Retaining element comprising intumescent material

Abstract

A retaining element (2) for a fitting (20) for press connection to a pipe, having a main body (26) which consists at least in part of a non-metallic material, the main body (26) consisting at least in part of an intumescent material.

Description

[0001] Holding element with intumescent material

[0002] The present invention relates to a holding element for a fitting for press-connecting to a pipe, comprising a base body which consists at least partially of a non-metallic material, wherein the base body is designed to hold and / or fix a pipe to be inserted.

[0003] Furthermore, the present invention relates to a fitting for press-connecting to a pipe, comprising a base body, a stop element formed circumferentially in the base body and projecting inwards, a press sleeve connected to the base body and forming an outer contour, the press sleeve having a chamber directed inwards towards the pipe to be received, and a holding element arranged in the chamber.

[0004] The technical field relevant to the present invention is the on-site installation of piping systems, in which a piping system consisting of pipe sections and fittings is generally installed for the conveyance and transmission of a fluid, i.e. a liquid or a gas. A fitting is basically understood to be a connecting piece for a pipeline, and a fitting is most frequently used to connect two or more pipe sections. Accordingly, the fitting preferably has two or more press sections, for example in the form of press sleeves. The most common fittings include straight connections, changes of direction in the form of pipe bends, reducers, branches such as T-pieces or intersections. However, a fitting can also be understood to be a pipe connection of a valve or other component. For example, thermometers or pressure gauges, as fittings, only have one connection for one pipe section.Thus, a fitting of a valve has only one press section for connecting a pipe section to the valve. Press connections are used to connect the pipe sections to the fittings and other components. In these press connections, a press section of a fitting is radially deformed inward with the pipe section inserted using a press jaw, creating a permanent and tight, possibly even permanent, connection. The fittings can be provided with a sealant, such as an O-ring, to ensure the tightness of the connection, or they can be formed by direct contact between the materials of the pipe section and the fitting, for example, a metallic seal.The pressing technology used for radially forming the press section primarily involves radially acting press systems as well as press systems that use radial-axial pressing, whereby part of the fitting is displaced axially during the pressing process in order to thereby effect radial forming. The pipeline systems generally described above are used in particular for the transport of drinking or heating water, gas for operating a heating system or industrial gases. In principle, any fluid medium can be transported in the pipelines. With press fittings, a distinction is made as to whether a pipe is sealed and fixed from the outside during pressing or whether at least part of the fitting, for example in the form of a support sleeve, stabilizes the pipe to be sealed from the inside. The present invention relates in particular to the type of fitting in which the pipe is sealed and fixed from the outside.This does not fundamentally preclude the possibility of locating a component of the fitting inside the pipe, but this is generally not the case. Furthermore, the present invention can also be used for pipes that are to be sealed from the inside.

[0005] Solid materials are preferred for pipes that require external sealing, such as rigid pipes. Metallic materials are particularly suitable for this purpose, such as stainless steels such as ferritic steels such as 1.4520 and 1.4521, austenitic steels such as 1.4404, duplex steels such as 1.4462, gunmetal, SiBr, and copper.

[0006] Non-metallic materials such as plastics can also be considered as solid materials if the non-metallic material or plastic has sufficient properties for pressing and permanently connecting to pipes. Examples of suitable materials include the following: polyethylene (PE), in particular cross-linked polyethylene (PE-X), silane-crosslinked polyethylene (PE-Xb) or physically cross-linked polyethylene (PE-Xc), polyethylene with increased temperature resistance (PE-RT), polyvinyl chloride (PVC), polypropylene (PP) with appropriate wall thicknesses, polyphenyl sulfone (PPSU), polyetheretherketone (PEEK) or polyaryletherketone (PAEK), polyamide (PA), in particular aliphatic bio-based polyamide (PA410, PA12, PA12-GF30), or polypropylene random copolymer with modified crystal structure and increased temperature resistance (PP-RCT).Furthermore, multi-layer composite pipes can be designed to be sufficiently rigid for external sealing, for example using a thicker aluminum layer; fiber-reinforced pipes can also be used.

[0007] For the purposes of this application, a rigid pipe is defined as a pipe connected to an externally sealed fitting. The strength of the pipe material is sufficient that the external forces acting through the fitting enable a permanent seal, but do not deform the rigid pipe, or only slightly, so that the connection remains stable and tight.

[0008] Fittings for press-connecting to a pipe, in particular a pipe that is to be sealed from the outside, for example a rigid pipe, can have various designs. A holding element can be provided inside the fitting, and further fixing elements can also be provided. The holding element and optional fixing elements can fix the pipe in the required position relative to the fitting before and after pressing and / or hold the pipe in the fitting against the pull-out direction. The holding element is therefore preferably used as a holding element. Furthermore, the holding element can alternatively or additionally serve as a spacer element, functionally as a spacer between other elements provided inside the fitting. Furthermore, the holding element can alternatively or additionally also fulfill the function of a sealing element and seal existing gaps between other elements of the fitting and / or the press-connection arrangement.In addition to the holding element, a sealing element, usually a sealing ring, for example an O-ring, can be provided to seal the fitting against the outside of the pipe.

[0009] When pressed together, the optional sealing element sits seamlessly against the compression sleeve and the pipe being inserted, as it is positioned in the area of ​​the stop element, i.e., where the inserted pipe rests and ends. This gap-free design not only improves the tightness of the connection but also improves hygiene by preventing dead spaces and areas prone to stagnation. Depending on the further design of the fitting, a reliable seal can also be achieved with a press-fitted arrangement of pipe and fitting without a sealing element.

[0010] The pipe is preferably secured against pull-out and / or excessive internal pressure by means of a holding element, the inner surface of the base body being designed accordingly to hold and / or fix the pipe. The base body of the holding element is preferably essentially hollow-cylindrical and can therefore, for example, be designed as a ring whose outer contour is adapted to the inner side of the base body of the fitting. It is also possible for the base body to be constructed in one piece or composed of several elements. After the fitting is press-connected to the pipe, a reliable seal can be achieved so that pressurized fluids can be conducted through the press-connected arrangement of pipe and fitting without loss.

[0011] If the pressurized fluid is a gas, it is necessary for safety reasons to create a gas-resistant seal that allows the gas to pass through the press-fitted assembly of pipe and fitting with essentially no loss, even at high temperatures. A gas installation is therefore required to be HTB-resistant. The term "Higher Thermal Load Capacity" (HTBJ) requires that a gas installation, for example a gas-carrying pipeline, can withstand a temperature of 650°C for a period of 30 minutes. The temperature requirement depends on the relevant directives, for example the EU directives in EU member states. This prevents the gas installation from posing an explosion hazard in the event of a fire, unless the explosion hazard is prevented by alternative protective measures.For example, during a high-temperature (HTT) test of an assembly consisting of a fitting press-fitted to a pipe, the assembly is exposed to a temperature of 650 °C for 30 minutes, and the leak rate is measured under a specific internal pressure, which must not exceed a certain value. Resistance to high temperatures is also necessary or at least advantageous for fluids other than gases, so an HTB-resistant installation is generally preferable for fluid-carrying piping systems.

[0012] HTB resistance is particularly problematic for combinations of fittings and pipes where material combinations with different thermal expansion coefficients are used, for example a press connection with a fitting made of a ferritic steel, for example 1.4521, and a pipe made of an austenitic steel, for example 1.4404. This is because when material combinations with different thermal expansion coefficients are used, an increase in temperature, for example due to heating during the HTB test, results in enlarged gaps between the pipe and fitting, which can lead to insufficient or borderline tightness of the press connection. But this also applies to pure material combinations of pipe and fitting, for example a press connection with a fitting and a pipe made of an austenitic steel, for example 1.4404, when the press connection heats up, enlarged gaps can occur and this can result in a lack of tightness in the press connection. A particular problem when the temperature of a press connection with a sealing element, which is often made of rubber, for example HNBR (“hydrogenated nitrile-butadiene rubber”), increases is that the sealing element can be completely destroyed and can therefore no longer provide a seal. This is particularly problematic at temperatures of up to 650 °C, as occurs, for example, in the HTB test. In existing arrangements for press-fitting and pipe connections, an additional component is often used which is intended to fill the gaps created during the HTB test, for example through expansion, and thus seal it.The disadvantage of this solution is that the additional component must be incorporated as an additional component into a press-connected assembly consisting of a fitting and a pipe. This requires more space within the fitting, for example, in the chamber of the

[0013] Fittings. On the other hand, providing an additional component increases production costs.

[0014] Furthermore, intumescent materials are known from the state of the art, for example, intumescence-based additives that expand or foam many times their volume when the temperature increases, thus serving as a seal. Intumescence generally refers to the property of a material to expand or swell when the temperature increases.

[0015] Intumescence is therefore an increase in volume of a solid body without chemical transformation upon application of heat energy. Foamed intumescence-based additives are heat-resistant and slow or prevent the passage of heat energy through the material containing the intumescence-based additive.

[0016] Intumescent materials are characterized by the fact that they begin to expand above a certain temperature, which is usually between 200 and 350 °C. They are used as seals, for example as sealing strips in buildings, or in the form of a paste, for example in the form of a flame-retardant layer. In the event of a fire, intumescent materials perform the important function of sealing cavities, gaps, and joints that can arise from the expansion of the various components of the building component or building. However, unlike flame-retardant plastic parts, such intumescent materials generally have no function outside of a fire situation associated with an increase in temperature of the component in which the material is used. In addition, the use of intumescent materials has so far been limited to a few areas.

[0017] Furthermore, the production of retaining strips filled with expandable graphite by injection molding is known in the prior art. A disadvantage of these retaining strips is that the injection molding process, and thus the production of such a retaining strip, presents several challenges. For example, the injection molding temperature must not be set too high, and gentle material processing with regard to the expanded graphite particles used is required. Particularly when using plastics with a high melting or processing temperature for the retaining strip, the expanded graphite can dissolve during the manufacturing process. Thus, a retaining strip filled with expandable graphite cannot be satisfactorily produced by injection molding.

[0018] Against this background, the present invention is based on the technical problem of specifying an element for a fitting for press-connecting to a pipe and a fitting with such an element, by means of which a substantial sealing of a press connection with a fitting and a pipe is achieved even at high temperatures and which eliminates the disadvantages described for the prior art.

[0019] The technical problem outlined above is solved according to the invention in a holding element for a fitting for press-connecting to a pipe, with a base body which consists at least partially of a non-metallic material, wherein the base body is designed to hold and / or fix a pipe to be inserted, in that the base body consists at least partially of an intumescent material.

[0020] By using the retaining element according to the invention, an additional element for sealing in the event of a fire can be dispensed with and, at the same time, the escape of gases or other media can be prevented. HTB resistance is achieved in particular for components containing materials with different thermal expansion coefficients. Due to the expansion of the intumescent material, even particularly large gaps, for example in certain material combinations, can be sealed by the retaining element. This enables more favorable material combinations, particularly in gas installations. As a result, the retaining element according to the invention can ensure the HTB resistance of a component by reliably sealing possible gaps between different components of the component during the HTB test, for example between a press-fitted fitting and a pipe or pipes.

[0021] The technical problem outlined above is further solved in a fitting for press-connecting to a pipe, comprising a base body, an inwardly projecting stop element formed circumferentially in the base body, a press sleeve connected to the base body and forming an outer contour, the press sleeve having a chamber directed inwards towards the pipe to be accommodated, and a holding element arranged in the chamber, in that the holding element is designed according to the holding element according to the invention or a preferred embodiment of the holding element. The press sleeve of the fitting can be formed integrally with the base body. Furthermore, the press sleeve can be designed separately from the base body and can be connected to it irreversibly or detachably. For example, the press sleeve can be slipped or pressed onto the base body.The holding element according to the invention has a base body on which further elements can optionally be arranged in order to fulfill the required function of the holding element. For example, elements are provided which serve the function of the holding element as a holding element, for example fixing elements for fixing the pipe, which guide and hold the pipe to be inserted. Furthermore, elements can be provided which support the function of the holding element as a spacer element or sealing element, for example elements made of a material that is softer than the rest of the base body and which serve to seal it. By designing the base body according to the invention at least partially from an intumescent material, an expansion of the holding element by several times its volume under the influence of heat can be achieved in the event of a fire.This allows the retaining element to securely close gaps created in a component due to heat exposure and ensure a seal even in the event of a fire. The retaining element can therefore be used advantageously in conjunction with materials with different thermal expansion coefficients.

[0022] The proportion of intumescent material in the base body can be selected within a wide range, depending on the specific application of the retaining element or fitting in which the retaining element can be used. For pure material combinations of fitting and pipe, a lower (by weight) proportion of intumescent material in the base body may be necessary. However, when combining materials with different thermal expansion coefficients for the fitting and pipe, it may be necessary to use a higher (by weight) proportion of intumescent material in the base body. For example, the selected (by weight) proportion of intumescent material in the base body can be between 5 and 50 wt.%.

[0023] In the following, various embodiments of the holding element and the fitting are described, whereby the individual embodiments are each applicable to both the holding element and the fitting and can also be combined with each other.

[0024] According to the invention, the base body is designed to hold and / or fix a pipe to be inserted. Preferably, the base body is configured to hold the pipe to be inserted, in particular the pipe to be inserted into the fitting, counter to the withdrawal direction. In particular, the holding element is designed as a holding element, for example as a holding strip, i.e. the base body preferably has a substantially cuboid geometry that can be bent into a hollow cylinder. Preferably, a holding element designed as a holding strip can be joined together to form a ring, which is preferably not closed. The holding element is preferably designed to be flexible so that it can easily adapt to different geometries and, in addition, both a fixing and / or holding function and a sealing effect are improved by the holding element, in particular in the normal temperature range, i.e. outside of a fire situation.The flexibility can be achieved or influenced in particular by the proportion of non-metallic material, in particular a plastic portion, of the base body of the holding element. The holding element is preferably designed to be arranged in a fitting for press-connection. According to one embodiment of the fitting, the holding element is configured to hold the pipe to be inserted counter to the withdrawal direction. In particular, the base body of the holding element is configured to hold the pipe to be inserted counter to the withdrawal direction. In this way, the pipe can be easily and precisely fixed in the fitting before pressing.

[0025] The retaining element is preferably used for an externally sealing fitting for press-connecting to a pipe that is to be sealed from the outside, for example, a rigid pipe. The retaining element is preferably arranged inside the fitting, into which the pipe can be inserted for press-connection.

[0026] According to a further embodiment, the base body is made at least partially of a plastic. Preferred plastics include polyolefins, such as polypropylene (PP) and polyethylene (PE), or polyamide (PA), as matrix materials into which the intumescent material can be incorporated. Furthermore, the solid materials or plastics known from the prior art for pipes can be used.

[0027] According to a further embodiment, the proportion of intumescent material in the base body is 10 to 25 wt.%. Preferably, the proportion of intumescent material in the base body is 20 wt.%, particularly preferably 25 wt.%. The remaining portion is preferably formed by a non-metallic material, in particular plastic.

[0028] In tests, particularly in HTB tests of a fitting with a retaining element containing a specific proportion of intumescent material in the base body, a retaining element with a proportion of 10 to 25 wt.%, preferably 20 and particularly preferably 25 wt.%, has proven particularly effective for sealing in the event of a fire, especially when using expandable graphite as the intumescent material. It has been found that with such a proportion of intumescent material of 10 to 25 wt.%, preferably 20 wt.%, particularly preferably 25 wt.%, the retaining element can effectively reduce the risk of explosion in gas-carrying pipelines by sealing the gas-carrying pipelines, particularly with satisfactory holding / fixing behavior.

[0029] According to a further embodiment, expandable graphite is used at least partially as the intumescent material. Expandable graphite is preferably produced by chemically treating graphite, whereby graphite is treated with substances that are incorporated into the graphite's lattice structure, thereby widening the spacing between the graphite layers. Graphite pretreated in this way expands when exposed to heat, multiplying its volume. Preferred substances include, for example, strong acids and / or oxidizing agents such as hydrogen peroxide or potassium permanganate.

[0030] According to a further embodiment, alkali silicate is used at least partially as the intumescent material.

[0031] The preferred intumescent material is one that carbonizes and / or vitrifies under the influence of heat. Carbonizing substances that form a carbon framework in the event of a fire include carbohydrates, such as mono-, di-, or polysaccharides like sugar, starch, and cellulose, which may interact with salts of strong inorganic acids, such as phosphoric or sulfuric acid. Materials that vitrify or ceramize in the event of a fire include alkali silicates, alkali aluminosilicates, alkali magnesium silicates, phosphates, phosphate-containing silicates or aluminates, or inorganic boron compounds and mixtures thereof.

[0032] Other preferred intumescent materials are materials with bound crystal water, such as vermiculite and alkali silicates, which expand when exposed to heat due to the split-off and evaporated crystal water. Preferably, the material of the base body does not contain polyvinyl chloride (PVC), in the sense that there is no detectable proportion of PVC. PVC has the disadvantage that the highly corrosive gas HCl is released in the event of a fire. The high proportion of plasticizer in the PVC has a detrimental effect. Due to migration of the plasticizer in the PVC, a retaining element containing PVC can lose flexibility through aging. This adversely affects the sealing effect in the event of a fire. Furthermore, the plasticizer can come into contact with or interact with other materials in the environment and have a detrimental effect.

[0033] According to a further embodiment, the base body has slots. The slots are preferably formed axially in the base body. Such slots can make the retaining element flexible or improve its flexibility and facilitate the installation of the retaining element within a component, for example, within a fitting. The base body preferably has a closed ring shape. In order to insert the retaining element into a fitting or into an undercut chamber of the compression sleeve, the base body must be compressed radially. This compression is made possible by the preferably provided axially extending slots.

[0034] Furthermore, according to a further embodiment, the base body has joints, preferably hinges, particularly preferably film hinges. In this case, the base body can be designed as a completely closed ring or strip with joints, wherein the joints interlock and can enable a flexible shape of the base body and thus of the retaining element. This can facilitate the installation of the retaining element in the fitting.

[0035] According to a further embodiment, clamping elements are provided on the base body. According to this embodiment, the pipe is secured against pull-out and / or against excessive internal pressure by the clamping elements, which are provided on the base body and are in particular received or held by it. The clamping elements can absorb the pull-out force by deforming the pipe at specific points. In a fitting, the clamping elements can be supported on the wall of the compression sleeve. This ensures a direct flow of force from the pipe via the compression sleeve into the fitting. The holding element itself preferably only has a supporting function after pressing and contributes little or not at all to pull-out protection.

[0036] According to a further embodiment, cutting elements are provided on the base body. The cutting elements are preferably made at least partially of metal. The cutting elements can serve as clamping elements or be formed on the base body in addition to these. The cutting elements preferably cut into the pipe during pressing and thus contribute to securing the pipe in the pressed state.

[0037] The base body can be designed as a ring made at least partially of a non-metallic material, in particular plastic, into which the cutting elements, for example the metallic cutting elements, are mounted as clamping elements. The cutting elements can be designed in the form of wire elements, which can be arranged in particular in recesses provided for this purpose on the base body. The clamping elements can be fixed to the base body in a force-fitting, form-fitting or material-fitting manner, for example using an adhesion promoter. The number of clamping elements can be determined depending on the requirement or dimension; preferably at least three clamping elements are provided. The same clamping elements can also be used for fittings for different pipe dimensions.

[0038] Furthermore, it is preferred that the clamping elements optionally provided on the base body are arranged in the distal region of the chamber, opposite the stop elements of the fitting. When the compression sleeve is pressed, the clamping elements are clamped diagonally and counter to the pipe's extension direction between the deformed compression sleeve and the pipe wall, generating a counterforce counter to the extension direction. This arrangement enables effective fixation of the pipe in the pressed fitting.

[0039] Furthermore, the optional clamping elements can also be designed as a block, which generates a counterforce against the pipe's extension direction and / or supports the pipe against the inner wall of the fitting when increased internal pressure occurs. This can further improve the stability of the press connection between the fitting and pipe.

[0040] Furthermore, the base body can have inward-facing webs spaced from the clamping elements, wherein the webs define an azimuthal inner cross-section in sections that is the same size as or slightly smaller than the outer diameter of the pipe to be inserted. The clamping ring performs a pipe-holding function through the webs. The webs hold the inserted pipe when the fitting is not pressed, so that the pipe cannot slip out of the fitting without considerable tensile force. The webs also guide the pipe when it is inserted into the fitting. If the inner cross-section is slightly smaller than the outer diameter of the pipe, the pipe is also offered slight resistance when being inserted. This gives the user haptic feedback when inserting the pipe that the pipe is inserted deep enough into the fitting.

[0041] The fitting's stop element signals to the user that the pipe to be connected has been inserted sufficiently deep into the fitting. The stop element preferably consists of at least two inward-facing recesses, such as punch marks, and preferably three punch marks. In contrast to a fully circumferential recess, individual recesses result in fewer dead spaces and thus improved hygiene conditions. The fitting is preferably designed for press connection to a pipe that is to be sealed from the outside, such as a rigid pipe, with the press sleeve, together with the retaining element, sealing the pipe to be connected from the outside.

[0042] According to a further embodiment of the fitting, a sealing element is arranged in the chamber adjacent to the stop element. The optional sealing element serves in particular to seal the pipe against the fitting, so that a medium conveyed through the pipe cannot escape from the press connection of fitting and pipe when pressed together. In the pressed together state, the sealing element preferably rests gap-free against the press sleeve and the pipe to be inserted, as it is preferably arranged adjacent to the stop element, i.e. where the inserted pipe rests and ends. The gap-free design improves hygiene by avoiding dead spaces and areas subject to stagnation.

[0043] Furthermore, it is preferred that the optional sealing element is designed as a lip seal at least in part and, after pressing, seals the gap between the pipe and the compression sleeve up to the end of the inserted pipe. This way, a particularly tight connection can be achieved. Furthermore, a high degree of hygiene can be ensured and crevice corrosion can be avoided. Because the sealing element is designed geometrically as a lip seal at least in part, the gap between pipe and fitting can be completely closed by the sealing element up to the end of the pipe after pressing the fitting. This way, especially in conjunction with the described point pipe stop, dead spaces in which media can collect can be avoided. The lip seal therefore preferably ensures the required system tightness. Alternatively, the optional sealing element can also be designed as a classic O-ring.

[0044] According to a further embodiment, the fitting is designed for press-connection to a pipe to be sealed from the outside, for example a rigid pipe, wherein the press sleeve, together with the holding element and the sealing element, seals the pipe from the outside.

[0045] In the following, the invention is explained using exemplary embodiments with reference to the drawing. In the drawing,

[0046] Fig. 1 shows an embodiment of a holding element according to the invention,

[0047] Fig. 2a e an embodiment of a fitting according to the invention for

[0048] Connecting to a pipe to be sealed from the outside with a holding element according to Fig. 1,

[0049] Fig. 3a-b an example of a fitting without a retaining element,

[0050] Fig. 4 a fitting according to Fig. 2 with a modified shape of the cutting element and

[0051] Fig. 5a-j show several examples of cutting elements with different geometries.

[0052] In the following description of the various embodiments according to the invention, components and elements with the same function and the same mode of operation are provided with the same reference numerals, even if the components and elements in the various embodiments may have differences in their dimensions or shape.

[0053] Fig. 1 initially shows an embodiment of a holding element 2 according to the invention, in which the base body 26 is designed as a plastic ring mixed with expandable graphite. In this embodiment, the proportion of expandable graphite in the material of the base body 26 is 25 wt.%. Metallic cutting elements are arranged in the base body as clamping elements 27. The base body further has circumferential slots 26a and 26b, which make the base body 26 and thus the holding element 2 flexible as a whole and facilitate installation in a fitting. In addition, the base body 26 can thus be designed as a circumferentially closed ring and can be more easily reduced in radius during pressing.

[0054] The clamping elements 27 are designed as cutting elements in the form of wire elements that are inserted into recesses provided for them. The clamping elements 27 are thus fixed in the base body 26 with a positive fit. The clamping elements 27 can be manufactured in various ways, for example, as cast parts or as stamped parts. The number of clamping elements 27 is six in this case, but can be determined depending on the requirements or dimensions of the base body 26.

[0055] Furthermore, the base body 26 has inwardly directed webs 26c spaced from the clamping elements 27, wherein the webs 26c define an inner cross-section that is equal to or slightly smaller than the outer diameter of a pipe 4 to be inserted. Furthermore, inwardly directed webs 26d are also formed, which guide a pipe 4 to be inserted during insertion.

[0056] Figs. 2a to 2e show an embodiment of a fitting 20 for connecting to a pipe 4 to be sealed from the outside, with a half element 2 previously explained with reference to Fig. 1. Figs. 2a to 2c show the fitting 20 in the unpressed state, whereas Fig. 2d shows the fitting 20 in the pressed state. Fig. 2e shows the fitting 20 in the pressed state after exposure to heat.

[0057] The fitting 20 comprises a base body 24 and an inwardly projecting stop element 25 formed circumferentially in the base body 24. Furthermore, a compression sleeve 21 is provided, which is connected to the base body 24 and forms an outer contour 22 and has a chamber 23 directed inward toward the pipe 4 to be received. A retaining element 2 according to Fig. 1 is arranged in the chamber 23. Furthermore, a sealing element 28 is arranged in the chamber 23 adjacent to the stop element 25 and has a round portion 28a and a flat portion 28b forming a lip seal.

[0058] The press sleeve 21 is integrally connected to the base body 24, so that the press section in the form of the press sleeve 21 and the base body 24 can advantageously be manufactured as a single piece. The stop element 25 in this case consists of two inwardly directed and radially opposite recesses 25a, which are designed, for example, as punch marks. The pipe stop is thus made at specific points and not circumferentially, thereby avoiding dead spaces, even when a pipe 4 is inserted and the seal 28 seals in the area of ​​the stop element 25. In Fig. 2b, a pair of radially opposite punch marks is shown for both sides of the fitting 20, one pair for each fitting side.

[0059] The pipe 4 is secured against pulling out and / or against excessive internal pressure by means of the holding element 2, which serves here as a holding element. The circumferential slots 26a and 26b, which are provided on the base body 26, facilitate assembly in the fitting 20 within the press sleeve 21.

[0060] The clamping elements 27 of the base body 26 are arranged in the distal region of the chamber 23, opposite the stop elements 25, and absorb the pull-out force by selectively deforming the pipe 4 (see Fig. 2d), while supporting themselves against the wall in a distal outer corner region 21a of the compression sleeve 21. This ensures a direct flow of force from the pipe 4 via the compression sleeve 21 into the fitting 20. After pressing, the holding element 2 merely has a supporting function and contributes only slightly or not at all to the pull-out protection.

[0061] The webs 26c hold the pipe 4 in the unpressed state of the fitting 20 as shown in Fig. 2c, so that the pipe 4 cannot slip out of the fitting 20. Furthermore, the webs 26c guide the pipe 4 as it is inserted into the fitting 20. If the inner cross-section of the inner surfaces of the webs 26c is slightly smaller than the outer diameter of the pipe 4, the pipe 4 is subjected to slight resistance as it is inserted. Thus, the user receives haptic feedback when inserting the pipe 4 that the pipe 4 is inserted into the fitting.

[0062] The seal 28 is designed as a lip seal with sections 28a and 28b and, after compression, seals the gap 29 between the pipe 4 and the compression sleeve 21 up to the end 4a of the inserted pipe 4. For this purpose, the seal 28 rests with the round section 28a on an inclined section within the chamber 23 and is thereby positioned. The flat section 28b is arranged between the compression sleeve 21 and the pipe 4 to be inserted, which is particularly evident in the compressed state in Fig. 2d. After compression, the gap 29 is thus filled.

[0063] The pressing process is clear by comparing Figures 2c and 2d. The two pressing jaw halves 10a and 10b are moved radially inwards and the pressing contour 8 of the two pressing jaw halves 10a and 10b makes contact with the pressing sleeve 21 radially inwards. As a result, on the one hand, the holding element with the base body 26 is deformed in such a way that the clamping elements 27 press inwards into the material of the pipe 4 and thus the pipe 4 is fixed to the fitting 20. On the other hand, when the pressing sleeve 21 is deformed, the seal 28 and in particular the section 28b as a lip seal is also deformed radially inwards and the seal 28 seals the gap 29. ■

[0064] The sealing element 28 thus ensures a high degree of hygiene and prevents crevice corrosion. Furthermore, a particularly tight connection is achieved. In conjunction with the point-type pipe stop 25, this prevents dead spaces in which media can collect. The lip seal also ensures the system's tightness. This high degree of tightness can be ensured, in particular, in the event of a fire when the fitting is exposed to heat for an extended period, for example, to a temperature of 650 °C for a period of 30 minutes according to an HTB test. This is shown in Fig. 2e. The heat exposure has caused gaps 17 and 19 to form between the compression sleeve 21 and the pipe 4.However, the gaps 17, 19 are closed by the material of the inflated or foamed base body 26', which has a volume many times larger, so that the medium conveyed in the pipe 4 cannot escape from the press connection of pipe 4 and fitting 20. Thus, in the case of a gas conveyed in the pipe 4, for example, the risk of explosion in the event of a fire can be reduced or even avoided. In contrast to the holding element 2 with intertumescent material, the sealing element 28 cannot withstand the effects of heat and is almost completely destroyed. Only remnants 28' of the sealing element remain in the gap 19 between the pipe 4 and the press sleeve, but cannot close it.

[0065] To illustrate the effect of the retaining element 2 according to Figs. 1 and 2, Figs. 3a and 3b show a fitting 30 without a retaining element, in which only a sealing element 38 is arranged in the chamber 33 between the pipe 4 and the compression sleeve 31. Fig. 3a shows the pressed state of the fitting 30 at room temperature, whereas Fig. 3b shows the pressed state of the fitting under the influence of heat, for example, during a heat-resistant test. In the pressed state at room temperature according to Fig. 3a, the sealing element 38 closes gaps between the compression sleeve 31 and the pipe 4, so that a fluid-tight press connection between the pipe 4 and the fitting 30 is achieved.

[0066] Fig. 3b shows that gaps arise between the press sleeve 31 of the fitting 30 and the pipe due to the effect of heat. It can be seen that, compared to Fig. 3a, the sealing element 38 is almost completely destroyed under the effect of heat, so that only remnants 38' of the sealing element remain in the gaps 37, 39. However, these remnants 38' are no longer able to seal the gaps 37, 39, so that the medium 35 carried in the pipe 4 can escape from the press connection of pipe 4 and fitting 30, as shown in Fig. 3b. In contrast to the exemplary embodiment of the fitting 20 according to the invention with holding element 2 according to Figs. 1 and 2, the fitting 30 thus causes an acute safety risk in the event of a fire, especially if the medium 35 carried in the pipe 4 is an explosive gas.

[0067] Figs. 4 and 5a-l serve to indicate various shapes of the cutting elements of the clamping element 27. These cutting elements are fundamentally made at least partially of expandable graphite, regardless of the design of the holding element 2 for the fitting 20. Therefore, the embodiments of the cutting elements described below are also independent of the type of holding elements 2.

[0068] Fig. 4 shows a fitting 20 according to Fig. 2 in cross-section. The only difference is the shape of the clamping element 27, here with a rectangular cross-section in the azimuthal direction. The lower edge of the clamping element 27 has a cutting edge, which is highlighted with a thicker line.

[0069] Figures 5a to 5i show a number of possible configurations. Where two cross-sections are shown, the left cross-section is an axial view, and the right cross-section is an azimuthal view. The respective cutting edge is highlighted with a thicker line.

[0070] Fig. 5a shows a cutting element with a round axial cross-section and a rectangular azimuthal cross-section. The cutting edge runs parallel to the axial direction and has a short dimension in the azimuthal direction, resulting in a linear cutting edge with a narrow width.

[0071] Fig. 5b shows a cutting element with a rectangular axial cross-section and a polygonal azimuthal cross-section with an oblique cutting edge and another shape that is or can be adapted to the inner contour of a chamber in a compression sleeve. Fig. 5c shows a cutting element with a round axial cross-section and an irregular polygonal azimuthal cross-section. The cutting edge runs obliquely to the axial direction with an increasing radius, and in the azimuthal direction, a short cutting edge results, resulting in a linear cutting edge with a narrow width.

[0072] Fig. 5d shows a cutting element with a hexagonal axial cross-section and a rectangular azimuthal cross-section. The cutting edge runs parallel to the axial direction, and in the azimuthal direction, the cutting edge is the length of one side of the hexagonal cross-section.

[0073] Fig. 5e shows a spherical cutting element with a round axial cross-section and a round azimuthal cross-section. Thus, the cutting edge is circular with a small diameter, i.e., in the broader sense, point-shaped.

[0074] Fig. 5f shows a cutting element with a round axial cross-section and an L-shaped azimuthal cross-section. The I-shape extends in the axial direction and forms two short axial cutting edges. Fig. 5g shows a cutting element with a round axial cross-section and an azimuthal cross-section in the shape of a horizontal hourglass. This creates short cutting edges in the axial direction, which are also, in the broader sense, point-shaped with a short radius. Fig. 5h shows a cutting element with a round axial cross-section and an azimuthal cross-section in the shape of a horizontal screw. This results in a point-shaped cutting edge with a small diameter in the broader sense.

[0075] Fig. 5i shows a cutting element with a round axial cross-section and an azimuthal cross-section in the form of a horizontal threaded pin. This creates at least two, in particular three, cutting edges, which are again point-shaped in the broader sense.

[0076] Fig. 5j shows a cutting element with a star-shaped axial cross-section with protruding elevations and a rectangular azimuthal cross-section. The cutting edge resulting from these cross-sections extends over the axial length of the cutting element and is linear in the extended sense.

[0077] The invention therefore also relates to a cutting element for a holding element for a fitting for connecting to a pipe to be sealed from the outside, wherein the cutting element is designed with an axial cross-section and an azimuthal cross-section, wherein cross-sections are selected from the following group: a) round axial cross-section and rectangular azimuthal cross-section with a cutting edge running parallel to the axial direction, b) rectangular axial cross-section and irregularly polygonal azimuthal cross-section with a cutting edge running obliquely to the axial direction, c) round axial cross-section and irregularly polygonal azimuthal cross-section with a cutting edge running obliquely to the axial direction, d) polygonal, in particular hexagonal axial cross-section and rectangular azimuthal cross-section with a cutting edge running parallel to the axial direction, e) round axial cross-section and round azimuthal cross-section with an almost point-shaped cutting edge,f) round axial cross-section and I-shaped azimuthal cross-section with two short axial cutting edges, g) round axial cross-section and azimuthal cross-section in the shape of a horizontal hourglass with two short cutting edges spaced apart in the axial direction, h) round axial cross-section and azimuthal cross-section in the shape of a horizontal screw with an almost point-shaped cutting edge, i) round axial cross-section and azimuthal cross-section in the shape of a horizontal threaded pin with at least two axially spaced and almost point-shaped cutting edges, j) star-shaped axial cross-section and rectangular azimuthal cross-section with a cutting edge extending over the axial length of the cutting element.

Claims

Patent claims Holding element (2) for a fitting (20) for press-connecting to a pipe (4), with a base body (26) which consists at least partially of a non-metallic material, wherein the base body (26) is designed to hold and / or fix a pipe (4) to be inserted, characterized in that the base body (26) consists at least partially of an intumescent material. Holding element (2) according to claim 1, characterized in that the base body (26) consists at least partially of a plastic. Holding element (2) according to claim 1 or 2, characterized in that the proportion of intumescent material in the base body (26) is 10 to 25 wt. %. Holding element (2) according to one of claims 1 to 3, characterized in that expandable graphite is used at least partially as the intumescent material. Holding element (2) according to one of claims 1 to 4, characterized in that alkali silicate is used at least partially as the intumescent material. Holding element (2) according to one of claims 1 to 5, characterized in that the base body (26) has slots (26a, 26b). Holding element (2) according to one of claims 1 to 6, characterized in that clamping elements (27) are provided on the base body (26). Holding element (2) according to one of claims 1 to 7, characterized in that cutting elements (27) are provided on the base body (26).Fitting (20) for press-connecting to a pipe (4), with a base body (24), with a stop element (25) formed circumferentially in the base body (24) and projecting inwards, with a press sleeve (21) connected to the base body (24) and forming an outer contour (22), wherein the press sleeve (21) has a chamber (23) directed inwards towards the pipe (4) to be accommodated, and with a holding element (2) arranged in the chamber (23), characterized in that the holding element (2) is designed according to one of claims 1 to 8.

10. Fitting (20) according to claim 9, characterized in that the holding element (2) is designed to hold the pipe (4) to be inserted counter to the pull-out direction.

11. Fitting (20) according to claim 9 or 10, characterized in that a sealing element (28) is arranged in the chamber (23) adjacent to the stop element (25). • 12. Fitting (20) according to claim 11, characterized in that the fitting (20) is designed for press connection to a pipe (4) to be sealed from the outside, wherein the press sleeve (21) together with the holding element (2) and the sealing element (28) seals the pipe (4) from the outside.

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