Explosion Caused By Fumigation – Case Study
Yellow grain had been loaded in all cargo holds up to the hatch coverings by a bulk carrier. Fumigation technicians arrived on board after the loading was completed and fumigated the cargo using fumitoxin pellets.
The fumigation pellets were required to be placed subsurface, according to the shipment documents. The technicians poured the pellets from flasks while stepping on the hatch coverings or hatch comings in this case. After a little more than an hour of effort, all of the cargo hatches were closed and the ship was set to sail.
A series of explosions
An explosion happened in one of the holds a few hours later. The hatch covers had shifted somewhat, and blue-grey smoke could be seen pouring from beneath the edges, according to the crew. A third explosion occurred about an hour later in a second hold, and a fourth occurred a few minutes afterward. Shortly later, explosions erupted in the other holds.
Cause of the explosion
Fumitoxin pellets and similar fumigants contain roughly 55% aluminum phosphide, which interacts with water to form phosphine, a very poisonous and powerful fumigant. When phosphorus gas is combined with air at a concentration of more than 1.8 percent to 2% by volume, it forms an explosive combination (the lower flammable limit).
In each of the holds, the phosphine content in the air surpassed the lower flammable limit. The fumigant pellets in each hold were not spread evenly throughout the cargo surface or applied to the subsurface; instead, they were simply poured on top of the cargo.
This technique of administration allowed the pellets to accumulate in small places and encouraged a relatively quick interaction of the pellets with moisture, resulting in phosphine gas concentrations beyond the lower flammable limit, resulting in the explosions.
What can we learn from this incident?
- The management should offer training to the team to ensure that they are aware of the fumigation needs and procedures.
- The crew must make certain that the fumigation pellets are dispersed in accordance with the cargo documentation.
- To prevent pest infestation, agricultural items in bulk can be fumigated in ship holds. For fumigation, solid aluminum phosphide (or something similar) is commonly employed.
- Aluminum phosphide produces phosphine, a poisonous and combustible gas that kills insects when it combines with water vapor (humidity) in the air. Heat is also given off during the reaction.
- Just before closing holds, the solid fumigant can be applied in fabric socks or as pellets on the surface.
- After that, the holds are kept closed for a while before being ventilated. Due to the harmful fumigant, people must stay away from holds that are being fumigated.
- The fumigant can react too rapidly if there is an excessive amount of fumigant in one spot, or if the fumigant comes into touch with liquid water, such as perspiration or moisture.
- This can generate a lot of heat, which can cause the cargo and/or packaging, such as bags or paper, to catch fire. The fumigant gas itself may ignite under certain conditions, resulting in an explosion.
- It is critical that the fumigant be used according to the manufacturer’s recommendations.
- Due to the fact that holds are always left unventilated after fumigation, there is a possibility of excessive condensation, which might result in sweating or leaking.
- This can result in cargo damage as well as the above-mentioned fire and explosion dangers.
- Before fumigation, which is generally carried out by specialized businesses, weather conditions and cargo characteristics, such as moisture content, must be carefully examined.
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