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CLASS 8 - CORROSIVE
SUBSTANCES
Note: The
following description is not intended to be a definitive technical description of what is
termed a dangerous goods under the New Zealand Standard 5433:1999 - Transport of Dangerous
Goods on Land or The United Nations Recommendations on the Transport of Dangerous Goods.
Corrosive materials are those which react
chemically with the steel, aluminium or skin. These fall into the UN class 8. Products
with a corrosive hazard include:
- Acids such as hydrochloric, sulphuric and so
on.
- Alkalis (bases) such as sodium hydroxide,
ammonium hydroxide.
- Amines such as dimethyl amine.
- Some gases such as Chlorine and Ammonia
Packages with class 8 material inside are
identified with the following label:
| The effect of corrosive
material is a slow chemical reaction, unlike other classes of dangerous goods which have
immediate hazard risks e.g. flammablity, explosive or even radioactive. Since corrosives have to contact the material directly to
have any effect, the corrosive risk is usually considered a lower risks. |
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An excellent example of a product which presents a
very specific hazard due to the mode of transport is Mercury. Under the UN system, mercury
(chemical symbol Hg) is a class 8 material, with the relatively low hazard rating of
packing group III. For air transport, mercury is assigned packing group I. The reason is
simple, airplanes are made out of aluminium and mercury's corrosive properties attack
aluminium resulting in a weakening of the strength of the aircraft. Hence, airlines take
particular precautions with mercury.
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