1、 NOTICE OF COPYRIGHT This is a copyright document and may not be copied or distributed in any form or manner without the permission of ISA. This copy of the document was made for the sole use of the person to whom ISA provided it and is subject to the restrictions stated in ISAs license to that pers
2、on. It may not be provided to any other person in print, electronic, or any other form. Violations of ISAs copyright will be prosecuted to the fullest extent of the law and may result in substantial civil and criminal penalties. STANDARD ISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod) Functional Safety:
3、Safety Instrumented Systems For the Process Industry Sector Part 3: Guidance For the Determination of the Required Safety Integrity Levels Informative Approved 2 September 2004 ISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod) Functional safety: Safety Instrumented Systems for the Process Industry Sector P
4、art 3: Guidance for the Determination of the Required Safety Integrity Levels - Informative ISBN: 978-1-55617-921-1 Copyright 2004 by IEC and ISA. All rights reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced, stored in a retrieval system
5、, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise), without the prior written permission of the Publisher. ISA 67 Alexander Drive P.O. Box 12277 Research Triangle Park, North Carolina 27709 USAISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod) 3 Copy
6、right 2004 ISA. All rights reserved. Preface This preface, as well as all footnotes, is included for information purposes and is not part of ISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod). This document has been prepared as part of the service of ISA the Instrumentation, Systems, and Automation Society
7、toward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms and asks that they be addressed to the Secretary, Standards and Practices B
8、oard; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-8411; Fax (919) 549-8288; E-mail: standardsisa.org. The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the Internatio
9、nal System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is further aware of the benefits to USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countri
10、es. Toward this end, this Department will endeavor to introduce SI-acceptable metric units in all new and revised standards, recommended practices, and technical reports to the greatest extent possible. Standard for Use of the International System of Units (SI): The Modern Metric System, published b
11、y the American Society for Testing any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. The IEC collaborates closely with th
12、e International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subj
13、ects since each technical committee has representation from all interested National Committees. 3) The documents produced have the form of recommendations for international use and are published in the form of standards, technical specifications, technical reports or guides and they are accepted by
14、the National Committees in that sense. 4) In order to promote international unification, IEC National Committees undertake to apply IEC International Standards transparently to the maximum extent possible in their national and regional standards. Any divergence between the IEC Standard and the corre
15、sponding national or regional standard shall be clearly indicated in the latter. 5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with one of its standards. 6) Attention is drawn to the possibility tha
16、t some of the elements of this International Standard may be the subject of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 61511-3 has been prepared by subcommittee 65A: System aspects, of IEC technical committee 65: Ind
17、ustrial-process measurement and control. The text of this standard is based on the following documents: FDIS Report on voting 65A/367/FDIS 65A/370/RVD Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. 12 ISA-84.00.01-2
18、004 Part 3 (IEC 61511-3 Mod) Copyright 2004 ISA. All rights reserved. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. IEC 61511 series has been developed as a process sector implementation of IEC 61508 series. IEC 61511 ANSI/ISA-84.00.01-2004 (IEC 61511 Mod) cons
19、ists of the following parts, under the general title Functional safety Safety Instrumented Systems for the process industry sector (see Figure 1): Part 1: Framework, definitions, system, hardware and software requirements Part 2: Guidelines for the application of IEC 61511-1 ANSI/ISA-84.00.01-2004 P
20、art 1 (IEC 61511-1 Mod) Part 3: Guidance for the determination of the required safety integrity levels The committee has decided that the contents of this publication will remain unchanged until 2007. At this date, the publication will be reconfirmed; withdrawn; replaced by a revised edition, or ame
21、nded. ISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod) 13 Copyright 2004 ISA. All rights reserved. INTRODUCTION Safety instrumented systems have been used for many years to perform safety instrumented functions in the process industries. If instrumentation is to be effectively used for safety instrumented
22、 functions, it is essential that this instrumentation achieves certain minimum standards and performance levels. This International Standard addresses the application of safety instrumented systems for the Process Industries. It also requires a process hazard and risk assessment to be carried out to
23、 enable the specification for safety instrumented systems to be derived. Other safety systems are only considered so that their contribution can be taken into account when considering the performance requirements for the safety instrumented systems. The safety instrumented system includes all compon
24、ents and subsystems necessary to carry out the safety instrumented function from sensor(s) to final element (s). This International Standard has two concepts which are fundamental to its application; safety lifecycle and safety integrity levels. This International Standard addresses safety instrumen
25、ted systems which are based on the use of Electrical (E)/Electronic (E)/Programmable Electronic (PE) technology. Where other technologies are used for logic solvers, the basic principles of this standard should be applied. This standard also addresses the safety instrumented system sensors and final
26、 elements regardless of the technology used. This International Standard is process industry specific within the framework of IEC 61508 (see Annex A of IEC 61511-1 ANSI/ISA-84.00.01-2004 Part 1 (IEC 61511-1 Mod). This International Standard sets out an approach for safety lifecycle activities to ach
27、ieve these minimum standards. This approach has been adopted in order that a rational and consistent technical policy be used. In most situations, safety is best achieved by an inherently safe process design. If necessary, this may be combined with a protective system or systems to address any resid
28、ual identified risk. Protective systems can rely on different technologies (chemical, mechanical, hydraulic, pneumatic, electrical, electronic, programmable electronic). Any safety strategy should consider each individual safety instrumented system in the context of the other protective systems. To
29、facilitate this approach, this standard requires that a hazard and risk assessment is carried out to identify the overall safety requirements; requires that an allocation of the safety requirements to the safety instrumented system (s) is carried out; works within a framework which is applicable to
30、all instrumented methods of achieving functional safety; details the use of certain activities, such as safety management, which may be applicable to all methods of achieving functional safety. This International Standard on safety instrumented systems for the process industry: addresses all safety
31、life cycle phases from initial concept, design, implementation, operation and maintenance through to decommissioning; enables existing or new country specific process industry standards to be harmonized with this standard. 14 ISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod) Copyright 2004 ISA. All rights
32、reserved. This standard is intended to lead to a high level of consistency (for example, of underlying principles, terminology, information) within the process industries. This should have both safety and economic benefits. In jurisdictions where the governing authorities (for example national, fede
33、ral, state, province, county, city) have established process safety design, process safety management, or other requirements, these take precedence over the requirements defined in this standard. This standard deals with guidance in the area of determining the required SIL in hazards and risk analys
34、is (H the determination of tolerable risk, see Annex A; a number of different methods that enable the safety integrity levels for the safety instru-mented functions to be determined, see Annexes B, C, D, E, and F. In particular, this part a) applies when functional safety is achieved using one or mo
35、re safety instrumented functions for the protection of either personnel, the general public, or the environment; b) may be applied in non-safety applications such as asset protection; c) illustrates typical hazard and risk assessment methods that may be carried out to define the safety functional re
36、quirements and safety integrity levels of each safety instrumented function; d) illustrates techniques/measures available for determining the required safety integrity levels; e) provides a framework for establishing safety integrity levels but does not specify the safety integrity levels required f
37、or specific applications; f) does not give examples of determining the requirements for other methods of risk reduction. 1.2 Annexes B, C, D, E, and F illustrate quantitative and qualitative approaches and have been simplified in order to illustrate the underlying principles. These annexes have been
38、 included to illustrate the general principles of a number of methods but do not provide a definitive account. NOTE Those intending to apply the methods indicated in these annexes should consult the source material referenced in each annex. 1.3 Figure 1 shows the overall framework for IEC 61511-1 AN
39、SI/ISA-84.00.01-2004 Part 1 (IEC 61511-1 Mod), IEC 61511-2 ANSI/ISA-84.00.01-2004 Part 2 (IEC 61511-2 Mod), and IEC 61511-3 ANSI/ISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod), and indicates the role that this standard plays in the achievement of functional safety for safety instrumented systems. Figure
40、 2 gives an overview of risk reduction methods. For existing SIS designed and constructed in accordance with codes, standards, or practices prior to the issue of this standard (e.g., ANSI/ISA-84.01-1996), the owner/operator shall determine that the equipment is designed, maintained, inspected, teste
41、d, and operating in a safe manner. 18 ISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod) Copyright 2004 ISA. All rights reserved. Figure 2 Typical risk reduction methods found in process plants (for example, protection layer model) 2 Terms, Definitions and abbreviations For the purposes of this document, th
42、e definitions and abbreviations given in Clause 3 of IEC IEC 61511-1 ANSI/ISA-84.00.01-2004 Part 1 (IEC 61511-1 Mod) apply. 3 Risk and safety integrity general guidance 3.1 General This clause provides information on the underlying concepts of risk and the relationship of risk to safety integrity. T
43、his information is common to each of the diverse hazard and risk analysis (H discussions and agreements with the different parties involved in the application; industry standards and guidelines; industry, expert and scientific advice; legal and regulatory requirements both general and those directly
44、 relevant to the specific application. 3.3 Role of safety instrumented systems A safety instrumented system implements the safety instrumented functions required to achieve or to maintain a safe state of the process and, as such, contributes towards the necessary risk reduction to meet the tolerable
45、 risk. For example, the safety functions requirements specification may state that when the temperature reaches a value of x, valve y opens to allow water to enter the vessel. The necessary risk reduction may be achieved by either one or a combination of Safety Instrumented Systems (SIS) or other pr
46、otection layers. A person could be an integral part of a safety function. For example, a person could receive information, on the state of the process, and perform a safety action based on this information. If a person is part of a safety function, then all human factors should be considered. Safety
47、 instrumented functions can operate in a demand mode of operation or a continuous mode of operation. 3.4 Safety integrity Safety integrity is considered to be composed of the following two elements. a) Hardware safety integrity that part of safety integrity relating to random hardware failures in a
48、dangerous mode of failure. The achievement of the specified level of hardware safety integrity can be estimated to a reasonable level of accuracy, and the requirements can therefore be apportioned between subsystems using the established rules for the combination _ 1In determining the necessary risk
49、 reduction, the tolerable risk needs to be established. Annexes D and E of IEC 61508-5 outline qualitative methods, although in the examples quoted the necessary risk reduction is incorporated implicitly rather than stated explicitly. 2For example, that a hazardous event, leading to a specific consequence, would typically be expressed as a maximum frequency of occurrence per year. 20 ISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod) Copyright 2004 ISA. All rights reserved. of probabilities and considering common cause failures.
