Tailored local design of deep sea FRP composite risers

Abstract

The use of fibre reinforced polymer (FRP) composite materials in offshore engineering for deep sea riser systems has drawn considerable interest due to the potential weight savings and improvement in durability that can be achieved. The design of FRP composite risers consists of two stages: (1) preliminary local design based on critical local load cases (LCs) and (2) global analysis of the full length composite riser under global loads including platform motion, hydrostatic pressure, gravity, buoyancy, wave and current loads to determine and assess critical locations. The preliminary local design stage is necessary to obtain a first estimate of the laminate configuration -fibre orientations and layer thicknesses of the tube wall, since the deformations and hence the forces and bending moments due to the global loads, depend on the geometric configuration. This paper describes the methodology, LCs, analysis procedure and results of the first stage, the local design of the composite riser. The local design is conducted using five different LCs as prescribed by the standards. In this study, geometric configurations of eight different composite body and liner combinations were optimised to provide minimum structural weight. Previous composite riser designs have mainly focused on axial and hoop reinforcements; in the present study, fibre reinforcements at other orientations are included. The highlight of the current study is that it shows that the use of off angle fibre orientations in addition to axial and hoop reinforcements offer substantial weight savings.

Tailored design of top-tensioned composite risers for deep-water applications using three different approaches

“…In Table 8, the stacking sequence, each layer's thickness (both liner and composite lamina) and structural weight are listed with three different design approaches. Also, the structural weight (170 kg/m) and thickness (25 mm) of a steel riser with the same inner diameter as required to meet the same design requirements 33 are presented in Table 8.…”

CFD Simulation of Vortex Induced Vibration for FRP Composite Riser with Different Modeling Methods

“…The steel riser was monolithic, while the composite risers consisted of an inner liner, a composite structural body and an external sacrificial layer ( Figure 1). The geometries of these three risers are from the previous studies [6,10] …”

“…The following geometry was utilized to create the basic geometry of flow field: 10D × 20D for 2D simulation and 10D × 20D × 12.5 m for 3D simulation. The basic geometry of the risers were based on previous design results [6,7,10,13].…”

“…In the 1990s, tests of mechanical capacities of the composite riser tube were performed by National Institute of Standards and Technology (NIST) and Advanced Technology Programs (ATPs) [4]. Then, more tests, including field tests and optimized designs of composite risers, were conducted by different research institutes and global enterprises [5][6][7][8][9][10][11][12][13]. These prototypes prove that FRP composite risers have significant benefits in weight saving compared to steel risers.…”

Experimental Study on Vortex-Induced Vibration of Risers Considering the Effects of Different Design Parameters

“…For the Al riser and the Ti riser, the design process and working conditions are similar to those of high-grade steel risers, since all their materials are isotropic. In contrast, FRP composite risers, which are a laminated structure with anisotropic materials, have a different design process and design considerations [1,2]. Many studies, including static analysis and testing, dynamic response, durability under working condition, and so on, have been conducted since the 1950s [3] on the most traditional risers.…”