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ClassNK issues guidelines to prevent hull brittle cracks

ClassNK issues guidelines to prevent hull brittle cracks

Tokyo: Nippon Kaiji Kyokai (ClassNK) has published a new technical study entitled 'Guidelines on Brittle Crack Arrest Design'. The release is intended as a technical reference to help prevent the propagation of brittle cracks that may occur in the hull structure and possibly threaten the safety of a ship through structural rupture or other catastrophic damage.

ClassNK says that in order to ensure the safety of a ship, it is essential that effective measures be taken to ensure that brittle cracks which may lead to breakage of the hull do not occur.  At the same time, it is also vitally important to adopt measures to arrest the propagation of brittle cracks in the event that any such cracks to occur.

As part of a primary research and development project, ClassNK established a research committee on brittle crack arrest design together with shipbuilders, steel manufacturers, universities, and research institutes in 2007.  The committee studied and investigated the propagation behavior of brittle cracks and the technical measures that would be necessary to prevent their propagation with respect to the extremely thick steel plates used in the construction of very large containerships.  These efforts also included the conduct of large-scale model tests and advanced computer analysis of brittle crack arrest designs.

The results of these studies have been summarized in the "Guidelines on Brittle Crack Arrest Design".  It also describes measures developed by ClassNK for arresting the propagation of brittle cracks at appropriate locations in the event that such cracks do occur, including the formulation and implementation of measures for brittle crack arrest design as a backup to preventing brittle fracture.  It is firmly believed that this reference will prove invaluable in the effective conduct of brittle crack arrest design.  

ClassNK is currently proceeding with further research and development aimed at enhancing the structural integrity of large and ultra large container carriers as part of its ongoing efforts to realize ever-greater safety and reduced environmental loads at sea.

The guidelines will be available for downloading from the ClassNK website from 7 September 2009 onwards.  [05/09/09]