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. TECHNICAL REPORT ISA-TR96.05.01-2017 Partial Stroke Testing of Automate
3、d Valves Approved 25 October 2017 ISA-TR96.05.01-2017 Partial Stroke Testing of Automated Valves ISBN: 978-1-945541-67-4 Copyright 2017 by 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, o
4、r transmitted in any form or by any means (electronic mechanical, photocopying, recording, or otherwise), without the prior written permission of the Publisher. ISA 67 T.W. Alexander Drive P.O. Box 12277 Research Triangle Park, North Carolina 27709 - 3 - ISA-TR96.05.01-2017 ISA Preface This preface,
5、 as well as all footnotes and annexes, is included for information purposes and is not part of ISA-TR96.05.01-2017. This document has been prepared as part of the service of ISA towards a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but
6、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 T.W. Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-8411; Fax (919
7、) 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 International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is further a
8、ware 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 countries. Toward this end, this Department will endeavor to introduce SI-acceptable metric units in all new and revised st
9、andards, 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 Society for Testing certifies industry professionals; provides education and training; publishes book
10、s and technical articles; hosts conferences and exhibits; and provides networking and career development programs for its 40,000 members and 400,000 customers around the world. ISA owns A, a leading online publisher of automation-related content, and is the founding sponsor of The Automation Federat
11、ion (www.automationfederation.org), an association of non-profit organizations serving as “The Voice of Automation.“ Through a wholly owned subsidiary, ISA bridges the gap between standards and their implementation with the ISA Security Compliance Institute (www.isasecure.org) and the ISA Wireless C
12、ompliance Institute (www.isa100wci.org). The following people served as members of ISA96.05 and contributed to this document: NAME COMPANY V. Mezzano, Chair Fluor Corporation W. Weidman, Managing Director Consultant L. Beckman SafePlex Systems, Inc. S. Boyle Consultant F. Cain Flowserve Corporation
13、K. Enos Rexa, Inc. K. Gandhi Kellogg Brown designers who identify automated valve applications whose potential failure rate in the operating environment indicates the need for more frequent testing than supported by the operability and maintainability requirements; and operations and maintenance per
14、sonnel who need to understand how partial stroke testing is performed and what it indicates about the mechanical integrity of an automated valve. Guidance related to the use of partial stroke testing in safety instrumented system (SIS) applications has been removed from this technical report. Refer
15、to ISA84 documents for guidance on SIS applications. The user of this document should be familiar with the operation of automated valves in order to fully understand the benefits of partial stroke testing. Where partial stroke testing is applied on safety related automated valves, the user is referr
16、ed to ISA-TR84.00.02, IEC 61508, and IEC 61511 Ed. 2. THE EXAMPLES OF PARTIAL STROKE TESTING DISCUSSED HEREIN REPRESENT POSSIBLE SYSTEM CONFIGURATIONS AND ARE PROVIDED FOR ILLUSTRATION PURPOSES ONLY. ANY DIAGNOSTIC COVERAGE VALUES ILLUSTRATED ARE PROVIDED AS EXAMPLES ONLY AND SHOULD NOT BE INTERPRET
17、ED AS A RECOMMENDATION. THE PERFORMANCE OBTAINED IN ACTUAL APPLICATIONS IS SPECIFIC TO THE OPERATING ENVIRONMENT IN WHICH THE AUTOMATED VALVE IS USED. AS SUCH, NO GENERAL RECOMMENDATIONS CAN BE PROVIDED THAT WOULD BE APPLICABLE IN ALL SITUATIONS. THE USER OF THIS TECHNICAL REPORT IS CAUTIONED TO CLE
18、ARLY UNDERSTAND HOW PARTIAL STROKE TESTING PROVIDES DETECTION OF VALVE ACTUATION PROBLEMS AND THE SPECIFIC ASSUMPTIONS RELATED TO ANY MANUFACTURERS CLAIMS. NOTE: If the PST is not implemented properly by the user, the PST could contribute to unwanted process shutdowns, erroneous valve failures, as w
19、ell as possible over-torqueing of the valve. Comments on the content of this document should be sent to ISA; 67 T.W. Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709. This page intentionally left blank. - 11 - ISA-TR96.05.01-2017 Introduction Significant investments have been made
20、in mechanical reliability and preventive maintenance programs for fixed equipment. These programs yielded significant performance improvements, demonstrating that it was acceptable to run the fixed equipment for longer periods between maintenance intervals (or turnarounds). The improvements have ext
21、ended the maintenance interval to the point where, in some market sectors, the fixed equipment is no longer the weakest link for reliable process operation. Attention is now shifting to standby devices, such as automated valves, which operate in a demand mode. Standby devices are used in many critic
22、al applications, such as instrumented protective systems, safety instrumented systems, life safety systems, emergency shutdown systems, and fire and gas systems (see ref. 2.1). Critical equipment reliability is important since failure may result in significant process impact. A reliable standby devi
23、ce operates as intended when required, does not require frequent repair and maintenance, and does not cause an inadvertent process disruption or shutdown. An important aspect of safety is the capability to detect device failure (e.g. incipient, degraded, and functional) so that identified failures c
24、an be corrected. For automated valves, complete on-line testing is limited in many applications. The extension of fixed equipment maintenance intervals (unit outages) has resulted in reduced off-line test opportunities and the automated valve must meet the required reliability in the operating envir
25、onment. Partial stroke testing can be performed on-line with a wide variety of equipment and can be executed either manually or automatically. This technical report discusses the applications where partial stroke testing may be useful, various approaches used for partial stroke testing, and data ana
26、lysis. Advantages and disadvantages are also discussed. Partial stroke testing may provide early detection of failures associated with the valve automation and provide indications of developing failures associated with the valve movement. Partial stroke testing is an approach that may enable the ide
27、ntification of certain failure modes associated with automated valves. Consequently, the number of valve failures detected will be different for rising stem and rotary actuators. This page intentionally left blank. - 13 - ISA-TR96.05.01-2017 1 Scope ISA-TR96.05.01-2017: is informative and does not c
28、ontain any mandatory requirements. is limited to automated valves normally operating in either a full open or full closed position. introduces the concept of margin analysis as a method of assessing PST results. relates loss of functional margin with possible failure modes and discusses the effectiv
29、eness of different PST approaches in identifying a loss of functional margin. discusses the possibility and effects of over-stroking the automated valve. discusses the possibility and effects of over-torqueing the stem of the automated valve. discusses the rationalization/justification in performing
30、 PST (benefits vs risk). The boundary of the automated valve includes the following: a) Valve, Actuator, Control Systems, Ancillary Components, and Monitoring Devices b) Actuation media regulation and filtration system c) Actuated valves whose safe position is specified d) Automated valves that empl
31、oy only pneumatic or hydraulic actuators e) Guidance related to testing of electric valve actuators is provided in ANSI/ISA-96.02.01 and are excluded from the scope of this technical report Guidance is provided for the following: a) Identifying when partial stroke testing may be useful b) Various cr
32、iteria to consider when selecting the partial stroke method, e.g., automated versus manual test execution, spurious trip potential, actuator force or torque output, and on-line maintainability c) The advantages and disadvantages of four basic methods of partial stroke testing: mechanical limiting, t
33、ravel limiting, position based, and solenoid operated valves d) The capability and limitations of the four measurement, analysis, and acceptance criteria approaches used to assess PST results. 2 References ISA-TR84.00.02, Safety Integrity Level (SIL) Verification of Safety Instrumented Functions, IS
34、A, Research Triangle Park, NC. IEC 61508-1, Ed. 2.0, Functional safety of electrical/electronic/programmable electronic safety-related systems Part 1: General requirements, IEC, Geneva, Switzerland. ISA-TR96.05.01-2017 - 14 - IEC 61511-1, Ed. 2.0, Functional safety Safety instrumented systems for th
35、e process industry sector Part 1: Framework, definitions, system, hardware and application programming requirements, IEC, Geneva, Switzerland. IEC 61511-1/Amendment 1, Ed. 2.0, Amendment 1 Functional safety Safety instrumented systems for the process industry sector Part 1: Framework, definitions, s
36、ystem, hardware and application programming requirements, IEC, Geneva, Switzerland. 3 Abbreviations DC diagnostic coverage ELP External leakage-process ELS External leakage-supply FMEA failure mode and effects analysis FO fast operation FTC Failure to close FTO Failure to open FTR Failure to regulat
37、e HSL Hydraulic system leakage LFM Loss of functional margin L/P Leakage/Passing (final element) LRT Leak rate test LTE Leakage to environment MAST maximum allowable stem torque or thrust PST partial stroke testing SF Structural failure SPO Spurious operation STC Slow to close STO Slow to open 4 Def
38、initions 4.1 actuator output the torque, thrust, or force capacity of the actuator. - 15 - ISA-TR96.05.01-2017 4.2 availability The degree to which an automated valve is in a specified operable and committable state when in service and called on to operate, at an unknown, i.e. a random, time. 4.3 by
39、pass: an action taken to override, defeat, disable, or inhibit equipment operation. These actions prevent equipment from operating as required. 4.4 dangerous failure: failure affecting equipment in a system that has the potential to put the system in a fail-to-function state or to cause the process
40、to be put in a hazardous state. 4.5 design margin: a theoretical value that is a result of the various safety factors applied during the design and sizing process. Safety factors may be applied by valve manufacturers, actuator manufacturers or specified by the user to increase the expected valve and
41、 actuator operating requirements to account for uncertainties in the sizing and selection process and to allow for changes in the requirements due to degradation of components over some period of time in service. 4.6 diagnostic coverage: fraction of failures detected by automatic on-line diagnostic
42、tests. The fraction of failures is computed by using the failure rates associated with the detected failures divided by the total rate of failures. 4.7 failure: inability of equipment to function as specified 4.8 failure mode: a symptom, condition, or effect by which a failure is observed. Failure m
43、odes are often divided into various categories: incipient, degraded, and functional 4.9 failure rate: The ratio of the total number of failures in a fixed population to the total cumulative observed time 4.10 full stroke test: timed movement of a valve from one position to the other position e.g. fu
44、lly open to fully closed or fully closed to fully open 4.11 functional margin the measured difference between the torque, thrust, or axial force required to move a valve to its required safe position and the capability of the actuator to move it to that position under process design conditions. When
45、 the valve and actuator are new, functional margin is generally equal to the design margin. After some period of time in service, functional margin may change due to valve and actuator degradation. 4.12 normal operation: operation of the process within the design envelope. Normal operation includes
46、any planned operational mode, such as steady-state, reduced rates, maintenance, testing, start-up, and shutdown. 4.13 off-line: process equipment is not operational (i.e., shutdown). 4.14 on-line: process equipment is operational (e.g., running, producing product). 4.15 operating environment: where
47、equipment is intended to be used, such as external environmental conditions, process operating conditions, communication robustness, process and system interconnections, and support system quality. ISA-TR96.05.01-2017 - 16 - 4.16 partial stroke test: a test that initiates travel of the automated val
48、ve toward a designated safe state but limits travel distance to an intermediate or partial stroke position. 4.17 process safety time: time period between a failure occurring in the process or its control system and the occurrence of the hazardous event. 4.18 reliability: the probability that the equ
49、ipment operates according to its specification for a specified period of time under all relevant conditions. 4.19 review: an inspection of the process equipment, drawings, procedures, emergency plans, and/or management systems, etc., usually by an on-site team and usually problem-solving in nature. 4.20 risk: a measure of human injury, environmental damage, or economic loss in terms of the event frequency of occurrence and the severity of the injury, damage or loss. 4.21 safe state: a state of the process wh
