When Are Human IPLs Valid, and How Are Their Pfds Assured in Practice

Rigorous systems are usually in place to ensure the availability of engineered controls to prevent process safety incidents. Do we apply the same rigor to ensure administrative controls are equally available? This paper presents the updated approaches first introduced in papers developed during the writing of Guidelines for Initiating Events and Independent Protection Layers, 2015, CCPS. These approaches have been proven in the field in many chemical facilities. Similar approaches have also been used for decades at nuclear power plants. Case studies of successes are shared in this paper, including from Eastman, which has begun using human IPLs once again, after pausing to get a validation program established.