Improved riser tensioner bearing system

Abstract

A serial bearing ( 300 ) for a riser tensioner system is provided. The serial bearing improves lateral and axial load performance when severe side-loads are transferred to the riser tensioner system.

What is claimed is: 
     
         1 . A serial bearing for a riser tensioner system, said serial bearing including:
 a radial bearing mount;   a spherical bearing mount;   an intermediate mount disposed between the radial bearing mount and the spherical bearing mount;   a radial bearing stack disposed between the radial bearing mount and the intermediate mount; and   a spherical bearing stack disposed between the spherical bearing mount and the intermediate mount.   
     
     
         2 . The serial bearing of  claim 1 , wherein the radial bearing stack includes a high capacity laminate (HCL). 
     
     
         3 . The serial bearing of  claim 2 , wherein said HCL is formed using direct bonding. 
     
     
         4 . The serial bearing of  claim 2 , wherein said HCL is formed using sequential bonding. 
     
     
         5 . The serial bearing of  claim 1 , wherein the spherical bearing stack includes a high capacity laminate (HCL). 
     
     
         6 . The serial bearing of  claim 5 , wherein said HCL is formed using direct bonding. 
     
     
         7 . The serial bearing of  claim 5 , wherein said HCL is formed using sequential bonding. 
     
     
         8 . The serial bearing of  claim 1 , wherein said spherical bearing stack has a spring rate of about 1.2×10 7  lbf/inch in compression, about 22,000 lbf/inch in shear, and about 9×10 5  lb·ft/deg for cocking. 
     
     
         9 . The serial bearing of  claim 1 , wherein said spherical bearing stack has a radial spring rate of about 781,000 lbf/inch, a torsional spring rate of about 1900 in-lbf/deg, a cocking spring rate of about 4000 in-lbf/deg, and an axial spring rate of about 4.7×10 6  lbf/inch. 
     
     
         10 . The serial bearing of  claim 9 , where said axial spring rate and said radial spring stack are nonlinear and are configured to increase in a stiffness as a load acting upon said spherical bearing stack increases. 
     
     
         11 . The serial bearing of  claim 9 , wherein said spherical bearing stack has cocking spring rate less than or equal to about 4000 in-lbf/deg. 
     
     
         12 . The serial bearing of  claim 1 , wherein at least one of the radial bearing mount and the spherical bearing mount are configured for connection to a riser. 
     
     
         13 . The serial bearing of  claim 12 , wherein a cocking motion of said spherical bearing stack is about +/−15 degrees from a vertical direction relative to said riser. 
     
     
         14 . The serial bearing of  claim 1 , wherein the radial bearing stack includes at least one of ring shaped elastomeric elements and ring shaped shim elements.