Answer
Hot gassing is the process of eliminating liquid pockets/puddles remaining at the bottom of the tank after standard stripping operations. If cold Propane liquid is left behind when inerting begins, it will form non-condensable traps or freeze up when exposed to nitrogen.
How to Line Up for Hot Gassing
Verify the cargo tank is completely stripped of pumpable liquid.
Line up the Cargo Compressor to draw Propane vapor from the top of the cargo tank.
Direct the compressor discharge through the Cargo Heater.
Set the heater parameters to warm the vapor up to roughly +20∘C to +30∘C.
Route this superheated, pressurized Propane vapor back into the bottom liquid line/sump spray lines of the same cargo tank.
The hot gas transfers its thermal energy to the liquid remnants, rapidly vaporizing them. Continue this cycle until tank temperature indicators confirm no cold liquid pockets remain.