On 20 March 2013, an engineer on board the bulk carrier Nireas was carrying out the routine task of draining water from the ship’s main air receiver when the air receiver drainage pot observation window exploded. The engineer was fatally injured by flying debris from the observation window.
What the ATSB found
The ATSB investigation found that the drainage pot observation window glass exploded when it was exposed to the air receiver pressure. This pressure accumulated in the drainage pot because the water being drained restricted the flow into and through the pot outlet line.
The investigation also found that the shipyard which built the ship, and designed and installed the condensate drain system, considered that the drain system was open to atmosphere. When the design of the drainage pot was modified to create a closed system, the shipyard did not ensure that the design was adequately engineered, tested and approved prior to installation, despite having procedures in place which should have ensured such scrutiny.
During the course of the investigation, it was brought to the attention of the ATSB that similar designs of drainage systems had been, and continued to be, fitted in ships by various shipyards around the world.
What's been done as a result
All similar drainage pot observation window glasses were removed on board Nireas and its sister ship. The drainage pots were later modified, under the supervision of Lloyd’s Register, to include a partly open steel plate in place of the observation glass.
The ship builder advised the ATSB that it had contacted all owners of ships in which it had fitted this design of drain system. They informed them of the accident and requested that all observation glasses be removed and for the pots to remain unobstructed.
In July 2013, the Australian Maritime Safety Authority (AMSA) issued Marine Notice 11/2013, to draw industry attention to this accident and request that appropriate safety action is taken where such systems are encountered on board ships. This Marine Notice is being updated and the latest version is available on the AMSA website: www.amsa.gov.au
The ATSB has also issued a safety advisory notice addressed to all classification societies, advising them of the accident, the safety implications of the installation and use of closed condensate drainage/inspection systems and of the need to draw the attention of the shipping industry to these issues.
This accident identifies the need to follow a formal process of risk assessment when considering possible equipment modifications. Such a process should ensure that all associated risks are identified, considered and appropriately treated.