Safety observations reliability

It has often been observed that the application of adhesives to metal fabrication, in common with many other technological innovations, was pioneered by the aircraft industry. It is ironic that this industry, in which safety and reliability command paramount attention, should lead the departure from traditional methods of joining. Today adhesives are used to bond critical parts in commercial and military aircraft and helicopters, spacecraft, rockets, missiles and the US Space Shuttle. The American Primary Adhesively Bonded Structure Technology (PABST) Programme, which ran from 1976-81, was an imaginative attempt to advance significantly the use of bonded... 

From a technical point of view, safety and security concerns are certainly similar, but there is one very important difference. While we can get a reasonable confidence level from a safety pomt of view by empirically observing reliability (this plane has flown thousands of hours with not one observed safety defect), we are not nearly so ready to accept this kind of empirical evidence for security. The fact that someone could walk by the World Trade Center buildings every day for decades and see them still standing did not prove they were invulnerable to attack. When it comes to security, the use of formal methods becomes more attractive. It is comforting to be able to prove mathematically that a program meets its security requirements. We will discuss later on whether this is achievable in practice. 

Failure is a term widely used in technical practice especially concerning dependability theory. It is inevitable to realize that a failure is of key importance for operation and function of technical items. Theory and practice in particular shows that failures occur under different situations, various circumstances, ranging conditions, etc. For safety and reliability practitioners failure is a basic term in theory, and it is key and essential for observing stochastic relations of item behaviour. It is an event which is used in probability theories on a general level the term probability event is used. In dependability theory it is necessary to realize the fact of failure as a stochastic term, to understand its meaning, and to understand other links. What we need to catch up here is the meaning and relation to safety. The requirements on polymer composites are to be failure safe or to prevent further failure propagations—once failures occur. For more details see e.g. Elsayed 1996, Meeker Luis 1998, Stodola et al. 2013, Werbinska-Wojciechowska 2013,Werbiiiska 2007. 

There is very little published work on the reliabihty of audit systems. Kuusisto (2001) conducted an extensive study on the reliability of auditing methods. His dissertation reviews the literature on this topic and reports an original study of the inter-observer reliability of the D S method and of an improved audit method labeled Method for Industrial Safety and Health Activity Assessment (MISHA). In an initial test, Kuusisto audited six companies in the United States, using the D S method. He compared the audit scores he recorded with the scores of internal audits conducted by a company employee who also used the D S method. Statistical testing indicated that the rehabihty was poor to moderate. In only one of the companies did the reliability reach the moderate level. Two companies reached the fair level, two reached the slight level, and one was poor. 

NOAEL (no-observed-adverse-effect level) is defined as the highest dose at which no adverse effects are observed in the most susceptible animal species. The NOAEL is used as a basis for setting human safety standards for acceptable daily intakes (ADIs), taking into account uncertainty factors for extrapolation from animals to humans and inter-individual variabilities of humans. The adequacy of any margin of safety or margin of exposure must consider the nature and quality of the available hazard identification and dose-response data and the reliability and relevance of the exposure estimations. In some cases, no adverse endpoint can be identified such as for many naturally occurring compounds that are widespread in foods. In that case, an ADI Not Specified is assigned. ... 

Screening hundreds of compounds against 80-100 targets/year is an expensive research endeavor Ho vever, it is one of the crucial parts of predinical safety assessment and is also required by regulatory authorities [9]. Beside a better understanding of compound bioactivity profiles, which in some cases can be reliably linked to clinically observed side effects, there is also a particular aspect of the generated data which makes it worthwhile to be analyzed in more detail. 

The 1996 Food Quality Protection Act (FQPA) now requires that an additional safety factor of 10 be used in the risk assessment of pesticides to ensure the safety of infants and children, unless the EPA can show that an adequate margin of safety is assured with out it (Scheuplein, 2000). The rational behind this additional safety factor is that infants and children have different dietary consumption patterns than adults and infants, and children are more susceptible to toxicants than adults. We do know from pharmacokinetics studies with various human pharmaceuticals that drug elimination is slower in infants up to 6 months of age than in adults, and therefore the potential exists for greater tissue concentrations and vulnerability for neonatal and postnatal effects. Based on these observations, the US EPA supports a default safety factor greater or less than 10, which may be used on the basis of reliable data. However, there are few scientific data from humans or animals that permit comparisons of sensitivities of children and adults, but there are some examples, such as lead, where children are the more sensitive population. It some cases qualitative differences in age-related susceptibility are small beyond 6 months of age, and quantitative differences in toxicity between children and adults can sometimes be less than a factor of 2 or 3. 

Safety shutdown valves, which are normally wide open and operate infrequently, are expected to respond to a safety trip command reliably and without fault. To achieve the level of reliability required in this application, the safety valve must be periodically tested to ensure positive operation under safety trip conditions. To test the operation of the shutdown system without disturbing the process, the traditional method is to physically lock the valve stem in the wide-open position and then to electrically operate the pneumatic shutdown solenoid valve. Observing that the pneumatic solenoid valve has properly vented the actuator pressure to zero, the actuator is seen as capable of applying sufficient spring force to close the valve, and a positive safety valve test is indicated. The... 

Advertising successes of the process safety improvement effort demonstrates that improvement is possible. Well-crafted stories also explain the benefits that accrue to everyone in the organization. Of particular interest are stories where a process safety weakness was observed, possibly during a process safety audit, and an improvement effort corrected the identified weakness before it could manifest into an accident. Metrics can validate such improvements. Another example is improved reliability from timely maintenance of safety devices as demonstrated by metrics that educate personnel not only about the hazards, but also about the importance of reliable safety systems in managing those hazards. 

Manufacturers must consider and take action upon certain observations. Similarly, they should be keenly aware and analyze the clinical studies and non-clinical data, beginning with the in vitro studies. These should include the results of receptor binding studies that may be available from the originator s data, and which should be able to measure any changes in the activity of the molecule. In terms of describing the safety of the molecule, in vivo studies should be undertaken, often utilizing reliable animal models. 

Irradiation vessels suitable for use at 20 kTorr have been described elsewhere (5). Thick-walled KG-33 capillaries with dimensions 9.0 mm o.d. X 3.5 mm i.d. X 110 mm 1 can be used over the range 20-100 kTorr. Capillaries with dimensions 9.0 mm o.d. X 2.7 mm i.d. X 115 mm 1 have been used at this laboratory up to 500 kTorr. Because these procedures are dangerous, reliable safety precautions should be routinely observed (5). 

With these constraints in mind, the temperature shift of the peak maximum observed in DTA scanning experiments using different heating rate contains significant safety information. Even more important, however, is the fact, which has now repeatedly been shown that reliable information for the safety assessment of chemical processes cannot be obtained from a single measurement but firom a series of measurements only. 

The consequences of error in chemical weapons demilitarization are potentially large, and any involved organization must maintain a consistently low error rate over extended time periods to ensure public safety and public confidence. The committee observed that some of the principles that apply to high-reliability organizations were evident at all sites visited. 

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