Integrity of offshore structures (2020)
This NORSOK standard is the principal standard for offshore structures, and together with the normative standards in this document, it constitutes a common basis covering those aspects addressing design requirements, integrity management and assessment of all types of offshore structures. The standard especially refers to NS-EN ISO 19900, Petroleum and natural gas industries - General requirements for offshore structures and represent the full set of requirements valid for the NORSOK set of standards from NS-EN ISO 19900, in particular the partial safety factor method (also called the LRFD method) based requirements. Since this document is based on the same principles and requirements as NS-EN ISO 19900, NS-EN ISO 19900 may be treated as supplementary.
The 2020 edition of the document has undergone a major revision where the main changes since last edition are as follows:
- The document has been restructured to make a more readable arrangement of the different sections.
- Requirements have been rewritten to be in accordance with the NORSOK digitalization initiative.
- Requirements have been substituted with references to updated NORSOK and ISO documents.
- Introduced a section on design principles.
- Robustness assessment have been modified to give clear requirements.
- Requirements to nonlinear analysis have been adjusted.
- Verification chapter has been restructured to provide clear requirements and recommendations.
- Reliability based method is moved into a separate section.
- The two steps in the ALS check is updated for clarity and to align with robustness definition.
- Requirements to standards for materials and fabrication of steel, aluminium and concrete structures have been updated with latest revision of ISO and NORSOK M-standards.
- Soil investigation and geotechnical design requirements have been substituted with ISO references.
- Snow and ice actions for damaged case scenarios have been updated.
- Stationkeeping requirements have been replaced with a reference to NS-EN ISO 19901-7 Annex B.2.
- Section on subdivision, stability and freeboard has been rearranged and requirements earlier applicable only to the Norwegian Continental shelf are now made mandatory for structures designed according to this document.
- Requirement to return period of environmental actions have been updated for ALS damaged condition.
- A new section on “Facilities normally not manned” is introduced maintaining existing requirements and adding a new requirement regarding ALS check.
- External underwater parts marking of floating units is included (moved from NORSOK N-005)
- New requirement to air gap has been introduced.