OIL TANKER TANK WASHING/CLEANING OPERATION
It is the process by which Tanks are washed by fixed/portable machines using cold/hot sea water or Fresh water.
REASON FOR TANK CLEANING
Tank cleaning is carried out prior following:
1. Tank Entry
2. Grade Change
PRECAUTIONS DURING TANK CLEANING OPERATION
Guidelines as per ISGOTT & Company specific checklists must be complied with. The following precautions are among those taken in account:
i) BEFORE WASHING OPERATION
a) Tank washing plan must be prepared and discussed with all concerned.
b) All Concerned pumps and pipelines must be tested as per company procedures.
c) Ensure, all scuppers are well plugged and anti-pollutions gears in place.
d) The tanks must be well inerted with Oxygen content below 8%. Gas tests must be made at various levels.
ii) DURING TANK WASHING OPERATION
a) Before actual washing, the tank bottom should be flushed with water and stripped. The flushing water should be drained to the tank designed or designated to receive slops.
b) If the tank has a venting system that is common to other tanks which are not to be washed, the tank must be isolated to prevent ingress of gas from other tanks.
c) If portable washing machines are used, all hose connections should be made up and tested for electrical continuity before the washing machine is introduced into the tank.
d) Required pressure must be maintained at all times inside the wash line.
e) During tank washing, regular gas tests must be made at various levels. Consideration should be given to the possible effect of water on the efficiency of the gas measuring equipment.
f) The tank should be kept drained during washing. Washing should be stopped to clear any build-up of wash water.
g) Steam should not be injected into the tank.
h) Precautions relating to sounding and the introduction of metallic equipment should be taken as per ISGOTT.