Abstract: A centralizer system is provided for use in a marine riser system, the centralizer being preferably heat-shrink fitted to an upset portion of a keel joint, the upset portion having tapered sections on the upper and lower ends that gradually blend into the outer diameter of the pipe used as the keel joint, the centralizer preferably comprising axially extending annular grooves in surrounding relationship to the upset portion, the grooves serving to permit forces acting on the centralizer to be redirected or dissipated to thereby prevent excessive buildup on a selected region of the upset portion adjacent the radial grooves.

Abstract: A centralizer system is provided for use in a marine riser system with an insulated pipe, which may be a titanium stress joint. The centralizer system utilizes one or more centralizers mounted such that insulation material is provided in an annulus between the one or more centralizers and the stress joint. A clamp is utilized to axially affix either one centralizer or multiple centralizers to the stress joint. The clamp is comprised of a plurality of sections with cylindrical interior surfaces which are tightened together using fasteners. The cylindrical interior surfaces avoid damage to the insulation layer which may be elastomeric. The clamp and each centralizer have radially directed projections thereon which interlock the clamp with each centralizer. Because the clamp is axially affixed, the centralizer is then also axially affixed. In one embodiment, the centralizer is axially moveable to a desired axial position prior to being interlocked to the tightened clamp.