1. Spare parts definitions and classifications

There are a number of possible definitions of a spare part, which correspond to different approaches to the problem posed by spare parts.

• The simplest definition of a spare part, and the one that best reflects the general idea of what a spare part is, is as follows: "a spare part is a part intended to replace a defective or damaged part of an asset in operation". This definition clearly implies that the spare part is an elementary component, and this is most often the case, but there are exceptions, as we shall see.

  Example

  Let's take the example of a high-pressure hydraulic network, comprising components such as pumps, hydraulic motors, cylinders, valves, etc. The very design of these devices, which involve adjustments with very small tolerances, calls for very strict maintenance...