Analysis and tests of response of subsea equipment to acoustic vibrations

Our client experienced potentially damaging acoustically-driven vibrations on topsides equipment caused by flow-induced vibrations inside a flexible gas-export riser and was concerned that vibrations on subsea equipment might have been similarly damaging.

This equipment is too deep for diver access, meaning that inspection and monitoring is difficult.  Jee formed a consortium with Bureau Veritas, Sound Research Laboratories and Cranfield University to investigate the immediate vibrations and advise.

Initially, finite element (FE) modelling was done to assess likely stress levels on subsea equipment.  This was then followed by small-scale tests and finally full-scale tests at pressure, underwater on replica subsea equipment.

We were able to advise our client on the likely effect of the vibrations on their subsea equipment and to propose specific modifications to the equipment.  This has enabled our client to export gas at increased flow rates.

Benefits to our client include:

• Ability to continue gas export
• Ability to export gas at increased flowrates
• Better understanding of the vibration mechanism
• Advice on future monitoring