Safety Lifecycle Research Articles

Fusion analyses of lifecycle safety and damage tolerance for cracked structures

The important problem of damage detectability is proposed and the relationship between fatigue life and damage detectability of cracked structures is elucidated through cracked gear tooth models with detailed analyses of the fatigue fracture properties and vibration modes and frequencies. It is shown that the detectability of the damage or faults in a large portion of fatigue life of the structures is poor, where the crack is relatively small. The damage detectability of a structure depends not only on the size of the crack, but also on the location and structure details of the crack and the diagnosis techniques used. It is pointed out that damage monitoring or diagnosing techniques can only be used to structures with enough damage tolerant capability and enough long detectable life duration for safety guarantee. Through the whole text, an integrated description on fusion technology of lifecycle safety guarantee of mechanical structures is provided.

Optimizing the Life Cycle Safety, Health and Environment Impact of New Projects

Too often the approach to the concept selection for a process development is based on the operational safety risks with little attempt made to address the health and environmental issues. This paper directs the reader towards the total ‘holistic’ and integrated SHE (safety, health and environment) approach from concept to demolition for any process project. It draws on the approach developed for the offshore oil and gas industry and shows that the methodology can be transferred to the chemical/pharmaceutical industry provided there is a conscious attempt to use the tools already available. The existing experience shows that the tools developed for the offshore oil and gas industry, with the inherent risk criteria can be a powerful tool for choosing the best overall SHE-based project. The final analysis for the offshore industry shows that the decisions are mostly dictated by the ‘operational phase’ of the project cycle. However the abandonment of an offshore installation does have many significant SHE issues. The paper shows that the ‘holistic’ approach to SHE developed for the offshore oil and gas industry can be transferred to the onshore chemical industry. It is therefore a challenge to others to develop the models such that the optimized SHE can be achieved for the onshore process industry.

Design, Organisation, Planning According to Functional Safety Methodology

This paper deals with the problems of the planning and the design of safety related control systems. Such systems are used not only for protection purposes, but first of all for control purposes, as the many operation functions, e.g. start, stop, emergency stop, restart are considered as safety related functions. The safety life cycle of the system is presented and its design phase is discussed in details. The measure of functional safety - integrity level - is defined and the corresponding requirements are referenced. On this basis, the organising actions, required by the functional safety methodology, are presented.

Safety integrity level analysis for processes: Issues and methodologies

AbstractThe performance based ANSI/ISA S84.01 and IEC 61508 standards provide overall risk based safety life cycle models for industrial processes. Among other guidance, they provide the basic methodology and guidelines for the identification of safety instrumented systems necessary for a process to meet the established target risk levels. In order to arrive at risk based solutions, many practical issues need to be addressed. Such issues include identification of target risk levels, identification of hazardous events associated with the process under consideration, establishing the existing risk associated with the process, and selection of appropriate non‐instrumented and instrumented safety systems to meet the target risk. This paper outlines the basic methodology, and discusses some of the related issues mentioned above. Further, it provides a few methodologies to establish the requirements of the safety instrumented systems and their safety integrity levels.

Safety lifecycle management. A flowchart presentation of the IEC 61508 overall safety lifecycle model

Safety in the process industry is currently playing an increasingly important role. In the European Union the Seveso II directive requires that companies that store certain amounts of dangerous liquids or gases shall take appropriate measures to reduce the potential risks. Concerning safety-related systems, the (draft) IEC 61508 standard is already adopted by many companies to comply with the Seveso II directive. Contrary to the older standards, IEC 61508 does not only cover the classical technical aspects, but also the business processes that are relevant for the entire safety lifecycle. The standard introduces a structure that consists of safety lifecycle models. The overall safety lifecycle describes required activities associated with safety during the entire lifecycle of the equipment, from the concept phase to the decommissioning phase. For a real operating process installation a study has been performed to investigate what steps should be taken in order to implement the IEC 61508 safety standard. This study is based on the overall safety lifecycle model and uses a flowchart approach that addresses all relevant items of the overall safety lifecycle. Copyright © 1999 John Wiley & Sons, Ltd.

Safety lifecycle management. A flowchart presentation of the IEC 61508 overall safety lifecycle model

Safety in the process industry is currently playing an increasingly important role. In the European Union the Seveso II directive requires that companies that store certain amounts of dangerous liquids or gases shall take appropriate measures to reduce the potential risks. Concerning safety-related systems, the (draft) IEC 61508 standard is already adopted by many companies to comply with the Seveso II directive. Contrary to the older standards, IEC 61508 does not only cover the classical technical aspects, but also the business processes that are relevant for the entire safety lifecycle. The standard introduces a structure that consists of safety lifecycle models. The overall safety lifecycle describes required activities associated with safety during the entire lifecycle of the equipment, from the concept phase to the decommissioning phase. For a real operating process installation a study has been performed to investigate what steps should be taken in order to implement the IEC 61508 safety standard. This study is based on the overall safety lifecycle model and uses a flowchart approach that addresses all relevant items of the overall safety lifecycle.

Safety instrumented system design: Lessons learned

AbstractEngineering is a bold discipline. Engineers are constantly reaching for new heights, searching for new materials and greater efficiency. Unfortunately, part of that process means we occasionally exceed known boundaries. It is regrettable, but it would appear that human nature requires that we learn the hard way. While this is an obviously painful process, we can learn more from our few mistakes than from our many successes. Our many successes may contain flaws that are never revealed under normal conditions, and we may go on repeating them over and over. It is only when expected conditions are exceeded, and failure is the result, that we learn where we went wrong [12].Valuable lessons can be learned from failures, and there are plenty of examples from industry in general as well as specific details regarding failures of safety control system. For example, the UKHSE (Health and safety Executive) issued a publication in 1995 [2] that reviewed 34 accidents that were directly caused by control and safety system failures. The HSE published the reviews so that engineers could learn from and hopefully not repeat the mistakes discussed in the book. The IEC and ISA standards on this subject, as well as the CCPS Guidelines, are based upon a “Safety Life Cycle” which is a set of steps one should go through in the overall design process in an effort to ensure that nothing falls through the cracks.As responsible engineers, we should not have to learn the hard way. Plants have become too large and the risks have become too great for us to learn by mere trial and error. Because we cannot do a recall on all refineries we need to get things right the first time. We can, however, learn from the mistakes of otherts without re‐inventing the wheel or operating in isolation.

Mastering Safety of Open & Distributed Systems in Compliance with IEC 61508

New architectures of control system based on communication networks and highly integrated technology make use of new methods to justify and master the safety life cycle of the systems. New concepts have been pioneered for the Alspa 8000-P320 system used for energy application (including nuclear applications) : “à la carte” safety, safety life cycle (according to lEC 61508) integrated within system design, integrity level computation for each assembly using IEC 61508 methodology. Justification of coverage of self-tests has been improved by a specific FMEA instead of unpracticable physical fault injection. Operational results confirm the validity ofthe design methodology