Offshore Gas Terminals - Guidance on Design and Construction

Abstract

Abstract 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 GuidanceStructural designSide by Side AnalysisArrangement and LayoutRisk Assessment issuesIntegrated control systemsInspection of Containment SystemsValidity of Codes and Regulations The DNV Offshore Guidance itself additionally addresses issues such as :Conversion of gas shipsSloshing assessmentFatigue assessmentCorrosion issuesRegasification and liquefaction plantClassification and regulatory complianceAssessment of novel conceptsQualification of technology Introduction 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.