Practice for determining friction in hydraulic winch systems

Abstract

This paper presents a method for estimating friction in hydraulic active heave compensated (AHC) offshore winches. The method is a two-step approach where the first step is to model the friction loss in the hydraulic motors based on data from the sub-supplier. The second step requires real-life testing, where the remaining friction losses in the winch system is identified and modeled. In this context, a practice is characterized by obtaining a friction loss estimation with the highest possible accuracy over the widest possible range of operating conditions with a limited amount of experimental work. The method benefits from the use of parametric models, sub-supplier data, and real-life measurements on a 150 t AHC crane from National Oilwell Varco Norway (NOVN). The work is an important part of developing a simulation model that can be used actively in virtual testing and verification of crane operations at NOVN. A friction loss model developed from the proposed method was implemented in a NOVN simulation model. Computed and measured hydraulic pressures showed deviations of less than 10% from measured results for a 150 t crane operating in AHC.