Hi Raghuvarun,
There will be several methods depending upon the your final objectives of such requirement.
In case you want to just maintain the spare part and the Equipment from which it has been removed, then use Catalog Codes. In the Object part Catalog maintain the Spare part in the Code part and the Equipment number in Item Text.
This method is hassle free.
In case the requirement's like physically identifying the spare-part etc., then the process would be very complex. You need to opt for not only Material Codes but also the Serialization of all these spare parts.
So you need to first consolidate your objectives of the requirement you have asked for. Then post a Query in detail explaining the objectives.
In most of the cases such requirements are satisfied with ideas like the 1st case I proposed, i.e., Catalogs & Codes.
Jogeswara Rao K