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Retention of slops on chemical tankers - safety procedure

Regulation for retention of slops ? : All processing and discharging of slops on tankers which are carrying a cargo of noxious liquid substances in bulk is to be in strict compliance with the requirements of Annex II of MARPOL 73/78 and procedures described in the approved ship’s specific Procedure and Arrangements Manual (P & A Manual). The above regulations (the latest amended version) must be available on board, and consulted before the loading of any noxious cargo is considered.

All operations with respect to a chemical cargo which take place on board the vessel, including discharge into the sea or removal by ventilation of residues, is to be properly recorded in the Cargo Record Book for Ships Carrying NLS in Bulk.



chemical tanker navigation at sea
Substances posing a threat of harm to the environment are divided by MARPOL 73/78 Annex II into four Categories – X, Y, Z and OS. Category X substances are those posting the greatest threat to the marine environment, while category OS substances are those posing the least threat.

Water contaminated with chemical cargo (e.g. tank washings) may be discharged ashore, into barges and, under certain circumstances, into the sea. When washing tanks, which contained special cargoes, it is preferable to wash each tank separately and pump the washings independently to the shore, barge or sea rather than accumulate an unknown mixture in a slop tank.

If tank washing or slops are to be transferred to a barge alongside the Ship to Ship Transfer Guide is to be followed, and it must be ensured that the necessary hose connections are properly made. Barge personnel must be acquainted with the nature of the hazards and with the safety precautions, which must be observed in the interest of both parties.

Under no circumstances must water with noxious cargo be discharged overboard into port or enclosed waters, without the express permission of the appropriate authority. At sea, water contaminated with cargo must only be discharged overboard when absolutely necessary, and in strict compliance with Annex II of MARPOL 73/78 and ship’s P&A Manual.

To minimise the risk of vapour or liquid cargo blowing back on board, water contaminated with cargo is, whenever possible, to be discharged overboard through a designated overboard discharge on the side opposite from the wind, taking into account the location of seawater intakes. The Protective clothing must be worn by personnel on deck. Particular care must be taken not to intake the noxious vapour into ship’s accommodation and engine room. Alteration of the ship’s course and/or speed must also be considered to reduce the risk.

When chemical tankers are carrying a cargo or part cargo of oil in bulk they must also comply with the applicable requirements .


Tank Cleaning IMO regulation///MARPOL 73/78 Annex II MEPC 2/ Circ. 15 Annex /10

This is to draw your kind attention that The International Maritime Organisation (IMO) MARPOL 73/78 ANNEX II regulates the discharge of Noxious Liquid Substances and the use of chemicals that are used for tank cleaning purposes.

The IMO is changing current regulation MEPC./Circ.363 in order to cut down on the number of chemicals used for tank-cleaning purposes. For future products no perfume or colouring agents will be allowed in tank-cleaning chemicals that will be discharged to sea inside the shore limits as listed in the MARPOL 73/78 ANNEX II.

All tank-cleaning products approved to MEPC./Circ.363 prior to 1 January 2007 need to be re-evaluated based on criteria outlined in MEPC1/Circ 590. All IMO approved products evaluated through MEPC./Circ.363 before 1 January 2007 will cease to be valid on 1 August 2010.

The new and revised regulation MEPC 2 /Circ.15 came into force on 1 August 2010. All cleaning additives evaluated and found to meet the requirements of paragraph 13.5.2 of Annex II of MARPOL 73/78 are consolidated into annex 10 of the MEPC.2/Circular 15.




Related Info:

Voyage planning and related considerations

Cargo sampling safety precautions

Preparation for cargo operation

Preparing a cargo tank atmosphere

Cargo unloading operation safety precautions

Liaison between ship and shore

International regulations for control of noxious liquid chemicals into sea

How to arrange disposal of tank cleaning waste ?

Retention of slops on chemical tankers

Preparations prior allowing personnel into cargo tanks / enclosed spaces

How to rescue injured or unconscious person from enclosed spaces

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