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.
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Preliminary report release 31 May 2013
The information contained in this preliminary report is derived from the initial investigation of the occurrence. Readers are cautioned that it is possible that new evidence may become available that alters the circumstances as depicted in the report.
On 20 March 2013, an engineer on board the bulk carrier Nireas was fatally injured after being struck by flying debris when the observation window of a main air receiver drainage pot exploded. At the time of the explosion, the ship was at anchor off Gladstone, Queensland, and the engineer was carrying out the routine task of draining water from the pressurised air receiver.
What the ATSB found so far
Initial analysis of the accident indicates that the observation window glass of the drainage pot exploded when it was exposed to the air receiver pressure. However, all of the factors which contributed to the failure of the glass have not yet been established.
What's been done as a result
All six similar drainage pot observation window glasses on board Nireas have been removed pending verification of the drainage arrangement design to the satisfaction of Lloyd’s Register, the ship’s classification society.
The ATSB has contacted Nireas’ managers, the ship builder, Lloyd’s Register, the flag state (Liberia) and the Australian Maritime Safety Authority. They were all informed of the accident and asked that the owners and operators of any ships fitted with similar systems be advised of this accident and that appropriate safety action should be taken by them to prevent similar accidents on board their ships.
Nireas’ managers have advised the ATSB that they have also removed the drainage pot observation window glasses from the only other ship managed by them that is fitted with similar drainage arrangements.
The ship builder has advised the ATSB that it has contacted all owners of ships in which it had fitted this design of drain system informing them of the accident and requesting that all observation glasses be removed and for the pots to remain unobstructed.
The investigation is ongoing and it will focus on determining why the observation glass failed, whether the drainage pot was fit for purpose and whether there were any underlying issues in relation to the design, construction, testing, or certification of the drainage pot.
The condensate drainage pots fitted to Nireas’ main air receivers were not fit for purpose as they were not capable of withstanding the internal pressures that were likely to accumulate in service.
|Who it affects:||Regulators, classification societies, masters, owners and operators of ships|
|Date:||20 March 2013||Investigation status:||Completed|
|Time:||0744 EST||Investigation level:||Complex - click for an explanation of investigation levels|
|Release date:||04 March 2014|
|Report status:||Final||Occurrence category:||Accident|
|Highest injury level:||Fatal|
|Type of operation||At anchor, engine room routine operation|
|Damage to vessel||Minor|
|Departure point||Shanghai, China|