Removing liquid and residue prepares physical areas for the specialist who manages ventilation and atmospheric testing. It does not produce a gas-free certificate or approve entry.
Physical areas needed by the atmosphere specialist
The atmosphere specialist needs sumps, low connections and other product-retaining surfaces physically prepared. The handover should state where cleaning stops and specialist testing begins.
Pass on the recorded physical condition
The contractor removes product, sludge and accessible residue from the locations named by the atmosphere specialist. That specialist then controls ventilation, testing and any gas-free statement from the recorded physical condition.
Recent contents, temperature, internal coatings and connected pipework all affect the residue that may remain. Vents, dead legs and low points need to be identified even when the visible tank floor looks clear. The responsible site specialists confirm isolation and the checks required before any later access or hot work.
Where geometry allows, remote tank cleaning may remove material from outside. This can reduce the need for access during the cleaning stage, but it cannot override the site’s confined-space or atmosphere procedures.
Cleaned areas and known limits
At handover, record treated surfaces, outlets and inaccessible areas, plus any visible residue or unexpected layer. It can include relevant photographs and recovered material records. It should not contain a general statement of safety that belongs to a different competent person and test.
If inspection follows, connect the cleaning plan with tank inspection preparation so the required plates, seams and fittings are accessible before the next team arrives.
The cleaning boundary is written down before the atmosphere specialist attends. It names the free liquid, sludge and accessible residue the contractor is expected to remove.
The cleaning limit for the testing specialist
Ventilation, gas testing and any gas-free declaration stay with the competent party appointed for those tasks. The handback gives that party the cleaned areas, limitations and time of completion.
Clear the sump and connections named by the testing team
Ventilation and atmosphere testing may continue after visible residue has been removed. Keep that time outside the cleaning completion estimate unless the responsible specialist has included it. This prevents the vessel being treated as ready simply because cleaning equipment has left. Record who receives control of the tank afterwards and who arranges the specialist atmosphere checks. Keep the vessel’s intended vent route available so the appointed testing team can assess the atmosphere without an unplanned change.
Material held in a sump or connected low line can affect the specialist atmosphere work that follows. The physical handover names those retained areas so ventilation and testing teams do not inherit an unexplained condition. The handover time matters because the vessel condition can change while ventilation equipment is being set up. Any later seepage from a named low connection remains attached to that location instead of being described as a general failure of the surface clean. The receiving specialist may need a particular sump, nozzle or low connection physically clear before its own ventilation and testing begins. Naming that location avoids a handover in which the shell appears clean but the area most relevant to atmosphere work remains obscured.