This paper describes work performed within a Joint Industry Project aiming to evaluate the lifetime of deep sea handling ropes. Various HMPE (High Modulus Polyethylene) fiber ropes, with and without coatings, have been studied under both tensile and cyclic bend over sheave (CBOS) loading. A large test program has enabled both tension-cycle to failure relationships and empirical expressions for residual strength after cycling to be determined. A special device was then developed to apply a known couple to the sheave, allowing both dynamic friction measurements to be made and the influence of applied couple on cycles to failure to be measured. These experimental data were used in the development of a numerical model which can be used to study the influence of rope and sheave parameters.

This paper describes the SIRIUS (Safe Installation with Ropes In Ultradeep Sea) JIP full scale testing program conducted to determine the bend fatigue performance of large diameter fibre ropes with HMPE fibres (Dyneema®) on small diameter sheaves, together with a summary of the results and the impact the results have on installation operations. The test rig has previously been used for testing of Ø109 mm steel wire ropes and these results will be used as benchmark for the fibre ropes tested at similar Safety Factors. Steel wire rope together with active heave compensation has been used for subsea deployment applications for many years. However, with the requirement to install heavy subsea hardware in increasingly deeper water, there is a need to use large diameter fibre rope as part of the deployment system.

The use of synthetic fiber ropes for subsea installation is extending, as the offshore industry explores deeper waters, but there are few data available to evaluate the lifetime of these materials. In a previous OMAE presentation the authors described results from the first phase (2010–2013) of a JIP aiming to understand the mechanisms controlling the long term behavior of HMPE fibre ropes [1]. This presentation will describe the results from the second phase of this study (2014–2018) in which predictive models have been developed and applied to a range of improved braided rope materials. Two modeling approaches will be discussed, an empirical method based on residual strength after cycling, and a numerical approach using finite element software specifically adapted to fibre materials [2]. An extensive test program, which has generated a database of CBOS (cyclic bend over sheave) results for various grades of HMPE and different constructions, will be described. Comparisons have been made with steel wire handling lines in order to quantify the benefits of fibre ropes for these deepwater applications.

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