Gimbal assemblies, located beneath the spider on offshore rigs, provide the necessary compliance between the riser system and vessel to protect drilling equipment from excessive stress and damage. LORD gimbal pads and assemblies are designed under strict process and quality controls to ensure each part performs consistently. Through proprietary tools originally developed for the aerospace industry, we can accurately and dynamically model the stiffness of any gimbal system in any plane of rotation. The result is a product designed to handle extreme loading and environmental conditions for improved pad life.
There are four main areas that influence the fatigue life of a traditional gimbal pad; elastomer choice, part configuration, bonding technology and inherent design of the traditional gimbal bearing system. LORD gimbal pads address the first three areas to provide longer service life and decreased maintenance, serving as a drop-in replacement in most applications. Our universal joint style gimbal bearing overcomes the inherent high strain design issues of the traditional gimbal array to significantly improve fatigue life. The universal joint style gimbal bearing is designed for extreme applications where deck space is limited. LORD gimbal pads utilize a proprietary natural rubber formulation that provides greater fatigue life than the nitrile traditionally used. Environmental protection is achieved through another LORD proprietary material called HPC, which stands for “High Performance Coating.” In addition to visual condition monitoring, LORD® HPC coating provides superior resistance to ozone, fluids and sunlight without impacting part function. After prolonged exposure to petroleum fluid, HPC-coated natural rubber retains all mechanical properties while exhibiting less swell than uncoated nitrile.
In a traditional gimbal assembly, the rotational motion of the spider causes massive strains in the elastomer at the bonded surfaces which results in local elastomer separation. With each cycle of rotation, the separation continues to propagate until the pad is only functioning through the frictional interfaces of the separated surfaces under the compressive load of the riser. LORD gimbal pads are designed to reduce strains, minimizing elastomer degradation. In the test pictured, LORD material and bond strength can achieve over 300% tensile strain without fracture, enabling less frequent replacement of the pads.
Bearing at Rest
Bearing Under Extreme Tensile Load (>300%)
Contact us to learn more about our gimbal assemblies and pads or to request a quote.