No, it is a rated lifespan. The belts get replaced during re-webbing and the hardware such as mounting points and locks get re-used.
According to the SFI Foundation, in order to retain the proper SFI rating, ONLY THE ORIGINAL MANUFACTURER is permitted to reweb and recertify them. Prior to January 2002, Simpson provided rewebbing services for their harness belts. However, they no longer will reweb or recertify their belts. We recommend that you replace harnesses that have been used for several years or have been subjected to a specific severe use situation.