AMERICAN N ATIONAL S TANDARD
ANSI/ISA-84.91.01-2012
Identification and Mechanical
Integrity of Safety Controls, Alarms,
and Interlocks in the Process Industry
Approved 20 September 2012
ANSI/ISA-84.91.01-2012
Identification and Mechanical Integrity of Safety Controls, Alarms, and Interlocks in the Process
Industry
ISBN: 978-1-937560-64-5
Copyright © 2012 by the International Society of Automation (ISA). All rights reserved. Not for
resale. Printed in the United States of America. No part of this publication may be reproduced,
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photocopying, recording, or otherwise), without the prior written permission of the Publisher.
ISA
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P.O. Box 12277
Research Triangle Park, North Carolina 27709
-3-
ANSI/ISA-84.91.01-2012
Preface
This preface, as well as all footnotes and annexes, is included for information purposes and is
not part of ANSI/ISA-84.91.01-2012.
This document has been prepared as part of the service of the International Society of
Automation (ISA) 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 Board; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle
Park, NC 27709; Telephone (919) 549-8411; Fax (919) 549-8288; E-mail: standards@isa.org.
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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 by the American
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ANSI/ISA-84.91.01-2012
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ADDITIONALLY, THE USE OF THIS DOCUMENT MAY INVOLVE HAZARDOUS MATERIALS,
OPERATIONS OR EQUIPMENT. THE DOCUMENT CANNOT ANTICIPATE ALL POSSIBLE
APPLICATIONS OR ADDRESS ALL POSSIBLE SAFETY ISSUES ASSOCIATED WITH USE IN
HAZARDOUS CONDITIONS. THE USER OF THIS DOCUMENT MUST EXERCISE SOUND
PROFESSIONAL JUDGMENT CONCERNING ITS USE AND APPLICABILITY UNDER THE
USER’S PARTICULAR CIRCUMSTANCES. THE USER MUST ALSO CONSIDER THE
APPLICABILITY
OF
ANY
GOVERNMENTAL
REGULATORY
LIMITATIONS
AND
ESTABLISHED SAFETY AND HEALTH PRACTICES BEFORE IMPLEMENTING THIS
DOCUMENT.
THE USER OF THIS DOCUMENT SHOULD BE AWARE THAT THIS DOCUMENT MAY BE
IMPACTED BY ELECTRONIC SECURITY ISSUES. THE COMMITTEE HAS NOT YET
ADDRESSED THE POTENTIAL ISSUES IN THIS VERSION.
The following served as members of ISA84 in developing this standard:
NAME
W. Johnson, Chair
V. Maggioli, Co-Managing Director
D. Zetterberg, Co-Managing Director
R. Dunn, Working Group Chair
A. Summers, Working Group Editor
R. Adamski
T. Ando
R. Avali
L. Beckman
J. Campbell
I. Chen
R. Chittilapilly
M. Coppler
M. Corbo
P. Early
C. Fialkowski
K. Gandhi
I. Gibson
J. Gilman
W. Goble
P. Gruhn
B. Hampshire
J. Harris
J. Jamison
R. Johnson
K. Klein
T. Layer
E. Marszal
N. McLeod
M. Mollicone
G. Ramachandran
R. Roberts
M. Scott
D. Sniezek
C. Sossman
R. Strube
L. Suttinger
COMPANY
Consultant
Feltronics Corp
Chevron Energy Technology Company
DuPont
SIS-TECH Solutions LP
RA Safety Consulting LLC
Yokogawa Electric Co
Westinghouse Electric Corp
Safeplex Systems Inc
Consultant
Aramco
Oil & Natural Gas Corp
Det Norske Veritas Certification Inc
ExxonMobil
Langdon Coffman Services
Siemens Inc
KBR
Consultant
JFG Technology Transfer LLC
Exida Com LLC
ICS Triplex
BP
UOP A Honeywell Company
EnCana Corporation Ltd
Consultant
Chevron
Emerson Process Management
Kenexis Consulting Corp
ARKEMA
SYM Consultoria
Systems Research Intl Inc
Suncor Energy Inc
AE Solutions
Lockheed Martin Federal Services
CLS Tech-Reg Consultants
Universal Instruments Corporation
Savannah River Nuclear Solutions
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T. Walczak
M. Weber
A. Woltman
P. Wright
ANSI/ISA-84.91.01-2012
Conversions Inc
System Safety Inc
Shell Projects and Technology-Engineering
BHP Engineering & Construction Inc
This standard was approved for publication by the ISA Standards and P ractices Board on
6 August 2012.
NAME
D. Dunn, Vice President
D. Bartusiak
P. Brett
J. Campbell
M. Coppler
E. Cosman
B. Dumortier
J. Federlein
J. Gilsinn
E. Icayan
J. Jamison
K. P. Lindner
V. Maggioli
T. McAvinew
R. Reimer
S. Russell
N. Sands
H. Sasajima
T. Schnaare
J. Tatera
I. Verhappen
W. Weidman
J. Weiss
M. Wilkins
D. Zetterberg
COMPANY
Aramco Services Co.
ExxonMobil Chemical Co.
Honeywell Inc.
Consultant
Det Norske Veritas Certification Inc.
The Dow Chemical Company
Schneider Electric
Federlein & Assoc. Inc.
NIST/EL
ACES Inc.
EnCana Corporation Ltd.
Endress + Hauser Process Solutions AG
Feltronics Corp.
Instrumentation and Control Engineering, LLC
Rockwell Automation
Valero Energy Corp.
DuPont
Azbil Corp.
Rosemount Inc.
Tatera & Associates Inc.
Yokogawa Canada Inc.
WCW Consulting
Applied Control Solutions LLC
Yokogawa IA Global Marketing (USMK)
Chevron Energy Technology Co.
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ANSI/ISA-84.91.01-2012
Contents
1
Scope ............................................................................................................................ 11
2
Normative references ..................................................................................................... 11
3
Definitions ...................................................................................................................... 11
4
Procedure ...................................................................................................................... 12
5
Informative references and related documents ............................................................... 13
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ANSI/ISA-84.91.01-2012
Foreword
ANSI/ISA-91.00.01 was initially developed to address a misunderstanding between regulators
and owner/operators with respect to implementation of United States OSHA (Occupational Safety
and Health Administration) 1910.119 as it related to process sector control systems in the USA.
Process sector owner/operators were being cited for having control systems that were not
compliant with OSHA 1910.119. At that time, there were no standards that distinguished between
basic process control systems and emergency shutdown systems that were covered under OSHA
1910.119 mechanical integrity requirements.
ANSI/ISA-84.01-1996 had been intended to clarify this issue but its complexity required an
extended development cycle (3-4 years). Therefore, ANSI/ISA-91.00.01 was approved as a fasttrack standard to clarify the difference between the basic process control system and the
emergency shutdown system. The standard was developed and issued in less than one year.
Over time, ANSI/ISA-91.00.01 as published became superfluous due to the publication of ISA84
standards and technical reports. However, the scope of mechanical integrity related to
instrumentation in the process sector includes process safety safeguards beyond emergency
shutdown systems.
Mechanical integrity of process safety safeguards includes inspection, testing, and
documentation. This updated version of ANSI/ISA-91.00.01 defines a general class of
instrumentation that should be addressed by the mechanical integrity program and provides the
associated requirements.
While this standard was originally developed to address concerns of users in the USA, the
principles and methodology presented may be applied globally by users in the process sector.
Finally, the ISA91 committee has been merged with the ISA84 committee due to the overlap in
the scope and purpose of the two committees. This has resulted in the issuance of this revised
standard with the new designation, ANSI/ISA-84.91.01.
Introduction
This standard establishes a procedure to identify the process safety functions that utilize
instrumentation to maintain safe operation in the process industry. In this standard, these
functions are implemented by safety controls, alarms, and interlocks.
Mechanical integrity and maintenance are important elements in process safety risk
management. In this standard, provisions for mechanical integrity and maintenance apply to
safety controls, alarms, and interlocks.
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1
ANSI/ISA-84.91.01-2012
Scope
1.1 This standard addresses the instruments that are classified as process safety safeguards by
the authority having jurisdiction (typically the owner/operator or local regulatory authority), and
establishes requirements for their mechanical integrity, including inspection/testing and
documenting the inspection/test results.
1.2 This standard is specific to process safety risk management in the process industry.
1.3 This standard does not address codes, regulations, and other requirements that apply only to
the nuclear power industry.
1.4 This standard does not address the mechanical integrity of non -process safety safeguards
(e.g., business or asset protection, environment al protection or non-instrumented safeguards).
2
Normative references
ANSI/ISA-84.00.01-2004 Parts 1-3 (IEC 61511 Mod), Functional Safety: Safety Instrumented
Systems for the Process Industry Sector .
3
Definitions
3.1
safety controls, alarms, and interlocks
process safety safeguards implemented with instrumentation and controls, used to achieve or
maintain a safe state for a process, and required to provide risk reduction with respect to a
specific hazardous event
NOTE 1 There are many types of safety controls, alarms, and interlocks, for example: safety alarm, safety interlock,
safety permissive, detection or suppression, emergency shutdown, safety critical control, and safety
instrumented system. Figure 1 illustrates their relationships to the process hazards analysis. The terms listed
in the illustration are not intended to be construed as the only terms applied to safety controls, alarms, and
interlocks; neither should it be assumed that each type is necessarily separate and independent.
NOTE 2 Refer to ANSI/ISA-84.00.01-2004 (IEC 61511 Mod) for additional requirements related to safety instrumented
systems.
NOTE 3 Examples of non-instrumented safeguards include rupture disks, relief valves, dikes, etc. They do not fall
within the scope of this standard.
ANSI/ISA-84.91.01-2012
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Figure 1 − Safety controls, alarms, and interlocks relationship to the process hazards
analysis (PHA)
4
Procedure
4.1 Identification
4.1.1 Safety controls, alarms, and interlocks shall be identified and documented in a manner that
clearly distinguishes them from other instrumented systems.
NOTE 1 Safety controls, alarms, and interlocks are typically identified during a process hazards analysis.
NOTE 2 Other instrumented systems include many types of safeguards that are not identified as process safety
safeguards or that are not required to provide risk reduction in the process hazards analysis for process
safety risks – for example, basic process control, batch control, state control, asset/business protection, and
quality control.
4.1.2 Safety controls, alarms, and interlocks shall be installed properly and consistent with the
design specification and manufacturer’s instructions.
4.2 Maintenance and testing
4.2.1 Safety controls, alarms, and interlocks shall be included in a mechanical integrity program
that uses periodic inspection/testing and preventive maintenance to maintain their integrity in the
operating environment.
4.2.2 Safety controls, alarms, and interlocks shall be periodically inspected, tested and
maintained in accordance with procedures that take into account good engineering practices.
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NOTE
ANSI/ISA-84.91.01-2012
Good engineering practice includes consideration of many factors, such as manufacturer recommendations,
other codes, standards and practices, internal practices, historical equipment performance, and prior
operating experience.
4.2.3 Periodic inspections shall assure that the instruments associated with safety controls,
alarms, and interlocks are installed properly and maintained in a manner consistent with the
design specifications and good engineering practices.
4.2.4 The frequency of mechanical integrity activities shall take into account good engineering
practices.
4.2.5 The records of inspections and tests of the safety controls, alarms, and interlocks shall
contain the following minimum documentation:
a) Date of inspection or test
b) Name of person who performed the inspection or test
c) Serial number or other unique identifier of the equipment on which the inspection or test
was performed
d) Description of the inspection or test performed (for example, checklist, procedure,
manufacturer’s recommendation)
e) Results of the inspection or test as compared to user-defined acceptance criteria (for
example, as-found and as-left conditions, corrective actions taken)
5
Informative references and related documents
5.1 US Occupational Safety and Health Administration (OSHA), “Process Safety Management of
Highly Hazardous Chemicals; Explosives and Blasting Agents, ” 29 CFR Part 1910, Federal
Register 57, 36, Washington, DC (1992).
5.2 US Environmental Protection Agency (EPA), “Accidental Release Prevention Requirements,”
40 CFR Part 68, Federal Register 61, 120, Washington, DC (1996).
5.3 Directive 96/82/EC of the European Parliament and the Council of 9 December 1996 on the
Control of Major Accident Hazards Involving Dangerous S ubstances and Directive 2003/105/EC
of the European Parliament and the Council of 16 December 2003 Amending Council Directive
96/82/EC on the Control of Major Accident Hazards Involving Dangerous Substances.
5.4 Control of Major Accident Hazards Regulations 1999, Statutory Instrument 1999/743 (as
amended), Her Majesty's Stationery Office, London 1999, ISBN 0 11 082192 0.
5.5 Guidelines for Safe and Reliable Instrumented Protecti ve Systems, Center for Chemical
Process Safety, May 2007, ISBN 978-0-471-97940-1.
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Developing and promulgating sound consensus standards, recommended practices, and
technical reports is one of ISA’s primary goals. To achieve this goal the Standards and Practices
Department relies on the technical expertise and efforts of volunteer committee members,
chairmen and reviewers.
ISA is an American National Standards Institute (ANSI) accredited organization. ISA administers
United States Technical Advisory Groups (USTAGs) and provides secretariat support for
International Electrotechnical Commission (IEC) and International Organization for
Standardization (ISO) committees that develop process measurement and control standards. To
obtain additional information on the Society’s standards program, please write:
International Society of Automation (ISA)
Attn: Standards Department
67 Alexander Drive
P.O. Box 12277
Research Triangle Park, NC 27709
ISBN: 978-1-937560-64-5