Seagoing chemical tanker design and operational routines all aim at reducing the risk for environmental pollution. Nevertheless: accidents
can happen or be caused by improper action by anyone involved on board, ashore or by other ships. Traditional
thinking rules that the vessel and her cargo should be salvaged on the basis of the values they represent. With chemical and oil cargoes this is not necessarily true. It is more a matter of containing the cargo on board or by other
means until the situation can be mastered with due regard to weather, shipping etc.
Spills of any size in port, due to over-fillings, hose breakage etc, should be reported to the Port Authorities at once.
Keep in mind that water supplies, other water intakes local fishing, public amenities etc can be affected with enormous
human and economical consequences unless immediate counteractions can be taken.
In order to reduce the danger for minor spillages deck scuppers should be closed, drip pans arranged under hose manifold
and a close watch kept when topping up the cargo tanks.
Any accidental spills in port area and how spills are to be
treated must be sought from Port Authorities, who will normally take charge of a spill situation.
Common cargoes which are particularly damaging to marine life when released to the sea: acetone cyanohydrin, acrolein.
Strongly negative aesthetic effects will be caused by the release of: aniline, creasote, dodecyl benzene, acrolein, acetone
cyanohydrin.
The biggest risk of a cargo spill is during cargo handling operations, either because of equipment failure or improper handling
procedures. Cargo spills are therefore most likely to happen in port. In the event of a spill, the following actions should be
taken immediately:
Activate the alarm.
Stop all cargo operations and close valves and hatches.
If alongside a berth, notify the terminal staff of the chemicals involved and possible risk posed to personnel.
Notify local port authorities, usually through the terminal staff.
Prohibit smoking and use of naked lights throughout the ship.
Clear all non-essential personnel from the area.
Close all accommodation access doors, and stop all non-closed circuit ventilation.
Arrange for main engines and steering gear to be brought to stand-by.
The primary factor affecting response will of course be the chemical or chemicals involved, but the action to be taken depends
on the circumstances of the spillage, as well as its size and location. If there is a possibility of cargo or cargo vapour entering
any accommodation or engine room air intake, appropriate preventive steps must be taken quickly. As a general rule, there
should be a full initial response to any spill, the emergency party wearing the appropriate protective clothing and breathing
apparatus.
Safety of personnel and the ship should take priority over environmental care. If it is possible and safe to do so, the released
liquid should be pumped or washed into a slop tank or other containment, or collected for safe disposal using absorbent
material. However, if it is not safe or if there is any doubt, the spillage should be washed overboard with very large amounts of
water. If at sea, the tanker should be manoeuvred so as to disperse the vapour away from the ships accommodation.
For small, localised and contained spills, it may not be necessary to implement all the action points in the ship's contingency
plan. However, the master must always keep in mind the local circumstances, the nature of the chemical involved, and the
potential harm to personnel, ship's structure and the environment. In most cases it is better to overreact than to delay action.
The general advice for a corrosive cargo spillage on deck is to wash the spilled liquid overboard with large quantities of water
from as far away as practicable. A fog nozzle should be used and not a direct jet of water. The emergency team should wear
appropriate protection, approach the spill from upwind and direct the spray of water to the edge of the spill, gradually working
towards the centre. The use of water on a fuming acid and other strong acids will initially cause a vigorous reaction that will
cause increased fuming. However, this will be temporary while the spillage will be dealt with rapidly. If at sea, the ship should
be turned off wind.
Deck valve and pipeline fittings leakage
If leakage develops from a deck pipeline, deck valve, cargo hose or metal arm, operations through that connection should be
stopped and the situation treated as an emergency until the cause has been identified and the defect remedied. Permanent means
for the retention of any slight leakage at ship and shore connections should have been provided. Operations should not be
restarted until the fault has been rectified and all hazards from the released cargo eliminated.
If a pipeline, hose or arm bursts, or if there is an overflow, all cargo and bunker operations should be stopped immediately and
the situation treated as a cargo spill.
Tank leakage within the ship
Leakage from a cargo tank into void or ballast spaces may cause damage to materials or equipment, and may create an
explosive atmosphere and a potential personnel risk. The actions to be taken may differ depending on the product involved and
other circumstances such as the weather, but should as a minimum include the following:
Identify the products involved and the risks associated with them.
Clear the area of all non-essential personnel.
Identify the location of the leak
Transfer the product in the leaking tank to an empty tank, if at all possible.
Consider notifying port and local authorities, and ship's operators.
Commence remedial measures.
Spills in confined spaces such as pumprooms should, where practicable, be first contained and then treated and collected for safe
disposal. Spills may be contained with dry sand, earth or proprietary chemicals. Acid residues can be neutralised with sodium
carbonate (soda ash) or special chemicals. Untreated acid spillage must be prevented from entering mild steel areas of the ship
as rapid corrosion can follow: in extreme cases the consequent hull corrosion has caused the ship to sink.
Leakages from one cargo tank to another, or multiple leakages where there is a risk of mixing incompatible chemicals, should
always be treated carefully. Where time allows, expert advice should be sought as to the possible risks involved.
A non-cargo space that has had a chemical leaking into it should be treated as a cargo space, and the same precautions taken. It
should be cleaned and gas freed before any attempt is made for repairs. Remedial measures should be decided upon after
consultation with the operator.
It should be borne in mind that individual ship has got own characteristics and limitations may involved handling various chemical cargoes . The master and all personnel in all cases must be aware of cargo/ship information that has been given and comply with relevant safety procedures.
Related Info
The biggest risk of a chemical cargo spill
The biggest risk of a cargo spill is during cargo handling operations either because of equipment failure or improper handling procedures. Cargo spills are therefore most likely to occur during the vessels stay alongside.
.....
Chemical spill via Annex II overboard line Overboard connections to sea are usually provided with spectacle blinds or dismountable spools and blanks. These lines are to be positively isolated at all times when not in use by putting the blanks in line or by removing spools and blinding.
.....
Cargo hose disconnection - Personal Safety on Chemical
Tankers Hose disconnection and checks of the line must be carried out with extra awareness, especially when handing toxic chemical cargoes. Crew training in cargo hose disconnection is important including Personal Safety on Chemical Tankers.
......
Risk with noxious liquid cargo contact
Different chemicals affect the human body in many different ways. A general information and some practical advice are available in Appendix,7, of "Medical first aid guide for use in accidents involving dangerous goods" published by IMO, WHO and ILO ref (36).
.....
Restriction on discharge of cargo residues into sea from chemical tankers
Discharge into the sea of cargo residues and tank cleaning products is strictly controlled. It is recommended that any discharge should be as far from land as practicable. ....
International regulations for control of noxious liquid chemicals into sea
MARPOL Annex II contains extensive regulations about the loading, carriage and discharge of noxious liquid cargoes, as well as the treatment of cargo residues remaining on board, washing of empty tanks and the final disposal of the contaminated washing medium.
.....
How to arrange disposal of tank cleaning waste ?
Substances posing harm to the environment are categorised by MARPOL 73/78 Annex II into four Categories X, Y, Z and OS. Category X substances are those posing the greatest threat to the Marine Environment, whilst Category Z substances are those posing the smallest threat......
Retention of slops on chemical tankersAt 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 ships P&A Manual.
.....
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.