Reliability and Safety Basics

The history of the reliability field may be traced back to the early 1930s, when probability concepts were applied to problems associated with electric power generation. However, its real beginning is generally regarded as World War II, when German scientists applied basic reliability concepts to improve the performance of their VI and V2 rockets [1-3]. Today, the reliability field has become a well-developed discipline and has branched out into many specialized areas, including mechanical reliability, power system reliability, software reliability, and human reliability and error [1,4]. Additional information on the history of the reliability field is available in Dhillon [4]. 

The history of the safety field goes back to 1868, when a patent for a barrier safeguard was awarded in the United States [5]. In 1893, the U.S. Congress passed the Railway Safety Act. Today, the field of safety has branched out into specialized areas such as system safety, workplace safety, and patient safety. A detailed history of the safety field is given in Dhillon [6]. 

This chapter presents various reliability and safety basics considered useful to understand subsequent chapters of this book as well as for the transportation industry at large. 

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Drawing together the latest research spread throughout the literature. Tmiisportation Systems Reliability and Safety eliminates the need to consult many different and diverse sources to obtain np-to-date information and research. It contains a chapter on mathematical concepts and another chapter on reliability and safety basics that form a foundation for understanding the contents of snhsecpient chapters. The hook also presents a chapter devoted to methods for performing transportation systems reliability and safety analysis. It includes a reference section at the end of each chapter for readers who wish to delve deeper into a specific area. 

The purpose of this research is to construct probabilistic safety models for a typical loop-type FBR plant so that an overall safety assessment can be performed. It is expected that (1) a systematic evaluation on the plant safety is conducted based on the quantitative analysis, (2) the insights on measures to enhance system reliability and safety are provided, (3) the operation and maintenance procedures are established based on a risk-based consideration, and (4) useful information is given to the development of basic policy on safety design and evaluation of a large LMFBR. 

For the problem of incomplete reliability information collection, developers should establish effective ways for rehability data collection, storage and analysis, specify content and management of reliabihty information data, and solve the problem of a serious shortage of basic rehabihty data. Data collection related to reliability and safety includes product development requirements, rehabihty design analysis, rehabihty evaluation, safety evaluation, similar product quality problems, and failure elimination. 

Risk is the basic category of security issues. It is derived from the theory of reliability and safety of systems. This is connected with situations of slight, uncertain or problematic effect of exposing to danger, loss or harm—with the likelihood that something will bring negative results. In this perspective, the risk is identified with the loss of safety (Babiarz Rak 2001). 

The basic elements influencing liferaft reliability and safety of the survivors on board are ... 

Pressure equipment is essential in many industries, including oil, chemical, textile food, waste and healthcare industry. In high risk industries, furthermore, pressure systems are critical also for major accident prevention. Thus in all involved industries, it is essential to assure pressure equipment reliability and safety. In this framework the knowledge about the pressure equipment failures is essential to drive inspection and maintenance activities. In particular the failure rates FR and failure mode FM, associate with a type of equipment, are the basic parameters. FRs, in particular, are essential for the risk assessment and FMs for the risk management. 

The reliability and safety data on which the exercise relies is often defined subjectively (e.g. consider the contributing factor for a basic control system). There may be a strong temptation for users to simply enter 0.1 for the risk reduction provided by the system without considering the actual performance of the system further and taking into account factors that may change this result. If this is repeated for several IPLs then misleading results could occur. The reliability of elements such as valves and transmitters ultimately depends on their service conditions it is well understood in industry that reliability is very dependent on environmental factors and the degree of wear and tear of elements. 

Some points to consider related to the six basic elements listed above are included in table 5.1. The manner in which the vulnerability assessment is performed is determined by each individual water/wastewater utility. Throughout the assessment process it is important to remember that the ultimate goal is twofold to safeguard public health and safety and to reduce the potential for disruption of a reliable supply of chemicals. 

Confidence in the quality and safety of food is an undisputed priority worldwide. The presence in food of undesired chemicals (basically residues and contaminants) as well as the lack of essential chemical substances at the required concentrations can pave the way to very serious consequences for human health. Chemical elements (be they major, minor, or trace elements) have a place of their own in this context. Needless to say, assessing the safety of food from both viewpoints demands entirely reliable experimental information, which in turn is based on the availability of fit-for-purpose powerful analytical techniques. 

Reactivity with ubiquitous contaminants (oil, rust, air, water, etc.) Training and experience of operational personnel Reliability of metering, agitation and heat transfer systems Integrity of basic process control system Reliability of safety instrumented systems... 

Three hazard analysis techniques are currently used widely Fault Tree Analysis, Event Tree Analysis, and HAZOP. Variants that combine aspects of these three techniques, such as Cause-Consequence Analysis (combining top-down fault trees and forward analysis Event Trees) and Bowtie Analysis (combining forward and backward chaining techniques) are also sometimes used. Safeware and other basic textbooks contain more information about these techniques for those unfamiliar with them. FMEA (Failure Modes and Effects Analysis) is sometimes used as a hazard analysis technique, but it is a bottom-up reliability analysis technique and has very limited applicability for safety analysis. 

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