Use remote equipment when the complete route can be reached, viewed and drained from outside. A manway alone says nothing about the rear of a baffle or a pocket without a recovery path.
External working is a good first option only when reach, visibility and drainage can all be demonstrated. An accessible manway on its own does not prove coverage behind baffles or beneath coils.
Test the complete remote route
Dimensions cover the opening, tool carrier, bends, internals and recovery point. The operator also needs a reliable camera or direct view of the active area. This is the practical basis for deciding when to use remote tank cleaning on a particular vessel.
The site’s confined-space team owns any later entry
Remote work may reduce what remains, but it does not declare the vessel safe to enter. Any later entry needs its own assessment, isolation, atmosphere controls and authorisation.
Ask how the contractor will confirm coverage from outside and how it will distinguish a cleaned surface from one that was never visible.
The remote tank cleaning service explains what a contractor needs to assess reach and recovery.