The invention relates to a system (1) for monitoring, operating and maintaining an industrial plant (2), in particular in the metal-producing industry or the steel industry, including: at least one mobile terminal device (3) with at least one sensor (4) for recording measured values within the industrial plant (2), at least one position sensor (5) for detecting the position of the at least one mobile terminal device (3) in the industrial plant (2), a central data processing device (6) for processing the measured values recorded by the at least one mobile terminal device (3) by means of the at least one sensor (4), taking into account the position of the at least one mobile terminal device (3) recorded by means of the at least one position sensor (5) in the industrial plant (2), and at least one communication network (7) for exchanging data between the at least one mobile terminal device (3), the at least one position sensor (5) and/or the central data processing device (6). The invention also relates to a method for monitoring, operating and maintaining an industrial plant (2), in particular in the metal-producing industry or the steel industry.