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Safety Instrumented Systems

Instrumented Protective Functions and Emergency Shutdown (ESD) and Process Shutdown (PSD) Systems

HIMA is the first port of call for many companies throughout the world when it comes to safety-related automation solutions. 

The secret of our success is that we focus uncompromisingly on the field of safety. 

That is because focus leads to absolute expertise and increases experience - and that in turn means better ESD, BMS and F&G.  

Go to HIMA Australia’s website for more information.  

   

The following papers have been generously provided to ICEweb by our valued sponsor HIMA - Please support our sponsors, without them ICEweb could not exist.

HIMA Australia are running the following courses;

TÜV Functional Safety Program - This course has been developed to provide an overview of current industry standards such as AS 61508 and AS 61511, functional safety concepts and current tools used to determine safety levels while applying industry recognised techniques and methodologies.  
Perth 29 June- 2 July 2010
, Melbourne 23-26 November

Analysis & Design of SIS Course - The objective of this course is to provide engineers with the functional safety knowledge required to analyse and design safety instrumented systems for the process industry in compliance with the analysis and realisation phases of the AS 61511 safety lifecycle.
Perth 20 April , Adelaide 27 April, Brisbane 8 June .

Operation & Maintenance of SIS Course - The objective of this course is to provide operations and maintenance personnel with the functional safety knowledge required to operate and maintain any safety instrumented system such that the designated functional safety is maintained throughout the operation and maintenance phase of the AS 61511 safety lifecycle.
Perth 21 April, Adelaide 28 April, Brisbane 9 June .

Electronic Machine Guarding - This training course is designed for electrical workers who design, modify, service and commission machines with electrical safeguards. From concept to commissioning, and well into the operational phase of a device, participants will have the skills and knowledge to comprehend and solve most machine safety problems.
Melbourne 16-17 March, Adelaide 4-5 May

HIQuad Maintenance Course - The HIQuad maintenance course is a two day course designed to provide hands on practical troubleshooting experience for the HIQuad range of safety controllers. Students will build an understanding of the safety principles of HIQuad programmable electronic systems.
Perth 9-10 March 2010

HIMatrix Engineering Project Development - This training course is designed to provide the knowledge required for control engineers to design, develop and deploy functional safety projects using HIMatrix Controllers. Participants are introduced to ELOP II Factory and guided through its vast array of functions. Details of how to utilise ELOP II Factory for rapid and accurate project development is discussed.
Perth 30 March – 1 April 2010

HIQuad Advanced System Training - This course provides a complete overview of the safety lifecycle of the HIQuad Programmable Electronic System (PES). It provides training on hardware and communication configurations including system architectures and maintenance along with the configuring, loading and modifying of a HIMA PES application program.
Perth 13-16 April 2010  

3.10  Integration today - Integration solutions - For years people have been discussing the subject of “integration” in automation technology. There are a variety of solutions available for the integration of safety and control systems. Provided the right decision is made you can take advantage of all the opportunities and potential synergies of integration, long-term.

3.10 Summary of Offshore Health and Safety Performance Report 2007-08 - The Offshore Health and Safety Performance Report 2007-08 was produced by the National Offshore Petroleum Safety Authority (NOPSA), with the aim to "move beyond the view of safety as compliance with codes and standards and towards an overall improved safety culture within an organisation. The report contains statistics, trends and observations of health and safety within the Australian offshore petroleum industry for the financial year 2007-08. Areas of concern highlighted include equipment design, risk awareness and management, procedures, ageing equipment, supervision and a shortage of skilled personnel.

Next Generation Safety Controller Maximizes Availability for Demanding Process Applications - The nemesis of all continuous processes is unplanned stoppage resulting from controls malfunction, equipment failure, or operator error. System availability can be improved significantly through the use of redundant control architectures – especially those that allow hot-swapping or on-the-fly program changes. Modern process safety solutions provide comprehensive diagnostics that help users to recognize safety-critical situations and act quickly and accordingly to avoid unnecessary system shutdowns. This paper from ARC highlights why companies should invest in process safety.

NOPSA competence findings in line with AS61511 - The Australian National Offshore Petroleum Safety Authority recently recommended that oil and gas facility operators implement formal staff competency management systems to ensure that basic skills requirements for safe plant operation are met.

Functional Safety: A Practical Approach for End-Users and System Integrators- Tino Vande Capelle,Dr. M.J.M. Houtermans - The object of this paper is to demonstrate through a practical example how an end-user should deal with functional safety while designing a safety instrumented function and implementing it in a safety instrumented system.
Modern 2oo4-Processing Architecture for Safety Systems-Prof. Dr.-Ing. habil. Josef Börcsök -This paper provides an overview of two out of four system architecture and associated considerations. 
Safety Bus Systems -Prof. Dr.-Ing. habil. Josef Börcsök - Modern distributed control systems are connected via bus systems, which need effective and uninterrupted communication between all subscribers. Therefore it is necessary for these communications to be fault tolerant and safe. For safety related systems, additional safety layers are required to fulfil these requirements.

Introduction in Safety Bus Systems-Prof. Dr.-Ing. habil. Josef Börcsök - This paper discusses how modern distributed control systems are connected via bus systems, and need effective and uninterrupted communication between all bus stations. Therefore it is necessary that these communications are fault tolerant and safe. 

Safety Critical Software-Prof. Dr.-Ing. habil. Josef Börcsök -This paper discusses the methodical analysis of hardware architectures used in safety-related applications. It provides an excursus on a safe computer system’s software technology and specifies the overview in greater detail.

Safety Systems -Prof. Dr.-Ing. habil. Josef Börcsök - This technical paper gives an excellent overview of Safety Systems covering development history, the fundamental considerations required, fault avoidance basis and measurement, fault control basis, along with external influences such as environmental demands, electromagnetic, mechanical and climatic considerations.

Comparison of PFD calculation -Prof. Dr.-Ing. habil. Josef Börcsök - This paper discusses the compares calculation methods.

Sharing Control & Safety Instruments-Are your layers overlapping?-Dirk Schreier - Since its release as an Australian standard in July of 2004, AS61511 is rapidly being accepted and applied on Safety Instrumented Systems throughout the process industry. Principles such as independence between control and protective instruments have existed for many years; however they continue to often be overlooked even with the introduction of this standard.

Risk Prevention and Mitigation-Where does gas detection fit in?-Dirk Schreier - It is quite common in today's process industry to see the terms fire and gas (F&G). These terms have been used hand in hand for many years and are also combined when referring to applications involving safety-instrumented systems. This article challenges the thinking behind this concept and demonstrates that although fire systems and gas detection systems both reduce risk; their methods are actually quite different.

Legal Implications in Australia for Companies and Individuals under “Industrial Manslaughter”-Dean McNair - There has been a lot of discussion in Australia recently over proposed new occupational health and safety (OH&S) legislation which will include the provision to prosecute corporations and individuals under industrial manslaughter laws. State and territory governments are enacting these new laws in response to workplace deaths in the hope that it will force company directors and senior executives to improve the safety cultures within their organisations.

Safety standard IEC 61508 - Consequences for automation technology and implementation at HIMA -This white paper provides an overview of IEC 61508 and how HIMA have addressed it's requirements.

SIL Assessments -Identification of Safety Instrumented Functions-Dirk Schreier - Since its release as an Australian standard in July of 2004, AS61511 is rapidly being accepted and applied on Safety Instrumented Systems throughout the process industry. AS61511 is a performance based standard with a risk-based approach to safety. Performance based standards are by nature very open to interpretation, and therefore allow for more than just one analysis technique. Some of the techniques currently applied in industry have some shortfalls in achieving the objective of the standard. This article looks at some common problems encountered during the analysis phase of the AS61511 safety lifecycle.

Communication with SafeEthernet -Franz Handermann- The application of SafeEthernet paves the way for the open automation- and network systems of the future.
Safety Considerations
Dr. Josef Börcsök,-Statistical evaluation of HIMA systems in the context of IEC 61508. This article contains the first comprehensive description of IEC 61508-compliant calculation of errors in safety-related systems in general and describes how relevant values for the H41q/H51q systems currently available from HIMA can be calculated. 
Critical Aspects of Safety, Availability and Communication in the control of a subsea gas pipeline- Requirements and Solutions - This is a large zipped file of 2.5 Meg so will take a while to download,  however it is worth it as shows safety related satellite communication
Transporting gas - with safety first!-Automation of an ethylene pipeline
Complete Burner Automation with Safety Controllers-A new solution for simple single and multi burner arrangements through to complex BMS applications, e.g. for power plants, waste incineration plants or processing plants. - Looking for more on Burner Management Systems? ICEweb's comprehensive BMS page has it!
Integrated safety controllers with safeethernet - By combining the world's fastest safety controllers "HIMatrix" with the world's fastest safety bus "safeethernet", HIMA is creating a hitherto unknown level of flexibility for safety-related automation. This flexibility is the basis for the development of new potential. The current system limits of safety-related automation concepts are disappearing, paving the way for truly application-based safety solutions. This creates new potential for increasing productivity and reducing the total costs for safety technology.
Comprehensive safety solutions for the South Pars gasfield exploration-ESD, F&G and HIPPS systems from HIMA ensure maximum safety and plant availability.

The Following links are compliments of our sponsor Emerson
Selecting Transmitters for Safety Instrumented Systems
SIS/IEC 61508 Frequently Asked Questions
If you go to the following SIS link you can register and download the following very useful documents which cover; 
Basic safety concepts
What is risk? / Reducing risk/ Safety standards
Building your SIS
Physical design/Functional design/ Verification & validation/ Installation & commissioning
Using your SIS
Operations & maintenance/ Modifications/ Decommissioning
The intelligent advantage
Smart SIS

The Following Links are compliments of our sponsor Pilz
Guide to Programmable Safety Systems - A comprehensive guide from Pilz
How functional safety helps to save lives -In this article Ron Bell explains functional safety and looks ahead to the revision of the IEC 61508standard that is due for publication in 2010.This article by Jeanne Erdmann was first published in the January 2008 edition of the IEC's E-TECH. http://www.iec.ch 
The Golden Rules of Risk Assessment - Frank Schrever - At its worst, the risk assessment is a bureaucratic time-waster that does nothing to make workplaces safer. On the other hand, following five golden rules mean risk assessments can be both functional and lifesaving. From Pilz and Manufacturers Monthly. 

The Following Links are compliments of our sponsor Moore Industries-Pacific, Inc.
The Ups and Downs of Alarms -read about alarms in a Safety Instrumented Systems  environment -Garry Prentice-Moore Industries International -Intech Magazine
Safety Instrumented Systems: The "Logic" of Single Loop Logic Solvers - What can the "new generation" of safety-certified Single Loop Logic Solvers do for you? 
9.09 Networked Safety- Mainstream or Marketing? Discussing the advantages and potential caveats of networked safety systems, and specifically the Fieldbus Foundation’s FF-SIF safety protocol, this article offers expert testimony and answers key questions about the technologies. Moore Industries’ Director of Technology, Charles Larson, contributes to the debate noting the considerable benefits of networked safety - from  Automation World
9.09 Emphasis on Safety - Rob Stockham, Moore Industries-Europe General Manager and safety expert, looks at the latest method being employed by the UK nuclear industry to access control systems in safety-related and safety-critical applications in power stations.

The following excellent papers have been generously provided to ICEWeb with the permission of World Renowned SIS expert
Dr Angela E. Summers, Ph.D.
President, SIS-TECH Solutions, LLC
12621 Featherwood Dr., Suite 120, Houston, TX 77034 USA
Phone: 281-922-8324 , Fax: 281-922-4362
For more papers and excellent links etc go to  http://www.SIS-TECH.com

3.10 SIF Proof Testing Yields Process Sector Reliability Data - William H. Hearn, Patrick Skweres, A. D. Arnold, and Angela E. Summers, Ph.D. - ANSI/ISA 84 requires periodic proof testing of SIFs to demonstrate the correct operation of the loop elements along with sufficient historical documentation to support analysis of discrepancies and validation of the SIF integrity and reliability. The analysis of proof test records is an important element of the quality assurance process necessary to support continued use of installed equipment. The CCPS Process Equipment Reliability Database (PERD) project has developed failure data taxonomies which provide a structure to capture data to support chemical process data collection and analysis. SIS-TECH® has been distributing a device failure rate database for more than 10 years. This paper describes how SIS-TECH® will collect device performance data under a quality plan during periodic SIF proof testing. This data will be contributed to PERD for review and analysis so that SIL Solver® failure rates can be validated against operating environment data.

3.10 Overfill Protective Systems - Complex Problem, Simple Solution - Angela E. Summers, Ph.D - Overfills have resulted in significant process safety incidents. Longford (Australia, 1998), Texas City (United States, 2005), and Buncefield (United Kingdom, 2005) can be traced to loss of level control leading to high level and ultimately to loss of containment. A tower at Longford and a fractionating column at Texas City were overfilled, allowing liquid to pass to downstream equipment that was not designed to receive it. The Buncefield incident occurred when a terminal tank was overfilled releasing hydrocarbons through its conservation vents. The causes of overfill are easy to identify; however, the risk analysis is complicated by the combination of manual and automated actions often necessary to control level and to respond to abnormal level events. This paper provides a summary of the Longford, Texas City, and Buncefield incidents from an overfill perspective and highlights 5 common factors that contributed to making these incidents possible. Fortunately, while overfill can be a complex problem, the risk reduction strategy is surprisingly simple.

3.10 Lessons Learned While Auditing Automation Systems for PSM Compliance - Angela E. Summers, Ph.D - While reliance on instrumentation has increased at an incredible pace, resources allocated to design and manage the equipment have declined in many companies, leading to more burden and expectations being placed on fewer and fewer people. Quality instrumented system performance relies on a rigorous management system that minimizes human error and equipment failure potential. This paper focuses on safety instrumented systems and applicable process safety management requirements. Observations from assessments and audits are provided, illustrating poor performing instrumented systems, inadequate operating and maintenance procedures, recordkeeping and retention practices, and out-of-date documentation.

3.10 Consistent Consequence Severity Estimation -Angela Summers, PhD, PE William Vogtmann and Steven Smolen - Most risk analysis methods rely on a qualitative judgment of consequence severity, overstatement creates excessive risk reduction requirements, understatement results in inadequate risk reduction. This paper provides justification for developing semi-quantitative look-up tables to support a LOPA team's assessment of consequence severity.
3.10 Safety Management is a Virtue - Angela E. Summers, Ph.D - This paper discusses various challenges to sustaining safe operation of process equipment. Each challenge is introduced using a Chinese fortune cookie to remind the reader that the barriers against progress are not new but have existed from many years. In most cases, the solutions are also well known and generally require deployment of robust equipment, proven techniques, and competent resources.
IEC 61508 Product Approvals - Veering Off Course - Upon close examination it appears that the product approval process of IEC 61508(1) has veered seriously off course, possibly rendering many safety instrumented system (SIS) applications less reliable than expected or required.
A Process Engineering View of Safe Automation -This step-by-step procedure applies instrumented safety systems (ISS) to continuously reduce process risk.
Quality Assurance in Safe Automation - A perfect process would have no hazards, but perfection is impossible in the real world. Nearly all process units have inherent risk associated with their design and operation. Safe operation is maintained with a risk reduction strategy relying on a wide variety of safety systems. This article focuses on the most common safety systems for managing process deviations during planned operating modes – instrumented safety systems (ISSs), such as safety alarms, safety controls, and safety instrumented systems (SIS). Rigorous quality assurance is necessary to achieve real-world risk reduction, so this article follows the Plan, Do, Check, and Act process to discuss quality assurance and its application to ISS.
Guidelines for Safe and Reliable Instrumented Protective Systems (IPS) - Written with guidance from members of the CCPS’s Guidelines for Safe and Reliable Instrumented Protective Systems subcommittee, author and safety standards expert Dr. Angela Summers explores the decision making processes necessary for the management of the protection systems commonly applied throughout the process industry. Based on the framework defined in the harmonized ANSI/ISA 84.01/IEC 61511 standards, this book provides readers with much-requested guidance in an easy to understand discussion that addresses IPS planning, risk assessment, design, engineering, installation, commissioning, validation, operation, and maintenance activities.
Achieve  Continuous Safety Improvement - This technical paper gives an insight of how to achieve continuous safety improvement.
Continuous Improvement in SIS - Discusses safety culture, Protective Management Systems and how to achieve continuous improvement.
The Evolution of Plant Automation - Most owner/operators continue the practice of implementing separate, and often diverse, platforms for the BPCS and SIS, this paper discusses the reasons behind this.
IEC 61511 and the Capital Project Process - A Protective Management Systems Approach
Random, Systematic, and Common Cause Failure: How do you manage them? - This paper provides an overview of random, systematic, and common cause failures and clarifies the differences in their management within IEC 61511.

Partial Stroke Testing of Block Valves - Chapter, “Partial Stroke Testing of Block Valves”, Instrument Engineers Handbook, Volume 4, Chapter 6.9 - For many operating companies, one of the most difficult parts of complying with the standards is the testing interval often required for final elements, such as emergency isolation valves or emergency block valves, this excellent chapter covers this in detail.

Safety Instrumented Systems - Published in Perry’s Handbook of Chemical Engineering 2007 - Covers Hazard and Risk Analysis, Design Basis,  Requirements Specifications, Engineering, Installation, Commissioning and Validation along with Operating Basis.
The Evolution of the Cookbook - This paper provides examples of simple “cookbook” approaches and illustrates how architectures must evolve when addressing higher integrity levels and/or process reliability.
User Approval of SIS Device -This paper explains the concept of user approval as documented in ANSI/ISA 84.00.01-2004, ANSI/ISA TR84.00.04, and the Center for ChemicalProcess Safety book, Guidelines for Safe and Reliable Instrumented Protective Systems.
Software Implemented Safety Logic - This paper discusses some of the requirements for implementing safety logic via software based systems.
Bridging the Safe Automation Gap Part 1
Part 1 discusses safe automation on a broad perspective examining safety culture, organization and hazards analysis issues. 
Bridging the Safe Automation Gap Part 2
Part 2 focuses on instrumented systems and discusses specification, implementation, operation, maintenance, and management of change. 
To Err is Human 
It must be recognized in our designs that given the right conditions that all things succumb to human error.
Fault Management Analysis
Examining a device based on repairable or replaceable components may be your best bet for designing failure out of your SIS. 
Partial-Stroke Testing of Block Valves
This paper discusses the various ways that you can partial stroke test block valves and illustrates the probability of failure on demand calculations. 
Common Cause and Common Sense Designing Failure Out of Your SIS
Angela E. Summers, Ph.D. and Glenn Raney-  The paper will focus on how to identify potential common cause events through the application of industry or internal design standards or through the use of qualitative assessment techniques. 

Improve Facility SIS Performance and Reliability
Angela E. Summers, Ph.D., P.E, President, SIS-TECH Solutions, LP and Bryan A. Zachary, Operations Manager

Introduction to Layer of Protection Analysis
This paper provides an overview of the LOPA process, highlighting the key considerations

High Integrity Protective Systems for Reactive Processes
This paper discusses how to assess, design, and implement HIPS to effectively manage potential overpressure of equipment used for reactive processes.

Perspectives on ANSI/ISA 84.00.01-2004 (IEC61511)-An Emerging International Consensus Standard
Angela E. Summers, Ph.D., P.E., President, SIS-TECH Solutions, LP

Bhopal: Could it Happen Again?
Angela E. Summers, Ph.D., P.E., President, SIS-TECH Solutions, LP

Estimation and evaluation of common cause failures in SIS
Angela E. Summers, Ph.D., Kimberly A. Ford, and Glenn Raney

Safety requirements specification in a capital project environment
Dr. Angela E. Summers, P.E.

Is your SIS "grandfathered" under ANSI/ISA S84.01-2004?
Kimberly A. Ford and Angela E. Summers, Ph.D., P.E.

Avoid bad engineering practices in safety instrumented system design
Angela E. Summers, Ph.D., P.E., President, SIS-TECH Solutions, LLC - As industry races toward compliance, it must work hard to prevent the creation and acceptance of bad engineering practices, which threaten the economics of plant operation and erode the effectiveness of SIS designs. 

Techniques for assigning a target integrity level
Angela E. Summers, Ph.D.

Using instrumented systems for overpressure protection
Dr. Angela E. Summers, PE, SIS-TECH Solutions, LLC

Viewpoint on ISA TR84.0.02 - simplified methods and fault tree analysis
Angela E. Summers, Ph.D., P.E.- Simplified equations and fault tree analysis are two techniques that can be used to verify safety integrity level. The two methods do yield different results but both provide acceptable approximations. 


Other "Super" SIS links
Fire Safe Actuators - A paper detailing an innovative concept from valued sponsor Samson Controls Pty Ltd
Recommendations on the Design and Operation of Fuel Storage Sites -This 52 page report sets out recommendations to improve safety in the design and operation of fuel storage sites.
SIS Links -TUV provides links to more Safety Instrumented Systems Information

SIS Technical Papers - Exida.com provides links and excellent technical information as follows on Safety Instrumented Systems;

Statistical Signature Analysis: Modeling Complex λD(t) from Proof Test Data and the Effects on Computing PFDavg - Julia V. Bukowski - To compute PFDavg, we must first have a model for λD(t), the failure rate of the equipment in the dangerous failure mode. A dangerous failure occurs when equipment designed for prevention or mitigation of an unsafe condition cannot properly respond to the unsafe condition, i.e., the equipment fails on demand. For example, consider a PRV, which, in normal operation, is closed. Should it fail in the "stuck-shut" mode, it would be in a state of dangerous failure as it would be unable to respond to an overpressure event if one occurred.

Final Elements and the IEC 61508 and IEC 61511 Functional Safety Standards Book
-
This book reviews and explains the application of the IEC 61508 and IEC 61511 functional safety standards as they apply to final control elements. The overall safety lifecycle and reliability requirements are reviewed with special focus on the challenges encountered when dealing with complex electro-mechanical subsystems. Throughout the book requirements for designing and implementing reliable and effective safety instrumented functions are covered in a clear step by step manner.

61508 and 61511; What Is an Operations Company Supposed to Do? - Eric Scharpf - The typical first reaction from the process operations side of the table when confronted with a new standard is, "How much will this cost and how much extra paperwork will it involve?".... IEC 61508 and 61511, the standards covering the design and use of a safety instrumented system to reduce process plant accidents, are no exception to this initial reaction.

Accurate Failure Metrics for Mechanical Instruments
-Dr. William M. Goble -Probabilistic calculations done to verify the integrity of a Safety Instrumented System design require failure rate data and failure mode data of all equipment including the mechanical devices.

Assessment Levels for Safety Equipment
 - Dr. William M. Goble - The end user must carefully choose all instrumentation equipment used in Safety Instrumented System (SIS) applications. All such equipment must be carefully justified... IEC 61511, Functional Safety for the Process Industries, requires that equipment used in safety instrumented systems be chosen based on either IEC 61507 certification to the appropriate SIL level or justification based on "prior use" criteria.

Common Cause Simulation
- Dr. William M. Goble - Fault tolerant systems have been designed for safety critical applications including the protection of potentially dangerous industrial processes.

Development of a Mechanical Component Failure Database
-Dr. William Goble & Julia Bukowski - In this paper, they present a methodology to derive component failure rate data for mechanical components used in automation systems based on warranty and field failure rate data as well as expert opinion.

Estimating The Beta Factor
- Dr. William M. Goble - A Safety Instrumented System (SIS) is often designed to help protect an industrial process against potentially dangerous hazards. These systems often use redundant equipment to achieve the needed levels of protection. If the design was done to meet requirements of IEC 61511 or IEC 61508, probabilistic evaluation is done to verify that the design achieves risk reduction goals.

Evolution of European Standards
- Rainer Faller - Slide show presentation of his Rockwell Automation 2002 speech

FMEDA - Accurate Product Failure Metrics
- John C. Grebe and Dr. William Goble - The letters FMEDA form an acronym for "Failure Modes Effects and Diagnostic Analysis." The name was given by one of the authors in 1994 to describe a systematic analysis technique that had been in development since 1998 to obtain subsystem / product level failure rates, failure modes and diagnostic capability.

Functional Safety Terms and Acronyms Glossary - exida - This list of functional safety terms and acronyms has been compiled from a number of sources listed at the end including the IEC 61508, IEC 61511 (ISA84.01) standards. It is meant to provide a general reference for engineers practicing safety lifecycle engineering in the process industry. As such it provides both safety and related non-safety term definitions in a clear useable form. It specifically highlights the most important terms and acronyms from the safety lifecycle standards with working level definitions. The reader is encouraged to pursue IEC 61508 or IEC 61511 for additional definitions and for additional information on applying the safety lifecycle to the process industry.

Getting Failure Rate Data
- Dr. William M. Goble - Safety verification calculations for each safety instrumented function are a key concept in functional safety standards like ISA 84.01 and IEC 61511.

IEC 61508 Overview
- exida - IEC 61508 is an international standard for the “functional safety” of electrical, electronic, and programmable electronic equipment. This standard started in the mid 1980s when the International Electrotechnical Committee Advisory Committee of Safety (IEC ACOS) set up a task force to consider standardization issues raised by the use of programmable electronic systems (PES). At that time, many regulatory bodies forbade the use of any software-based equipment in safety critical applications. Work began within IEC SC65A/Working Group 10 on a standard for PES used in safety-related systems. This group merged with Working Group 9 where a standard on software safety was in progress. The combined group treated safety as a system issue.

IEC61511 Standard For Functional Safety
- exida - IEC 61511 has been developed as a Process Sector implementation of the international standard IEC 61508: "Functional safety of electrical / electronic / programmable electronic safety-related systems."

Implementing IEC61508 In The Process Industries
- Dr. Eric W. Scharpf & Dr. William M. Goble - IEC 61508 and its process-specific companion IEC 61511 are providing new codification to safety instrumented systems and their application to the process industry.

Mechanical Database Verification Report
-Julia Bukowski - The purpose of this document is to report on exida's successful efforts to validate statistically certain random equipment failure rate data used in a mechanical parts failure rate and failure mode database and, by extension, to validate the techniques used to derive the data. To accomplish this, a Failure Modes, Effects, and Diagnostic Analysis (FMEDA) is initially used to predict the useful- life failure rate for the fail-to-open condition of a particular pressure relief valve (PRV) using the failure rates from the mechanical parts database. Next, this prediction is statistically tested against three independent data sets consisting of proof test data for PRV provided by Fortune 500 operating companies. The data sets all meet the intent of the quality assurance of proof test data as documented by the Center for Chemical Process Safety (CCPS) Process Equipment Reliability Database (PERD) initiative.

Mechanical Failure Rate Data for Low Demand Applications
- exida - The use of IEC 61508 [1] and IEC 61511 [2] has increased rapidly in the past several years. Along with the adoption of the standards has come an increase in the need for accurate reliability data for devices used in Safety Instrumented Systems (SIS), both electronic and mechanical. While the methodology of determining failure rates for electronic equipment is fairly well accepted and applied, the same can not be said for mechanical equipment. Several methods are currently being utilized for generating failure rates for mechanical components. These methods vary in their approach and often lead to dramatically different failure rates which can lead to significant differences when calculating the reliability of a safety instrumented function (SIF). Some methods can result in dangerously optimistic failure rate numbers.

Mechanical FMEDA Presentation
- Slide show presentation by Dr. William M. Goble

Modeling & Analyzing The Effects Of Periodic Inspection On The Performance Of Safety-Critical Systems
- Julia V. Bukowski - This paper presents a method for incorporating into Markov models of safety-critical systems, periodic inspections and repairs which occur deterministically in time.

Open IEC 61508 Certification of Products
-Rainer Faller & Dr. William Goble -IEC 61508 has been in use for several years since the final parts were released in 2000. Although written from the perspective of a bespoke system, it is more commonly used to certify products for a given SIL level. Valid product certification schemes must involve the assessment of specific product design details as well as an assessment of the safety management system of the product manufacturer and the personnel competency of those professionals involved in the product creation.

Partial Valve Stroke Testing
- Iwan van Beurden - The objective of a Safety Instrumented System (SIS) is to reduce the risk associated with a particular process to a level lower than or equal to the tolerable risk level.

PFDavg Calculations For Redundant Systems With Incomplete Testing
- Harry Cheddie - A common definition of a Safety Instrumented Function (SIF) as defined in Functional Safety Standards is "Function to be implemented by a Safety Instrumented System (SIS) to mitigate or prevent a specific hazardous event."

PLC vs Safety PLC
- Dr. William M. Goble - Safety Programmable Logic Controllers (PLCs) are special purpose machines that are used to provide critical control and safety applications for automation users. These controllers are normally an integral part of a safety instrumented system (SIS) which are used to detect potentially dangerous process situations.

Project Experience with IEC 61508 and its Consequence
- Rainer Faller -  This paper reports on the experiences with implementation of IEC 61508 in recent projects with European, North American and Japanese system vendors. The paper describes problems identified in implementing the standard and proposes a knowledge tool and a combination of software verification methods to mitigate these issues.

Real Time Operating Systems for IEC 61508
- Mike Medoff - In today’s world many potentially dangerous pieces of equipment are controlled by embedded software. This equipment includes cars, trains, airplanes, oil refineries, chemical processing plants, nuclear power plants and medical devices. As embedded software becomes more pervasive so too do the risks associated with it. As a result, the issue of software safety has become a very hot topic in recent years. The leading international standard in this area is IEC 61508: Functional safety of electrical/electronic/ programmable electronic safety-related systems. This standard is generic and not specific to any industry, but has already spun off a number of industry specific derived standards, and can be applied to any industry that does not have its own standard in place. Several industry specific standards such as EN50128 (Railway), DO-178B (Aerospace), IEC 60880 (Nuclear) and IEC 601-1-4 (Medical Equipment), are already in place. Debra Herrmann (Herrmann, 1999) has found a total of 19 standards related to software safety and reliability cut across industrial sectors and technologies. These standards’ popularity is on the rise, and more and more embedded products are being developed that conform to these standards. Since an increasing number of embedded products also use an embedded real time operating system (RTOS), it has become inevitable that products with an RTOS are being designed to conform to such standards. This creates an important question for designers: how is my RTOS going to effect my certification? This article will attempt to explore the challenges and advantages of using an RTOS in products that will undergo certification.

SIL Verification
- Dr. William M. Goble - The safety lifecycle (SLC) is one of the fundamental concepts presented in the ANSI/ISA 84.01 and IEC 61508 functional safety standards.

Software - Stress Vs. Strength - Dr. William M. Goble - Considering the components used in the current control systems, hardware failure cause have been widely studied.

Software Safety Technique
- Dr. William M. Goble - There is a strong trend toward the use of programmable electronics in safety instrumented systems. yet some users still avoid software-based systems.

State-Of-The-Art Safety Verification
- Dr. Eric W. Scharpf & Dr. William M. Goble -The past few years have brought significant changes to the control safety field in both technology (i.e., fieldbus) and regulation (i.e., IEC 61508).

What Does Proven In Use Imply?
- Rachel Amkreutz & Iwan van Beurden - The functional safety standards, IEC 61508, IEC 61511, and ANSI/ISA 84.01 each specify the Safety Integrity Level performance parameter of Safety Instrumented Functions.

What is PFDavg.?
- Dr. William M. Goble - IEC 61508 requires probabilistic evaluation of each set of equipment used to reduce risk in a safety related system.

The Grandfather Clause and existing equipment
- Dr. William Goble - International safety standards permit users to utilise a ‘Proven in Prior Use’ methodology to justify  SIS equipment ie., A Grandfather Clause ; but can users take on the responsibility? - Following a recent internally initiated audit of your facility’s SIS, you realized your systems do not meet the “grandfather clause” requirements described in ANSI/ISA 84.01.00. Now you face the task of bringing those systems into conformance with international safety standards. One of the questions your SIS team raised is, “Do our installed transmitters meet the ‘prior use’ requirements described in Section 11.5.3 of IEC 61511-1 – Requirements for the selection of components and subsystems based on prior use?” From the ISA and InTech.


Other SIS Links

Canadian Company ACM Automation provides some excellent articles and technical papers covering:-
HAZOP Budgeting Tool - How long will my HAZOP take?
Achieving High SIL Ratings with Partial Stroke Testing of Valves

SIL Determination Techniques Report, this excellent document covers;

  • SIL Determination and the Safety Life Cycle
  • SIL determination Techniques
  • ALARP and Tolerable Risk Concept
  • Semi-Quantitative Method – Fault Tree and Event Tree Analysis
  • Safety Layer Matrix
  • Calibrated Risk Graph
  • Layer of Protection Analysis (LOPA)
  • Evaluating the SIL Determination Options
  • Process Industry Observations
  • SIL Program Benefits

Other Useful Links
Safety Users Group - An independent, professional community dedicated to instrumented safety matters related to the oil, gas, petrochemical and chemical industries. Lots of information here!

3.10 SafetyBase.com is a site that is full of some excellent information about Boiler Management Systems, Machine and Process Safety. You’ll be able to share ideas with colleagues across the country, stay current with compliance requirements, and read the latest case studies, white papers, and articles that can help you keep your people safe and your process moving.

3.10 Center for Chemical Process Safety - The Global Community Committed to Process Safety - CCPS is a not-for-profit, corporate membership organization within AIChE that identifies and addresses process safety needs within the chemical, pharmaceutical, and petroleum industries. CCPS brings together manufacturers, government agencies, consultants, academia and insurers to lead the way in improving industrial process safety.



11.09Toolbox Talks - This excellent page from the 61508 Association gives you the essential toolbox tips in just a few sheets that will help your team to all be “singing from the same hymn sheet” which covers:
Directors
Senior Management
Purchaser
Project Manager
Project Engineer
Inspection and QA
• Operations
Maintenance
Service Engineer
What is Functional Safety Management
• Proven in use / Prior use claims
Functional Safety Management cross-reference
between IEC61508 and IEC61511

What is a Functional Safety System? A short description.
What is Conformity assessment? - Conformity Assessment is defined as "activity that provides demonstration that specified requirements relating to a product, process, system, person or body are fulfilled."
What is CASS? - Accredited Certification for Safety Systems -  to IEC 61508 and Related Standards - CASS is a scheme for assessing the compliance of safety related systems with the requirements of IEC 61508 and associated standards. It provides a systematic approach to be used by certification bodies and others when assessing compliance at all stages from the specification of safety requirements through the design, development and manufacture of system components to integration, commissioning, operation and maintenance. At each stage CASS takes the conformity assessor through the logical steps of defining the scope of the assessment, the target of evaluation, the requirements to be met and the process of demonstrating and recording conformity.
Legacy Systems - Basic Principles for Safety - Engineered systems are relied upon for safety in a wide range of work environments. There is however, a general lack of awareness of the exact role played by such systems, and whether adequate safety is, in fact, being achieved. This is particularly true of systems that have been in place for many years. This document describes how to assess the capability of so called Legacy Systems, focussing on how electrical, electronic, or programmable devices achieve adequate safety in conjunction with other technologies such as mechanical systems and operational expectations.
SIL-Loops to the Rescue - Poor Process Design shouldn’t have to Hide behind Safety Loops - Clive de Salis -You’ve probably never thought of it this way but it really is true: To have an SIL-rated loop is a failure. An SIL-3 safety loop means that the layers of safety that we as chemical engineers have put in place in the process design are inadequate to such an extent that the risk of the fatality is 1000 timesthe wrong side of tolerable. The failure, herefore, is a failure of the chemical engineer to design a process that has sufficient layers of safety to not require an SIL-rated loop.
SIL Certs can Seriously Impair Plant Safety - Clive de Salis -  Process operators are investing in certificates and experts - that the IEC standards do not require - at the expense of actual functional safety management. IEC61508 and particularly the process industry application of it in IEC61511 is gaining ground strongly for high integrity safety instrumented systems. However, the majority of industry is still naively asking for certification that the standard does not require, and has never needed, whilst ignoring its basic essentials. How long can this really go on for?
The 61508 Association provides additional articles to promote the benefits of IEC 61508 and accredited certification.


3.10  An Introduction to Inherently Safer Design - Inherently safer design (ISD) is a philosophy for addressing safety issues in the design and operation of chemical processes and manufacturing plants. When considering ISD, the designer tries to manage process risk by eliminating or significantly reducing hazards. Thanks to Centre for Chemical Process Safety.

Recommended Guidelines for the application of IEC 61508 and IEC 61511 in the petroleum activities on the Norwegian Continental Shelf - This very comprehensive 55 page guideline from the Norwegian Oil Industry association is very useful.
Introduction & background to IEC 61508  - Ron Bell - Over the past 25 years there have been a number of initiatives worldwide to develop guidelines and standards to enable the safe exploitation of programmable electronic systems used for safety applications. In the context of industrial applications (to distinguish from aerospace and military applications) a major initiative has been focussed on IEC 61508 and this standard is emerging as a key international standard in many industrial sectors. This paper looks at the background to the development of IEC 61508, considers some of the key features and indicates some of the issues that are being considered in the current revision of the standard. Thanks to the Safety Users group.
Reliability Prediction Method for Safety Instrumented Systems- PDS Method Handbook, 2003 Edition
 An Integrated Approach to Safety: Defense in Depth Ensuring safety requires reducing the risk of incidents, faults and failures that can disrupt normal operations. This effort goes far beyond simply installing fail-safe controllers or a safety instrumented system. In fact, to mitigate the risk of serious incidents that can cause injury to personnel, equipment and the environment, it is important to consider safety from all aspects of a plant’s operation - From Honeywell
Certified Functional Safety Expert Governance Board -The CFSE is now administered by the CFSE Governance Board which is in turn supported by a broad consortium of companies including Honeywell, Pilz, Siemens, TUV, exida and other leading safety related firms.
Partial Closing of Shutdown/Blowdown Valves - Useful news release from ICS Triplex
Safety and related Acronyms From the Laboratory Safety Institute

Functional Safety and Safety Integrity Levels - An application note from Bentley Nevada.

Valve system controls for safety - A matrix that substantially increases the level of safety in the process industries while significantly reducing the number of nuisance trips - Improved safety brings more nuisance trips, which means lost production.The single block valve is the weak point of the 2oo2D architecture and Parallel valve technology can provide 95% diagnostic coverage- G. Paul Baker and ISA InTech
PDS Data Handbook, 2003 Edition - PDS is a method used to quantify and balance the safety and production loss of Safety Instrumented Systems (SIS). The method accounts for all types of failure categories; technical, software, human, etc.- The 2006 edition of the PDS Method Handbook gives an updated version of the PDS method, including the mathematical details.
Converting relay-based logic solver to triple modular redundancy means safer plants at less cost - Keyur Vora and Ranjan Bhattacharya - When a leading Indian petrochemical plant noticed interlock operations and actuation happening six times a year due to shutdowns, they knew it was time for a change. Problems with trips in the oxidation reactor lead to huge costs in production and quality losses. Finally plant officials looked at upgrading the relay-based interlock system with triple modular redundancy (TMR) to enhance reliability and availability and reduce nuisance trips. From ISA and InTech.
Process Safety what are the Odds? - Enhancing a safety system's ability to perform on demand requires improved diagnostic coverage, maintenance, and regular testing. From controleng.com
How to Specify Solenoid Valves for a Particular Safety Integrity Level - S.A. Nagy - Selection must be done with care and understanding of safety and reliability standards to avoid the risks associated with an operational failure of a critical plant system - thanks to chem.info
Smart Instruments in Safety Instrumented Systems - Tom Nobes - The U.K.'s largest nuclear site operator implements IEC61508 and finds the quality of instrument firmware to be variable, but improving. Thanks to ISA.
Vessel overflow protection systems seem so simple, so straightforward—that is until one of them fails to work properly and your plant is the six o’clock news -  The underlying concept required of an automated overfill protection system seems so simple: If the level of a vessel reaches a pre-determined maximum, then stop the flow of liquid filling the vessel. Satisfying such a simple requirement occurs in toilets, clothes washers, and dishwashers every day, so what is the big deal? The big deal is the liquid in toilets, washers, and dishwashers is water, not a highly flammable, possibly toxic, fuel or chemical. In addition, remember if the overfill protection system fails and there is even a minor incident, government investigators are going to want to see evidence you applied the principles of IEC 61511. Thanks to InTech.
Equipment, don't fail me now - Calculating failure probabilities works better with systematic approach - Peter Morgan - One step in this approach is calculating the target probability of failure on demand (PFD) for the system. Because calculating PFDs for repairable systems commonly seems complicated, the approach does not curry favor with the average control and instrumentation specialist; some manufacturers defer the design analysis to others or they do not do it at all. But there is benefit in the approach for designing general protective systems in addition to meeting the mandatory requirements for a SIS. From the ISA and InTech.

 HSE documents

'The Strategy for Workplace Health and Safety in Great Britain to 2010 and beyond' http://www.hse.gov.uk/aboutus/hsc/strategy.htm

INDG218, 'A Guide to Risk Assessment Requirements' http://www.hse.gov.uk/pubns/raindex.htm

INDG163, 'Five Steps to Risk Assessment'
http://www.hse.gov.uk/pubns/raindex.htm

RR216, 'A methodology for the assignment of safety integrity levels (SILs) to safety-related control functions implemented by safety-related electrical, electronic and programmable electronic control systems of machines'
http://www.hse.gov.uk/research/rrhtm/rr216.htm

INDG316, 'Procedures for daily inspection and testing of mechanical power presses and press brakes'
http://www.hse.gov.uk/pubns/engindex.htm

INDG375, 'Power presses: a summary of guidance on maintenance and thorough examination'
http://www.hse.gov.uk/pubns/puwerind.htm

INDG229, 'Using work equipment safely'
http://www.hse.gov.uk/pubns/puwerind.htm

INDG270, 'Supplying New Machinery: a Short Guide'
http://www.hse.gov.uk/pubns/puwerind.htm

INDG271, 'Buying New Machinery: a Short Guide'
http://www.hse.gov.uk/pubns/puwerind.htm

INDG291, 'Simple guide to the Provision and use of Work Equipment Regulations 1998'
http://www.hse.gov.uk/pubns/puwerind.htm

RR125, 'Evaluation of the implementation of the use of work equipment directive and the amending directive to the use of work equipment directive in the UK'
http://www.hse.gov.uk/research/rrhtm/rr125.htm

HSC13, 'Health and Safety Regulation: a Short Guide'
http://www.hse.gov.uk/pubns/regindex.htm

INDG275, 'Managing Health and Safety: Five Steps to Success'
http://www.hse.gov.uk/pubns/manindex.htm

INDG343, 'Directors' Responsibilities for Health and Safety'
http://www.hse.gov.uk/pubns/manindex.htm

'Directors' Responsibilities for Health and Safety (INDG343): Frequently Asked Questions'
http://www.hse.gov.uk/pubns/manindex.htm


Training 
The Safety Users Group offers the following self training - Hardware Safety System Constraints Made Easy - An in-depth training course on IEC 61508 and IEC 61511 key hardware design concepts. This training course features hardware safety concepts as intended by IEC 61508 and IEC 61511 standards in an easy-to-understand format and at the viewer’s own pace. Topics covered are:

This training course includes a number of practical questions and answers followed by a separate QUIZ with over 25 questions, enabling you to measure your progress in digesting the course content.


Wish to learn more about Manufacturing and Automation Safety or Burner Management? ICEweb has this well covered on our MAS and BM pages.