Integrity plans.  MOCs can be difficult to evaluate without knowing if a “have to have” safeguard is impacted vs. a “nice to have.”  This article will present a method of organizing and prioritizing safeguards, the key to which is determining on what you base the safety of your process.  By identifying the subset of “have to have” safeguards, a concise Basis of Safety can be documented for the process.  This document can then be used for operator training, maintenance and asset integrity prioritization, MOC review, and identification of safety-critical equipment such as sensors, regulators, valves, etc.