ISA-TR84.00.02:2022

ISA-TR84.00.02-2022, Safety Integrity Level (SIL) Verification of Safety Instrumented Functions, is a comprehensive technical report by the International Society of Automation (ISA) providing guidance on the verification of safety integrity levels (SIL) for safety instrumented functions (SIF) within safety instrumented systems (SIS) in process industries. It supports ANSI/ISA-61511-1:2018 by detailing methodologies to assess and verify the average probability of failure on demand (PFDavg), probability of failure per hour (PFH) and spurious trip* rates through quantitative techniques such as fault tree analysis and Markov modeling. ISA-TR84.00.02 covers classification and estimation of random and systematic failures, diagnostic coverage, common cause failures, voting architectures and asset integrity programs essential for maintaining SIS performance. It includes practical examples, equations and annexes addressing complex scenarios like multiple safeguards, operator-initiated functions, partial testing and integration with mechanical safeguards. The technical report emphasizes that SIL verification is performance-based, requiring careful understanding of assumptions, device selection, management systems and operational data to maintain safety lifecycle compliance and effectively reduce risk. *A spurious trip, also known as a safe failure or false trip, isan unintended shutdown of a safety instrumented system (SIS) that occurs when a safety function is triggered without a genuine process demand.This means the system incorrectly believes there's a problem and initiates a shutdown, even though the process is operating normally.