Public Notification of Amendments to ClassNK Rules & Guidance

ClassNK amends its Rules in response to industry needs

26 December, 2014 (Tokyo) – Leading classification society ClassNK (Chairman and President: Noboru Ueda) has announced the release of amendments made to its Rules and Guidance for the Survey and Construction of Steel Ships.

ClassNK regularly revises and amends its Rules and Guidance as part of its ongoing efforts to improve the safety of life and property at sea. Amendments to Rules and Guidance reflect the latest research and development results, feedback from damage investigations, requests from the industry as well as changes made to relevant international conventions, International Association of Classification Societies (IACS) Unified Requirements and national regulations.

Amongst the recent amendments was an update to the rules regarding the Guidance for Temperature Gradient ESSO Tests (tests for brittle crack arrest toughness) and Double Tension Tests. The amendments are based on the outcome of ClassNK’s joint research project with the Iron and Steel Division of the Japan Welding Engineering Society that was launched in 2010. Through this project, testing criteria for qualitatively evaluating brittle crack arrest properties was established, helping to effectively streamline requirements related to temperature gradient ESSO tests.
Preventing brittle fracture and ensuring brittle crack arrestability are of significant importance in ensuring the structural reliability of steel ships and ClassNK aims to further enhance the structural integrity of steel ships through the new amendments.

The amendments, dated 19 December 2014, include the following:



Requirements  related  to “Arrangement  of  Fuel  Oil Tanks in Machinery Spaces of Category A”

Requests from industry

Requirements related to Guidance for Temperature Gradient ESSO Tests and Double Tension Tests”

Recent research and development results

Requirements related to “Structure of Bilge Keels”

 Feedback from damage investigations

Requirements related  to  “Strength  Calculations  for Gears”

Recent changes made to relevant IACS Unified Requirements

PDF files of all amendments made to the ClassNK Rules and Guidance are available free of charge for ClassNK “My Page” users. To register for this service, simply go to ClassNK’s website at and click on the “My Page Login” button.

For more information on this topic please contact:

ClassNK Development Operations Headquarters
Tel: +81 3-5226-2171