Lifting Device Having Hinged Segments

Abstract

Lifting devices for use with drilling risers, where the lifting devices have a plurality of segments, some of which are hinged to facilitate handling and provide multiple shear points between the hinged segments. One embodiment comprises a lifting device for a drilling riser, where the device includes a collar and a lifting lug. The collar has a cylindrical ring with one or more annular ribs connected to corresponding circular edges of the ring. The lifting lug is connected to the collar and the ribs. The collar has a plurality of segments, and at least a first one of the segments is pivotally connected to another one of the segments by a hinge. Each rib may taper smoothly from a smaller thickness at a top edge of the rib to a greater thickness at a base of the rib.

What is claimed is: 
     
         1 . A lifting device for a drilling riser, the device comprising:
 a collar having a cylindrical ring and a first annular rib connected to a first circular edge of the ring; and   a lifting lug connected to the collar;   wherein the collar has a plurality of segments; and   wherein at least a first one of the segments is pivotally connected to at least a second one of the segments by a hinge.   
     
     
         2 . The lifting device of  claim 1 , wherein the collar comprises a lug segment, a first hinged segment and a second hinged segment, wherein the lug segment has the lifting lug connected thereto, wherein the first hinged segment is pivotally connected to the lug segment by a first hinge, and wherein the second hinged segment is pivotally connected to the lug segment by a second hinge. 
     
     
         3 . The lifting device of  claim 2 , wherein the first hinged segment is configured to be connected to the second hinged segment by one or more bolts. 
     
     
         4 . The lifting device of  claim 3 , further comprising one or more spherical washers positioned between each of the one or more bolts and the first and second hinged segments, wherein a plurality of spherical seats for the spherical washers are provided on the first and second hinged segments. 
     
     
         5 . The lifting device of  claim 1 , further comprising a second annular rib connected to a second circular edge of the ring. 
     
     
         6 . The lifting device of  claim 1 , wherein each of the first and second annular ribs tapers from a smaller thickness at a top edge to a greater thickness at a base of the annular rib. 
     
     
         7 . The lifting device of  claim 6 , wherein the thickness at the base of each annular rib is at least half of a height of the annular rib. 
     
     
         8 . The lifting device of  claim 6 , wherein for each rib, an inner surface that faces the other rib has a minimum radius of curvature of at least half of a height of the rib. 
     
     
         9 . The lifting device of  claim 1 , further comprising an elastomeric layer positioned against a cylindrical inner surface of the collar. 
     
     
         10 . A drilling riser assembly comprising:
 a pipe section;   one or more buoyancy modules, wherein each of the buoyancy modules is annular and is positioned around the pipe section; and   a pair of lifting devices, wherein a first one of the lifting devices is secured to a first end of the pipe section and a second one of the lifting devices is secured to a second end of the pipe section, thereby retaining the one or more buoyancy modules on the pipe section;   wherein each of the lifting devices includes a collar and a lifting lug connected to the collar, wherein the collar has a cylindrical ring and a first annular rib connected to a first circular edge of the ring, wherein the collar has a plurality of segments, and wherein at least a first one of the segments is pivotally connected to at least a second one of the segments by a hinge.   
     
     
         11 . The drilling riser assembly of  claim 10 , wherein the collar comprises a lug segment, a first hinged segment and a second hinged segment, wherein the lug segment has the lifting lug connected thereto, wherein the first hinged segment is pivotally connected to the lug segment by a first hinge, and wherein the second hinged segment is pivotally connected to the lug segment by a second hinge. 
     
     
         12 . The drilling riser assembly of  claim 11 , wherein the first hinged segment is configured to be connected to the second hinged segment by one or more bolts. 
     
     
         13 . The drilling riser assembly of  claim 12 , further comprising one or more spherical washers positioned between each of the one or more bolts and the first and second hinged segments, wherein a plurality of spherical seats for the spherical washers are provided on the first and second hinged segments. 
     
     
         14 . The drilling riser assembly of  claim 10 , further comprising a second annular rib connected to a second circular edge of the ring. 
     
     
         15 . The drilling riser assembly of  claim 10 , wherein each of the first and second annular ribs tapers from a smaller thickness at a top edge to a greater thickness at a base of the annular rib. 
     
     
         16 . The drilling riser assembly of  claim 15 , wherein the thickness at the base of each annular rib is at least half of a height of the annular rib. 
     
     
         17 . The drilling riser assembly of  claim 15 , wherein for each rib, an inner surface that faces the other rib has a minimum radius of curvature of at least half of a height of the rib. 
     
     
         18 . The drilling riser assembly of  claim 10 , further comprising an elastomeric layer positioned against a cylindrical inner surface of the collar. 
     
     
         19 . The drilling riser assembly of  claim 10 , wherein a radius of curvature of an inner surface of each lifting device is greater than a radius of curvature of the pipe section, and wherein each lifting device is pre-stressed when installed on the pipe section.