Exam Question
(a) List SIX hazards associated with the carriage of liquefied gas in bulk. (8)
(b) Sketch and describe the details of construction of a free-standing prismatic tank within a gas carrier designed to carry liquefied gas (LPG). (8)
Class 2 (2nd Engineer)
SC&S
📅 Mar 2025
Reference Answer
### (a) Hazards Associated with the Carriage of Liquefied Gas in Bulk
Six major hazards associated with the bulk carriage of liquefied gases are:
1. **Flammability & Explosion**: Most liquefied gases (LPG, LNG) are hydrocarbons and are highly flammable. A leak can rapidly vaporize, forming a large, dense vapor cloud that is heavier than air and can travel long distances along the deck or sea surface. If this cloud encounters an ignition source within its flammable range (e.g., 2-10% by volume in air for propane), it can result in a catastrophic fire or vapor cloud explosion (VCE).
2. **Toxicity**: Certain gas cargoes, such as Ammonia (NH₃) and Vinyl Chloride Monomer (VCM), are highly toxic. Inhalation can cause severe respiratory damage, chemical burns to the lungs, and can be fatal even at low concentrations. Skin contact with these substances can also cause severe chemical burns. Strict cargo handling procedures and use of personal protective equipment (PPE), including chemical suits and breathing apparatus, are mandatory.
Six major hazards associated with the bulk carriage of liquefied gases are:
1. **Flammability & Explosion**: Most liquefied gases (LPG, LNG) are hydrocarbons and are highly flammable. A leak can rapidly vaporize, forming a large, dense vapor cloud that is heavier than air and can travel long distances along the deck or sea surface. If this cloud encounters an ignition source within its flammable range (e.g., 2-10% by volume in air for propane), it can result in a catastrophic fire or vapor cloud explosion (VCE).
2. **Toxicity**: Certain gas cargoes, such as Ammonia (NH₃) and Vinyl Chloride Monomer (VCM), are highly toxic. Inhalation can cause severe respiratory damage, chemical burns to the lungs, and can be fatal even at low concentrations. Skin contact with these substances can also cause severe chemical burns. Strict cargo handling procedures and use of personal protective equipment (PPE), including chemical suits and breathing apparatus, are mandatory.
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