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

Combustible gas concentration must be below 10% LEL throughout the space before a hot work certificate can be issued.

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

Hot work must not be performed on a bulkhead adjacent to a space containing flammable vapors or cargo, regardless of readings on the work side.

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

Any location within the space reading at or above 10% LEL disqualifies the entire space from hot work authorization.

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

The hot work permit is issued by vessel management and incorporates the Marine Chemist's atmospheric findings as the basis for authorization.

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

Hot slag can ignite residues or coatings in void spaces; work must stop immediately and the affected space must be inspected.

(CMC) Certified Marine Chemist Practice Test