CMC Vessel-Specific Hazards 2

Question 1

When a marine chemist issues a 'Safe for Workers' certificate for a cargo tank, what condition regarding oxygen must be met?

Accepted Answer

Oxygen level must be between 19.5% and 22%

Answer

Oxygen level must be exactly 21%

Answer

Oxygen level must be above 18%

Answer

Oxygen level must be above 20.9%

Question 2

Which vessel space presents the greatest risk of hydrogen sulfide accumulation due to organic sludge decomposition?

Accepted Answer

Cargo tank after carrying crude oil

Answer

Fore peak tank

Answer

Cargo pump room

Answer

Engine room bilge

Question 3

A void space adjacent to a fuel oil tank is being prepared for entry. What is the primary chemical hazard the marine chemist must evaluate beyond flammability?

Accepted Answer

Hydrocarbon vapor migration through tank boundaries

Answer

Carbon monoxide from combustion

Answer

Nitrogen enrichment from inerting

Answer

Chlorine from antifouling coatings

Question 4

During a ballast tank inspection on a chemical tanker, the marine chemist detects a slight sweet odor with readings of 1 ppm benzene. What is the appropriate action?

Accepted Answer

Issue a restricted entry certificate requiring air-supplied equipment

Answer

Proceed with entry using a supplied-air respirator

Answer

Declare the space safe since 1 ppm is below OSHA PEL of 1 ppm TWA

Answer

Ventilate for 30 minutes then re-test

Question 5

What unique hazard do double-bottom tanks on bulk carriers present that single-bottom vessels do not?

Accepted Answer

Difficult ventilation geometry creating dead pockets of inert or toxic gas

Answer

Higher risk of methane accumulation from grain cargoes

Answer

Greater hydrostatic pressure on personnel

Answer

Increased risk of electrical shock from cathodic protection

Question 6

A marine chemist is called to certify a pump room on a product tanker. Benzene content in the previous cargo was less than 0.1%. Which standard governs the atmospheric testing requirements?

Accepted Answer

NFPA 306 in conjunction with applicable OSHA standards

Answer

OSHA 29 CFR 1910.146 confined space standard only

Answer

IMO MSC/Circ.1401 alone

Answer

SOLAS Chapter II-2 regulations

Question 7

What is the significance of the 'Lower Explosive Limit' (LEL) reading of 10% on a combustible gas indicator when certifying a tank for hot work?

Accepted Answer

The space must be re-ventilated; hot work requires 0% LEL reading

Answer

The space is safe for hot work since it is well below the LEL

Answer

Hot work may proceed with fire watch present

Answer

The reading indicates the meter needs calibration