Riser Sections and Risers Made Therefrom

Abstract

A riser section having a generally tapered, e.g., frustoconical wall, the riser section having a first connector assembly at one end of the riser section and a second connector assembly at the other end of the riser section.

What is claimed is: 
     
         1 . A tapered riser section comprising:
 a riser body having a tapered wall, said tapered wall having a first end forming a first opening and a second end forming a second, larger opening;   an annular, radially inwardly extending lip on said first end;   an annular, radially outwardly extending flange on said second end;   at least one lip connector formation formed on said lip;   said body, said lip, and said lip connection formation forming a monolithic structure;   at least one flange connection formation on said flange;   said body, said flange, and said flange connection formation forming a monolithic structure.   
     
     
         2 . The riser section of  claim 1 , wherein said lip comprises an upper, axially facing lip surface and there is at least one key projecting axially from said lip surface and at least one keyhole formed in said lip and said flange has a lower, axially facing flange surface and there is at least one key projecting from said flange surface and at least one keyhole formed in said flange. 
     
     
         3 . The riser section of  claim 2 , wherein there are at least two circumferentially spaced keys on said lip surface, at least two circumferentially spaced keyholes in said lip, at least two circumferentially spaced keys on said flange surface, and at least two circumferentially spaced keyholes in said flange. 
     
     
         4 . The riser section of  claim 2 , wherein said keys comprise stem portions attached to and extending from said lip surface and said flange surface and a head portion formed on each of said stems, said head portions having a larger diameter than said stem portions, and wherein said keyholes comprise a generally key shaped opening having a first portion having a size large enough to allow said head portion to pass therethrough and a second, elongate portion large enough to allow said stem portion to be received therein, said second portions of said keyholes being too small to allow said head portions pass therethrough. 
     
     
         5 . The riser section of  claim 2 , wherein there are two keys circumferentially spaced from one another by 180° and there are two keyholes circumferentially spaced from one another by 180° in each of said lip and said flange.