CMC Chemical Hazard & Risk Management 3 — Questions and Answers
Question 1: Under NFPA 306, which condition requires a Marine Chemist certificate before hot work can begin on a vessel?
- Any vessel underway in international waters
- Vessels in repair yards, shipyards, or where hot work could create fire or explosion hazard in spaces containing flammable vapors (Correct answer)
- Vessels carrying fewer than 12 passengers
- Commercial fishing vessels under 26 feet LOA
Correct answer: Vessels in repair yards, shipyards, or where hot work could create fire or explosion hazard in spaces containing flammable vapors
NFPA 306 requires a Marine Chemist certificate for hot work on vessels where fire or explosion hazards exist due to flammable vapors, particularly in shipyard and repair environments.
Question 2: When assessing risk from a spilled corrosive liquid in a bilge space, which hazard interaction is of greatest concern to a Marine Chemist?
- The corrosive reacting with structural steel to generate hydrogen gas (Correct answer)
- The corrosive raising the flash point of residual bilge water
- UV degradation of the corrosive reducing its pH
- Electrostatic charge buildup on the corrosive surface
Correct answer: The corrosive reacting with structural steel to generate hydrogen gas
Strong acids reacting with iron or steel liberate hydrogen gas, which can accumulate to explosive concentrations in confined bilge spaces.
Question 3: A Marine Chemist is evaluating inhalation risk from a chemical with a vapor pressure of 200 mmHg at 25°C and a TLV-TWA of 0.1 ppm. What does the high vapor pressure indicate?
- The chemical presents a low inhalation risk because it evaporates quickly and dilutes
- The chemical can generate airborne concentrations far exceeding its TLV, indicating high inhalation risk (Correct answer)
- High vapor pressure means the chemical is non-flammable
- The chemical requires only dermal hazard controls, not respiratory protection
Correct answer: The chemical can generate airborne concentrations far exceeding its TLV, indicating high inhalation risk
A high vapor pressure means the substance readily forms vapors that can reach concentrations many orders of magnitude above a very low TLV, making inhalation a primary concern.
Question 4: Which OSHA standard specifically governs permit-required confined space entry on general industry vessels and shipyard employment?
- 29 CFR 1910.146 and 29 CFR 1915.12 (Correct answer)
- 29 CFR 1926.65 and 29 CFR 1910.119
- 46 CFR 197 Subpart B and 33 CFR 126
- 49 CFR 173 Subpart D and 29 CFR 1910.1200
Correct answer: 29 CFR 1910.146 and 29 CFR 1915.12
29 CFR 1910.146 covers permit-required confined spaces in general industry, while 29 CFR 1915.12 specifically addresses confined and enclosed spaces in shipyard employment.
Question 5: The concept of 'hierarchy of controls' when managing chemical hazards aboard a vessel places which control method at the highest priority?
- Personal protective equipment (PPE)
- Administrative controls such as job rotation
- Engineering controls such as local exhaust ventilation
- Elimination or substitution of the hazardous chemical (Correct answer)
Correct answer: Elimination or substitution of the hazardous chemical
The hierarchy of controls prioritizes elimination first, followed by substitution, then engineering controls, administrative controls, and finally PPE as the last resort.
Question 6: A Marine Chemist performing a pre-entry test detects 15% LEL in a space classified as requiring a 'Safe for Hot Work' certificate. What is the correct course of action?
- Issue the certificate with a restriction limiting welding to short bursts
- Deny the certificate; LEL must be 0% for hot work authorization (Correct answer)
- Allow entry for inspection only since 15% LEL is below the explosive range
- Issue the certificate if supplied-air respirators are available to workers
Correct answer: Deny the certificate; LEL must be 0% for hot work authorization
A 'Safe for Hot Work' certificate requires 0% LEL; any detectable flammable vapor concentration disqualifies the space from hot work authorization.
Question 7: Which chemical property best predicts whether a liquid cargo will accumulate as vapor in the lowest point of a hull space?
- Boiling point
- Vapor density relative to air (Correct answer)
- Water solubility
- Auto-ignition temperature
Correct answer: Vapor density relative to air
Vapor density determines whether a chemical vapor sinks (>1 relative to air) and accumulates in low-lying areas such as bilges and double bottoms.
CMC Chemical Hazard & Risk Management 3
Under NFPA 306, which condition requires a Marine Chemist certificate before hot work can begin on a vessel?