OPTIMIZATION OF INERT GAS SYSTEM MAINTENANCE TO PREVENT EXPLOSIONS IN THE CARGO TANKS OF THE MT. GRIYA CIREBON

Abstract

The MT. Griya Cirebon is a crude oil tanker whose loading and unloading operations rely heavily on the reliability of the Inert Gas System (IGS). The IGS serves to reduce the oxygen concentration inside the cargo tanks to prevent explosions caused by the mixing of hydrocarbon vapors with air. During the author’s onboard project aboard the MT. Griya Cirebon between October 2021 and August 2022, two recurring failures disrupted unloading operations: the inert gas supply temperature rose to 60°C — far above the permissible limit of 5°C above seawater temperature — and an oxygen concentration in the inert gas reaching 6.54%, exceeding the maximum limit of 5% set by the IMO. This study employed a qualitative descriptive method using observation, interviews, and documentation to identify the root causes and formulate corrective actions. The results showed that the high inert gas temperature was caused by suboptimal scrubber unit performance due to inadequate maintenance of the seawater spray nozzles and the scrubber pump (impeller wear, clogged suction lines, and dirty filters). The high oxygen content was caused by a leak in the rubber flexible hose upstream of the inert gas blower, triggered by strong vibrations resulting from shaft/impeller misalignment and material fatigue in the rubber hose. Recommended solutions include scheduled maintenance in accordance with the manual, replacement of damaged impellers and rubber flexible hoses, realignment of the blower shaft, and calibration of the oxygen analyzer. Implementing these measures will restore IGS performance and ensure the safety and operational efficiency of the tanker’s cargo operations.