In the practice of engineering, classification of SSCs usually ends at equipment level, for example a control cabinet or switchgear based its safety function. However, classification of the parts is also necessary and meaningful. Although IAEA SSG-30 and TECDOC-1787 methodology provided is applicable to parts in equipment, safety function description of equipment usually has no direct relation to its parts, or in other word, has no strong connection. EPRI NP-5652 gives guideline on parts classification method in appendix B, but the guideline is at large.

To solve the problem, a practical classification method especially for parts is given in this paper. The method improved in this paper is based IAEA SSG-30 principle, EPRI NP-6895 and simplified FMEA. Firstly, this method take the equipment safety function classification and function description as starting; secondly, for every part in equipment, answering three main questions to determine whether the fixed part is safety related or not. Finally, the fixed part is classified as safety related or none safety related.

The practical classification method improved in this paper is not only applicable to electrical parts, but also applicable to the mechanical parts. When parent equipment’s function is not safety-related, this approach is also applicable, and then the analysis basement is equipment’s operation function.

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