(105a) Safety Incidents in Ethylene Plants

Many similar safety incidents occur in ethylene plants throughout the world. While these should be well known to plant operators, our paper lists these more common safety incidents along with their root causes. We then discuss several less common safety incidents that have occurred: ? Heater over-firing on partial trip ? Heater over-firing on emergency fuel ? Column over-filling

All these incidents were related to or caused by problems in the control system. Some occurred because the operators did not use or fully understand the system. Others resulted from faulty configuration or a lack of understanding of the process by the systems design engineer.

We believe that these particular incidents are important because they can potentially occur in any ethylene facility. Also, they involve the control system, which is often treated as a black box. As such, it represents a gap in the knowledge of some operators and engineers.

The paper then discusses a potential control related safety issue related to Safety Instrumented Systems (SIS). Many plants utilize SIS based flare reduction approaches. These systems require rigorous periodic testing to retain their required reliability.

We then discuss incident analysis techniques and provide a list of key factors based on our experience.