RR1092 - Practical method for calculating mooring chain wear for floating offshore installations. Mooring Integrity Joint Industry Project Phase 2

Mooring integrity for floating offshore installations is an important safety issue for the offshore oil and gas industry. This report is one outcome from Phase 2 of the Joint Industry Project on Mooring Integrity. This work ran from 2008 to 2012 and had 35 industry participants. It followed the Phase 1 work described in HSE Research Report RR444 (2006). The Phase 2 work compiled research on good practice and is summarised in HSE Research Report RR1090 (2017).

Long lengths of steel chain links are used in the mooring lines of floating installations. As an installation moves, the tension and position of the upper ends of its mooring lines change producing rotational movement between adjacent chain links that results in wear. As part of ensuring that mooring chains to do not fail, it is important to have robust estimates of inter-link wear. This report describes the formulation of a practical analytical method to calculate inter-link wear. The report details: the relevant wear mechanisms (adhesion, corrosion, surface fatigue and erosion); how the links move under the influence of environmental forces including consideration of the influences of the manufacturing and proof testing processes; and the underlying theory and calibration approach used to develop the method.

For ease of use by practitioners applying the method, a summary is provided in Appendix A of the report.

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Updated 2021-04-15