Abstract

Both flexible risers and catenary moorings are fundamental to the feasibility and often viability of floating protection systems.

Dynamically, both systems exhibit non-linear behaviour in the geometric and material sense and the design codes draw the designers attention to these.

In the case of flexible risers, there is a lack of historical reference data to correlate service life.

This paper describes the development of a Service Life Prediction Model for flexible risers.

Deep water catenary moorings have received significant attention in the past (ref 1), highlighting some of the problems associated with dynamic amplification of line tension.

In shallow to moderate water depth (40 - 100m), catenary moorings harden up very quickly with excursion by virtue of the loss of catenary. This paper takes this further in the dynamic context and examines dynamic amplification of chain loads as a function of excursion, attachment elevation, and wave spectrum.

Fatigue of mooring lines is also addressed and a proposed model is described.