File Name: reliability maintenance and safety engineering .zip
Safety engineering is an engineering discipline which assures that engineered systems provide acceptable levels of safety. Safety engineering assures that a life-critical system behaves as needed, even when components fail. Analysis techniques can be split into two categories: qualitative and quantitative methods. Both approaches share the goal of finding causal dependencies between a hazard on system level and failures of individual components.
Qualitative approaches focus on the question "What must go wrong, such that a system hazard may occur? The complexity of the technical systems such as Improvements of Design and Materials, Planned Inspections, Fool-proof design, and Backup Redundancy decreases risk and increases the cost. Traditionally, safety analysis techniques rely solely on skill and expertise of the safety engineer. In the last decade model-based approaches have become prominent. In contrast to traditional methods, model-based techniques try to derive relationships between causes and consequences from some sort of model of the system.
The two most common fault modeling techniques are called failure mode and effects analysis and fault tree analysis. These techniques are just ways of finding problems and of making plans to cope with failures, as in probabilistic risk assessment. One of the earliest complete studies using this technique on a commercial nuclear plant was the WASH study, also known as the Reactor Safety Study or the Rasmussen Report.
Failure Mode and Effects Analysis FMEA is a bottom-up, inductive analytical method which may be performed at either the functional or piece-part level.
For functional FMEA, failure modes are identified for each function in a system or equipment item, usually with the help of a functional block diagram. For piece-part FMEA, failure modes are identified for each piece-part component such as a valve, connector, resistor, or diode. The effects of the failure mode are described, and assigned a probability based on the failure rate and failure mode ratio of the function or component.
This quantiazation is difficult for software a bug exists or not, and the failure models used for hardware components do not apply. Temperature and age and manufacturing variability affect a resistor; they do not affect software. Failure modes with identical effects can be combined and summarized in a Failure Mode Effects Summary.
Fault tree analysis FTA is a top-down, deductive analytical method. In FTA, initiating primary events such as component failures, human errors, and external events are traced through Boolean logic gates to an undesired top event such as an aircraft crash or nuclear reactor core melt. The intent is to identify ways to make top events less probable, and verify that safety goals have been achieved.
Fault trees are a logical inverse of success trees, and may be obtained by applying de Morgan's theorem to success trees which are directly related to reliability block diagrams. FTA may be qualitative or quantitative. When failure and event probabilities are unknown, qualitative fault trees may be analyzed for minimal cut sets. For example, if any minimal cut set contains a single base event, then the top event may be caused by a single failure.
Some industries use both fault trees and event trees. An event tree starts from an undesired initiator loss of critical supply, component failure etc. As each new event is considered, a new node on the tree is added with a split of probabilities of taking either branch. The probabilities of a range of "top events" arising from the initial event can then be seen.
The offshore oil and gas industry uses a qualitative safety systems analysis technique to ensure the protection of offshore production systems and platforms. The analysis is used during the design phase to identify process engineering hazards together with risk mitigation measures.
The technique uses system analysis methods to determine the safety requirements to protect any individual process component, e. The first stage of the analysis identifies individual process components, these can include: flowlines, headers, pressure vessels , atmospheric vessels, fired heaters , exhaust heated components, pumps, compressors , pipelines and heat exchangers.
Other undesirable events for a pressure vessel are under-pressure, gas blowby, leak, and excess temperature together with their associated causes and detectable conditions. Once the events, causes and detectable conditions have been identified the next stage of the methodology uses a Safety Analysis Checklist SAC for each component.
For example, for the case of liquid overflow from a vessel as above the SAC identifies: . The analysis ensures that two levels of protection are provided to mitigate each undesirable event. For example, for a pressure vessel subjected to over-pressure the primary protection would be a PSH pressure switch high to shut off inflow to the vessel, secondary protection would be provided by a pressure safety valve PSV on the vessel.
X denotes that the detection device on the left e. PSH initiates the shutdown or warning action on the top right e. ESV closure. The SAFE chart constitutes the basis of Cause and Effect Charts which relate the sensing devices to shutdown valves and plant trips which defines the functional architecture of the process shutdown system.
The methodology also specifies the systems testing that is necessary to ensure the functionality of the protection systems. Typically, safety guidelines prescribe a set of steps, deliverable documents, and exit criterion focused around planning, analysis and design, implementation, verification and validation, configuration management, and quality assurance activities for the development of a safety-critical system.
Thereby, higher quality traceability information can simplify the certification process and help to establish trust in the maturity of the applied development process. Usually a failure in safety- certified systems is acceptable [ by whom?
Once a failure mode is identified, it can usually be mitigated by adding extra or redundant equipment to the system. For example, nuclear reactors contain dangerous radiation , and nuclear reactions can cause so much heat that no substance might contain them. Therefore, reactors have emergency core cooling systems to keep the temperature down, shielding to contain the radiation, and engineered barriers usually several, nested, surmounted by a containment building to prevent accidental leakage.
Safety-critical systems are commonly required to permit no single event or component failure to result in a catastrophic failure mode. Most biological organisms have a certain amount of redundancy: multiple organs, multiple limbs, etc. For any given failure, a fail-over or redundancy can almost always be designed and incorporated into a system. There are two categories of techniques to reduce the probability of failure: Fault avoidance techniques increase the reliability of individual items increased design margin, de-rating, etc.
Fault tolerance techniques increase the reliability of the system as a whole redundancies, barriers, etc. Safety engineering and reliability engineering have much in common, but safety is not reliability. If a medical device fails, it should fail safely; other alternatives will be available to the surgeon. If the engine on a single-engine aircraft fails, there is no backup.
Electrical power grids are designed for both safety and reliability; telephone systems are designed for reliability, which becomes a safety issue when emergency e. US "" calls are placed. Probabilistic risk assessment has created a close relationship between safety and reliability. Component reliability, generally defined in terms of component failure rate , and external event probability are both used in quantitative safety assessment methods such as FTA.
Related probabilistic methods are used to determine system Mean Time Between Failure MTBF , system availability, or probability of mission success or failure. Reliability analysis has a broader scope than safety analysis, in that non-critical failures are considered. On the other hand, higher failure rates are considered acceptable for non-critical systems. Safety generally cannot be achieved through component reliability alone. When adding equipment is impractical usually because of expense , then the least expensive form of design is often "inherently fail-safe".
That is, change the system design so its failure modes are not catastrophic. Inherent fail-safes are common in medical equipment, traffic and railway signals, communications equipment, and safety equipment. The typical approach is to arrange the system so that ordinary single failures cause the mechanism to shut down in a safe way for nuclear power plants, this is termed a passively safe design, although more than ordinary failures are covered.
Alternately, if the system contains a hazard source such as a battery or rotor, then it may be possible to remove the hazard from the system so that its failure modes cannot be catastrophic. The U. One of the most common fail-safe systems is the overflow tube in baths and kitchen sinks.
If the valve sticks open, rather than causing an overflow and damage, the tank spills into an overflow. Another common example is that in an elevator the cable supporting the car keeps spring-loaded brakes open. If the cable breaks, the brakes grab rails, and the elevator cabin does not fall. Some systems can never be made fail safe, as continuous availability is needed. For example, loss of engine thrust in flight is dangerous. Redundancy, fault tolerance, or recovery procedures are used for these situations e.
This also makes the system less sensitive for the reliability prediction errors or quality induced uncertainty for the separate items. From Wikipedia, the free encyclopedia. Engineering discipline which assures that engineered systems provide acceptable levels of safety. This article includes a list of general references , but it remains largely unverified because it lacks sufficient corresponding inline citations. Please help to improve this article by introducing more precise citations.
January Learn how and when to remove this template message. Main article: Failure mode and effects analysis. Main article: Fault tree analysis. Further information: Inherent safety. Further information: Reliability engineering.
Retrieved 7 February Proceedings of the 36th International Conference on Software Engineering. ICSE IEEE Software. Federal Aviation Administration. Retrieved Guidelines for Development of Civil Aircraft and Systems. Society of Automotive Engineers. Guidelines and methods for conducting the safety assessment process on civil airborne systems and equipment. Department of Defense.
From its origins in the malachite mines of ancient Egypt, mining has grown to become a global industry which employs many hundreds of thousands of people. Today, the mining industry makes use of various types of complex and sophisticated equipment, for which reliability, maintainability and safety has become an important issue. Mining Equipment Reliability, Maintainability, and Safety is the first book to cover these three topics in a single volume. Mining Equipment Reliability, Maintainability, and Safety will be useful to a range of individuals from administrators and engineering professionals working in the mining industry to students, researchers and instructors in mining engineering, as well as design engineers and safety professionals. All topics covered in the book are treated in such a manner that the reader requires no previous knowledge to understand the contents. Examples, solutions and test problems are also included to aid reader comprehension.
reliability, maintenance, safety & risk. • Part 3: Identification and assessment of hazards in particular fault tree analysis. • Part 4: Hazard and operability studies.
IJRQSE is a refereed journal focusing on both the theoretical and practical aspects of reliability, quality, and safety in engineering. It is also capable of teasing out more accurate insights from accident datasets, or degradation and survival data for example that were. The idea behind Reliability Engineering and Resilience is to answer the safety problems concerns which may refer to a … System safety The application of engineering and management principles, criteria, and techniques to achieve acceptable mishap risk, within the constraints of operational effectiveness and suitability, time, and cost,throughout all phases of the system life cycle.
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Reliability and Safety Engineering presents an overview of the basic concepts, together with simple and practical illustrations. This book is also appropriate as a graduate and PhD-level textbook for courses in risk and safety analysis, reliability, safety engineering, and risk management offered within mathematics, operations research, and engineering departments. In addition, the book treats issues such as: What are safety principles and what roles do they have? Performance office, Attention: Director of Engineering Reliability and Performance who shall How do safety principles relate to the law; what is the status of principles in different domains? Safety engineering is not a subject which is adequately covered in most undergraduate degrees, so this MSc programme brings together those topics relating to the safety and reliability of engineering products and systems, including the legislative framework, in a unified approach. During day-to-day use, thousands of lives are lost each year due to accidents, directly or indirectly, resulting from poor transportation system reliability and safety.
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You can reduce the risk of injuries by keeping your equipment—tractors, harvesters, and other machines—in good condition. Drilling and Related Operations. Perform maintenance on a regular schedule. Be Consistent. Turning and Related Operations. Common Cause Failures 2. Condition Monitoring,Demand of condition Monitoring,Process of Condition Monitoring,Installation Cost,Operating Cost,On load and off load-Testing,Visual condition Monitoring,temperature sensitive tapes,Electrical resistance method,linear polarization method,Corrosion potential Measurement,Leakage detection monitoring methods,Types of leakage method,Leakage Monitoring,Ultrasonic testing.
Get this from a library! Reliability, maintenance and safety engineering. [A K Gupta].
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Request PDF | On Oct 1, , Ajit Kumar Verma and others published Different distributions used in reliability and safety studies with suitable the components' maintenance and testing intervals (), the maintenance.