Abstract
To ensure the integrity of offshore jack-up rigs, a novel torque transducer has been developed through 18-month-long joint collaborations cross industries globally.
A medium size offshore jack-up rig uses a set of fifty-four units of AC-driven jacking systems to jack the platform up and down. Due to inevitable manufacturing tolerances and poor correlation between motor current and its torque at standstill and near-zero speed, the synchronization and even load distribution among the fifty-four climbing pinions of these jacking systems has been a challenge. Uneven load sharing among these fifty-four climbing pinions can overload and then break some of them prematurely. Broken climbing pinions can result in catastrophic rig accident and human casualties.
This novel torque transducer measures the climbing pinion resistant torque directly through reading the torsional deflection of the pinion precisely. A series of design verification through finite element analysis and design validations through factory acceptance tests have been conducted successfully.
With this new torque transducer installed, the load on each climbing pinion can be read simultaneously and then controlled either manually or with a variable frequency drive.
Different from any existing standard torque transducer mounted between electric motor and the input shaft of jacking system, this new novel torque transducer is designed to be mounted inside the climbing pinion and then reads the torque load on the pinion directly. The accuracy of this direct torque reading is regardless of the gear transmission efficiency, which, in fact, governs the reading accuracy of the current existing standard torque transducers available in the market.
