🔍 Key Concepts

• Inert gas system (IGS) requirements for cargo tanks on tankers carrying flammable cargoes • What it means, in practice, when a cargo tank is no longer connected to the inert gas main • The safety options for a tank that is NOT protected by inert gas (e.g., inerted vs gas-free)

💭 Think About

• If a cargo tank is cut off from the inert gas system, does it still have protection against flammable atmospheres? What are the two general safe conditions for a cargo tank that has carried flammable cargo? • Look at each choice and ask: does this action directly address the tank’s atmosphere safety (risk of flammable mixture, over/under-pressure), or is it about something else? • Think about whether operating another valve on the inert gas line alone would change the fact that the tank is isolated from the system.

✅ Before You Answer

• Verify which options actually change the internal atmosphere of the tank (not just external piping configuration). • Consider tanker safety principles: a cargo tank carrying flammable cargo should be either kept inert (oxygen below limiting value) OR gas freed – which options fit into those categories? • Check whether “venting to atmosphere” or “ballasting” by themselves ensure the tank cannot develop a flammable vapor/air mixture.