ISA TR84.00.04 PART 2

Introduction

Used in conjunction with ISA-TR84.00.04-2005 Part 1, the exampleset forth in this technical report is provided to illustrate how toapply ANSI/ISA-84.00.01-2004 Parts 1-3 (IEC 61511Mod). It isintended to demonstrate one method to meet the requirements of thestandards. The reader should be aware that ANSI/ISA-84.00.01-2004Parts 1-3 (IEC 61511 Mod) is performance based, and that manyapproaches can be used to achieve compliance. Some of the methodsapplied in this example include: what-if and HAZOP techniques forhazard and risk analysis, LOPA for allocation of safety functionsto protection layers, fault tree analysis for SIL verification, andladder logic to document the application software requirements.Other techniques and tools could be utilized at each of these stepsin the safety lifecycle to meet the requirements of thestandards.

NOTE — Throughout this technical report, the term”ISA-84.01-2004″ is used to refer to ANSI/ISA-84.00.01-2004 Parts1-3 (IEC 61511 Mod).

The example utilizes the similar chemical process presented inAIChE CCPS, Guidelines for Safe Automation of ProcessApplications, 1993, and in PIP PCESS001 1999, SafetyInstrumented Systems Guidelines.

The safety lifecycle application in the CCPS version was basedon the initial version of IEC 61508. The safety lifecycleapplication in the PIP version was based on ANSI/ISA-S84.01-1996.The safety lifecycle example herein is based on ISA-84.01-2004. Asa result, the evolution of new design requirements can be assessedby comparing this example with previous versions.

This example selects a subsystem of a process and applies to itthe design philosophy, procedures, techniques, and verificationmethodology discussed in ISA-84.01-2004.

This example shows cradle-to-grave documentation for each SIF.This documentation pedigree gives auditors and plant personnel themeans to track the SIF through the safety lifecycle phases back tothe process hazards analysis (PHA) that created it. Each SIF isclearly identified in each document to facilitate tracking betweenlifecycle phases. A vital part of safety is the ability todemonstrate to others (e.g., auditors, regulators, insurancecompanies) that the risk reduction provided by each SIF isadequate.

This example does not represent a complete design for apolymerization process because of the extensive detail that isrequired to achieve a high-integrity, safely automated design. As aresult, this example includes a number of simplifications.

All references shown refer to information within this exampleunless otherwise noted.

Edition:

05

Published:

01/01/2005

ANSI:

ANSI Approved

Number of Pages:

84

File Size:

1 file , 3.5 MB