AS/NZS IEC 60812:2020 pdf download – Failure modes and efects analysis (FMEA and FMECA).
3.1.7 element level of sub-division of a system, item or process hierarchy at which failure modes are to be identified 3.1 .8 scenario possible sequence of specified conditions under which the system, item or process functions are performed Note 1 to entry: Conditions may include activities or factors outside the defined item or process boundaries under study which may affect the performance of the item or process. Note 2 to entry: Physical conditions include all environmental factors such as temperature, humidity, light levels, shock, contamination, radiation levels. Note 3 to entry: Organizational conditions include factors such as staffing levels, physical/psychological stresses. 3.1.9 failure cause set of circumstances that leads to failure Note 1 to entry: A failure cause may originate during specification, design, manufacture, installation, operation or maintenance of an item. Note 2 to entry: Examples of a failure cause may be contamination or inadequate lubrication which leads to the failure mode of bearing seizure. Note 3 to entry: Failure causes for a process might include human error mechanisms such as stimulus overload, memory failure, misunderstanding, false assumption. [SOURCE: IEC 60050-1 92:201 5, 1 92-03-1 1 , modified — Note 2 and Note 3 have been added.] 3.1.1 0 failure mechanism process that leads to failure Note 1 to entry: The process may be physical, chemical, logical, psychological or a combination thereof. [SOURCE: IEC 60050-1 92:201 5, 1 92-03-1 2, modified — Note 1 has been reworded.] 3.1.1 1 likelihood chance of something happening Note 1 to entry: In this document, the term “likelihood” is used to refer to the chance of something happening, whether defined, measured or determined objectively or subjectively, qualitatively or quantitatively, and described using general terms or mathematically [such as probability or a frequency over a given time period].
3.1.1 3 detection method means by which a failure mode or incipient failure become evident 3.1.1 4 control design features, or other existing provisions, that have the ability to prevent or reduce the likelihood of the failure mode or modify its effect Note 1 to entry: Controls can also be referred to as compensating provisions. 3.1.1 5 criticality <of a failure mode> importance ranking determined using a specified evaluation criteria Note 1 to entry: The criticality evaluation criteria normally refer to the effects of the failure mode on the top-level in the system, item or process hierarchy. Note 2 to entry: Criticality measures normally combine severity of effect with at least one other characteristic of a failure mode. Note 3 to entry: The specific meaning of criticality is dependent upon the evaluation method defined within an analysis and is discussed in detail within this document. Note 4 to entry: Criticality relates to the failure mode and not to the failure causes (if the latter are identified at all). 3.1.1 6 treatment action to modify the likelihood and/or effects of a failure mode Note 1 to entry: Treatment is sometimes referred to as mitigation. Note 2 to entry: Treatment may involve actions to eliminate the failure cause, change the likelihood of the failure mode occurring, and/or change the consequences. 3.1.1 7 human error discrepancy between the human action taken or omitted, and that intended or required EXAMPLE Performing an incorrect action; omitting a required action; miscalculation; misreading a value. [SOURCE: IEC 60050-1 92:201 5, 1 92-03-1 4]
4 Overview 4.1 Purpose and objectives An FMEA is a method in which an item or a process is broken down into elements and, for each element in turn, failure modes and effects are identified and analysed. This is to identify any required improvements by eliminating adverse effects or reducing their likelihood or severity. The purpose of adding a criticality analysis is to enable prioritization of the failure modes for potential treatment. The reasons for which FMEA is undertaken include the following: • to identify those failure modes which have unwanted effects on system operation, for example preclude or significantly degrade operation or affect the safety of the user and other persons; • to improve the design and development of items or processes in a cost effective manner by intervening early in the development programme; • to identify risks as part of a risk management process (ISO 31 000); • to satisfy statutory and business obligations by demonstrating that foreseeable risks have been identified and accounted for; • to provide a foundation for other dependability analyses (Annex D discusses the relationship between FMEA and other dependability analysis methods); • to develop and support a reliability test programme ; • to provide a basis for planning maintenance and support programmes such as through reliability centred maintenance (IEC 60300-3-1 1 ); • as a key process within an asset management system (ISO 55000). In general, FMEA is a method to analyse the effect of single failures. If FMEA is used to analyse failure of interdependent items, then these can be considered, with limitations, in the analysis (5.3.6 and 5.3.7.2).