Note: Descriptions are shown in the official language in which they were submitted.
CA 02148431 1999-10-07
Sealing arrangement for sealing conduits
The invention concerns a sealing arrangement for exteriorly
sealing conduits.
In a sealing arrangement of that kind, the housing which is in
an opened and slacl~ condition is arranged, with the sealing m~nber,
around a conduit or pipe which is to be sealed off. By tightening the
housing, the annular bead of the sealing member is moved radially
towards the outside of the wall of the conduit until the sealing
surface of the annular bead presses against the wall of the conduit,
with the required contact pressure force or sealing force. If the
gaseous or liquid agent contained in the conduit is subjected to
different operating pressures (reduced pressure or increased
pressure), the contact pressure force with which the annular bead
bears against the wall of the conduit must be adapted and adjusted
for the respective differences in pressure and thus force, at the
sealing surface, as between the space which is under pressure and the
surirounding atmosphere. If an excessively low contact pressure force
is applied, the seal may lose sealing integrity when the internal
pressure is increased, as the annular bead which is for example in
the form of a circular arc lifts away from the wall of the conduit.
It will therefore be necessary as a precaution to apply an increased
contact pressure force in over to afford an adequate sealing effect,
even in regard to the maxim~un differences in pressure and force i.n
the sealing region.
When using thin-wall pipes or conduits however, in
consideration of the limited strength thereof, the contact pressure
force to be applied by the seal may not exceed a canparatively low
value which is dependent on the strength of the conduits. That
limitation on the contact pressure force to be applied is to be taken
into consideration in particular when dealing with pipes of plastic
material of lower strength than pipes of metal. However, as stated,
that contact pressure force which is admissible only to a limited
extent can result in an inadequate sealing effect, in particular when
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CA 02148431 1999-10-07
the situation involves fluctuating pressures which cause the seal to
be 'wr~rked', that is to say the seal performs micro-movements in the
elastic range, and when the situation involves a low pressure or a
reduced pressure in respect of the agent, when difficulties occur in
terms of providing a seal with conventional sealing arrangements.
The invention is therefore based on the problem of providing a
sealing arrangement of the general kind set forth, which permits a
universal and durable sealing action for conduits of different
materials and strengths, both at low conduit pressures and at high
conduit pressures and also when the join is subjected to a high level
of loading.
In a sealing arrangement of the general kind set forth, that
problem is solved in that the sealing manber has an annular gap which
subdivides the annular bead in the axial direction into a first
radial bead portion at the inward side of the seal and a second
radial bead portion at the outward side of the seal, wherein the gap
extends from the sealing surface into the annular bead at such an
inclination that an acute-angled sealing lip is formed on the second
radial bead portion adjoining the gap.
When the sealing arranggnent is fixed to a conduit, for
example at a point on a pipe which is suffering fran a leak or at the
location of a conduit join, the sealing surface of the first radial
bead portion is caused to bear against the wall of the conduit when
the housing is tightened, so as to form a first sealing means. The
axially enlarged length of the sealing surface fornvs a widened
sealing region so that the radial bead portion applies a low contact
pressure force which loads the wall of the conduit to an admissible
degree and which is still sufficient to provide a first, inner
sealing action. By virtue of the inclined gap which is arranged at an
angle relative to the longitudinal axis of the conduit, when the
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sealing arrangement is tightened the firet radial bead portion
presses against the sealing lip of the second radial bead portion,
whereby the sealing lip bears firmly against the wall of the cronduit
and forms an additional outer second sealing means, the sealing
action of which is improved by the inwardly directed sealing lip. In
that way it is also possible reliably to seal off conduits in which
the agent therein is under a low pressure.
As, when the arrangement is used at a pipe join, the annular
bead which provides the sealing action is not disposed in the region
of action of the conduit forces (axial movement or torsional
movement), but bears against the peripheral surface of the conduit
and is pressed against it there with a controlled force, the sealing
arrangement rgnains durably elastic by virtue of a low level of
mechanical loading. In relation to pipe joins, there is no need for
the pipe ends to precisely butt together and the pipe ends do not
have to be especially machined as the sealing n~nber according to the
invention has a good sealing effect both on a rough surface and also
on a smoth surface.
In an advantageous anboditnent ; the first radial bead portion
has an axial annular groove in the form of an undercut configuration,
on its side which is the inward side as considered in the axial
direction, that is to say, on that side of a cavity in the sealing
arrangement, which is towards the agent that is present in the
conduit and that is to be sealed off relative to the surrounding
atmmsphere. The undercut configuration thus forms a pronounced,
projecting sealing lip which converges at an acute angle. If, upon an
increase in the pressure in the conduit, the pressure in the space or
cavity in the sealing arrangement also increases gmportionally, then
pressing against the undercut configuration on the first radial bead
portion, then on the one hand the projecting sealing lip is pressed
substantially radially against the wall surface of the conduit while
on the other hand the first radial bead portion is deformed
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substantially in the axial direction. That deformation, by way of the
compressed gap, presses inclinedly on the second radial bead portion
whereby the latter presses against the wall of the conduit with an
increased contact pressure force and foans an additional seal which
is pxnportional to the increased pressure and which has a progressive
sealing action.
The sealing member may have a transitional region of a
recessed configuration, which adjoins the undercut configuration of
the first radial bead portion in a direction towards the region of
the sealing menber, which is for examp7.e of a cylindrical shape. The
first radial bead portion can then defaan more easily with a radial
canponent as its elasticity of deformation is improved by weakening
of its base in the transitional region.
If, in accordance with a further gnbodiment, the sealing lip
of the second radial bead portion is arranged displaced outwax~ly in
a radial direction relative to the sealing surface of the first
radial bead portion, then when the sealing arranganent is tightened
the sealing surface of the first radial bead portion bears first
against the wall of the conduit. It i.s thereafter that the sealing
lip of the second radial bead portion bears against the wall of the
conduit so that it cannot push itself under the sealing surface of
the first radial bead portion. That arranganent results in the
sealing lip being in a defined position on the wall of the conduit,
and that defined position, upon an increase in pressure, results in a
more uniform seal being pnxiuced, with an improved sealing action,
even in relation to rough or uneven surfaces.
If the sealing surface of the outer second radial bead portion
is divided into an axially inclined sealing surface and a sealing
surface which extends parallel to the axis of the arrangement, then,
when the sealing arrang~nent is tightened in position, the contact
pressure force in the inclined sealing surface rises approximately
linearly while the sealing surface which is parallel to the axis of
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the arranggnent bears against the wall of the conduit only slightly
with a negligible contact pressure force or without any force.
Accordingly it is only necessary to apply the minimum required
contact pressure force which leads the conduit with a minimian amount
of pressure in relation to surface area, without causing deformation
of the conduit.
Preferably the sealing member is of a mirror-image symmetrical
configuration in the axial direction. In that case the sealing member
can be used in a particularly desirable fashion by virtue of the
radial bead portions bearing against a pipe connection at both sides
thereof, as the same sealing conditions occur at the two radial bead
portions. That therefore gives a seal which is resistant to shock and
impact and which is also resistant to vibration and shaking or
jarring and which particularly in the case of gas conduits affords an
enhanced level of safeguard against fire and explosion, as is
indispensable for example in areas which are liable to earthquakes.
Preferably the sealing member is fitted into the housing
loosely or with a snug or press fit involving a relatively low
insertion force. In that case, when the housing is closed or upon
movgnents in respect of the ends of the conduit, the sealing msnber
can move slightly at its periphery relative to the housing so that no
stresses are built up in the sealing mianber, which could restrict the
sealing action. The application of a lubricant or slip agent to the
outer periphery of the sealing manber and/or the inner periphery of
the housing can further reduce undesired friction which would impede
the canpensating movanent.
The invention is described in greater detail hereinafter by
means of an e:r~bodiment with reference to drawings in which:
Figure 1 is. a diagrammatic sectional view of a sealing
arrangement according to the invention, surrounding a pipe join,
Figure 2 shows the sealing arrangement of Figure 1 in the
tightened condition with the resulting radial pressure force pattern
at the sealing surface of the sealing arrangement,
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29.4~43~.
Figure 3 is a diagrammatic sectional view of the sealing
arranggnent in the case of a rising pressure in the conduit, with the
resulting radial pressure force pattern at the sealing surface of the
sealing arrang~nent, and
Figure 4 is a perspective view of the partially sectioned
housing with the sealing arranggnent in the tightened condition.
Referring to Figure 1, shown therein is a pipe connection
between two pipes 1 and 2 of a conduit. The pipes 1 and 2 adjoin each
other with their respective open ends which face towards each other.
They can be fitted with a gap 3 or in butting relationship without a
gap or only with a small gap. Likewise the pipe connection can be
formed for example by screwing or by the pipe ends being fitted one
into the other (not sk~wn). A simple connection of that kind is not
gas-tight or fluid-tight so that leakages can occur due to escape of
the agent contained in the cronduit.
The drawings show the pipe connection with a gap 3 in order
clearly to indicate the possibility of the agent in the conduit
escaping therefran. The sealing arrangement which is designed
syrm~etrically relative to a line or cross-sectional area as indicated
at A-A in Figure 1 is only strewn in the drawings with its middle
region and its right-hand half. The specific embodiment described
hereinafter is described with reference to the geanetry in relation
to a sectional view, but is intended to relate to a rotationally
symmetrical sealing arrangement.
A housing 4 is of a substantially rotationally symmetrical
configuration in the manner of a sleeve or a pipe clamp and is
provided with a mechanical closure device so that it can be fixed to
a pipe or conduit by embracing around samie. In the initially slack
condition the housing 4 is arranged approximately centrally over the
pipe connection, that is to say over the gap 3. The two axial ends 6
of the-housing 4 are then disposed over the end regions of the pipes
1 and 2. At each of its ends 6 the housing 4 has a radially inwardly
extending terminal wall 7.
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21~8~'~1
Fitted in the interior of the housing 4 is a rotationally
syrtmetrical, annular sealing member 8 of elasta~r material which is
in the form of a sleeve member. The sealing manber 8 bears with its
outside against the inside periphery of the housing 4. Before the
sealing member 8 is fitted into the housing 4, a lubricant paste or a
similar lubricating material can be applied to the outside of the
sealing m~r~ber 8 or the inside of the housing 4.
In the present description of the sealing arrangement the term
inside diameter or the term inside radius denotes the inside
dimension of the sealing me~r~ber 8 at a respective cross-section. In a
first middle region 9 which engages over the connection between the
pipes 1 and 2, the sealing member 8 is of an inside diameter which is
larger than the outside diameter of the pipes 1 and 2 so that a
substantially annular cavity 10 ranains on the inward side of the
seal, between the middle region 9 of the sealing member 8 and the
outside walls or surfaces of the pipes 1 and 2, even when the housing
4 is in the tightened condition, as shown in Figure 2.
Adjoining the middle region 9 in the axial direction is a
transitional region 11 which is of larger inside diameter than the
middle region 9 of the sealing manber. That transitional region 11
can be in the foam of an annular groove with inclined or bevelled
side walls or of a cross-section in the form of a circular arc or
similar shape. The transitional region 11 goes into a sealing annular
bead 12 of smaller inside diameter which is subdivided into twn bead
portions, mare specifically the radial bead portions 14 and 18, by a
recess in the form of a narmw slot-like groove or annular gap 13.
The first radial bead portion 14 adjoins the transitional
region 11 in the axial direction. The radial bead portion 14 has a
sealing surface 15 which extends substantially parallel to the
surface of the conduit, in an axial direction, to the gap 13.
Provided on the radial bead portion 14, towards the transitional
region 11, is an axial groove in the form of an undercut
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214$43.
configuration 16 which, in a direction towards the pipe 2, goes inta
the sealing surface 15 of the radial bead portion 14, that
configuration forming a projecting, acute-angled sealing lip 17 which
faces approximately axially inwardly towards the pipe connection.
When considered axially, that is to say when viewing towards
the right in Figure 1, the gap 13 extends at an obtuse angle which
can be for example between about 110° and 130° fran the sealing
surface 15 of the radial bead portion 14 into the interior of the
sealing member 8 or the annular bead 12. The greatest depth or the
greatest diameter of the gap 13 approximately corresponds to the
inside diameter of the middle region 9 of the sealing mgnber 8,
The axially adjoining region of the sealing mgnber 8, which
extends fran the gap 13 to the texrni.nal wall 7 of the housing 4,
forms the second radial bead portion 18. The second radial bead
portion 18 has a first sealing surface 19 which, with the side wall
of the radial bead portion 18 which is defined by the gap 13,
forms a sealing lip 21 which converges at an acute angle. The inside
diameter defined by the front edge of the sealing. lip 21 is smaller
than the diameter of the adjacent outer edge 22 of the radial bead
20 portion 14, said edge 22 being forn~ed as the boundary line between
the sealing surface 15 of the radial bead portion 14 and the gap 13.
The first sealing surface 19 extends with an enlarging diameter in
the axial direction and goes into a second sealing surface 23 which
extends with a constant diameter as far as the teaninal wall 7 of the
housing 4.
The sealing mgr~ber 8 is of mirror-image symmetrical
configuration and at its left-hand e~ region (not shown) has an
annular bead corresponding to the annular bead 12, in a mirror-image
sycrmetrical arrangement.
For clamping the sealing arrangement in position, the housing
4 is tightened for exa~le by s screw closure (not shown) so that the
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housing 4 is pressed in a radial direction against the pipe 2 and
against the pipe l,the radial bead portion 14 bearing with its sealing
surface 15 against the pipe 2. By the housing 4 being further
tightened, the radial bead portion 14 is radially car~pressed, with
elastic deformation of its rubber-like or springy material, in which
case its side surface which is towards the gap 13 fills the gap 13,
canes to bear against the side wall 20 of the second radial bead
portion 18 and presses against the side wall 20. The housing 14 is
radially tightened until the second sealing surface 23 of the radial
bead portion 18 bears against the pipe 2 without any pressure or with
a slight pressure. The side region of the radial bead portion 14,
which is towards the gap 13, then also presses against the second
radial bead portion 18 and the sealing lip 21, thus resulting in the
sealing manber 8 being in the clamped condition shown in Figure 2
with the pressure pattern at the sealing surfaces 15, 19 and 23,
which arises by virtue of the specific geanetry of the radial bead
portions 14 and 18. in the operation of tightening the sealing
arrang~nent therefore the arrangement pnxiuces a dual sealing action,
insofar as on the one hand the sealing surface 15 of the radial bead
portion 14 and the sealing surface 19 of the radial bead portion 18
press against the pipe 2, and on the other hand the radial bead
portion 14, filling the gap 13, additionally presses against the
radial bead portion 18 and in particular the sealing lip 21 thereof
and thus produces a second sealing effect. That affords a reliable
fine, delicate sealing action even in relation to a low pressure in
the conduit and in relation to vacuum if only a low contact pressure
force is applied at the annular bead 12.
If the pressure as indicated at p in Figure 3 of the agent in
the conduit rises, the pressure in the cavity 10 also increases
proportionally. That pressure p applies a force to the side of the
radial bead portion 14, which is towards the cavity 10, constituted
by the transitional region 11 and the undercut configuration 16, so
that the sealing lip 17 and the sealing surface 15 are ~ditionally
pressed against the surface of the pipe 2 by the above-described
elastic deformation of the radial bead portion 14. Therefore, by
virtue of the undercut configuration, the radial bead portion 14 can
also be deformed radially against the pipe 2, upon an increase in the
pressure in the agent in the conduit and thus an increase in the
pressure in the cavity 10. The pressure p also results in additional
deformation or ctv:vature of the radial bead portion 14 in the axial
direction so that it presses against the radial bead portion 18 and
in particular the sealing lip 21 thereof and thus results in an
increase in the contact pressure force applied by the sealing m~nber
8 with its annular bead 12 against the pipe 2. The resulting pressure
pattern at the sealing surfaces 15, 19 and 23 is diagrammatically
7.5 sk~wn in Figure 3, in which reference F, in the direction indicated
by the arrow, denotes the force produced by the c7.amping action of
the sealing arrangement, in the sealing annular bead 12, while p
denotes the force produced by the rising pressure. Thus, with a low
initial pressure in the conduit, it may be sufficient to have a low
contact pressure force which does not have to be designed for a
maximian pressure and which therefore applies only a low loading to
the wall of the conduit, while with an increasing pressure the
crontact pressure force or the sealing force is increased
conccenitantly therewith.
The housing 4 of the sealing arrangenent as w~e7d. as the
closure menbers and clamping screws preferably canprise metal, nbre
especially high-quality stainless steel.
The sealing m~ber or sealing sleeve 8 canprises synthetic
rubber .which is selected in dependence on the respective agent
involved. Thus an EPIaM-robber (ethylene-pxnpylene-diene elastomer) is
suitable for all qualities of water, for waste water or sewage, air,
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solids and chemical products, while an NBR-rubber (acrylonitrile-
butadiene elastaner) is used in relation to gas, oil, fuels and
propellants and other hydrocarbons.
As described, the sealing arrangement can be used for sealing
off a connection between ts4o pipes of a conduit, which are to be
joined together. In that case the tsvo pipes can be fixed in their -
rtutual positions by holding means so that the sealing arrangenent is
essentially restricted to the function of providing a sealing action.
The sealing arrangement however may also perform the function
of holding the ends of the pipes 1 and 2 for
example in relation to
freely laid waste water or sewage pipes, in which case it then holds
the ends of the pipes in ~tually centered relationship.
The sealing arrang~nent according to the invention can bridge
over and seal off both a leaky point in a pipe or conduit and also a
narxvw or wide gap between the ends of adjoining pipe portions of a
pipe join so that the sealing arrangement can be used as a length-
compensating means. The sealing arrangement is also suitable when the -
axes of the end portions of the adjoining pipes are displaced in a
radial direction, when the ends of the pipe portions are angularly
displaced, and when the ends of the pipe portions involve a
rotational movsnent in opposite relationship, as well as in relation
to different pipe diameters.
The sealing arxang~nent can be used with many pipe materials.
Thus the pipes may ca~rise steel, including longitudinally welded or
spiral-welded, non-ferrous metal such as aluminium, copper and alloys
thereof, plastic material such as PE, PP, PVC, ABS, or glass fiber-
reinfarced plastic (GRP), or other materials such as glass, fiber
cement or ceramic.
The housing 4 and the sealing member 8 may be designed to be
divided in a longitudinal plane at one half thereof or continuously
so that the sealing arranggnent can be c~npletely divided or can be
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2148~3~.
pivoted about a hinge disposed on the housing. In that case the
sealing arrangement is particularly easy to fit as the pipes which
are to be sealed thereby do not have to be separated fmn each other.
In particular the sealing arrangsnent can be used as a repair
assanbly on a leaking pipe.
If the plane of division or separation which passes through
the longitudinal axis of the sealing arrangement is displaced thmugh
an angle relative to the longitudinal axis, between the twv radial
bead portions 14 and 18, that avoids the existence of a rectilinear
continuous separating gap in the region of the annular bead 12, That
means that the improved sealing action is still retained.
The sealing manber which has been described in relation to a
x~tationally symmetrical sealing arrangement can also be of a
horizontal, flat configuration, in which case the geanetries of the
radial bead portions are transferred to a flat sealing arrang~r~ent,
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