Clashing or colliding can take place between a riser and its adjacent risers or other lines/structures. Clashing is of great concern for the design of top-tensioned riser (TTR) arrays in deep water. Understanding the impact behavior between risers is essential for developing reliable clashing mitigation approaches during design phase. Further, monitoring of risers clashing is useful during operation and installation of the systems.

A critical consideration of clashing monitoring is how to quantify the impact. Traditional methods need a priori information which is difficult to be obtained accurately. This paper proposed a new method of monitoring risers clashing by using wavelet scalograms of dynamic responses that doesn’t need such priori information. The method was investigated through numerical simulation of a pair of TTR risers operated from tension-leg platform (TLP) that are subjected to current and floater motions. The wavelet scalograms of the risers’ velocities and accelerations were utilized to quantify impact. It was verified that the wavelet scalograms can indicate clashing severity quite well.

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