Chemical Tanker Guide Online
Home || Chemical hazards || Various chemicals || Cargo Stowage || Care ||Tank cleaning ||Handling equipments ||



Disposal of tank washings ,slops and dirty ballast - chemical tankers guideline

During normal operations of a chemical carrier, the main need to dispose of chemical residues, slops or water contaminated with cargo will arise during or immediately after tank cleaning. Final disposal of slops or washwater should be in accordance with the ship's P&A Manual. Tank washings and slops may be retained on board in a slop tank, or discharged ashore or into barges.

Mandatory pre-wash water

Mandatory pre-wash procedures should be conducted strictly in accordance with the ship's P&A Manual, and the resulting contaminated wash water should always be discharged to shore. The intention of MARPOL is that this should happen immediately following the cargo discharge operations, and in the same port. However, occasions do arise when adequate shore reception facilities for the washings are not provided, and the ship must retain the washings on board until arrival at another port. MARPOL addresses this matter, and the P&A Manual will provide guidance on the correct procedures for a particular ship. During such a voyage, the slops and tank washings should be given the same safety and environmental care as the original cargo.



Dirty ballast

Dirty ballast, caused by ballasting into a cargo tank before the tank is cleaned, should be treated as slops, and must be disposed of in accordance with MARPOL and the ship's P&A Manual.

Safety precautions during discharge of cargo slops into the sea

When discharge overboard is permitted, it should only be undertaken when the ship is at sea normally be below the waterline through an underwater discharge outlet on the side of the ship away from essential water inlet valves. In the interests of safety, this procedure should be adopted even when it is not a mandatory requirement.

When any discharges are made above the waterline, care should be taken to avoid cargo vapour or liquid blowing back on board. If such a risk exists, discharge should be made below the waterline: if this is not possible, consideration should be given to altering the ship's course or speed to reduce the risk, and personnel on deck should wear appropriate protective clothing.

Management of slop tanks

Compatibility of various cargo and cleaning chemicals should be considered just as carefully when handling slops as when handling the cargoes themselves. Particular care is needed when washing several tanks which have contained dissimilar cargoes, and compatibility should be taken into account when selecting the destination tank for stripped wash water. The following should be avoided:

Mixing of slops from Annex I (oil) cargoes with slops from Annex 11 (chemical) cargoes.

Mixing of slops from incompatible cargoes.

Mixing of slops from vegetable oils or fats with chemical slops or petroleum oil slops.

If the ship's cargo tanks are used as slop tanks, care should be taken to avoid introducing slops from cargoes which are incompatible with the tank coating. In this regard, some cargoes which are themselves compatible may, when mixed with water, form acids and thus damage a coating, e.g. slops from hydrolytic cargoes in a zinc coated tank.


Recommendations

Desloping of any kind of slops to a shore reception facility is a costly affair. Therefore it is highly recommended that in the event of any slops generation following pre agreement / written communication is made with charterers Operator.



Related Info:

Tank explosion case study

Pre-cleaning /washing of cargo tanks

Final cleaning of cargo tanks prior loading

Tank cleaning and posoning hazards

Testing of tanks and cargoes

Practical tank cleaning methods for various noxious liquid cargo

Special tank cleaning method

Determining proper tank cleaning by acid wash method

Supervision of all tank cleaning and gas freeing operations

Disposal of tank washings, slops and dirty ballast - safe method

Cargo handling safe practice for chemical products

Cargo compatibility and reactivity of various chemical cargo

Poisoning and required first aid treatment onboard

Procedure for slop disposal onboard chemical tankers

Determining presence of contaminants in chemical cargo

Checklist for handling dangerous liquid chemicals in bulk

Defining three main categories of noxious liquid chemicals at sea

Cargo handling equipments for handling noxious liquid substances in bulk

Cargo handling safe practices onboard modern chemical tankers

IMO codes guideline for modern chemical tankers

Controlling the atmosphere in cargo tanks with nitrogen supplied from shore

How to determine the level of a liquid in a chemical tank

Poisoning and required first aid treatment onboard

After tank cleaning gas freeing safety guideline for chemical tankers

Draegar safety tube prior entering enclosed spaces

Preparations prior allowing personnel into cargo tanks / enclosed spaces

How to rescue injured or unconscious person from enclosed spaces

Preparations for hot work and safety precautions

Total flooding method for seagoing chemical tankers

Water extinguishing method for fire protection

Foam extinguishing method for chemical tankers

Dry powder fire extinguishing method





More info:

Main Info pages!

Home page ||| Chemical hazards ||| Cargo planning & Stowage ||| Cargo loading ||| Cargo documents ||| Safe stability ||| Cargo care ||| Preparation for unloading ||| Inert gas systems |||Gas freeing ||| Nitrogen handling ||| Chemical handling Safe practice |||Handling equipments ||| Cargo & Ballast pumps ||| Cargo tanks |||Tank cleaning |||Special cargoes |||Spills emergencies |||Fire protection





Chemicaltankerguide.com is merely an informational site about various aspects of chemical tankers and safety tips that may be particular value to those working in: Chemical Handling, Chemical Storage, Liquefied Chemical Suppliers, Chemical Shipping, Chemical Transportation, Chemical Terminals, Bulk Chemical Services and Chemical Processing. If you are interested in finding out more about chemical tanker guideline please visit IMO official website. For any comment please Contact us

Copyright © 2011 Chemical Tanker Guide.com All rights reserved.