Maintenance: concepts and definitions

Ever since man first exercised his creative powers to design and use tools, then various and varied devices, right up to the machines and technical installations we know today, he has discovered, and suffered from, the phenomena of degradation and wear which gradually rendered the object in question unusable. It was not long, therefore, before he was prompted to take action to :

• avoid, or at least slow down, these degradation phenomena and their evolution;

• or restore the item to a condition where it can once again perform the function or service for which it was designed, when excessive deterioration had led to it being put out of use.

Since the beginning of the industrial era, the evolution of industrial objects and materials has been characterized by a constant quest for improved performance. What, for example, is there in common between the airplane of the 1930s, which carried a few passengers in precarious conditions, and today's AIRBUS A 380, or between an electric generator from the early 20th century and a 1,300 MW nuclear power plant? The creation of increasingly complex technical devices, whose malfunctions generate increasingly unacceptable risks in terms of both cost and safety, rapidly gave rise to new concepts that have now reached full maturity. These concepts are part of the current design of production systems, whether they are purely industrial (factories) or oriented towards the production of services (airports, hospitals, etc.). We soon realized that one of the essential conditions for mastering maintenance was to master its concepts, using words whose meaning would be perfectly defined. After all, a recipe book is not enough! Anyone who doesn't know what an "egg" is, or the meaning of the word "hard", won't be able to prepare a soft-boiled egg, even with a good cookbook. In addition to recipes, which are legion, even in maintenance, we'll be looking at the few methods that can be used to create maintenance recipes or operations. These few methods will, of course, be linked together by a single methodology, which, by virtue of its shared language, mode of reasoning and assessment, is first and foremost a way of thinking, otherwise it will become incoherent and fragmented.

It was with this in mind that, in the late 1970s, AFNOR, with the support of the French Ministry of Industry, set about establishing a body of standards relating to maintenance. One of the first standards to be established was the maintenance vocabulary, which was to be used to define all concepts. This approach, taken up at European level by the CEN (Comité Européen de Normalisation) in 1993, led to the establishment of, among other things, a European standard for maintenance terminology,...