In general, each process unit is cleaned by recirculation of ETI Cleaning & Gas-Freeing Solution™ using the unit's pumps. All vessels and exchangers are liquid filled except for large columns such as main fractionators or isostrippers, which are cascaded. The solution is heated to a temperature range of 180°F to 200°F using process unit reboilers, furnaces, and/or direct steam injection. The goal is to provide adequate flow through the entire system while minimizing the amount of temporary connections and blinding required prior to the start of the cleaning.