Prohibition of transport of dangerous goods by sea is based on different rules; the primary prohibition comes from IMDG Code.

Any substance or article which, as presented for transport, is liable to explode, dangerously react, produce a flame or dangerous evolution of heat or dangerous emission of toxic, corrosive or flammable gases or vapours under normal conditions of transport are forbidden from transport by sea.

Following are forbidden from transport by all modes of transport.

1. Mixtures of a hypochlorite with an ammonium salt
2. Ammonium bromate and its aqueous solutions and mixtures of a bromate with an ammonium salt
3. Ammonium chlorate and its aqueous solutions and mixtures of a chlorate with an ammonium salt
4. Ammonium chlorite and its aqueous solutions and mixtures of a chlorite with an ammonium salt
5. Ammonium permanganate and its aqueous solutions and mixtures of a permanganate with an ammonium salt

Above prohibition is promulgated through United Nations Model Regulations 18^th Revised Edition which is adopted by IMDG Code through chapters 1.1 and 3.3.

Dangerous Goods which may be acceptable by other modes but prohibited specifically for sea transport is listed in chapter 3.3 of IMDG Code, special provision 900, which are:

1. AMMONIUM HYPOCHLORITE
2. AMMONIUM NITRATE liable to self-heating sufficient to initiate decomposition
3. AMMONIUM NITRITES and mixtures of an inorganic nitrite with an ammonium salt
4. CHLORIC ACID, AQUEOUS SOLUTION with more than 10% chloric acid
5. ETHYL NITRITE pure
6. HYDROCYANIC ACID, AQUEOUS SOLUTION (HYDROGEN CYANIDE, AQUEOUS SOLUTION) with more than 20% hydrogen cyanide
7. HYDROGEN CHLORIDE, REFRIGERATED LIQUID
8. HYDROGEN CYANIDE SOLUTION, IN ALCOHOL with more than 45% hydrogen cyanide
9. MERCURY OXYCYANIDE pure
10. METHYL NITRITE
11. PERCHLORIC ACID with more than 72% acid, by mass
12. SILVER PICRATE, dry or wetted with less than 30% water by mass
13. ZINC AMMONIUM NITRITE

Let us look up some of the above prohibited chemicals’ properties to understand why they are prohibited for transport by sea.

METHYL NITRITE

EXTREMELY FLAMMABLE. Will be easily ignited by heat, sparks or flames. Will form explosive mixtures with air. Silane will ignite spontaneously in air. Vapors may travel to source of ignition and flash back. Cylinders exposed to fire may vent and release flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket. (Source 2012 Emergency Response Guide)

ETHYL NITRITE

Decomposes under exposure to air, light, water or heat to evolve toxic nitrous fumes. Inhalation of ethyl nitrite vapours, even in small quantities, rapidly affects the heart and can be dangerous.

PERCHLORIC ACID

Commercially available is up to 72% acid by mass. Perchloric acid becomes a strong oxidizer when heated or at higher concentration. Organic, metallic and non-organic salts formed from oxidation are shock sensitive and pose a great fire and explosion hazard. There are many documented accidents resulting from perchloric acid. [1].

CHLORIC ACID, AQUEOUS SOLUTION

With more than 10% chloric acid is prohibited due to its strong nature of oxidizing. It may deflagrate or explode upon contact with combustibles and organic materials.

Shipping Line’s Prohibition & Rejection

Apart from prohibition by IMDG Code, each Shipping Line has their own prohibition and restriction list. This contains outright prohibition, quantity limitation or acceptance from vetted shippers. Lines prepare this list basis accident happened in the industry, on their own vessel or envisaging greater liability.

Economic comparison of freight earned on a 20 or 40 ft box to the losses due to an accident caused by cargo within it will be hugely disproportionate.

In general, some lines prohibit or heavily restrict below:

1. Class 1 (Division 1.1 & 1.2)
2. Class 2.3
3. Class 3 – Liquid desensitized explosives
4. Class 4.1 – Solid Desensitized Explosives, temperature controlled self-reactive substances
5. Class 4.2 – Pyrophoric solids and liquids
6. Class 4.3 – Liquids
7. Cass 5.1 – Calcium Hypochlorite, Ammonium Nitrate
8. Cass 5.2 – Temperature controlled
9. Class 6.1 – In Carrier own reefers
10. Class 7 – All
11. Class 8 – In Carrier own reefers
12. Class 9 – Waste & Asbestos

Apart from this shipping lines have specific UN Numbers under each class either prohibited or restricted acceptance from certain shippers only.

Chemicals falling under Australia Group, Basel Convention, The United Nations Convention Against Illicit Traffic In Narcotic Drugs And Psychotropic Substances, and other similar international conventions and protocols may also be prohibited or restricted by carriers.

The cargo offered by shipper, whether falling under prohibited list or not, may get rejected by a line for any of below reasons.

• Goods involved are prohibited by the line’s in-house rules
• Goods involved are prohibited by Vessel owner / VSA
• Transit port prohibition
• Transhipment port prohibition
• Discharge port prohibition
• Quantity limit of transit port increase if this shipment is accepted
• Quantity limit of transhipment port increase if this shipment is accepted
• Quantity limit of discharge port increase if this shipment is accepted
• Direct delivery confirmation needed from consignee
• Import/Export permit required (UN Drug Control or CWC requirement)
• Special documents such as analysis report or competent authority report needed
• Technical name missing or not matching the proper shipping name
• Insufficient or non-appropriate packing details
• Segregation needed with other goods in same container
• Reefer temperature not as per regulations for said dangerous goods
• Flashpoint and Packing Group not matching
• Flashpoint variation from pure substance is too large
• Information in dangerous goods declaration not matching the details submitted in booking
• Segregation or stowage restriction on vessel
• Draft constrains at a port when loading DG on deck