The Structural Design Developments of Riser I-Tube Support in an FPSO

This paper deals with the optimized load case selection and the design developments for constructability and fatigue criteria of the Riser I-tube support structural design in an FPSO. Many risers including umbilical lines are arranged longitudinally in the outside of FPSO. Also Riser Pull-in System (RPS) is disposed for covering all risers. All risers have different loads in several environmental conditions and need different I-tube diameters. Accordingly their support structures have also different geometrical shape. In fact, it is quite a challenging task to consider all loads and load combination, i.e. Riser loads, environmental loads, the reaction load from RPS, internal tank load, etc. In this paper, the optimized load cases including its back-up descriptions are represented. During the structural design many options and alternative design approaches were explored in order to consider several problems, i.e. the structural arrangement, appropriate connections, constructability issues, the fatigue life, etc. Among these, the constructability and fatigue critically influenced the Riser I-tube support design. So together with the optimized load cases, the design developments on account of them also are represented in this paper.Copyright © 2009 by ASME