Understanding Crude Oil Washing
Crude oil washing (COW) is a critical process in the oil transportation industry. It involves the use of crude oil as a cleaning agent to remove residual oil from the cargo tanks of an oil tanker. This article aims to provide an understanding of the minimum requirements for tank washing at the discharge port during COW operations.
The Basics of Crude Oil Washing
In COW, the washing process is not determined by the number of tanks to be washed, but by the coverage of the tank surfaces. The International Convention for the Prevention of Pollution from Ships (MARPOL) specifies that 85% of the vertical surface area and 90% of the horizontal surface area inside a tank must be covered by the direct impingement of the jet. This ensures that the majority of the tank’s interior is adequately cleaned, reducing the amount of residual oil left behind.
Discharge Port Requirements
When a tanker arrives at the discharge port, there are specific requirements for COW. If there are no additional instructions from the charterers or receivers, MARPOL requires that during every discharge, at least the tanks designated to carry any ballast water during the voyage should be crude oil washed. This is to ensure that these tanks are clean before they are filled with ballast water, preventing any contamination.
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In addition to this, it is common practice to crude oil wash about 25% of the remaining tanks on a rotational basis. This is done for sludge control, ensuring that the build-up of sludge in the tanks is minimized.
Conclusion
Crude oil washing is a vital process in the oil transportation industry, ensuring that tanks are kept clean and reducing the environmental impact of oil transportation. However, it’s important to note that these are general guidelines and the specific requirements may vary depending on the ship’s operations manual and the regulations of the discharge port. Therefore, it’s always recommended to refer to the ship’s Crude Oil Washing Operations Manual for specific procedures and precautions.
In conclusion, the process of crude oil washing is not just about the number of tanks cleaned, but about ensuring that the majority of each tank’s surface area is adequately washed. This ensures the efficiency of the process and contributes to a more sustainable and environmentally friendly oil transportation industry.
