DRAFT RECOMMENDED PRACTICE
ISA-dRP105.00.01-201XCD3
Management of a Calibration Program For Monitoring And Control Systems
Approved xx month xxxx
ISA-dRP105.00.01-201X
Quality Management System for Implementation and Maintenance of an Industrial Calibration Program
ISBN:
Copyright © 201X by ISA, the International Society of Automation. 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, or transmitted in any form or by any means (electronic mechanical, photocopying, recording, or otherwise), without the prior written permission of the Publisher.
ISA
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Preface
This preface, as well as all annexes, is included for information purposes and is not part of
ISA-dRP105.00.01-201X.
This document has been prepared as part of the service of 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: .
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 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 countries. 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 by the American Society for Testing & Materials as IEEE/ASTM SI 10-97, and future revisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors.
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The following people served as members of ISA Committee ISA105:
NAME COMPANY
This recommended practice was approved for publication by the ISA Standards and Practices Board on
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Table of Contents
1 Scope 9
2 Normative References 10
3 Definition of Terms and Acronyms 10
4 Establishing a Calibration Program 10
4.1 Concepts 10
4.1.2 Loop calibrations versus device calibrations 11
4.2 Program Planning 11
4.2.1 Calibration system development 11
4.2.3 Calculating theoretical loop accuracy 11
4.2.4 Establishing Required Loop accuracy 12
4.2.5 Calibration equipment requirements 12
4.2.6 Calibration personnel requirements 12
4.2.7 Loop Performance Verification 13
4.2.8 Verification Intervals (loop criticality) 13
4.2.9 Responsibilities 14
4.2.10 Records System 14
5 Implementation of a Calibration Program 14
5.1 Concepts 15
Implementation 15
Program scope 15
5.2 Activities 15
5.3 Functions 15
6 Maintaining the Calibration Program 15
6.1 Control 15
6.2 Assurance 15
6.3 Improvement 15
7 Examples 16
AnnexA – Example Documentation 20
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Introduction
Purpose
The purpose of this recommended practice is to provide the basic framework for developing and maintaining a consistent calibration program for industrial automation and control systems. The recommended practice provides guidance for establishing a calibration program and establishes consistent requirements and methodologies related to verification and calibration of monitoring and control systems by considering the accuracy of each loop required by the process and then adjusting loop component(s) to achieve that loop accuracy.
Accurate, reliable, and repeatable operation of loops in monitoring and control systems is vital to maintaining the safety and reliability of a facility. A well-considered calibration program, properly implemented and maintained, can directly contribute to the assurance of the desired operation of the monitoring or control system for the facility. A calibration program establishes periodic assessments to be performed to monitor control system performance. Data acquired during these assessments not only aids in the establishment of future calibration intervals, but also is critical in the allocation of capital and operational resources. Clearly defined policy and procedures support the efforts of maintenance planners to schedule adequate labor and equipment for calibration both during and between facility outages. Procedures reduce the likelihood of human errors due to improper practices, assure the desired results of the calibration effort, and promotes the proper operation of monitoring and control systems.
Workforce and other economic factors directly affect the maintenance levels in most industries. As a result, many facilities have increased the calibration intervals for monitoring and control systems and their components. In some cases, facilities have simply eliminated routine calibration checks. The result is decreased accuracy and increased failure rates, both of which negatively affect facilities’ operations in many ways, including safety.
In the process industries, more hardware faults occur in measuring instrumentation, transmitters, and control valves than in the logic systems itself. Reducing or eliminating calibration and maintenance automation instrumentation and systems increases the likelihood of system problems, including:
· Reduced operator diligence in diagnosing failures of SIS equipment
· Inability of maintenance personnel to respond to SIS failures in a timely manner
· Increased errors in SIS equipment repair, calibration, inspection or testing
· Reduced efforts in preventative maintenance
· Reduced documentation of problem resolution
Maintenance practices for devices such as gauges and indicators, unfortunately, may occur only when the error in reading becomes large enough to be obvious to the operator or technician. Maintenance personnel routinely make decisions based on these devices. A faulty indication on such a device could lead to the release of energy. System accuracy and safety requirements should drive the calibration intervals for these devices.
Companies striving to maintain a safe working environment while ensuring the reliability of their facilities use calibrations as a means of verifying the functionality and accuracy of their equipment.
In the coming years, companies that employ automation professionals will lose a great number of senior technical and engineering staff members. Outsourcing has also contributed to this problem, as many companies are no longer capable of producing qualified automation professionals. In fact, manufacturers and companies providing technical support are also facing a growing shortage of experienced automation professionals. Whether companies use internal resources or rely on contractors, following this recommended approach to calibration will enable them to capture critical knowledge on their automation instrumentation and systems. Like other aspects of maintenance, there are many things to consider when establishing a company calibration program. Certainly, this is the case with the calibration of monitoring and control loops in a control system. This document presents a recommended approach to developing, implementing and maintaining a calibration program that is intended to lead to increased accuracy and reliability of monitoring and control systems, decreased production costs, and quality control improvements. More important, this approach is also intended to lead to increased safety of operation.
This approach to calibration has proven successful when companies have adhered to the concepts set forth in these guidelines, enabling those companies to realize the full benefits from a standardized approach to calibration.
The intended audience for this document is any company or industry that utilizes instrumentation in the monitoring and control of a process or facility.
Organization
This recommended practice is organized ….
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1 Scope
General Applicability
The recommended practice detailed in this document defines a baseline definition and model of a quality management system that can be utilized to implement and maintain a calibration program for industrial monitoring and control systems. It is applicable to all industrial monitoring and control systems.
Calibration
Industrial measurement and control systems have a direct impact on safety and operating performance, both being directly related to operating costs. When a measurement and control system is not meeting the operating accuracy needs of the process, safety risks and operating costs increase.
A calibration system for an industrial monitoring and control system is a methodology to periodically verify the accuracy performance of the components in that monitoring and control system and, when necessary, make adjustments to those components to bring them within their manufacturer rated accuracy and the loop within its required performance accuracy.
Each user company/facility must establish a calibration system specific to its needs. This recommended practice discusses the essential features of a calibration system and provides guidance how to establish such a system.
This proposed approach to the calibration of automation instrumentation and systems takes in consideration all known loop measurement errors and establishes calibration tolerances based on the process requirements. Successful implementation of this approach requires management commitment to make this a living process. Critical factors in the process include:
· Developing a comprehensive list of Instrumentation Equipment
· Establishing loop tolerances
· Establishing loop accuracy requirements
· Proper selection and use of field calibration equipment
· Maintaining calibration intervals
· Using qualified staff member to perform calibrations.
Exclusions
This document does not provide or recommend manufacturer-specific calibration procedures for specific instruments as these are established by the instrument manufacturer and are outside the scope of this document.
Regarding monitoring and control loops that are part of safety systems, these guidelines are intended to be supplemental to and not modify the requirements of ANSI/ISA 84 and all its parts.
2 Normative References
ANSI/ISA-84.00.01-2004 Part 1 (IEC 61511-1 Mod), Functional Safety: Safety Instrumented Systems for the Process Industry Sector - Part 1: Framework, Definitions, System, Hardware and Software Requirements.
3 Definition of Terms and Acronyms
Accuracy- the degree of conformity of a device’s output to its actual value.
Calibration – the act of adjusting (by comparison with a standard) the accuracy of a device to its reference standard.
The formal definition of calibration by the International Bureau of Weights and Measures is the following: "Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties (of the calibrated instrument or secondary standard) and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication."
Error – the difference between an indicated value and the actual value.
Loop – all of the hardware and software components that work together to make a process measurement and execute control of that process parameter.
Device Tolerance - the permissible limit of variation, from a known standard, in the device indicated process measurement
Loop Tolerance – the permissible limit of variation, from a known standard, in the loop indicated process measurement.
Verification – the act of checking the performance and accuracy of a loop or loop component to determine whether it is performing within required tolerances.
Reliability - the probability that the measurement will remain in-tolerance throughout the established calibration interval.
Observed Reliability -fraction of instruments that are found to be in-tolerance when calibrated.
4 Establishing a Calibration Program
4.1 Concepts
4.1.1 Monitoring and control instrumentation and systems currently used in industry range from pneumatics to digital electronics. These devices are as varied as the processes they monitor. Devices with moving parts require regular maintenance. These mechanical devices are much more susceptible to mechanical performance issues (e.g. binding and dragging due to environmental contamination) than are other automation instrumentation. Analog electronic instrumentation is subject to drift in settings and output. Digital instrumentation has multitudes of parameter settings that must be set properly to achieve desired operation. Devices not operating to their manufacturer’s specifications and/or not properly configured for the specific application can result in operational issues, such as off-spec quality and productivity issues, and safety issues. And then there is always the instrument failure. All of this results in a need for the loops important to safety, quality and correct operation of the facility be periodically checked for proper operation and calibrated when necessary.