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MEO CLASS 1 · ORAL QUESTION 16

Cargo leak in LPG carrier

Answer

A cargo leak in a gas carrier occurs when liquid or vapor escapes from the primary cargo containment (tank) into the hold space or secondary barrier. Under the IGC Code, this triggers an immediate statutory and operational emergency response.

Immediate Action Plan

  1. Emergency Shutdown (ESD): Actuate the ESD immediately to stop all cargo transfer pumps, close manifold valves, and isolate cargo tank liquid/vapor lines.
  2. Raise Alarm & Muster: Sound the Emergency Alarm. Evacuate non-essential personnel from deck and hazardous zones.
  3. Inert Gas / Nitrogen Purging:
    • Maintain a positive pressure of dry Inert Gas ($\text{N}_2$) in the hold space surrounding the cargo tank.
    • Ensure oxygen levels inside the hold space remain strictly below 1% to prevent the formation of a flammable atmosphere.
  4. Gas & Temperature Monitoring:
    • Monitor fixed gas sampling heads continuously (LEL detectors in hold space).
    • Monitor cargo hold temperature sensors (cold spots on inner hull indicate liquid leakage).
  5. Cargo Transfer / Liquid Management:
    • If liquid has accumulated in the hold space sump, pump it back to an intact cargo tank or deck tank using the dedicated hold space emergency cargo pump or eductor system.
    • Transfer remaining liquid cargo from the leaking tank to an intact tank using cargo deepwell pumps.
    • If in loaded condition where other cargo tanks are already full or not enough space is available, in that case cargo to be remain hold space. Hold space is designed to temporarily contain leaked liquid cargo for a limited duration (typically 14 days)
  6. Controlled Evaporation & Reliquefaction: Run the hold space vapor suction line to the ship’s reliquefaction plant. Draw the boil-off gas from the hold space sump, reliquefy it, and pump the condensate back into the upper spray headers of full cargo tanks (utilizing ullage/vapor space) or send it to deck tanks.
  7. Inert Gas Maintenance: Keep a continuous positive dry Nitrogen/ inert gas cushion inside the hold space to ensure the atmosphere remains strictly non-flammable (<1% O2).
  8. Emergency STS / Refuge Port: Notify the DPA, Flag State, and Class, company , DPA to arrange an emergency Ship-to-Ship (STS) transfer or seek a Port of Refuge to pump out the leaking tank and hold space liquid into a shore tank or barge.