Robotic inspection device for tank and pipe inspections includes a housing configured to be positioned on a portion within a flow apparatus. The portion has a wall with a coating on the wall. The coating has a coating thickness. The device has a magnetic transducer mounted to the housing. The magnetic transducer is configured to measure a magnetic flux permeability through the coating on the wall. A computer system is mounted to the housing. The computer system is operatively coupled to the magnetic transducer. The computer system includes one or more processors and a computer-readable medium storing instructions executable by the one or more processors to perform operations. The operations include receiving magnetic flux permeability measured by the magnetic transducer at a location on the portion and determining a coating thickness at the location based on the magnetic flux permeability measured at the location.