Structural design of self-elevating units - LRFD method
|Publication Date:||1 July 2019|
Scope and application
All marine operations shall, as far as practicable, be based upon well-proven principles, techniques, systems and equipment and shall be undertaken by qualified, competent personnel possessing relevant experiences.
A self-elevating unit is designed to function in a number of modes, e.g. transit, operational and survival. Design criteria for the different modes shall define and include relevant consideration of the following items:
- intact condition, structural strength
- damaged condition, structural strength
- fatigue strength
- accidental damage
- air gap
- overturning stability
- watertight integrity and hydrostatic stability.
Limiting design criteria when going from one mode to another shall be established and clearly documented.
Serviceability (SLS) condition is not covered in this standard.
For novel designs, or unproven applications of designs where limited or no direct experience exists, relevant analyses and model testing, shall be performed which clearly demonstrate that an acceptable level of safety is obtained.
Self-elevating units shall be based on environmental conditions specified by the designer. Worldwide service operation is not applicable.
Structural design covering marine operation sequences is not covered in this standard. Marine operations may be based on DNV-ST-N001 Marine operation and marine warranty.
For application of this standard as technical basis for classification, see Ch.3.
Flag and shelf state requirements are not covered by this standard.
Governmental regulations may include requirements in excess of the provisions of this standard depending on the type, location and intended service of the offshore unit or installation. The 100 year return period is used to ensure harmonisation with typical shelf state requirements and the code for the construction and equipment of mobile offshore drilling units (MODU code).
In case of conflict between requirements given in this standard and other DNV documents, the requirements given in this standard prevail.