AAOM Handbook

SS.05 Identify Historical Threats

Context

The purpose of a Service Strategy is to identify the most cost effective way to manage risks related to a process, hence delivering the safe, cost effective life required from the process. To define the Service actions for a process it is first necessary to identify the probable and priority risks, and then to identify the most appropriate Service Strategy for dealing with each risk. Finally, the selected Strategy can be turned into a set of actions (the right work) that can be executed at the right time and in the right way. Materials science has defined a set of mechanisms by which material failures can be categorised. When looked at from a boarder context it can be observed that, with some adaptation, these can provide a set of hazard types that could be useful in considering probable risks across many types of processes: • Stress - materials science subdivides this into catastrophic overstress that produces sudden failures (e.g. fracture), prolonged high stress that produces creep deformation and prolonged cyclic stress that produces fatigue failure. Similar types of results can be produced in people. Some examples of potential forms of stress are; physical/mechanical, thermal, voltage, radiation, mental, etc. • Chemical - in materials science terms this would be due to the (re)action of chemicals such as oxygen, acids, alkalis, but in a broader context could also include drugs, alcohol etc. • Wear - materials science subdivides wear into different mechanisms for the removal of material e.g. abrasion, erosion, fretting etc. • Fouling - accumulation of material e.g. silting, scaling, contamination etc. • Obsolescence - this is not a category used in materials science but reflects a type of hazard that arises from the loss of support for either the products or services of a process, e.g. due to innovation or competition, the imposition of constrictions to the process, e.g. imposition of new standards/laws, or the loss of essential resources for the continued operation of the process, loss of people, skills or knowledge, loss of parts sources etc. The above hazard mechanisms may act either alone or in combination, and when acting in combination may produce an unwanted event that does not occur with either of the mechanisms absent e.g. stress corrosion cracking, the result of a combination of highly alkaline environment and high physical stress levels. A failure mechanism classification of 'Random' is sometimes applied to electronic components. However, this is a situation where the consequences related to an unwanted event are visible (the failure), but the underlying mechanism is usually not readily identifiable, rather than the result of a different hazard release mechanism. Analysis of electronic failures most commonly reveals evidence of overstress, fatigue or chemical reaction. However, the