Pipe joints or couplings – Packed – Flanged pipe
Reexamination Certificate
1998-03-27
2001-05-22
Knight, Anthony (Department: 3626)
Pipe joints or couplings
Packed
Flanged pipe
C285S336000, C285S363000, C285S365000, C277S608000, C277S611000, C277S614000
Reexamination Certificate
active
06234545
ABSTRACT:
BACKGROUND OF THE INVENTION
The subject invention is directed toward the art of pipe and tube joints and couplings and, more particularly, to an improved flange type joint.
The invention is especially suited for forming connecting joints in critical processing systems where fluid entrapment or retention within the system must be avoided. In such systems, it is often difficult to eliminate recesses or pockets that retain process fluid between system runs or when switching fluids in a common line.
The problem of recesses and fluid trapping pockets is especially prevalent with respect to connecting joints which rely on resilient, elastomeric seals and packings. The typical prior packed joint was often difficult to assemble and frequently resulted in undesired discontinuities between the connected sections. Consequently, the need has existed for a joint construction which is easy to assemble and which does not produce pockets, recesses, or undesirable discontinuities which can trap process fluids.
In packed joints of the type under consideration, the components must generally be axially driven together under relatively high force to produce the necessary sealing pressures. Also, the joints are typically used in systems where frequent disassembly for cleaning, maintenance, and/or system changeover.
To meet the high force and rapid disassembly requirements, it has been the practice to use circumferentially extending, multi-section clamping rings. The rings sections have internal wedge surfaces that act against corresponding wedge surfaces on the exterior of the joint to drive the joint components axially together. Actuation of the clamp ring is generally accomplished by a thumb screw which pulls the sections together.
While generally satisfactory, problems have been encountered with the clamp rings. For example, in systems subject to substantial vibration, loosening of the clamp ring and loss of sealing force has occurred. Additionally, the repeated high force tightening and releasing of the thumb screws has produced significant galling and erosion of the nose of the thumb screws and/or the engaged portion of the clamp rings. This makes it difficult to retighten the clamps and also generates metal particles which are often highly undesirable in the system environment.
SUMMARY OF THE INVENTION
The subject invention provides a highly effective flange type, packed connection joint which eliminates entrapment areas. The joint of the invention provides a primary seal area closely adjacent the fluid flow path and a secondary seal area radially and axially spaced from the primary seal area.
The subject invention also provides a joint clamping system and arrangement wherein the above-discussed problems are overcome and high joint clamping forces are generated. The arrangement is such that assembly and disassembly of the joint can be performed rapidly and repeatedly without loss of effectiveness.
In accordance with one aspect of the invention, there is provided a flange connection for joining the ends of a pair of cylindrical pipes in axially aligned communicating relationship. The connection includes a separate flange member joined to the end of each pipe. Each flange member has a radially extending end face which is generally perpendicular to the axis of the pipe. A central circular opening extends through each end face in communication with the interior of the respective pipe. Means are provided for clamping the flanges together in axial alignment. In this invention, the feature of primary importance comprises a seal chamber formed by duplicate axially inward extending annular recesses formed in each flange circumferentially about the central opening with a circumferentially continuous engagement face located radially outward of each recess in a plane perpendicular to the central axis of the pipes. The recesses have axially open outer ends in opposed mating relationship and radially spaced planar side walls which are inclined toward one another to bottom walls which lie in planes perpendicular to the axis of the pipes. A narrow circumferentially continuous groove opens radially inward from the seal chamber to the central circular opening in alignment with the plane of the engagement faces. The groove is defined by axially spaced planar side walls. A resilient seal ring is compressed in the seal chamber with a narrow portion compressed between the planar side walls which define the narrow groove. The radial innermost extent of the narrow portion forms a smooth transition surface between the circular openings in the flanges. The size of the seal ring is such that when the engagement faces are clamped together, a primary seal pressure on the seal ring is generated by the planar side walls of the groove. A secondary seal pressure is generated on the seal ring by the planar bottom walls of the mating recesses.
Preferably, the dimensional relationships between the seal ring and the flange recesses are such that when the seal ring is placed in position on one of the flanges, there is a dimensional interference between the seal ring and the radial inner inclined side wall. The dimensional interference is sufficient to retain the seal ring in position while the other flange face is brought into position. This greatly facilitates assembly of the joint, especially in vertical positions.
The engagement between the seal ring and the radial inner inclined side wall provides alignment of the seal ring with the central circular opening prior to assembly with the opposing flange. In addition, when the opposing flange comes into engagement, the radial inner inclined side wall provides alignment of both flanges with each other and the central circular opening even prior to compression of the seal ring.
Ideally, the dimensional interference between the inner inclined side wall and the seal ring is sufficient to secure the assembly as a unit even prior to the installation or tightening of the associated clamping means.
In accordance a more limited aspect of the invention, the axially spaced planar side walls of the narrow groove can be parallel and perpendicular to the axis of the pipe or they can be inclined to produce a narrowing of the groove inwardly toward the axis of the pipe.
In accordance with a still further aspect of the invention, the seal ring is sized so as to substantially completely fill the seal chamber and the narrow groove upon assembly.
In accordance with a further aspect of the invention, the dimensional relationships between the seal ring and the groove are such that on make-up of the joint, the ring engages the planar bottom walls of the mating recesses prior to engagement by the planar side walls of the groove. Additionally, the relative dimensions are maintained such that the first primary sealing pressure is generated between the planar side walls of the groove and the seal to a relatively high level while a higher backup sealing pressure is generated on the seal ring by the planar bottom walls of the recesses.
In accordance with another aspect of the invention, an improved clamp ring assembly is provided for clamping adjacent pipes having flanged in longitudinal aligned relationship. The assembly generally includes a clamp ring having a flexible body section terminating in free ends and including a groove extending between the free ends along a side of the body section to engage the flanged ends and pull them axially together when the body section is encircled about the flanged ends and the free ends are forced toward one another. Locking means are provided to selectively force the free ends toward one another when the body section is encircled about the flanged ends. The locking means generally comprise a threaded clamp screw having opposite ends with one end connected with one of the free ends of the body section and the other end threadedly carrying a wing nut. The wing nut comprises a nut body having a nose portion engageable with the other free end of the body section for applying force thereto. The nose portion is pivotal relative to the nut body and a friction reducing, resil
Babuder Gerald A.
Fisher, Jr. Ronald K.
Calfee Halter & Griswold
Knight Anthony
Swagelok Company
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