Chemical-tanker inert-gas operation
What is being checked
The inspector is checking whether the vessel's arrangements for use of inert gas on a chemical tanker are planned, understood and executed using vessel-specific limits, verified line-up, effective communication and traceable records.
Ready onboard
0/6 completePractice questions
Answer aloud, then open the preparation point.
1What are the critical controls for use of inert gas on a chemical tanker?
Explain the vessel-specific sequence, limits and safeguards for cargo reactivity, purity requirement, dew point, oxygen limit, tank pressure, contamination risk, compatibility and code or P&A Manual requirements.
2How was the line-up independently verified?
Identify both verifiers, the physical route checked, valve-position confirmation and the record completed before starting.
3What conditions require the operation to stop?
Stop for loss of communication, unexpected pressure or level, leakage, alarm, incorrect line-up or any of these specific failures: oxygen or moisture contamination, unsafe pressure, incompatible inert gas, plant failure or air ingress.
4Show the most recent complete operation.
Trace the plan through cargo plan, oxygen and dew-point logs, tank-pressure trends, P&A Manual and terminal agreement, including any deviation and its authorisation.
5What is the first response to an abnormal condition?
Stop or stabilise the operation, raise the alarm, isolate the source where safe, verify tank and system condition and coordinate with the terminal and Master.
Where an observation may arise
The vessel procedure did not adequately address cargo reactivity, purity requirement, dew point, oxygen limit, tank pressure, contamination risk, compatibility and code or P&A Manual requirements.
The plan was copied or did not reflect the actual cargo, tank condition, terminal limits or equipment status.
A critical valve or connection was not independently checked, or the recorded position conflicted with the physical system.
Responsible personnel could not explain their limits, monitoring duty, communications or stop-work authority.
The plan, log or checklist could not be reconciled with cargo plan, oxygen and dew-point logs, tank-pressure trends, P&A Manual and terminal agreement.
The response did not adequately control oxygen or moisture contamination, unsafe pressure, incompatible inert gas, plant failure or air ingress.
Master's practical note
Use the latest real operation, not a model checklist. Follow one critical parameter from the agreed plan to the CCR display, deck condition and final record.
Equipment boundary and references
Equipment boundary: Apply the vessel's approved cargo manuals, cargo-specific data, terminal agreement and company limits. Do not operate cargo equipment solely to demonstrate it during an inspection.
References
- OCIMF SIRE 2.0 Question Library Part 2, Version 1.0, Question 8.2.1
- IMO IBC Code
- MARPOL Annex II
- OCIMF ISGOTT, Sixth Edition
Last reviewed: 2026-09-14