Gimbal bearing system and method

Abstract

Embodiments relate generally to gimbal bearings for installation of a riser string. Gimbal bearing embodiments comprise a top ring and a bottom ring, with a plurality of high capacity laminate bearings located therebetween, the high capacity laminate bearings comprising at least one of natural rubber and a marker layer. Each high caparity laminate bearing might comprise alternating layers of steel shims and elastomeric elements bonded together via adhesive. Embodiment designs provide for improved gimbal bearing characteristics, which may improve the effective lifespan of such gimbal bearings.

What is claimed is: 
     
         1 . A gimbal bearing comprising:
 a top ring;   a bottom ring; and   at least one high capacity laminate (HCL) bearing positioned between and affixed to the top and bottom rings;   wherein the HCL bearing comprising at least one of natural rubber and an elastomeric marker layer.   
     
     
         2 . The gimbal bearing of  claim 1  wherein each of the at least one HCL bearings comprise a bonded shim pack. 
     
     
         3 . The gimbal bearing of  claim 2  wherein each bonded shim pack includes alternating layers of shims and elastomeric elements. 
     
     
         4 . The gimbal bearing of  claim 3  wherein each of the at least one HCL bearings further comprises a top interface member and a bottom interface member associated therewith. 
     
     
         5 . The gimbal bearing of  claim 4  wherein each interface member is bonded to an end of a shim pack and bolted to the corresponding ring. 
     
     
         6 . The gimbal bearing of  claim 1  wherein the top ring and bottom ring each are split but are operable to be joined into an integrated whole. 
     
     
         7 . The gimbal bearing of  claim 1  wherein the bottom ring further comprises integrated lift points. 
     
     
         8 . The gimbal bearing of  claim 3  wherein one or more of the elastomeric elements do not have the same spring rate. 
     
     
         9 . The gimbal bearing of  claim 3  wherein the marker layer comprises a color different from at least one of the elastomeric elements. 
     
     
         10 . The gimbal bearing of  claim 9  wherein the marker layer comprises an inner layer of one color different from and contrasting with that of a surface layer. 
     
     
         11 . The gimbal bearings of  claim 2  wherein: the gimbal bearing comprises a plurality of HCL bearings; the bottom ring has a larger diameter than the top ring; the bonded shim packs angle inward as extending upward from the bottom ring to the top ring; and the bonded shim packs are spaced evenly about the circumference of the top and bottom rings 
     
     
         12 . A gimbal bearing comprising:
 a top ring;   a bottom ring; and   a plurality of shim stack assemblies located between and affixed to the top and bottom rings;   wherein the plurality of shim stack assemblies are spaced evenly about the circumference of the top and bottom rings; and   wherein at least one of the shim stack assemblies comprises at least one of natural rubber and an elastomeric marker layer.   
     
     
         13 . The gimbal bearing of  claim 12  wherein each of the plurality of shim stack assemblies comprise a bonded shim pack, a top interface member, and a bottom interface member; and wherein each bonded shim pack comprises alternating layers of steel shims and elastomeric elements. 
     
     
         14 . The gimbal bearing of  claim 12  wherein the gimbal bearing has a maximum cocking angle of about ten (10) degrees. 
     
     
         15 . The gimbal bearing of  claim 13  wherein the steel shims comprise 4130 Alloy Steel. 
     
     
         16 . A method of forming a gimbal bearing for a riser string, comprising the steps of:
 forming a plurality of bonded shim packs with alternating layers of steel shims and elastomer elements;   affixing top and bottom interface members to each bonded shim pack to form a plurality of shim stack assemblies;   affixing the plurality of shim stack assemblies to a top ring and a bottom ring, with each shim stack assembly positioned between the top ring and the bottom ring; and   providing at least one of the shim stack assemblies with natural rubber and a marker layer;   wherein the plurality of shim stack assemblies are spaced evenly about the circumference of the top and bottom rings.   
     
     
         17 . The method of  claim 16  wherein the elastomeric elements may vary in spring rate. 
     
     
         18 . The method of  claim 16  wherein each set of top and bottom interface members are affixed to the corresponding bonded shim pack using bonding adhesive, and wherein each set of top and bottom interface members are removably affixed to the top and bottom rings. 
     
     
         19 . The method of  claim 16  further comprising forming the top and bottom rings with clamshell configuration. 
     
     
         20 . The method of  claim 19  further comprising positioning the riser string within the top and bottom rings, installing the riser string, opening the clamshell top and bottom rings, and removing the gimbal bearing from the installed riser string.