Patent Description:
Airplanes use a great variety of tube systems. Tube systems usually distribute materials, liquids, gases and/or aerosols to the different locations where they are needed. These materials may have different chemical and/or physical properties. For example, the transported materials may react with other elements such as the elements used for the material of the tube system. Or they may have different temperatures and/or pressure.

When developing a Zero-Emission airplane the use of hydrogen (H<NUM>) is relevant. For distributing H<NUM> to engines or fuel-cells a distribution system is needed which comprises different types of tube systems. Such distribution systems used for the transport of H<NUM> usually are double-walled allowing the detection of any leakage of H<NUM>.

For instance, a hose-in-shroud design is used to transport H<NUM> within an airplane where a hose is surrounded by a jacket.

When linking the tubes and/or hoses for a hose-in-shroud system special care needs to be taken in order to prevent leakage of H<NUM>.

<CIT> describes in claim <NUM> a semi-permanent duct assembly comprising in combination a pair of duct sections aligned in end-to-end relation, each of said duct sections having an outwardly extending flange at one end, coupling means for engaging said flanges to retain said ducts tightly in end-to-end relation comprising at least one arcuate coupling element having a recess therein adapted to be received over said flanges, and a flexible sheet metal band adapted to be encircled about said coupling means, with one end of said band in exposed, overlapping relationship, said coupling means being of less circumference than the circumference of said flanges so as to leave space between the ends of said coupling means, said band being maintained under tension, to hold said coupling means tightly about said flanges, by said exposed end of said band being welded to said band so that the ends of said band are in contact with each other only on their overlapping surfaces, whereby said band can be. quickly removed by inserting a cutter in the space between the ends of said coupling means and severing said sheet metal band, thereby providing access to said coupling means and in turn said duct assembly.

<CIT>, according to the abstract available by Espacenet, describes an apparatus for connecting a pipe. The apparatus for connecting a pipe according to an embodiment of the present invention is an apparatus for connecting a pipe to connect a first pipe and a second pipe, comprising: a first hub flange coupled to an end portion of the first pipe; a second hub flange coupled to an end portion of the second pipe; a clamp coupling the first hub flange to the second hub flange; and a fixating unit preventing rotation between the clamp and the first hub flange and the second hub flange.

<CIT> describes in claim <NUM> a clamp for coupling together a pair of opposing tube flanges, said clamp comprising: a first flat tension band curved in an arc sub-tending an angle slightly less than <NUM> degrees; a second flat tension band of similar shape to said first band; a plurality of circumferentially spaced substantially identically shaped V lugs individually coupled on the side opposite the V-shaped opening by a pivotal means to the inner surface of said first band and said second band, said pivotal means which couples each of said lugs to said tension bands lying substantially in the same plane and fixed to said V lugs along a line equidistant from the ends of said V-shaped lugs, said V lugs being adapted to be wedged over said opposing tube flange; connecting means secured, respectively, to each end of said first band and said second band whereby respective ends of said first band and said second band may be circumferentially fastened together to in turn urge said V lugs over said opposing tube flanges, said pivotal means enabling relative rotative movement between said lugs and said first band and said second band, respectively, whereby said V lugs may be individually aligned with respect to said opposing tube flanges.

<CIT>, according to its abstract, describes a duct section and system, including a laminated shroud, acting as a secondary duct, for aerospace and other applications, and a method for constructing same. The duct structure incorporates a metallic primary duct tube, with a laminated shroud surrounding the primary duct tube and separated therefrom by an annular gap. The laminated shroud includes a metallic inner layer and a polymeric outer layer. Preferably, the thin metallic layer is a corrosion resistant material such as corrosion resistant stainless steel or titanium. In one embodiment of the invention, the outer polymeric layer is a polyimide material, such as polyimide resin-impregnated fiberglass cloth.

It might be seen as an object of the invention to provide an efficient connection for tube systems.

This and other objects are achieved by the subject matter of each independent claim. Further embodiments of the invention are described in the respective dependent claims and the following description.

According to an aspect a clamping apparatus for connecting flanges of tubes and/or hoses is provided. The clamping apparatus comprises a first bracing device and a second bracing device.

The first bracing device connects a first mounting device and a second mounting device. The first bracing device has a partially circular shape with a first inner wall and a first outer wall. In an example the first bracing device is arranged between the first mounting device and the second mounting device. In one example the shape is half circular shape. In another example the shape is a quarter circular shape.

The second bracing device connects a first connecting device and a second connecting device. In an example the second bracing device is arranged between the first connecting device and the second connecting device.

The first inner wall of the first bracing device has a first recess, and the first outer wall of the first bracing device is adapted to contact the second bracing device.

The second bracing device is adapted to contact the first outer wall of the first bracing device in order to apply substantially radial force on the first outer wall of the first bracing device.

In an example the first outer wall and/or the surface of the first outer wall is adapted in such way that the second bracing device is able to stably contact the first outer wall. In an example the first outer wall has a substantially plane surface in order to allow for a good contact with a substantially plane surface of the second bracing device. A good contact between the first bracing device and the second bracing device may allow for a good force distribution and/or for a good protection.

The shape of the first recess is adapted to substantially convert the radial force applied to the first outer wall of the first bracing device into an axial force inside the inner wall. The force in an axial direction of a tube may help to press two flanges of two tubes to be connected together in order to form a sealed connection between the two tubes.

The first mounting device and the second mounting device each comprise at least two attachment devices for connecting the first connecting device and the second connecting device of the second bracing device. In this way the first and second bracing devices may be joined. The attachment devices may also allow for aligning the first and second bracing devices and/or to generate a force in a radial direction.

The clamping apparatus may offer an intrinsic redundancy for the clamping apparatus when used for a tubular distribution system. The clamping apparatus may prevent loss or damage of the system due to a single failure. The size of the clamping apparatus is small enough to be fed through a jacket and/or a shroud. The clamping apparatus may avoid a single failure outage and may allow for continuously using of a tube system even in cases where a single part of the clamping apparatus breaks.

It may be seen as an idea of the invention to introduce a second load-path for the clamp and to use a high number of fixing devices, attachment devices and/or mounting devices in order to maintain the functionality of a connection linked by the clamping apparatus even when one single part of the clamping apparatus breaks. At the same time the dimension of the whole clamping apparatus and/or of a clamping system may be kept small enough to be fit into a shroud and/or a jacket. In an example the clamping apparatus uses four bolts instead of one or two and therefore may still meet the requirements of holding a tube system together after one bolt is damaged and/or lost.

In another example both the first bracing device and the second bracing device are adapted to generate the force in the radial direction and to convert it in a force which substantially is effective in the axial direction. The force may be generated by pressing the first and second mounting devices and/or the first and the second connecting devices against a mount. The mount may be another clamping apparatus and/or a wall. This pressing force may be used to decrease a diameter of a substantially circular opening formed by the circular shape of any of the bracing devices and as a result clamping a tube connection which is inside the substantially circular opening. In general, the contour of the opening of the first bracing device and/or the second bracing device is adapted to the contour of the cross section the tube to be connected.

In case the first bracing device fails, the pressure can still be generated by the second bracing device. In case the second bracing device fails, the pressure can still be generated by the second bracing device. In other words, the first bracing device is adapted as a first load-path, the second bracing device is adapted as a second load-path. The first and second load paths may substantially be independent from another.

According to another aspect the first recess has a V-shape. The V-shape may help converting a substantially radial force into an axial force. The V-shape may extend along the inner wall of the first bracing device in a circumferential direction.

According to yet another aspect the second bracing device is at least partially made of a substantially flexible material and/or designed as a flexible element.

The flexible element may be a wire, a ribbon, a band, a strap and/or a belt. Such element, particularly when made of steel, in particular stainless steel, may help to apply a force onto the first bracing device and may build a second load-path. In case the first bracing element fails the second bracing element may still hold the clamping apparatus together and vice versa.

According to a further aspect the second bracing device is at least partially made of a substantially rigid material and thus supports the first bracing element.

According to another aspect the second bracing device has a partially circular shape with a second inner wall and a second outer wall, wherein the second inner wall of the second bracing device has a second recess. The shape of the second recess is adapted to engage with the first outer wall of the first bracing device. In an example, the contour of an opening of the second bracing device may be adapted to the contour of the cross section the outer wall of the first bracing device.

The form of the second bracing device may substantially correspond to the form of the first bracing device. The second bracing device may take into account that the first bracing device needs to be covered and therefore the size of the second bracing device is larger than the size of the first bracing device.

In this way the second bracing device maybe adapted to cover the first bracing device and may help to prevent that a single failure, e.g. a break and/or crack in the first bracing device, damages the whole tube system.

According to another aspect the second recess has a V-shape and thus the shape of the second recess is substantially similar to the first recess. The V-shape may help to introduce a force in a substantially axial direction into the first bracing device.

According to yet another aspect of the present invention the at least two attachment devices are adapted to receive at least one of the fixing devices selected from the group of fixing devices consisting of a bolt, a pin, a screw, a clip; and a rivet.

The fixing devices may be combined with the at least two attachment devices in order to connect the first bracing device and the second bracing device. In another example the fixing devices may also be used to mount the first and/or second bracing device to a mount and/or to another clamping apparatus.

According to a further aspect the first bracing device and the second bracing device are connected to another.

The connection may combine the bracing devices to form a clamping system which is tolerant to a single failure.

According to another aspect the first bracing device and the second bracing device are connected by a hinge. The hinge may prevent disassembling of the first bracing device and the second bracing device in case of a single failure.

Connecting and/or joining the first bracing device and the second bracing device may remind a worker to fix both devices. In other words, the first bracing device and the second bracing device and/or the first and second clamps are joined together in order to allow proper installation substantially only after both bracing devices are correctly mounted to another. The hinge for example can comprise an elastic element and/or a spring element in order to prevent mounting the clamping apparatus to the tube without fixing the first and second bracing devices to another. In a case where the first and second bracing devices were not fixed together, they may not fit into a corresponding jacket and the incorrect assembling may be discovered during the installation.

According to a further aspect a clamping system is provided, comprising at least two of the inventive clamping apparatuses wherein the at least two clamping apparatuses are connected by at least four fixing devices selected from the group of fixing devices consisting of a bolt, a pin, a screw, a clip and a rivet.

A clamping system may allow for a secure connection of tubes wherein the clamping system is resilient to a single failure.

According to another aspect a tube system is provided, comprising a first tube with a first flange and a second tube with a second flange, wherein the first flange and the second flange are connected by at least one of the inventive clamping apparatuses and/or by at least one inventive clamping system.

According to yet another aspect at least one of the first tube and the second tube is/are a hose.

In one exemplary embodiment the tube system further comprises a jacket, wherein the first tube and the second tube and the clamping apparatus and/or the clamping system are surrounded by the jacket. In an example the jacket may be another tube.

According to another aspect the tube system is built as a hose-in-shroud system.

According to a further aspect an airplane is provided, comprising at least one of the inventive clamping apparatuses, the inventive clamping system and the inventive tube system.

The operation security may be increased by using the inventive clamping apparatus, the inventive clamping system and/or the inventive tube system in an airplane or aircraft.

Exemplary embodiments of the present invention will be described in the following, with reference to the following drawings. The illustration in the drawings is schematic and may be not to scale. In different drawings, similar or identical elements are provided with the same reference numerals.

<FIG> shows a schematic partial cross section view of a V-flange connection for a better understanding of the present invention. In this connection two tubes, e.g. a first hose <NUM> and a second hose <NUM>, are to be connected. Each hose <NUM>, <NUM> has a flange 101a, 102a formed at their respective ends. In order to prevent any material transported inside the hoses <NUM>, <NUM> from leaking out of the connection of the first hose <NUM> with the second hose <NUM> the first flange 101a and the second flange 102a are pressed together in an axial direction 104a, 104b in order to form a press fit and/or a seal. The axial direction 104a, 104b is substantially a direction along the virtual longitudinal axis <NUM> and/or in parallel thereto. A seal <NUM> that is used between the first and second flanges 101a, 102a and that is substantially surrounding the virtual longitudinal axis <NUM>, may additionally help to seal the connection of the first and second flanges 101a, 102a. In order to provide space for the seal <NUM> one of the connection surfaces 107a, 107b may has a step.

An axial direction 104a, 104b may be any direction parallel to the longitudinal axis <NUM>. In order to generate pressure in the axial direction 104a, 104b one end of each hose <NUM>, <NUM> is angled compared to the radial direction. The radial direction may be substantially perpendicular to the longitudinal axis <NUM>.

The angled ends 106a, 106b of the flanges 101a, 102a are distant from the connection surfaces 107a, 107b. The connection surfaces 107a, 107b are orientated substantially perpendicular to the longitudinal axis <NUM>, i.e. in radial direction.

Clamp <NUM> has a V-shaped cross sectional profile and generates an axial force to the connection surfaces 107a, 107b when a radial force in the direction to the longitudinal axis <NUM> is applied to the clamp <NUM>.

<FIG> shows a schematic partial cross section view of a V-flange connection for a flange with stepped connection surfaces 107a', 107b' for a better understanding of the present invention. The steps built in the connection surface 107a' of the first flange and the connection surface 107b' of the second flange allow for forming a further barrier in order to provide a high sealing effect for a tube connection.

<FIG> shows a front view of a V-shaped band for a better understanding of the present invention. In this design a sheet metal retainer <NUM> is surrounded by a band <NUM> or strap <NUM> with tangential wraps. The band <NUM> is tightened by a T-bolt <NUM> which connects two ends of the band <NUM> and allows to vary the diameter in radial direction of a circle and/or of a cylinder formed by the sheet metal retainer <NUM>. In order to be flexible for diameter variation the sheet metal retainer <NUM> comprises retainer gaps <NUM>.

The band <NUM> is made of flexible material and/or of a flexible design.

<FIG> shows a front view of a V-shaped retainer for a better understanding of the present invention. In this design two trunnion retainer halves <NUM> are connected by a rivet hinge <NUM>. Opposite of the rivet hinge <NUM> an eye-bolt <NUM> in a safety latch <NUM> is used to generate a radial force substantially in the direction to the center of a circle formed by the trunnion retainer halves <NUM>.

The trunnion retainer halves <NUM> are made of rigid material and/or of rigid design.

<FIG> shows a side view of the V-shaped retainer of <FIG> for a better understanding of the present invention.

The connectors shown in <FIG> show V-clamp connections that are typically used on different aircrafts. Different standards are available for such pneumatic connectors.

<FIG> shows a perspective view of a hose-in-shroud arrangement according to an exemplary embodiment of the present invention.

A hose-in-shroud arrangement <NUM> may be used for distribution of H<NUM> to engines or fuel-cells in an airplane. As shown in <FIG> the hose-in-shroud arrangement <NUM> is double-walled, so that any leakage of H<NUM> can be detected and safety measures can be taken. The protection tube <NUM>, shroud <NUM> or jacket <NUM> is a tube with a flange <NUM> for connecting to another shroud (not shown in <FIG>).

During the installation of a hose-in-shroud arrangement <NUM> and/or of a hose-in-shroud system <NUM> a tube <NUM>', e.g. a hose, is fed through the shroud <NUM> to form a substantially coaxial arrangement. To allow this arrangement inside the shroud <NUM>, any connection including a clamp fixing the connection needs to be smaller than the inner diameter of the shroud <NUM>.

The tube <NUM>' extends into an axial direction 104b. The end of the tube <NUM>' protruding from the shroud <NUM> has a flange 102a' which may be used to connect to another tube (not shown in <FIG>) for extending the length for a corresponding tube system. The flange 102a' has the contacting surface 107b' or connection surface 107b' for directly contacting the other tube and an angled, sloped and/or declined surface 106b'. The angled surface 106b' faces the flange <NUM>.

<FIG> shows a schematic partial cross-sectional view of a force distribution on a connection of two flanges 701a, 702a according to an exemplary embodiment of the present invention.

A V-shaped first bracing device <NUM> or clamp <NUM> is pressed in a radial direction 704c towards the surface of a tube <NUM>, <NUM>. When the radial force is applied to the outer wall of the first bracing device <NUM> the V-shape of the first bracing device <NUM> converts the radial force into an axial force in axial directions 704a, 704b. The radial force is directed to a longitudinal axis (not shown in <FIG>) of the tubes <NUM>, <NUM> and/or to a center (not shown in <FIG>) of tubes <NUM>, <NUM>. In other words, the radial force is directed substantially parallel to the connection surfaces 707a, 707b.

The axial directions 704a, 704b are substantially directed in opposite axial directions and are directed towards another. This pressure towards another forms a press fit which also seals the inside of tubes <NUM>, <NUM> from the outside, i.e. the gap between tube <NUM>', <NUM>, <NUM> and a corresponding shroud <NUM>. The sealing effect of the press fit is supported by an additional sealing element <NUM>, e.g. an O-ring.

The flanges 701a, 702a have angled surfaces 706a, 706b or angled planes 706a, 706b and are attached to the end of the tubes <NUM>, <NUM> which need to be connected. A combination of the V-shaped first bracing device <NUM> and the substantially V-shaped angled surfaces 706a, 706b of the flanges 701a, 702a presses the flanges 701a, 702a together and provides the tightness for the connection of the tubes <NUM>, <NUM>.

The tightness of the connection allows for using a tube system <NUM>, <NUM> connected with a bracing device for the transport of H<NUM>. The connections meet the special requirements with regard to preventing leakage of H<NUM> through the coupling. Such a connection solution helps to replace a Harrison fitting with a swivel nut which may not be appropriate for the transport of H<NUM> due to the leakages for gas through a Harrison fitting.

<FIG> shows two clamping apparatuses <NUM>, <NUM>' in an open position according to an exemplary embodiment of the present invention.

In the following only one clamping apparatus <NUM> of the two clamping apparatuses <NUM>, <NUM>' is described in detail because the structure of the other clamping apparatus <NUM>' is substantially the same. Each of the two clamping apparatuses <NUM>, <NUM>' has substantially the shape of a half circle.

The clamping apparatus <NUM> comprises a first bracing device <NUM> and a second bracing device <NUM>'. The first bracing device <NUM> connects a first mounting device 709a and a second mounting device 709b. In other words, the first bracing device <NUM> is positioned between the first mounting device 709a and the second mounting device 709b. The first bracing device <NUM> has a partially circular and/or cylindrical shape with a first inner wall <NUM> and a first outer wall <NUM>.

The second bracing device <NUM>' connects a first connecting device 712a and a second connecting device 712b. In other words, the second bracing device <NUM>' is positioned between the first connecting device 712a and the second connecting device 712b.

The shape of the first mounting device 709a and the second mounting device 709b and the first connecting device 712a and the second connecting device 712b substantially correspond to another.

The first inner wall <NUM> of the first bracing device <NUM> has a first recess <NUM>.

The first outer wall <NUM> of the first bracing device <NUM> is adapted to contact the second bracing device <NUM>'.

The second bracing device <NUM>' is adapted to contact the first outer wall <NUM> of the first bracing device <NUM> in order to apply a substantially radial force on the first outer wall <NUM> of the first bracing device <NUM>. The radial force is a force substantially directed in a radial direction 704c, which is the direction towards an imaginary center of the circular shape of the first bracing device <NUM>. The center may correspond to a longitudinal axis of a tube that is to be connected to another tube using the first bracing device708 (the tubes are not shown in <FIG>).

The shape of the first recess <NUM> is a V-shape and is adapted to substantially convert the radial force applied to the first outer wall <NUM> of the first bracing device <NUM> into an axial force inside the first inner wall <NUM>, in particular when it gets into contact with the angled surfaces 706a, 706b of a flange 701a, 702a.

The first mounting device 709a and the second mounting device 709b of the first bracing device <NUM> each comprise at least two attachment devices 714a, 714b, 714c, 714d for connecting the first connecting device 712a and the second connecting device 712b of the second bracing device <NUM>'.

The second bracing device <NUM> comprises corresponding attachment devices 714a', 714b', 714c', 714d' which may be aligned with the at least two attachment devices 714a, 714b, 714c, 714d.

By connecting the first bracing device <NUM> and the second bracing device <NUM>' the second bracing device <NUM>' becomes a secondary load path for the primary load path of the first bracing device <NUM>. Providing at least two load paths allows for a single failure of one of the first bracing device <NUM> and the second bracing device <NUM>'.

Mounting the first bracing device <NUM> and/or the second bracing device <NUM>' to a mount and/or to a second clamping apparatus <NUM>' substantially allows for generating the force in a radial direction. This radial force may be generated in the first load-path and/or the second load-path, formed by the first bracing device <NUM> and the second bracing device <NUM>' respectively.

The attachment devices 714a, 714b, 714c, 714d, 714a', 714b', 714c', 714d', e.g. holes and/or bores, may receive a fixing device (not shown in <FIG>) 901a, 901b, 901c, 901d in order to mount the first bracing device <NUM> and/or the second bracing device <NUM>'. The fixing device may be used to generate a radial force by moving the clamping apparatus <NUM>' in a radial direction of a tube system. In other words, the fixing device may be substantially positioned for generating a force in the radial direction 704c. In an example the fixing device 901a, 901b, 901c, 901d is positioned substantially perpendicular to a longitudinal axis of a tube to be connected. In another example the fixing device 901a, 901b, 901c, 901d is arranged along a tangential direction to at least one of the first bracing device <NUM> and/or the second bracing device <NUM>'. Examples for a fixing device 901a, 901b, 901c, 901d are a bolt, a pin, a screw, a clip and a rivet.

The design of the clamping apparatus <NUM>, <NUM>' allows for a single failure without substantially breaking the connection of the tubes. The second bracing device <NUM>' may be used as a shelter for the first bracing device <NUM>. In this way also a second load-path for the clamp is provided and a clamp-connection uses at least <NUM> fixing devices 901a, 901b, 901c, 901d and corresponding attachment devices 714a, 714b, 714c, 714d, 714a', 714b', 714c', 714d' instead of only <NUM> or <NUM>. In other words, every fixing device 901a, 901b, 901c, 901d and/or attachment devices 714a, 714b, 714c, 714d, 714a', 714b', 714c', 714d is doubled in order to allow for a single failure. In one example one fixing device is used to link two attachment devices 714a, 714b, 714c, 714d, 714a', 714b', 714c', 714d' of the first bracing device <NUM> and the second bracing device <NUM>', respectively. One fixing device links the first bracing device <NUM> with the second bracing device <NUM>'. In other words, for every bracing device <NUM>, <NUM>' the appropriate number of fixing and/or attachment devices is provided such as each single bracing device <NUM>, <NUM>' alone were responsible of forming the tube connection.

The clamping apparatus <NUM> can be used for a H<NUM>-distribution system. Substantially all components are at least doubled in order to allow for a redundant design. The clamping apparatus <NUM> and/or a V-clamp connection formed with the clamping apparatus <NUM> may prevent a complete damage and loss of the functionality due to a single failure.

The clamping apparatus <NUM>, <NUM>' is small enough to be fed through a shroud <NUM>. The robustness against a single failure allows for a low maintenance inside the shroud <NUM>.

The second bracing device <NUM>' has a partially circular and/or cylindrical shape with a second inner wall <NUM> and a second outer wall <NUM>. The second inner wall <NUM> of the second bracing device708' has a second recess <NUM>, wherein the shape of the second recess <NUM> is adapted to engage with the first outer wall <NUM> of the first bracing device <NUM>. In an example the second recess <NUM> has a V-shape and/or the first outer wall <NUM> of the first bracing device <NUM> has a V-shape as well. In order to embed the first bracing device <NUM> into the second bracing device <NUM>' the dimensions of the second bracing device <NUM>' are larger than the dimensions of the first bracing device <NUM>. In a case of just embedding the first bracing device <NUM> and second bracing device <NUM>' may touch another without substantially execute pressure to another. Only when the inner bracing device may break the pressure is executed by the outer bracing device.

On one side of first mounting device 709a and/or the second mounting device 709b and the first connecting device 712a and/or the second connecting device 712b the first bracing device <NUM> and the second bracing device <NUM>' are connected by a hinge <NUM>. The hinge <NUM> may help to let a user who handles the clamping apparatus <NUM>, <NUM>' recognize if the clamping apparatus <NUM>, <NUM>' is not yet ready to be mounted inside the shroud. The hinge <NUM> also prevents that only one clamping apparatus <NUM>, <NUM>' of the first bracing device <NUM> and/or the second bracing device <NUM>' is installed. As the first bracing device <NUM> and/or the second bracing device <NUM>' are always linked by the hinge <NUM>, it is substantially impossible to forget one of the redundant parts of the clamping apparatus <NUM>, <NUM>' when a tube connection is made.

In one example the hinge <NUM> may be used as a leverage in order to apply a substantially radial force on the first outer wall <NUM> of the first bracing device <NUM> and/or to build up a tension. The final pressure to the flanges of a tube may be generated by attaching the clamping apparatus to a mount.

The hinge <NUM> is an additional attachment device and/or fixing device on the side where it is used. In this way the side where the hinge <NUM> is used has three attachment devices. In other words, the side where the hinge <NUM> is used may only uses one single of the attachment devices 714a, 714b, 714c, 714d, 714a', 714b', 714c' and uses the hinge <NUM> as the second attachment device in order to still allow for a single failure.

<FIG> shows a clamping system <NUM> in a closed position according to an exemplary embodiment of the present invention.

The clamping system <NUM> comprises the first clamping apparatus <NUM> and the second clamping apparatus <NUM>', wherein the two clamping apparatuses <NUM>, <NUM>' are connected by four fixing device 901a, 901b, 901c, 901d, e.g. four bolts. An additional fixing device is formed by the hinges <NUM>, <NUM>'.

The clamping system <NUM> can be used to connect two tubes (not shown in <FIG>) inside the substantially circular opening <NUM> surrounded by the two clamping apparatuses <NUM>, <NUM>'. The contour of the circular opening <NUM> substantially corresponds to the contour of the tubes to be connected.

Also, elements described in association with different embodiments may be combined.

Claim 1:
A clamping apparatus (<NUM>, <NUM>') for connecting flanges (101a, 102a) of tubes, comprising:
a first bracing device (<NUM>);
a second bracing device (<NUM>');
wherein the first bracing device (<NUM>) connects a first mounting device (709a) and a second mounting device (709b);
wherein the first bracing device (<NUM>) has a partially circular shape with a first inner wall (<NUM>) and a first outer wall (<NUM>);
wherein the second bracing device (<NUM>') connects a first connecting device (712a) and a second connecting device (712b);
wherein the first inner wall (<NUM>) of the first bracing device (<NUM>) has a first recess (<NUM>);
wherein the first outer wall (<NUM>) of the first bracing device (<NUM>) is adapted to contact the second bracing device (<NUM>');
wherein the second bracing device (<NUM>') is adapted to contact the first outer wall (<NUM>) of the first bracing device (<NUM>) in order to apply a substantially radial force on the first outer wall (<NUM>) of the first bracing device (<NUM>);
wherein the shape of the first recess (<NUM>) is adapted to substantially convert the substantially radial force applied to the first outer wall (<NUM>) of the first bracing device (<NUM>) into an axial force inside the first inner wall (<NUM>);
wherein the first mounting device (709a) and the second mounting device (709b) each comprise at least two attachment devices (714a, 714b, 714c, 714d) for connecting the first connecting device (712a) and the second connecting device (712b) of the second bracing device (<NUM>').