Photo: CRP Subsea

CRP Subsea, Hellenic Cables: Bend stiffeners prolong power cable fatigue life

CRP Subsea and Hellenic Cables have completed dynamic cable testing at the University of Exeter, which included individual tests of power cable alone and power cable with bend stiffener to compare performance and fatigue.

The results show that when tested with a CRP Subsea Bend Stiffener the power cable survived 3.7 times as many cycles and was on average 72.5% stiffer than the power cable alone.

According to CRP Subsea, this highlights the importance of a bend stiffener’s presence to extend the fatigue life of the system to be used in future floating offshore wind applications.

Two tests were performed, with the first including performance characterization tests that involved bending the cable to a 3.7° angle at the headstock whilst holding a constant force of 40 kN, 60 kN, and 80 kN at the tailstock at a 10-second cycle period.

Secondly, the fatigue testing involved bending the cable to 4° while holding a constant force of 80 kN. The cycle period was steadily decreased from 10 seconds to 1 second, to minimize overall test duration.

The test plan was identical between the power cable only and the power cable with bend stiffener combination, including the change in cycle period.

“These results are encouraging but expected and explain why the use of a CRP Subsea Bend Stiffener in such a system is critical. The CRP Subsea Bend Stiffener material has undergone an extensive and rigorous material qualification. This along with the comprehensive design methodology, manufacturing, and quality systems have been fully reviewed and approved by Lloyds Register,” said John Duggan, principal design engineer at CRP Subsea.

“Our Bend Stiffener is designed to maintain a cable or flexible pipe above a given minimum bend radius in a dynamic application. This, in turn, increases the life of the product by protecting it against damage and fatigue, which can result due to over bending.”

The collaboration is part of the EU-funded MaRINET2 program.