Use Process Historian Data to Verify Safeguards

Use field-level data from process historians to verify safety assumptions made during hazard analyses.

The chemical process industries (CPI) have driven toward performance-based design requirements to identify and manage risk, typically following a safety lifecycle model. As seen in the International Society of Automation (ISA) and International Electrotechnical Commission (IEC) 61511 standards (1, 2), the starting point of such a lifecycle is the hazard and operability (HAZOP) study or process hazard analysis (PHA), where the process hazards are identified and the risk assessment is performed.

High-consequence scenarios that are identified during the HAZOP are then assessed more carefully using a layers of protection analysis (LOPA). While the HAZOP and PHA are qualitative studies, the LOPA is a quantitative study that determines whether the probability of occurrence and severity of consequences meet a company’s risk tolerance. As part of this process, HAZOP/LOPA team members estimate the initiating event frequency (IEF), the failure frequency for components of the process control system, and the probability of failure-on-demand for independent protection layers (IPLs) like the safety instrumented system (SIS).

IEC 61511 requires defined performance targets for the SIS, a design that is verified and validated to achieve those requirements, and a functional safety management (FSM) process that demonstrates analysis of expected SIS performance against actual or achieved performance. This article demonstrates how to use operations data from your existing historians to verify assumptions made during the HAZOP/LOPA stage...