OTC 21848--Coupled Dynamic Analysis of Stinger and Pipeline

摘要

This paper presents recent developments in the methodology to address the structural integrity of stingers and pipelines during pipelay submarine installation. Specific attention is given to the comprehensive coupling of kinematics of a single or multiple articulated segments of stinger interacting in synchrony with sea loading, vessel motions and in combination with buoyancy and inertial forces. This in conjunction with the pipeline engaging from the seabed through the unilateral action of roller supports allotted between the barge and several stinger segments. A time domain dynamic and fatigue analysis is conducted utilizing nonlinear finite element solver. In a classical structural code the computed wave loads are based on the stinger’s position remaining fixed. The nonlinear approach presented allows the stinger to rise and fall as the wave passes. For articulated types, the finite free rotation at the hinges respects the kinematics of the assembly. This new method has been applied to the design of new stingers and capitalizes on history of lesson learned in their construction spanning many decades. Establishing the structural demand on a dynamic system is a blend of deterministic and stochastic loading conditions. These conditions often occur simultaneously and for a new design are mainly forecasts. The prognostic usage shares the stinger between pipelay and transit or abandonment mode and differential exposures to wave directions from head sea to quartering and beam seas. This new approach offers a detail determination of response patterns of the stinger sections such as bending in the surge-sway plane, torsion in the roll direction and inertial effects in the surge-heave plane. These patterns address the tension-compression time histories expected for all stinger structural members to allow its fatigue life prediction as well as providing insight in the estimation of accumulated fatigue damage in the pipeline during installation. The method provides the ability to capture anisotropies, transitions, field joints and pipeline ancillary mechanical equipment often incorporated in the pipeline on board the vessel as the line is laid.