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1. The Development Of Crude Oil Storage Tank Cleaning For
Tankers

2. Crude oil storage tank cleaning, or commonly called
Crude Oil Washing (COW), is mainly the process of
cleaning the storage using the oil itself. Prior to strict
environmental regulations, tankers were cleaned using
jets that sprayed seawater inside the containers. Also,
before ballast tanks were introduced in ship design,
water had to be stored in order for the propeller to be
properly immersed at sea.

3. After some time, multiple regulations has been
introduced to lessen the waste produced when cleaning
the tanker ships after every trip. The owners of these
vessels have also found ways to use these regulations in
order to lessen the oil waste to decrease costs in running
them. In here, we will be tackling the many
advancements for the past few decades up until the
current regulations of the industry.

4. Thousands of tanker ships carry oil from rig platforms to
refineries for processing every day. Thus, it is important
to ensure the profitability of each delivery and to lower
costs as much as possible. One easy way was to clean
the tanks that were storing fuels regularly. If left
unattended, the fuels will form a sticky layer on the
walls that will not be transferred to the refinery and will
be weight that the tanker would need to carry on its way
back to the platform.

5. Initially, the cleaning method used was to pump in
heated seawater and jet sprayed to remove the layer of
oils from the surface, which were then pumped
overboard. This method resulted in high amounts of fuel
being discharged into the sea. Pollutants were highly
concentrated on piers and docks where the ships were
being cleaned.

6. In 1954, the Oil Pollution Convention (OILPOL) was
adopted as a measure to lessen pollution through the
prohibition of the release of waste within 50 miles from
the nearest land. On some instances, this limit was
extended to 100 miles on environmentally protected
sites, where the spillage may have very grave impacts.

7. Due to the pollution that was still being produced by the
OILPOL adaption, a new process was introduced where
the tanks were still cleaned using pressurized heated
water, but instead of disposing the waste, it is first
placed into a special slop tank. While the ship is on its
return voyage, the oil, which is lighter than water, would
eventually float on top. The water, which settled at the
bottom, will be returned to the sea. This process is
called the Load on Top.

8. The Load on Top was very successful that an
approximate of 8 million tons of fuel per year was saved
from being dumped into the sea. It also made significant
savings for the companies that owned the ships as the
oil that remained after removing the sea water was
simply topped with fresh new crude oil.

9. Another improvement for the crude oil storage tank
cleaning process was once again introduced and called
the Crude Oil Washing, which used pressurized fuel and
sprayed onto the walls to remove the layered sediments
that got stuck. This latest process eliminated the use of
water, thus removing the need to separate the
petroleum from a cleansing agent that would usually
produce waste.

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