Gas leak causes death on Indian Naval ship

[20/07/16] A sailor and a civilian contractor were killed and two others injured by a toxic gas leak during maintenance work during the first refit of the INS Vikramaditya in June 2016.

Work was taking place in the sewage treatment plant compartment of the ship at the time. This is where waste from toilets and urinals is treated before it is discharged into the sea. The waste is aerated with fresh air which decomposes the waste. However, if air is not present, anaerobic bacteria are formed, which produce toxic gases including hydrogen sulphide (H2S).

Hydrogen sulphide is produced when sewage breaks down. It is colourless and highly flammable The gas has a distinctive “rotten egg” smell at low levels (0.01-1.5ppm), but you can lose your ability to smell the gas at higher concentrations (from about 100-150ppm).

At low concentrations the gas causes irritation of the eyes, nose and respiratory system, but at higher concentrations the gas can cause difficulty breathing, shock, coma and death. At 700-1000ppm, death can occur within minutes.

The Navy ordered an inquiry into the incident and action was taken to ensure that the sewage treatment plant was made safe.

INS Vikramaditya is India’s largest Naval Ship, joining the fleet in 2013. The aircraft carrier was built by the Russian Navy until it was decommissioned and purchased by the Indian Navy.

This is the third-high profile Indian Naval accident to take place in 2016. In April a sailor lost his leg and two others were injured when an oxygen cylinder exploded on INS Nireekshak. In March, a fire broke out on INS Viraat which resulted in the death of an Engineer Mechanic.

Incidents involving hydrogen sulphide have happened to other naval fleets. In 1981, a sailor aboard the Australian Tobruk was killed following a leak. In 1985, the Stalwart had an incident where three people died and sixty were injured. In 2006, four sailors on a training exercise aboard the Maitland were gassed. Although they all survived, one sailor was discharged from service due to ill health.

Incidents are not limited to naval fleets either. In 2005 a leak of hydrogen sulphide killed three employees when they tried to repair a leaking pipe on a Royal Caribbean Cruise.

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