Flexible joint for fluid conduit systems

Claim 1

A flexible joint for fluid conduits having a central longitudinal axis and opposed ends and comprising, a first member having a first annular portion fixed thereto which extends at an angle with respect to said axis toward one of said opposed ends, a second member having a second annular portion which extends outwardly thereof away from said axis and toward the other of said opposed ends, and a primary seal in the form of a substantially tubular bellows having an inside diameter; said first member having a small diameter portion defining one end of said joint and an adjoining gradually flaring main body, said first annular portion extending from a large diameter edge of said main body and roughly parallel to a portion thereof, and said second member having a tubular portion which corresponds in diameter to the small diameter portion of said first member with said tubular portion having an outer end which defines the other opposed end of said joint and an inner end terminating in said second annular portion; said primary seal providing a zero leakage connection between said members yet allowing relative movement thereof and having end portions with one end portion fixed to said first annular portion and its opposite end portion fixed to said second member so that said primary seal is arranged concentrically around said tubular portion of said second member; said annular portions defining a secondary seal for said joint and being arranged so that increased fluid pressure in said joint tends to separate said members and urge said annular portions into tighter sealing engagement, said secondary seal arranged upstream of said primary seal to isolate said primary seal from fluid flow induced stresses; said annular portions being hooked together to prevent mechanical disengagement of said members and being arranged concentrically outwardly of said inside diameter to permit greater angular displacements of said members for a given maximum outside diameter envelope for said joint, said annular portions having cooperating load-bearing and sealing surfaces which allow fluid seepage therebetween during normal operation, said fluid serving to lubricate said surfaces and reduce bending loads on Said joint, yet being trapped by said primary seal.