A worker on Emerald Princess died at Port Otago on February 9 when a corroded nitrogen cylinder burst while the cruise ship was in Dunedin.
Allan Allarde Navales' death prompted warnings for cruise industry over corroded cylinders that could pose a "significant danger to seafarers and passengers."
An interim report released by TAIC (Transport Accident Investigation Commission) on Thursday said a burst nitrogen cylinder caused the death of the father-of-two.
On the morning of the accident, some of the crew were checking the life boat launching davits, that were each fitted with 4 high-pressure nitrogen cylinders. They noted the pressure of nitrogen system for lifeboat 24 davit, a crane used for lowering life boats, had dropped to around 165 bar, that was below the nominal working pressure range (180-210 bar).
As no leaks were detected, the workers decided to replace the manifold as they thought it was unlikely the pressurised cylinders had been compromised structurally. One of the 4 nitrogen cylinders burst as the crew tried to repressurise the system, wounding Navales (an engine room fitter standing close by) fatally.
Remains of the burst cylinder were recovered, together with the other 3 cylinders from the same frame. The top of the burst cylinder was not found, having possibly been ejected into sea.
The cylinders were examined by a metallurgist expert at TAIC's technical facility. He found the burst cylinder had suffered corrosion at the point of failure. Other cylinders onboard the ship were found to feature similar corrosion-related damage.
The cylinders were inspected each year by the authorised representative of the manufacturer. They were found to be in good condition at the last inspection, 2 weeks before the accident.