Apparatus for servicing a structure

Apparatus for servicing an elongate structure 30 having accretion 51a and/or degraded layer(s) on an external surface thereof comprises a frame (1 figure 1) for assembly or arrangement around the structure and arranged to be driven along the structure. A tool carriage 15 connected to the frame may carry one or more tools 23 for servicing the structure. The one or more tools comprise a cutting tool 62 (e.g. a rotary or reciprocating cutter 66, abrasive blade, chisel blade, circular or reciprocating saw or milling tool), arranged to cut in a direction parallel to surface of the structure to remove accretion and/or degraded layer(s) 50 at least partially from the structure without substantially damaging the structure. An inspection tool 61 may be arranged to inspect a wall of the structure. The radial position of the inspection tool may be adjusted in response to detected thickness of the accretion and/or degraded layer(s). Other tools may include a wall thickness measuring probe, a clearance sensor, a camera and one or more distance sensors and which may include optical or magnetic sensors.