Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED PIPE REPAIR CLAMP
The present invention relates to a repair clamp.
More particularly, the invention provides an improved pipe repair clamp. The
clamp
according to the invention could be used in some cases as a coupling to join
two pipe
ends.
Where extensions, repairs or replacements have to be carried sometimes out
under field
conditions it is usually much easier to use pipe clamps which do not requiring
welding.
Furthermore if the work is to be carried out near flammable materials welding
will be
prohibited, and other methods must be used.
Many prior art pipe couplings are designed to squeeze together a pair of
sloping side
flanges assumed to be strongly attached or integral with the pipes. Examples
of this type
of coupling are seen in US Patents Nos. 4,568,115 to Zimmerly, 4,722,561 to
Heckethorn
et al., 4,919,453 to Halling et al., 5,277,458 to Tschann, 5,509,702 and
5,645,303 to
Warehime et al., and 5,707,089 to Fend. Pipes and other cylindrical bodies not
provided
with such flange can not be coupled by devices of this type.
A pipe clamp suitable for use under field conditions is a generally hollow
cylindrical
body provided with means for gripping and sealing the pipes inserted therein.
The
diameter range of a clamp or a coupling of a designated size is limited. Such
limitation is
satisfactory where the outer diameter of the pipeline to be serviced or
extended is known
in advance. However as field service workers may need to deal with pipes made
according to different standards and made of various metals or plastics, prior-
art pipe
couplings may have limited applications.
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While a full review of prior-art pipe couplings or clamps would be volumous,
the state of
the art can be assessed reasonably well from a review of the above, and
additional, more
recent US Patents.
Wilkins discloses a complex pipe coupling in US Patent No 6,007,106 which
includes a
plastic seal having high resistance to various chemicals.
The present inventor has disclosed a moderate-cost coupling in US Patent No.
6,293,556
B 1 which is capable of sealing pipes of two different diameters.
Wolfsdorf in US Patent No. 6,312,025 provides clamping elements to restrain
axial
separation of the two pipes.
In US Patent 6,361,082 B1 Hauld et al. discloses a pipe coupling intended for
connecting
plastic tubing of the type used for small diameter low pressure installations.
The coupling
includes an eccentric tightening arrangement.
A pipe coupling seen in US Patent no. 6,378,915 Bl to Katz is based on an
outer housing,
seal members and a nut-like member which is screwed to the outer housing to
compress
the seal members.
Provision to resist axial separation, and to effect sealing, are included in a
coupling
device seen in European Patent Application EP 0 974 780 A1 to Hulsebos. The
device is
however quite complex, and is not intended to cope with large diameter
variations.
The present inventor has disclosed a band-type pipe clamp and coupling in US
Patent No.
5,271,648. Clamping was effected by the use of two complementary plates 3 and
4, the
band extremities extending slightly beyond the outer edges of said plates.
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Anchoring of the band extremities was however found to be limited, and the
band was not
utilized to provide a support for the screw clamps.
Bearing in mind this state of the art, it is now one of the objects of the
present invention
to obviate the disadvantages of prior art pipe couplings and to provide a band-
type repair
clamp wluch has a larger diameter range than prior-art and which could also be
used as a
pipe coupling..
It is a further object of the present invention to provide a wide-range pipe
repair clamp
provided with improved fastening means.
It is yet a further object of the present invention to provide a wide-range
pipe repair clamp
at moderate cost by use of a simple tension band to squeeze a flexible high-
friction liner
against the outer surface of the pipe.
Finally it is an object of the present invention to provide a clamp where the
band and the
fastener means are integral.
The present invention achieves the above objects by providing a wide-range
pipe repair
clamp, comprising:
a) a metal clamping band to surround 360° of said pipe, said band being
extended at both
ends to form a hollow shape including a flat base, a wedge-shaped section and
a convex
r ounded section, elongated aperhires being provided to allow passage for
screw fasteners
through said hollow shape, narrow edges of said wedge-shaped sections being in
contact
with each other to form a substantially triangularly shaped space between said
formed
ends;
b) a flexible inner sealing sleeve disposed inside said clamping band;
c) a pair of profile strips each having a major face for contacting the outer
surface of said
convex rounded section, and an opposite seating face for shoulder support of a
plurality
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of screw fasteners, said strips having apertures to allow passage of said
fasteners, said
profile strips sliding over said convex rounded section when said fasteners
are tightened
or loosened to maintain said seating face perpendicular to the axes of said
fasteners; and
d) said plurality of screw fasteners inserted into said apertures wherein the
tightening of
said screw fasteners reduces the size of said triangularly shaped space and
tightens said
metal clamping band to compress said flexible inner sleeve sealingly against
the outer
diameter of said pipes.
In a preferred embodiment of the present invention there is provided a wide-
range pipe
repair clamp wherein said hollow shape being formed at both ends of said band
is filled
with a crush-resistant material.
In a most preferred embodiment of the present invention there is provided a
wide-range
pipe repair clamp wherein the allowed pipe diameter variation is about 50%
more than
known similar clamps.
Yet further embodiments of the invention will be described hereinafter.
In U.S. Patent no. 5,203,594 Straub describes and claims a pipe coupling which
is split in
a longitudinal direction and has inwardly bent end walls and a steel insert
sheet of
analogous design bridging the housing gap. Possibly the bent walls are
intended to
prevent extrusion of the flexible sleeve under pressure, but their effect is
to sharply
reduce diametrical flexibility. Furthermore the tightening method shown has no
leverage;
tightening the screws by 5 mm will tighten the band by 5 mm.
In contradistinction thereto the present invention uses a plain band without
any bent-over
lips visible when viewed in a longitudinal cross-section, thus easily
achieving the
required flexibility. Axial extrusion of the flexible inner sleeve can be
prevented without
providing end walls - this being the subject of one of our co-pending patent
applications.
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It will thus be realized that the novel clamp of the present invention serves
to provide an
economically viable device for repairing of pipes. Larger pipe diameters are
accommodated simply by using a longer steel band and larger rubber sleeve,
thus the
larger the pipe diameter the greater the cost advantage relative to other
designs.
Review of the present specification will also make clear that the pipe clamp
is not limited
for effecting temporary or permanent repair of a damaged pipe but can also be
used for
joining pipe ends. As a free pipe end is often unavailable in such
circumstances the clamp
can be dismantled and fitted over the failed section to stop further leakage.
With regard to the pair of profile strips contacting the outer surface of the
convex rounded
section, these are shown in the drawings with multiple apertures, the strips
being as long
as the coupling. It will however be understood that discrete short strips or
pads could be
used.
The drawings show elastomer caps fitted over the screw ends. While not
functionally
essential, the caps improve the appearance of the coupling, make handling the
coupling
more pleasant, prevent inadvertent loss of the nut and washer, and protect the
screw ends
from possible damage.
The invention will now be described further with reference to the accompanying
drawings, which represent by example preferred embodiments of the invention.
Structural
details are shown only as far as necessary for a fundamental understanding
thereof. The
described examples, together with the drawings, will make apparent to those
skilled in the
art liow fiu-ther forms of the invention may be realized.
In the drawings:
FIG. 1 is a perspective view of a preferred embodiment of the clamp according
to the
invention;
FIG. 2 is a perspective view of an embodiment provided with curved clamp
strips;
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FIG. 3 is a perspective view of an embodiment wherein hollow spaced are filled
with a
crush resistant material;
and
FIG. 4 is a partially sectioned end view of an embodiment wherein the screw
fasteners are
secLUed against turning.
There is seen in FIG. 1 a wide-range pipe repair clamp 10 for temporary or
permanent
repair of pipes or for connecting a pair of pipes 12, 12' in axial sealing
relationship.
A metal clamping band 14 surrounds the pipe 12. The band 14 is extended at
both ends to
form a hollow shape 16 including a flat base 18, a wedge-shaped section 20 and
a convex
rounded section 22. The hollow shape 16 serves as a lever as seen in the
diagrams, and
also performs a second function in anchoring the band ends. It is quite cleat
that the band
and the tightening arrangement are integral.
Suitably the band material can be 0.7 mm stainless steel sheet. As the band
type coupling
requires only a small quantity of material, the durability, corrosion
resistance and
appearance benefits far outweigh the extra cost of the material.
Elongated apertures 24 are provided 14 to allow passage for screw fasteners 26
through
the hollow shape 16.
The narrow edges of the wedge-shaped sections 20 are in contact with each
other to form
a substantially triangularly-shaped space 28 between the hollow shapes 16, as
seen even
more clearly in FIG. 4. The screw fasteners 26 going through the triangularly
shaped
space 28 thus form a lever which increases the closure movement of the band
14.
A flexible inner sleeve 30, made of a rubber (for example Butyl, Styrene
butadiene or
neoprene) or a thermoplastic elastomer (for example polyurethane or an olefin)
compatible with the fluid to be carried in the pipeline, is disposed inside
the clamping
band 14 for sealing purposes. The sleeve 30 is preferably configured as a
curved
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overlappilig mat which will extend itself to handle any pipe diameter within
the range of
the coupling. In a co-pending patent application the present inventor
describes several
embodiments of such sleeves in more detail.
A pair of profile strips 32 each have a major face 34 for contacting the outer
surface of
the convex rounded section 22, and an opposite seating face 36 for shoulder
support of
the screw fasteners 26 and nuts 38. Apertures 40 are provided to allow passage
of the
fasteners 26. The profile strips 32 slide over the convex rounded section 22
when the
fasteners 26 are tightened or loosened and so maintain the seating face 36
perpendicular
to the axes of the fasteners 26.
The three screw fasteners 26 shown in the figure, are inserted into the
apertures 40.
Tightening of the nuts 38 reduces the size of the triangularly shaped space 28
and
tensions the metal clamping band 14. Thus the flexible inner sleeve 30 is
compressed to
seal against the outer diameter of the pipes 12, 12'.
Elastomer protective caps 41 are optionally fitted over the ends of screw
fasteners 26.
Allowed pipe diameter variation is at least 5.6% smaller and larger than
nominal size.
For example, a pipe coupling whose rated nominal diameter is 142 mm, can be
expected
to suit any pipe in the range 134 - 150 mm outside diameter.
With reference to the rest of the figures, similar reference numerals have
been used to
identify similar parts.
FIG. 2 illustrates an embodiment 42 which is helpful in retaining the desired
shape of the
hollow shapes 44 formed by the clamp band 46 extension.
The inner major face 48 of the profile strips 50 which contacts the outer
surface of the
convex rounded section 52 is concave. The radius of curvature matches the
radius of
curvature of the convex rounded section 52. When the screw fasteners 54 are
tightened to
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close the coupling 42 around a pipe 12 (seen in FIG. 1), the face 48
distributes pressure
evenly and so avoids distortion of the hollow shape 44.
Referring now to FIG. 3, there is seen a fitrther embodiment 56 of the wide-
range pipe
clamp coupling. The hollow shapes formed at both ends of the band 60 are
filled with a
crush-resistant material 62, such as wood or a closed-cell foamed plastic. The
material 62
allows the use of a thinner metal sheet band 60, which could not be used
otherwise due to
the compressive force applied by the profile strip 64 when the screw fasteners
66 are
tightened. The filling material 62 retains the desired shape of the hollow
shape whatever
the thickness of the metal clamping baud 60.
Seen in FIG. 4 is a detail of a wide-range pipe clamp 68. The screw fasteners
70 are
provided with a non-circular neck 72, for example having splines, serrations
or a
hexagonal section, adjacent to the fastener head 74. When the screw fastener
is tightened
the neck 72 bites into the aperture 76 of the profile strip 78. This prevents
the screw
fastener 70 from revolving about its own axis while a nut 58 is being
tightened.
The figure also shows a curved plate 80 spanning the gap under the triangular
space 28,
which applies pressure on the flexible inner sleeve 82 where there is no
contact with the
band clamp 60.
The scope of the described invention is intended to include all embodiments
coming
within the meaning of the following claims. The foregoing examples illustrate
useful
forms of the invention, but are not to be considered as limiting its scope, as
those skilled
in the art will readily be aware that additional variants and modifications of
the invention
can be formulated without departing from the meaning of the following claims.
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