CMC - Certified Marine Chemist Hot Work Procedures Questions and Answers 1 — Questions and Answers
Question 1: According to NFPA 306, which of the following locations requires a Marine Chemist's certificate before commencing hot work?
- On a weather deck in a designated area far from any tanks.
- Within a dry cargo hold that has been certified 'Safe for Workers' by a Shipyard Competent Person.
- On a pipeline connected to a fuel tank that has been emptied and cleaned. (Correct answer)
- In the galley for minor repairs on a stove.
Correct answer: On a pipeline connected to a fuel tank that has been emptied and cleaned.
NFPA 306 and OSHA regulations (29 CFR 1915.14) mandate that a Marine Chemist must certify a space as 'Safe for Hot Work' when the work is on pipelines, heating coils, pumps, or other accessories connected to spaces that have contained fuel or other flammable/combustible liquids. The other locations may not require a Marine Chemist's certificate, depending on the specific circumstances and the judgment of a Shipyard Competent Person.
Question 2: A welder is tasked with performing hot work on the bulkhead of a machinery space. The adjacent space is a double bottom tank that previously contained lube oil. What is the PRIMARY responsibility of the Certified Marine Chemist in this scenario?
- To personally supervise the welding operation to ensure it is performed correctly.
- To inspect and test the machinery space where the welding occurs AND all adjacent spaces, including the double bottom tank. (Correct answer)
- To ensure the welder is using the correct personal protective equipment (PPE).
- To provide a fire watch for the duration of the hot work activity.
Correct answer: To inspect and test the machinery space where the welding occurs AND all adjacent spaces, including the double bottom tank.
A Certified Marine Chemist's primary role is to identify and evaluate hazards in the work space and all adjacent spaces. According to NFPA 306, this includes testing for flammable gases, oxygen levels, and assessing the flammability of residues in both the space where the work is performed and any bordering compartments to prevent ignition through heat transfer. Supervising the work, checking PPE, and acting as a fire watch are responsibilities of other designated personnel.
Question 3: Which of the following is a required condition on a Marine Chemist's certificate for a space to be designated 'Safe for Hot Work'?
- The oxygen concentration must be exactly 20.9%.
- The concentration of flammable vapors must be below 10% of the Lower Explosive Limit (LEL). (Correct answer)
- All combustible materials must be removed from the entire vessel.
- The space must be continuously monitored by the Marine Chemist for the duration of the work.
Correct answer: The concentration of flammable vapors must be below 10% of the Lower Explosive Limit (LEL).
For a space to be certified 'Safe for Hot Work', both NFPA 306 and OSHA 29 CFR 1915 require the concentration of flammable vapors to be below 10% of the LEL. While oxygen must be within a safe range (typically 19.5% to 22%), it doesn't have to be exactly 20.9%. Removing all combustibles from the vessel is impractical; they must be removed from the work area or protected. A competent person, not necessarily the Chemist, is responsible for maintaining conditions after certification.
Question 4: A fire watch is required to remain on station after the completion of hot work for what minimum duration?
- 10 minutes
- 60 minutes
- Until the surface has cooled to ambient temperature
- 30 minutes (Correct answer)
Correct answer: 30 minutes
OSHA regulations and standard maritime safety procedures require a fire watch to remain in the hot work area for at least 30 minutes after the work has been completed. This is to detect and extinguish any smoldering fires that may have been started by sparks or slag.
Question 5: NFPA 306 defines hot work as any operation involving riveting, welding, burning, or similar fire-producing operations. Which of the following activities may also be classified as hot work by a Marine Chemist?
- Hydrostatic testing of a pipe
- Cleaning a tank with a non-flammable solvent
- Abrasive blasting or grinding (Correct answer)
- Opening a bolted manhole cover
Correct answer: Abrasive blasting or grinding
NFPA 306, paragraph 1-05, explicitly states that grinding, drilling, abrasive blasting, or similar spark-producing operations are considered hot work unless deemed otherwise by a certified marine chemist. The other activities do not typically generate sparks or a sufficient heat source to be classified as hot work.
Question 6: A Marine Chemist's certificate has been issued for hot work in a specific tank. The next day, before work resumes, the Shipyard Competent Person (SCP) conducts re-testing. What is the purpose of this re-testing?
- To issue a new, superseding certificate.
- To verify that the conditions under which the original certificate was issued have been maintained. (Correct answer)
- To calibrate the Marine Chemist's testing equipment.
- To expand the scope of the hot work beyond the original certificate's limitations.
Correct answer: To verify that the conditions under which the original certificate was issued have been maintained.
The Marine Chemist's certificate is valid only as long as the specified conditions are maintained. A Shipyard Competent Person is responsible for subsequent inspections and tests to ensure that conditions have not changed due to factors like gas freeing, cleaning, or leakage. This ensures the continued validity of the original certificate; the SCP does not issue a new one or change its scope.
CMC - Certified Marine Chemist Hot Work Procedures Questions and Answers 1
According to NFPA 306, which of the following locations requires a Marine Chemist's certificate before commencing hot work?