Digital Repository, Youth Symposium on Experimental Solid Mechanics

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Applied methodology to design a machine to test the strength of offshore synthetic mooring ropes
A. Goncalves, F. E. G. Chimisso

Last modified: 2010-09-06


The technology of platform anchorage systems has been developing quickly nowadays. Due to the oil extraction in deep waters, the traditional anchorage types, such as anchor cable/wire rope/anchor cable, in the shape of a catenary, were replaced by an anchorage named “Taut-Leg”. This new way of anchorage, characterized by an anchor cable/synthetic cable/anchor cable, operates in a straight mode, thus reducing weight and providing an easier mooring operation. In addition, the synthetic ropes for platform offshore anchorage are long and robust, with higher number of sub ropes arranged in a parallel mode in order to increase mechanical strength. PETROBRAS has used this new form of technology since the beginning of this decade with polyester cables, and, despite this, there is a lack of knowledge about the behavior related to structural integrity (residual life, total life, etc.). Taking these needs into account, PETROBRAS and POLICAB have been interested in developing a test machine which will be capable to execute static rupture tests (maximum value of 300 ton) and fatigue tests (150 ton). Both tests will be applied to sub ropes, simulating the environment conditions (sea wave frequency and storm displacement). The main objective of this paper is to present the methodology used for choosing the best equipment which meets our needs, from the creative process to the conception of the equipment.