Pipe joints or couplings – Particular interface – Tapered
Reexamination Certificate
1996-09-19
2001-07-03
Luu, Teri Pham (Department: 3627)
Pipe joints or couplings
Particular interface
Tapered
C285S334200, C285S912000
Reexamination Certificate
active
06254147
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to fluid-tight connectors and in particular, though not necessarily, to wireline type fluid-tight connectors for providing metal-to-metal seals between opposed ends of tubes making up a pressure bearing string.
BACKGROUND OF INVENTION
A known type of fluid-tight connector means for connecting together opposite ends of two pipes, or tubes, comprises flanges provided on the ends of the pipes to be joined. A fluid-tight seal between the tubes may be obtained by bolting the flanges together around the circumference of the pipes. It is difficult and time consuming, however, to provide a circumferentially uniform seal with such an arrangement and, in order to improve the uniformity, it is common to insert an annular elastomeric gasket between the opposed flanges. It is often undesirable, however, to use elastomeric gaskets in hostile environments, such as those involving high temperatures, high pressures, or corrosive fluids in which they are likely to quickly decompose. In such hostile environments it is necessary to rely only upon metal-to-metal seals and to accept the above mentioned disadvantages.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided coupling means for enabling the fluid-tight coupling of opposed ends of first and second substantially tubular members by means of a pair of metal-to-metal seals, the coupling means comprising first and second metal sealing surfaces extending circumferentially around end regions of the first and second tubular members respectively, and a substantially annular interface member having circumferentially extending and axially spaced third and fourth metal sealing surfaces, the interface member being arranged in use between the coupling ends of the tubular members so that, with substantially no force being applied between member, said first and second sealing surfaces oppose, but are not aligned with, respective ones of the third and fourth sealing surfaces, the coupling means further comprising means for forcing said opposed ends of the tubular members together in a sense tending to compress the interface member, wherein at least one sealing surface of each pair of opposed surfaces is of a metal which is deformable under the action of the forcing means so as to increase the area of contact between the sealing surfaces of each pair of opposed surfaces, thereby to provide said metal-to-metal seals.
In a preferred embodiment of the invention, the sealing surfaces of the tubular members and of the interface member are arranged so that in use they do not lie in a plane perpendicular to the direction of the force applied by the forcing means. The sealing surfaces of each pair of opposed surfaces are misaligned in use, prior to compression, by less than 5°, preferably by less than 1.5° and more preferably still by approximately 0.50°. Compression of said deformable metal forces said adjacent surfaces substantially into alignment.
Preferably, said sealing surfaces are frustoconical. Preferably, the interface member is comprised of said deformable material. It will be clear, however, that the portion of the tubular members providing the first and second sealing surfaces could alternatively comprise deformable metal or that both these portions and the interface member could comprise deformable metal. Said deformable metal is preferably an alloy containing copper/beryllium, phosphor/bronze, or aluminium/bronze.
Preferably, the force applying means is arranged to distribute the applied force evenly around the circumferences of the tubular members, for example by engaging one or both of the tubular members by way of a screw thread.
Preferably, the force applying means comprises a substantially cylindrical collar for positioning coaxially around the opposed ends of the tubular members to be coupled. The collar is arranged to moveably engage at least one of said opposed ends, for example by means of an axially extending screw thread. Preferably, the collar moveably engages both of the opposed ends by means of axially extending, but oppositely directed, screw threads so that rotation of the collar about the tubular member forces said opposed ends together. Rotation of the collar may be achieved, for example, by means of a ratchet type tool arranged to be located in a locating recess on the collar and to engage teeth spaced around a circumferential region of one of the tubular members or around an intermediate surface mounted thereon.
It will be apparent that embodiments of the invention may provide a connector which makes use of metal-to-metal seals and which can be used to quickly connect and disconnect tubular members. Moreover, the metal-to-metal seals may be achieved uniformly around the circumference of the connection. Such connectors are particularly suitable for use in hostile environments, especially in high pressure/high temperature oil wells.
According to a second aspect of the present invention there is provided a method of coupling together opposed ends of first and second substantially tubular members to provide a fluid tight seal therebetween by way of a pair of metal-to-metal seals, the method comprising:
providing first and second metal sealing surfaces extending circumferentially around end regions of the first and second tubular members respectively;
axially aligning said opposed ends of the first and second tubular members, providing a substantially annular interface member having circumferentially extending and axially spaced third and fourth metal sealing surfaces;
disposing the interface member between said opposed ends of the tubular members so that the interface member is axially aligned with the tubular members and so that the first and second sealing surfaces oppose, but are not aligned with, respective ones of the third and fourth sealing surfaces; and
forcing said opposed ends together in a sense tending to compress the interface member, at least one sealing surface of each pair of opposed surfaces being of a metal which is deformable under the influence of the forcing action so as to increase the area of contact between the sealing surfaces of each pair of opposed sealing surfaces, thereby to provide said metal-to-metal seals.
Preferably, the step of forcing the opposed ends of the tubular members together comprises the step of arranging a substantially cylindrical collar coaxially around the opposed ends, so as to engage axially extending screw threads provided on both said opposed ends, and rotating the collar around the opposed ends. Rotation of the collar may be achieved by means of a mechanical advantage tool acting between the collar and one of the opposed ends.
According to a third aspect of the invention there is provided a method of coupling together opposed ends of first and second substantially tubular members to provide a fluid tight seal therebetween by way of a pair of metal-to-metal seals, the method comprising the steps of:
axially aligning said opposed ends of the tubular members so that they are spaced apart;
disposing a deformable interface member between the opposed ends so that first and second metal sealing surfaces, extending circumferentially around end regions of the first and second tubular members respectively, abut, but are not aligned with, respective ones of third and fourth circumferentially extending and axially spaced metal sealing surfaces of the interface member; and,
forming said pair of metal-to-metal seals by converting a rotational motion about the common axis to an axial compressive force thereby to deform the interface member to bring the sealing surfaces of the two pairs of abutting sealing surfaces into alignment.
REFERENCES:
patent: 3239245 (1966-03-01), Press et al.
patent: 4795198 (1989-01-01), Hjelset
patent: 5058929 (1991-10-01), Zentner et al.
patent: 5176409 (1993-01-01), Brooks
Expro North Sea Limited
Gifford, Krass, Groh Sprinkle, Anderson & Citkowski, P.C.
Luu Teri Pham
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