This part of IEC 61163 describes particular methods to apply and optimize reliability stress screening processes for lots of repairable hardware assemblies, in cases where the assemblies have an unacceptably low reliability in the early failure period, and when other methods, such as reliability growth programmes and quality control techniques, are not applicable. The reasons for using reliability stress screening may be time constraints and/or the very nature of the deficiencies that the reliability stress screening is designed to catch. The processes apply to any stage of a series production of repairable assemblies (see Figure 3). The methods for setting up a process can be used during production planning, during pilot-production, as well as during well-established running production. A prerequisite for the application of the methods is that a certain level of flaws remaining in the outgoing assembly can be specified. The processes described are general processes for reliability stress screening in cases where no specific process is described in a product standard. They are also intended for use by IEC committees in connection with preparation of product standards. A reliability stress screening process can form part of an overall reliability programme (see IEC 60300-2).