A number of floating offshore gas terminals are currently in development, a number of FSRUs have been installed and it is expected that the first LNG FPSOs will be entering detailed design phase and construction in the near future. Based on our experience within the gas industry and various conceptual assessments, DNV has produced a Guidance on key issues to be addressed in such projects. The Guidance addresses design issues, including selection of containment system, structural analysis of Floating Offshore LNG Terminal hulls as well as construction and testing issues.
The DNV Offshore Technical Guidance, OTG-02 " Floating Liquefied Gas Terminals??, an overview of which is presented in this paper, represents latest DNV and industry lessons on tackling design and construction issues for floating terminals.
This paper will only address a selected number of topics from the DNV Offshore Technical Guidance, namely:
Background for the Guidance
Structural design
Side by Side Analysis
Arrangement and Layout
Risk Assessment issues
Integrated control systems
Inspection of Containment Systems
Validity of Codes and Regulations
The DNV Offshore Guidance itself additionally addresses issues such as :
Conversion of gas ships
Sloshing assessment
Fatigue assessment
Corrosion issues
Regasification and liquefaction plant
Classification and regulatory compliance
Assessment of novel concepts
Qualification of technology
There are a number of options available for design of gas receiving and exporting terminals. Traditionally these have been built on land according to codes and standards, such as NFPA 59A, which have been specifically developed to address design and constructions issues of terminals to be built on relatively spacious sites but which may be in some proximity to the civil population on. These codes therefore include requirements and assumptions based on such arrangements.
Building such installations offshore, or close to shore, poses different challenges, for which at present, there is little relevant experience.