Buying a Used TBM: Inspection Checklist for EPB and Slurry Refurbishment

Second-hand tunnel boring machines are attractive for Latin American metro and water tunnel programs, where capital budgets are tight and schedules are fixed. The risk sits in condition, not age. Inspection should start with the cutterhead: structural cracking, worn cutter housings, deformation in the muck ring, and hard-facing loss. Then the main bearing and its seals — grease sampling, vibration history and seal leakage tell you whether the heart of the machine is serviceable.

The screw conveyor, hydraulic power pack and electrical cabinets deserve the same scrutiny: auger and casing wear, pump and valve condition, and PLC obsolescence often drive refurbishment cost more than the shield itself. Typical scope covers bearing and seal replacement, cutterhead retrofit — new housings, revised cutter spacing, larger disc upgrades for abrasive volcanic ground — plus hydraulic flushing and electrical modernization suited to mixed sedimentary faces.

A new-build machine takes many months to engineer and deliver; a correctly refurbished EPB or slurry TBM can be mobilised considerably faster, which matters when a metro shaft is