A gas cylinder that had just passed a mandatory detailed safety inspection exploded while being refilled and killed a member of the crew of the cruise ship Emerald Princess, 113,563gt, of Princess Cruises, at Port Chalmers on Feb 9 this year.
Expressing concern over the safety inspection, the New Zealand Transport Accident Investigation Commission (TAIC) said the Philippine crewman who died was near the cylinder when it burst as others in the crew were refilling it. No passengers or other crew members were injured.
The cylinder was one of four in a bank that supplied backup power for a lifeboat davit.
Blaming corrosion, the TAIC said that crew members knew that the cylinders were losing pressure but did not check for damage before refilling them, as “they thought it highly unlikely that the pressurised cylinders had been structurally compromised.”
Typical inert gas cylinders are rated to 2200 psi or more, and are heavily built to withstand the pressure. Metallurgists contracted by the TAIC found that an external area of the cylinder wall had wasted away, leaving less than 1/16th of an inch of steel at the location of the rupture, a gauge equivalent to heavy sheet metal.
The cylinder had just passed the ten-year mark for a mandatory detailed inspection and other cylinders on board were also found to have significant wastage.
The TAIC expressed concern that the system, and others like it, had been inspected just two weeks before the accident and judged to be in a satisfactory condition.