CRUDE OIL WASHING(COW)

WHAT IS COW?

Crude oil washing (COW) is a system whereby oil tanks on a tanker are cleaned out between      voyages not with water, but with crude oil - the cargo itself

The solvent action of the crude oil makes the cleaning process far more effective than when water is used.

The system helps prevent pollution of the seas from operational measures.

MARPOL Annex I Regulation 13 (6) requires every new crude oil tanker of 20,000 tons dead weight and above to be fitted with a cargo tank cleaning system using crude oil washing.

WHY COW?

•Previously, oil tanks on crude oil tanker were cleaned by water but this method of cleaning increased marine pollution and required bigger slop tanks to store left over residue and oil water mixture.

•In order to prevent this problem, a better non pollutant way was introduced where in oil carg  of the tank itself was used to clean the cargo tanks.

•When oil cargo is sprayed with pressure on tank walls and surfaces, the sediments sticking to the tank dissolves and converts into useful cargo which can be pumped out to the shore tanks.

•This system virtually eliminates the requirement of slop tanks on ships and almost all cargo can be transferred to the shore.

•Maintaining a pressure of at least 10 bar assists this process.

Before starting the operation

•confirm all pre arrival checks are performed.

•The complete COW operation to be discussed with ship and shore staff.

•Signal and Emergency signs to be discussed to stop the operation between

     shore and ship staff.

•Inert Gas plant to be working and oxygen content must be less than 5 %.

•Fixed Oxygen analyser to be checked and calibrated for proper functioning.

•Portable oxygen analyser should be made available and checked for proper

     functioning.

When the operation is under process

•The inert gas values to be frequently checked- Tank pressure and O2 value.

•A responsible person to be always present on deck.

•All deck lines and valves must be frequently checked for any leakages.

•Trim should be sufficient to assist the bottom washing of tanks.

The level of holding tanks to be continuously monitored to avoid overflow.

When the Operation is finished

•Drain tank wash line off crude oil

•Shut all the valves in the line used for the operation

•Stop and drain all the machines involved in the operation

•Drain all the cargo pumps after the operation is finished

Suspending Crude Oil Washing

Suspend COW operations immediately if:

•The oxygen content of Inert Gas being supplied exceeds 8% by Volume.

•Any indication of cargo oil leakage or malfunction in the COW system.

•COW operation is not carried out in accordance with the COW operation plan, or if communication between the CCR and main deck is lost.

•If the required necessary safety precautions as described and covered above cannot be followed.

•If terminal instruct to do so