Encyclopedia of Environmental Science and Engineering, Volume I and II

680 MARINE SPILLAGE—SOURCES AND HAZARDS

technology. As noted earlier, LNG, LPG and a variety of

special products carriers have all been built with double

hulls, as mandated by regulatory requirements.

Special Hazards in Tanker Operations In addition to colli-

sion and grounding, the following hazards to tank vessel oper-

ation should be considered as potential sources of pollution:

a) Fire—Of the many possible disasters which may

occur to a tank vessel in petroleum trades, fire is

among the most common. Should rupture of a

tank occur incidental to the fire, the cargo may

be burned, thus preventing extensive pollution.

However, gross structural failures may occur as

a consequence of fire damage, resulting in uncon-

trolled release of cargo that may not be consumed

by the fire.

b) Explosion—Despite the many regulations and

operational precautions, explosions occur when

an obscure source of ignition takes place in the

gaseous atmosphere above the liquid cargo level.

Some of the most disastrous incidents have taken

place when tankers in ballast with empty tanks not

gas-free have been involved in minor collisions.

It should be noted that the MARPOL requirements include

the installation of inert gas systems (IGS) on all tank vessels

of 20,000 DWT or greater. IGS systems consist of means for

pumping flue gas or treated gas from an inert gas genera-

tor into the cargo tanks to displace air with a combustible

oxygen content.

Special Products Carriers Casualties to the special prod-

ucts carriers described in earlier discussions involve unusual

FIGURE 8 Burmeister & Wain double hull product tanker design. Source: Burmeister & Wain Skibsvaerft A/S.

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