ISA TR84.00.02-2015 PDF

Full title and description

ISA-TR84.00.02-2015 — Safety Integrity Level (SIL) Verification of Safety Instrumented Functions. This technical report provides guidance and worked examples for verifying that Safety Instrumented Functions (SIFs) meet their assigned Safety Integrity Levels (SILs), including methodologies for quantifying probability of failure on demand (PFD/PFDavg), assessing spurious trip rates, and treating random, systematic, common-cause and common-mode failures.

Abstract

Informative technical report intended for users with a working knowledge of ISA/IEC functional safety documents. It explains techniques to support SIL verification — classification of failure modes, device failure-rate estimation, effects of diagnostics and mechanical integrity, treatment of common-cause and systematic failures, and quantitative methods (simplified equations, fault-tree and Markov approaches where applicable) to demonstrate that a SIF achieves its required SIL and acceptable spurious trip performance.

General information

• Status: Superseded (the 2015 technical report has since been updated by ISA-TR84.00.02:2022).
• Publication date: September 8, 2015 (designation -2015).
• Publisher: International Society of Automation (ISA).
• ICS / categories: Functional safety / process automation / safety instrumented systems (commonly associated ICS classifications used for related standards such as IEC 61511: 13.110; 25.040.01 — functional safety/process control).
• Edition / version: Technical Report — ISA-TR84.00.02-2015 (2015 edition).
• Number of pages: 136 (approx.; publisher listings show 136 pages for the 2015 TR).

Scope

Provides guidance for verifying that a Safety Instrumented Function (SIF) achieves its assigned Safety Integrity Level (SIL) and meets spurious trip rate constraints. The report assumes a SIS has already been identified by a hazard/risk assessment and does not replace hazard identification or SIL assignment activities; rather it supports the quantitative and qualitative verification of SIL through device-level failure-rate assessment, diagnostic and mechanical integrity considerations, and evaluation of systemic and common-cause contributions.

Key topics and requirements

• Methods for estimating average probability of failure on demand (PFDavg) for low-demand SIFs and related measures (PFH for continuous/high-demand modes discussed in later guidance).
• Classification and treatment of random hardware failures and systematic failures; guidance on selecting and documenting failure-rate data.
• Assessment of diagnostic coverage, mechanical integrity and the effect of testing/proof-test strategies on SIF performance and PFD.
• Consideration and estimation of common-cause/common-mode failures and techniques to address them in SIL verification.
• Application of quantitative techniques (simplified equations, fault-tree analysis, Markov models where applicable) and worked examples to demonstrate compliance with SIL targets and spurious trip constraints.
• Notes on limitations and topics deferred to later revisions (for example, expanded modeling for high-demand/continuous mode and lifecycle systematic contributions, which are addressed further in later editions).

Typical use and users

Used by process safety engineers, SIS designers, control-system engineers, safety managers, reliability engineers, third‑party assessors and asset owners responsible for demonstrating that SIFs meet assigned SILs. Typical applications include petrochemical, refining, chemical, pharmaceutical, pulp & paper, power generation and other process-industry facilities implementing safety instrumented systems.

Related standards

Closely related to and intended to support application of the ISA/IEC functional‑safety family and process‑industry standards, including ANSI/ISA‑84.00.01 (and IEC 61511 series), IEC 61508 (functional safety fundamentals), related ISA TRs (for example ISA‑TR84.00.03 on mechanical integrity and later TR revisions), and industry guidance such as CCPS LOPA and IEC/ISO technical reports referenced within the TR. The 2015 TR itself was later revised and consolidated in ISA‑TR84.00.02:2022.

Keywords

Safety Integrity Level (SIL), Safety Instrumented Function (SIF), Safety Instrumented System (SIS), PFD, PFH, spurious trip, common-cause failure, systematic failure, fault-tree, Markov, functional safety, ISA84.

FAQ

Q: What is this standard?

A: ISA-TR84.00.02-2015 is an informative technical report from the ISA84 committee providing guidance and calculation methods to verify that safety instrumented functions achieve their assigned Safety Integrity Levels (SILs).

Q: What does it cover?

A: It covers techniques to estimate PFD/PFDavg and spurious trip rates, classification of failure modes, device failure‑rate estimation, diagnostic and mechanical integrity impacts, and treatments for common‑cause and systematic contributions when verifying SIL.

Q: Who typically uses it?

A: Process safety engineers, SIS designers and maintainers, reliability engineers, safety auditors, and plant/asset owners in process industries use the guidance when performing SIL verification and documenting evidence that SIFs meet required performance targets.

Q: Is it current or superseded?

A: The 2015 technical report has been superseded by ISA‑TR84.00.02:2022; users should consult the 2022 edition for the most up‑to‑date guidance, although the 2015 TR remains a useful reference for earlier examples and methodologies.

Q: Is it part of a series?

A: Yes — it belongs to the ISA‑84 series of standards and technical reports addressing instrumented systems and functional safety for the process industries; related TRs include guidance on mechanical integrity, automation asset integrity, cybersecurity for the safety lifecycle and implementation guidance aligned with IEC 61511.

Q: What are the key keywords?

A: SIL, SIF, SIS, PFDavg, PFH, spurious trip rate, common-cause failure, diagnostic coverage, proof testing, fault-tree analysis, Markov analysis.