Vessel-Specific Hazards Flashcards
7 cards from real CMC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Vessel-Specific Hazards flashcards as text
On a Ro-Ro vessel, which vehicle deck hazard is unique compared to conventional cargo ship holds?
Answer: Accumulation of carbon monoxide and hydrocarbon vapors from vehicle engines during loading/unloading
During loading and discharge of motor vehicles, engine exhaust produces carbon monoxide and hydrocarbon vapors that can reach dangerous concentrations in the enclosed vehicle decks.
A marine chemist is asked to certify a cofferdam between a cargo tank and engine room on a tanker. What makes this space particularly hazardous?
Answer: It is a boundary space adjacent to both a flammable cargo tank and a machinery space with ignition sources
Cofferdams serve as fire breaks between cargo tanks and machinery spaces, making their atmospheric condition critical—vapor migration from the cargo side toward ignition sources in the engine room is the key hazard.
What is the primary atmospheric hazard unique to the fore peak tank of a vessel compared to other ballast tanks?
Answer: Greater oxygen depletion due to corrosion in this high-stress area with limited air circulation
The forepeak tank experiences high corrosion rates in the bow area and has limited natural ventilation, making oxygen depletion from metal oxidation a significant concern.
During tank cleaning on a chemical tanker after carrying acrylonitrile cargo, which combination of hazards requires the marine chemist's primary attention?
Answer: Flammability and acute toxicity from HCN-releasing vapor and skin absorption potential
Acrylonitrile is both flammable and metabolizes to release hydrogen cyanide in the body; skin absorption and inhalation of vapors present acute toxic risk, requiring both flammability and toxic vapor monitoring.
What is the hazard posed by residual nitrogen blanketing in a cargo tank on an LPG carrier when the marine chemist begins inspection?
Answer: Oxygen-deficient atmosphere due to nitrogen displacement of air, causing rapid incapacitation upon entry
Nitrogen blanketing completely displaces oxygen; personnel entering without supplied-air equipment lose consciousness within seconds without warning signs because nitrogen is odorless.
A marine chemist must certify a wing tank on a tanker for entry. Readings show 20.9% O2, 0% LEL, but the PID detector reads 15 ppm. What does an elevated PID reading indicate in this context?
Answer: Presence of volatile organic compounds (VOCs) that may include toxic substances below their explosive range
A photoionization detector (PID) reading of 15 ppm indicates the presence of ionizable organic vapors—potentially toxic substances—even though the combustible gas indicator shows 0% LEL, requiring identification of the source.
Which condition would cause a marine chemist to issue a 'Safe for Hot Work' restriction specifically requiring continuous atmospheric monitoring during hot work operations?
Answer: When adjacent tanks or spaces cannot be permanently isolated from potential vapor sources
When a space cannot be permanently isolated from adjacent potential vapor sources, continuous monitoring during hot work is required because conditions may change during the work period.