Pipe joints or couplings – Flexible joint – rigid members
Reexamination Certificate
1999-02-22
2001-12-11
Barrett, Suzanne Dino (Department: 3627)
Pipe joints or couplings
Flexible joint, rigid members
C285S047000, C138S140000
Reexamination Certificate
active
06328346
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a flexible mechanical joint and, more particularly, to a flexible mechanical joint for interconnecting at least two movable wall sections such as sections of pipeline insulation or sections of road pavements. The invention is particularly, but not exclusively, adapted to joining sections of substantially rigid pipeline insulation. However, it should be noted that, although the detailed description provided herein is directed primarily to a joint for joining of substantially rigid thermal insulation systems on pipelines and also to a joint for joining of sections of concrete pavements, such detailed description is provided for convenience and exemplary purposes and should not serve to limit the invention.
BACKGROUND OF THE INVENTION
A mechanical joint may be provided as a structural interface between two elongated structural sections when it is, otherwise, not practical to provide or construct a continuous section thereof. Examples of elongated structural sections to which the present invention is applicable include cylindrical sections of substantially rigid thermal insulations, relatively flat sections of substantially rigid insulations, thermally elongatable or otherwise movable structural walls, panels, pavements, and decking, and the like. Typically, there are certain manufacturing, installation and/or environmental constraints which necessitate using a sectioned design as opposed to a continuous design. For example, there is often a limit to the length that the elongated section may be constructed in place. Such is the case in the construction of sections formed from a construction material such as concrete which must be finished and/or shaped before the material dries or sets in place.
In other applications, the elongated section(s) may have a tendency to elongate or contract due to thermal conditions. Thus, expansion room between sections must be provided. In this regard, it is often advantageous to minimize the length of the sections so as to minimize the potential elongation and the structural stresses which can be associated with such elongation. Further, flexible mechanical joints may be provided as the structural interface between the two movable elongated sections so as to absorb the movement between the two sections and to minimize the stresses generated in the sections as a result of such movement. The flexible mechanical joint also functions to fill the gap between the sections and to provide some uniformity at interface of the two sections.
A thermal insulation system may be provided on a product pipeline to maintain the temperature of the product transported therethrough. The insulation system may function to maintain the temperature of the transported fluid below the temperature of the external environment, such as in the case of the transportation of crude oil, natural gas, or petroleum products such as LPG or benzene. In the alternative, the insulation system may function to maintain the temperature of the transported fluid above the temperature of the external environment. Such an insulation system is provided on steam lines and also on some hydrocarbon pipelines such as, for example, subsea hydrocarbon pipelines.
Pipeline insulation systems suitable for low or high temperature applications come in a variety of forms and may utilize a variety of insulation materials. Typically, the primary properties considered in selecting the insulation material are the material's resistance to heat transfer and its cost. In some applications, it may also be desirable to provide insulation systems having high structural rigidity and a high compressive strength. This is particularly desirable in the application of insulation on subsea hydrocarbon applications wherein the insulation system is subjected to high hydrostatic pressures. Accordingly, the substantially rigid insulation system should have a compressive strength sufficiently high to withstand the stresses created by such hydrostatic pressures. In this regard, insulation made of a syntactic composite and having a compressive strength in excess of about 3000 psi has proven effective.
SUMMARY OF THE INVENTION
It is a general object of the invention to provide a mechanical joint for joining or interconnecting two movable elongated structural sections such as sections of rigid insulation or sections of road pavements. A significant feature of the inventive mechanical joint is a flexibility sufficient to absorb the movement of the adjacent structural sections, particularly movement along a generally longitudinal direction.
With respect to one embodiment of the invention applicable to insulated pipelines, the installation of such an insulated pipeline is illustrated in FIG.
1
. Important to application of the present invention, the pipeline may be directed downward from a vessel in a manner wherein, initially, the section of pipeline immediately downward of the vessel takes a curve, concave configuration relative to the ocean floor. Further downward, the pipeline takes on a more convex configuration relative to the ocean floor, before being laid substantially flat or horizontally across the ocean bottom. As is typical in the prior art, each section of pipeline insulation is substantially rigidly or frictionally attached to the outside surface of the pipe. Accordingly, the insulation must also bend with the pipe or pipeline, e.g., when it is being laid across the ocean floor (as illustrated in FIG.
1
). In prior art methods, the tendency of the pipeline to bend or flex in this manner exerts compressive or tensile stress on the rigid insulation. Combined with the high hydrostatic pressure present in a deep ocean environment, there is a tendency for cracks to propagate or fractures to be initiated in the pipeline insulation system. As a result of the cracks or fracture failures, the integrity of the insulation system is compromised and the operation of the pipeline system is hampered.
Accordingly, one embodiment of the invention is an improved insulation system that is generally applicable in the conditions present in the deep ocean environment.
In one aspect of the invention, a flexible mechanical joint is provided for coupling, interconnecting, interlocking and/or joining a first elongated structural section (e.g, a concrete pavement section or a cylindrical section of insulation) with a second elongated structural section. The inventive joint is compressible and expandable at least along a substantially longitudinal direction upon movement of at least one of the first and second sections. For purposes of clarity, the referenced longitudinal direction is defined as a direction that is substantially parallel to a longitudinal line along which the two sections and the joint are substantially aligned, when the joint is disposed in a non-flex condition. In a pipeline insulation application, this longitudinal direction is substantially parallel with the longitudinal centerline of the pipe.
The joint includes a first connecting portion fixedly attached to the first section and a second connecting portion fixedly attached to the second section. The joint also has a flexible member that connects the first connecting portion with the second connecting portion and which is positioned between the two sections. The flexible member, which is preferably a substantially flat elongated member, is shiftable (e.g., rotatable relative to the first and second connecting portions) upon relative longitudinal movement between the first and second sections. Preferably, at least one of the first and second connecting portions includes an anchoring member frictionally engaging one of the first and second sections. For example, the anchoring member may have a lip that is secured into the one section.
As another feature of the mechanical joint, the first and second connecting portions define at least one variable space therebetween. The variable space has a longitudinal length or volume that varies in response to relative movement between the first and second sections along t
Brandon, Jr. Cecil M.
Masters Randy W.
Advanced Industrial & Marine Services
Barrett Suzanne Dino
Fulbright and Jaworski L.L.P.
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