🔍 Key Concepts

• Inert gas system operations during ballasting on tankers • How hydrocarbon vapors are normally contained, displaced, or vented when tanks are not gas-free • The purpose of mast risers, P/V (pressure-vacuum) valves, and common vent lines

💭 Think About

• Think about what happens to the inert gas and hydrocarbon vapors already in the tank when ballast water comes in—where do those gases go? • Which option would keep hydrocarbon vapors within the closed system instead of sending them straight to the atmosphere? • Among the choices, which one best uses existing cargo/venting arrangements to minimize direct venting of hydrocarbon vapors to open air?

✅ Before You Answer

• Identify which options cause direct venting to atmosphere (mast riser, P/V device, blowers) and which option keeps vapors within the closed venting/IG system. • Verify how a common vent line or a tank being discharged can receive displaced inert gas/vapors without unnecessary atmospheric release. • Check tanker cargo-handling best practices: during ballasting after cargo, which method is recommended to minimize hydrocarbon emissions rather than to speed up venting?