Confined Space Entry Requirements Flashcards

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

Answer: A marine chemist or competent person designated under OSHA 1915

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

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

Answer: Toxic and flammable gas hazard

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

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

Answer: Supply air respirators or SCBA must be used

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

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

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

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

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

Answer: Filling the space with an inert gas to prevent flammable atmospheres

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

Which instrument is specifically required to detect flammable vapors in a confined space before entry?

Answer: Combustible gas indicator (CGI) calibrated for the relevant vapor

A combustible gas indicator calibrated for the specific vapor present is required to assess flammable gas hazards.

What is the maximum allowable oxygen concentration in a vessel's confined space before it is considered oxygen-enriched and hazardous?

Answer: 23.5%

OSHA 1915 considers atmospheres above 23.5% oxygen as oxygen-enriched, creating increased fire and explosion risk.