Flexible risers

Our work on static/dynamic responses and design analysis of flexible/rigid risers and umbilicals has been supported by our proprietary program Zenriser. The program predicts the static and dynamic structural behaviour of single or multiple offshore flexible riser, top-tensioned riser or pipeline systems subject to hydrodynamic loading and vessel motion.

Zenriser can assist at any stage in the development of a riser or pipe system from a feasibility study through conceptual and detailed design to installation and operation. It can be used for preliminary static analysis to determine a system layout, for global dynamic response analysis to assess overall system response and for detailed dynamic response analysis to design particular components. It can also be used to determine clearances between flexible risers, mooring lines and pipelines.

As well as being able to study conventional single or multiple flexible riser systems (steep-S, lazy-S, steep wave, lazy wave, free hanging), Zenriser can be used to analyse a generalised multiple pipe situation composed of a series of pipes with any change in weight, stiffness or hydrodynamic properties along their lengths and clamped (tie-in) boundary conditions / bend stiffeners or flexjoints / taper joints.

Expertise gained through work on several projects includes:

• flexible riser system analysis and design to operational, survival or installation conditions
• flexible flowline analysis and design
• flexible jumper, spoolpiece, hawser and umbilical analysis and design
• deep water applications
• service life assessment
• assessment of installation procedures and interference between flexibles / subsea components.