DNV Releases Recommended Practice for Offshore Structures

A new update of DNV's Recommended Practice 'Fatigue Design of Offshore Structures' is now available. It has been updated in order to meet increased industry focus on the design of cost-optimal structures and the reliable operation of existing structures during their service life.

"The fatigue design of steel offshore structures has become a key issue as these are becoming more optimized with respect to weight, fabrication and cost. So in order to obtain structural designs which function properly during in-service life there has been a demand for more user-friendly, efficient, accurate and reliable standards," says Inge Lotsberg cheif specialist at DNV.

A new version of DNV's Recommended Practice 'Fatigue Design of Offshore Structures' has been issued to meet this demand. It has been improved with respect to the reliability of fatigue design based on new research and experience related to welded plated structures.

New types of dynamic loaded structures used to generate wind and wave energy are also covered in the new update. "The enhanced methodology is based on new research and experience and is utilized to ensure the safe operation of offshore structures and transportation of compressed natural gas," says Lotsberg.

10th anniversary

The first version of DNV-RP-C203 'Fatigue Design of Offshore Structures' was issued 10 years ago and has since then been continuously improved and revised. This work has been carried out in close cooperation with the industry and recognized research institutes. The technical basis for the standard has been published in more than 30 papers presented at international conferences and in recognized journals. "The content and application of this Recommended Practice has been presented to the industry through numerous courses held in Norway, Paris, London, Aberdeen and Houston," explains Gudfinnur Sigurdsson, Head of DNV's Section for Offshore Structures.

DNV-RP-C203 is the reference standard used by NORSOK for the fatigue design of offshore structures. NORSOK's standards are developed by the Norwegian petroleum industry to ensure adequate safety, added value and cost effectiveness for existing and future petroleum industry developments.

DNV-RP-C203 is also listed as a recommended standard in ISO 19902 "Fixed Steel Offshore Structures", issued in 2007 for the fatigue design of plated structures when calculating hot spot stress using the finite element method.

"And finally, DNV-RP-C203 and DNV-RP-C206 'Fatigue Methodology for Offshore Ships' are the main reference design standards for fatigue in a new book entitled Ship-shaped Offshore Installations, Design, Building, and Operation, which has been edited by Paik and Thayamballi. This book was published by Cambridge University Press in 2007. It is intended for practicing engineers, engineers in training and university students approaching more advanced engineering," concludes Lotsberg.