What is Slop tank requirements of an oil tanker as per MARPOL?

As per regulation 29 of MARPOL annex I every oil tanker of 150 GRT and above shall be provided with slop tanks the slop tanks capacity.

Slop Tank

It means a tank specifically designated for the collection of tank draining, tank washings and other oily mixture.The total capacity of slop tank on tanks shall not be less than 3% of the oil carrying capacity of the ship except the administration may accept.

  • 2% for such oil tankers where the tank washing arrangement are such that once the slop tank or tanks are charged with washing water this water is sufficient for tank washing and where applicable for providing the driving fluid for eductors, without the introduction of additional water into the system.
  • 2% where segregated ballast tanks or dedicated clean ballast tanks are provided or where a COW is fitted.
  • This capacity may be further reduced to 1.5% for such oil tankers where the tank washing arrangements are such that once the once the slop tank or tanks are charged with washing water, this water is sufficient for tank washing and where applicable for providing the driving fluid for eductors, without the introduction of additional water into the system.
  • 4% for combination carries where oil cargo is only carried in tanks with smooth walls this capacity may be further reduced to 0.8% where the tank washing system are such that with washing water, this water is sufficient for that washing and where applicable for providing the driving fluid for eductors, without, the introduction of additional water into the system.

As per regulation no 29 of MAROPL annex I, every oil tanker of 150 GRT and above shall be provided with slop tanks. The slop tanks capacity are to be 3% of the total oil carrying capacity of the vessel. It may be reduced to 2% of the tank washing arrangements are such that once the tanks are charged the water is sufficient for washing and to provided drive for educators, 2% where CBT and SBT are provided. It may be reduced to 1%.

AMIT KUMAR