THE CLEANING of tankage equipment involves the removal of six types of surface contamination. These may be classified as (1) water soluble light liquids, (2) light oils, (3) viscous water soluble materials, (4) heavy oils or greases, (5) solids, and (6) materials leaving a residual odor when removed. The terms light oils and greases are used here to designate all organic, water-insoluble materials.
Although certain of the water soluble compounds of categories 1, 3 and 5 present problems in providing the proper mechanical equipment for their removal, a clean surface can be produced with the use of a sufficient amount of hot water. Class 2 materials usually are removed without difficulty by steaming, alkali washing or in some few cases by solvent washing. Class 5 requires an appraisal of each separate problem and tests the ingenuity of a man in many instances to provide a rapid, economical cleaning method. Classes...
