CMC Confined Space Entry Requirements 3

Question 1

Who is responsible for testing a confined space atmosphere immediately prior to worker entry under NFPA 306?

Accepted Answer

A marine chemist or competent person designated under OSHA 1915

Answer

NFPA 306 requires a marine chemist or competent person to test the atmosphere before entry.

Question 2

What hazard class does hydrogen sulfide (H₂S) present in confined spaces aboard vessels carrying crude oil?

Accepted Answer

Toxic and flammable gas hazard

Answer

H₂S is both highly toxic and flammable, presenting dual hazards in crude oil cargo tanks.

Question 3

Under OSHA 29 CFR 1915.12, what is required when workers must enter an oxygen-deficient atmosphere?

Accepted Answer

Supply air respirators or SCBA must be used

Answer

OSHA 1915.12 mandates supplied-air respirators or SCBA for entry into oxygen-deficient spaces.

Question 4

A space on a vessel is designated 'Not Safe' by the marine chemist. Under what condition may workers enter?

Accepted Answer

Only after the marine chemist or competent person re-tests and re-designates the space as safe

Answer

A 'Not Safe' space may only be re-entered after the marine chemist or competent person re-tests and changes the designation.

Question 5

What does the term 'inerting' mean in the context of vessel confined space safety?

Accepted Answer

Filling the space with an inert gas to prevent flammable atmospheres

Answer

Inerting involves introducing an inert gas (such as nitrogen or CO₂) to displace oxygen and prevent flammable mixtures.

(CMC) Certified Marine Chemist Practice Test