Improved Bend Over Sheave Durability of HMPE Ropes for Deep Sea Handling

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.