Abstract: A system for the automatic tallying of uniquely serialized drill string components from which well depth is determined, in hole component inventories are maintained, individual components are tracked through the well bore, component diameters are identified with respect to blowout preventer seal elevations and the determination and measurement of individual component down hole service factors with cumulative totalization in a computerized data base management system for these service factors for the purpose of better equalizing wear in order to obtain optimum life from drill strings.