CHIRP Maritime draws lessons learned from a reported event where nitrogen leak in a tank led to two crew members being asphyxiated due to safety protocol violations and inadequate equipment.
Initial report
During a nitrogen inerting operation on a ship, nitrogen was being pumped into the tanks to displace oxygen, which helps preserve the cargo and prevents oxidisation. Before the process began, an able seaman (AB) conducted a final inspection to ensure the tank was clean and ready. However, after the inspection, the ship’s captain noticed the AB had not reported back as expected and sent the chief officer to check on him.
When the chief officer arrived, he found the AB unconscious on the lower platform inside the tank and immediately raised the alarm. The captain rushed to the scene, only to find the chief officer also unconscious on the upper platform. A rescue team equipped with breathing apparatus entered the tank and retrieved both men. Sadly, the First Officer could not be revived, while the AB was severely injured and required hospitalization.
The investigation revealed that a faulty valve had caused nitrogen to leak from an adjacent tank, displacing oxygen and creating a deadly environment. Although the crew was aware of safety protocols for confined space entry, they had not been followed. Critical steps such as conducting a risk analysis, performing gas measurements, and issuing an enclosed space entry permit were not carried out before the AB’s inspection. Furthermore, although both the AB and chief officer were wearing protective gear, they did not carry personal gas analysers.
This incident highlights serious safety failures that led to the tragedy and underscores the need for strict adherence to safety protocols, proper risk assessments, and the use of appropriate equipment when entering enclosed spaces.
CHIRP Comment
Tank inspections are typically conducted by an officer. In this case, nitrogen likely leaked from an adjacent tank through interconnected pipes, which can happen even with double-valve isolation. CHIRP strongly recommends that vessel Safety Management Systems (SMS) direct that, once inerting has started, all cargo spaces should be considered inert (ie dangerous), even those previously ‘certified safe’, and entry is prohibited. This episode clearly shows that hazards can, and do, arise through unforeseen leaks during inerting that render safe spaces lethal.
The incident sussgests a poor onboard safety culture. The management failed to adequately resource and train the crew or enforce safety protocols. The fact that no one questioned the decision to enter the tank without necessary safety controls suggests a lack of investment in both crew training and a robust safety culture.
These controls would have included critical safety steps, such as wearing a personal gas analyser to detect hazardous gases. The lack of challenge suggests that deviations from safety protocols were accepted practice on board.
Lessons learned
Culture – The organisation lacks a strong safety culture. Would you enter a tank if directed to do so without a proper enclosed-space entry permit? The company urgently needs to reassess its safety management system, involving both the flag state, class authorities, and its insurers, to implement substantial improvements in their operational procedures.
Situational Awareness- The crew did not fully understand the operational environment, and there was no intervention from other crew members to prevent the unauthorized entry. This lack of awareness tragically resulted in the loss of a crew member’s life.
Overconfidence- Confidence should never be a factor in enclosed-space entry. Such environments are inherently unnatural and carry a heightened risk of incidents occurring due to the numerous potential hazards within a tank. Proper precautions must always be taken, regardless of prior experience or perceived familiarity with the task.
