Houston, Texas: The high cost related to fatigue cracks has for a long time forced the industry to focus on fatigue. In relation to this, DNV will be releasing a new recommended practice ‘Fatigue Method for Offshore Ships’ that will help to control and document the fatigue capacity of offshore ships.

The aim of the new Recommended Practice RP-C206 is to ensure that all critical structural details are adequately designed to meet project fatigue requirements. It will also form a basis for the development of fabrication and in-service inspection plans.

This document captures the latest knowledge, methodologies and techniques from joint industry projects and our own internal research and experience, integrating it into DNV’s offshore service specifications and classification services. Based on the fatigue procedures described in the RP, DNV will introduce a new class notation ‘FMS’.

The new RP focuses on spectral fatigue analysis methods. These techniques are defined as a "first principles" approach, using directly calculated wave loads and stresses from site-specific metocean criteria.

DNV has in parallel developed a new software tool for the fatigue design of offshore ships hull girders based on the component spectral analysis approach described in the RP. This software tool is already incorporated in DNV’s existing NAUTICUS Hull software.

DNV has been managing such risks for the past 20 years. The new RP-C206 complements DNV’s current documentation ‘Fatigue Assessment of Ship Structures - Classification Note 30.7’ and ‘Recommended Strength Analysis of Offshore Steel Structures - RP-C203’.