(126a) Overcome the Challenges of Implementing SIF for Reactive Processes

Safety instrumented systems (SIS), which implement higher integrity instrumented safeguards, are generally used against process safety hazards with the potential to severely injure, or even kill, personnel or members of the public. Due to the energy inherent to industrial chemical reactive equipment, reactive processes are a common application for safety instrumented systems. However, these applications are more complicated to implement than the typical safety instrumented system, so more process engineering involvement is needed to get the design right.

Reactive application SIS typically focus on the prevention of runaway reactions by ensuring that the temperature or pressure never reach an unsafe state. However, reactive processes respond to loss of control in a way that can complicate the specification of trip point, response time, and sensor subsystem architecture for the SIS. Likewise, while some simple applications can address the reactive hazard by closing emergency block valves, others may require blowdowns, kill agents, and other complex response actions. This paper will discuss some of the unique challenges posed by reactive applications and will provide examples to illustrate how to overcome these challenges.