Cleaning from DPP to CPP
To load Clean Petroleum Products (CPP) after carrying Dark Petroleum Products (DPP), the tank must be cleaned to meet the water white standard and should be visually clean as well. If the crew has not previously performed tank cleaning, they may have limited or no experience. Herewith we try to explain the fundamental steps for cleaning from DPP to CPP. However, we strongly recommend consulting our operations department or your supercargo for specific cleaning guidance.
Tank cleaning preparations
When cleaning from DPP to CPP, the washing water used for prewashing, must be discharged into the slob tank. Washing to slobs is mandatory because the residues must be brought ashore. The use of the right temperature and pressure are important factors when you want to perform your tank cleaning job as good as possible. When talking about temperature, the temperature of the bulkheads, the ballast water and the natural surroundings needs to be taken into consideration. When talking about pressure, 8 bar is considered minimum. First, each tank needs to be prewashed at 60oC for approximate 1-2 hours. Then the washing water is discharged into a slob tank. Another option is to fill the slob tank with enough seawater to perform recirculation (400 cbm) and use this as the first cleaning step. It often requires two batches to clean the bulk out. Thereafter, those slob tanks must be cleaned in which the cleaning solution is going to be prepared.
CP Super Degreaser
For this type of cleaning its best to use a degreaser. We use CP Super Degreaser as example to explain the tank cleaning basics. Because of the high concentration of CP Super Degreaser, a small amount of product is in many cases sufficient. Depending on the level of contamination, we mostly recommend a solution of 5 to 10%. This solution must be recirculated through the butter wash heater and cleaning line back into the slob tank.
During the recirculation the temperature needs to be increased to 75-80oC. It is customary to install extra portable butter wash machines in the tank to be able to clean even the ‘shadow corners’ and other difficult-to-reach areas. Depending on the volume, recirculation needs to take place approximate 3-4 hours for each tank. Since the volumes which we are talking about in Petroleum Tanks are often huge, sea water is most likely to use during this type of cleaning. CP Super Degreaser provides excellent results, even when used in sea water.
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Post-treatment
When the recirculation procedure is finished, the tanks need to be rinsed with hot sea water and inspection needs to take place. As final activity, you can vent, mop and dry the tanks.
Technical support
At CP Metal Chemicals, customer satisfaction is our top priority. Providing the highest level of service is only possible when we have a complete understanding of our clients’ needs. If you’d like more information on the basic principles of tank cleaning or wish to discuss ways to improve the cleaning process, we are more than happy to assist!
Supercargo
All different cargoes, tank coatings and changing conditions during tank cleaning operations can lead to a new challenge every cleaning operation. Our in-house Supercargo is an expert in assistance and supervision in remote and on-board cargo tank cleaning operations. Need assistance? Please contact us for more information.
You can contact us via below details:
P: +31 (0) 10 299 49 99