CMC Hot Work Procedures 2

Question 1

A Marine Chemist is asked to certify a tank for hot work immediately after gas-freeing. What is the MOST critical pre-certification check?

Accepted Answer

Verify combustible gas readings are below 10% LEL throughout the space

Answer

Confirm the tank has been washed with fresh water

Answer

Check that adjacent tanks contain no cargo

Answer

Ensure the tank coating has fully cured

Question 2

During hot work on a tank bulkhead, the adjoining tank contains an inert atmosphere with residual hydrocarbon cargo. What is the correct action?

Accepted Answer

Prohibit hot work because the adjacent space poses a through-bulkhead ignition risk

Answer

Proceed if the work side reads below 10% LEL

Answer

Allow hot work if a fire watch monitors the adjacent tank

Answer

Reduce the inert gas pressure before proceeding

Question 3

Which condition would cause a Marine Chemist to DENY a hot work certificate in a freshly gas-freed tank?

Accepted Answer

Combustible gas reading of 0% LEL at the entry point but 12% LEL in a low corner

Answer

Oxygen reading of 20.9% by volume

Answer

Presence of ventilation equipment still running

Answer

Temperature inside the tank is 95°F

Question 4

What is the purpose of a 'hot work permit' as distinct from a Marine Chemist certificate?

Accepted Answer

It is the vessel management authorization document that references the Marine Chemist findings

Answer

It replaces the Marine Chemist certificate when a chemist is unavailable

Answer

It certifies the welder is qualified to perform the work

Answer

It documents the type of welding equipment approved for use

Question 5

Slag from overhead welding falls into an open void space during authorized hot work. What is the IMMEDIATE required response?

Accepted Answer

Stop hot work and inspect the void space for fire or smoldering material

Answer

Continue work if the void space previously tested safe

Answer

Notify the Coast Guard before taking any action

Answer

Increase ventilation flow to the void space

Question 6

A Marine Chemist certificate for hot work is typically valid for how long before re-testing is required?

Accepted Answer

Until conditions change or work is interrupted for more than a designated period, typically 4–8 hours

Answer

72 hours regardless of conditions

Answer

24 hours, renewable by the vessel's chief officer

Answer

Indefinitely as long as continuous ventilation is maintained

Question 7

When performing hot work near a cofferdam that separates a cargo tank from a ballast tank, the Marine Chemist should test:

Accepted Answer

Both the work space and all adjacent spaces including the cofferdam

Answer

Only the space where hot work will occur

Answer

Only the cargo tank side

Answer

The ballast tank only if it previously held petroleum cargo