A sealing device

Abstract: A sealing device for sealing two concrete pipe end portions in relation to each other comprises a sealing surface (4) in a socket (2) of one of the pipe end portions and a sealing surface (14) on a spigot end (12) of the other pipe end portion. The spigot end is introduced into the socket and there is between the sealing surfaces formed a sealing space in which an elastic material sealing element (26) is positioned in a compressed state. A closure device (28) is positioned in the sealing space between the interior of the pipe end portions and the sealing element (26) for preventing a medium conveyed in the pipe end portions from contacting the sealing element as well as the sealing surfaces at least in a region of the sealing element.

Description: The present invention relates to a sealing device for sealing two concrete pipe end portions in relation to each other. For providing a tight connection between concrete pipes there are often used socket pipes forming at one end a socket and at the other end a spigot, two pipes being jointed by introducing the spigot of one of the pipes into the socket of the other pipe. Thereby, a sealing surface in the socket of one of the pipe end portions and a sealing surface on the spigot end of the other pipe end portion introduced into the socket together form a sealing space which is connected with the interior of the pipe end portions. In the sealing space there is positioned an elastic material sealing element which is compressed between two opposite sealing surface portions of the sealing space. Concrete pipes of this kind area used for example for conveying waste water. It happens that the waste water contains aggressive substances, for example marsh gas or sulphurous gas effecting and degrading the concrete material of the pipes. It is possible to extend the life of the pipes by increasing the thickness of the pipe walls but a degradation of the concrete material in the areas of the sealing devices between the pipes inevitably leads to defective thightness of the pipe joints. This depends on the fact that the degradation of the sealing surfaces provides an increased width of the sealing space so that the compression of the sealing element necessary for the function thereof is successively decreased and lost. It is possible to reduce the risk of jeopardizing the function of the sealing device by providing a sealing device which comprises a closure device positioned in the sealing space between the interior of the pipe end portions and the sealing element for preventing the medium conveyed in the pipes from contacting the sealing element and the sealing surface portions positioned in the region of the sealing element. A sealing device of the kind comprising a closure device positioned in said sealing space is previously known from for example US-A-2 615 740. According to US-A-2 615 740 the closure device is constituted by an inwardly projecting flange which consists of a solid rubber material and which is relatively thin. Because of the possible variations of the width of the radially extending portion of the sealing space a closure device constituted by a flange in accordance with US-2-2 615 740 does not have a reliable capacity of acting as a closure means for preventing a medium conveyed in the pipe from entering the cylindrical section of the sealing space between the spigot and the socket. It should in this connection be noted that in a sealing space between a socket and a spigot end there can exist large tolerances in respect of the width of the radially extending section of the sealing space as this width is directly dependent on the relative position of the two connected pipes. In particular, in a joint between a spigot end and a socket, no means are provided for locking the socket and the spigot end in an exactly predetermined position in relation to each other. After the spigot end has been introduced into the socket, there is normally at least a small withdrawal of the spigot end from the socket, as well as possible angular deflections of the pipes in relation to each other. In either case, the width of the radially extending sealing space section will be increased at least at some point around the circumference of the pipe. Consequently, a closure element which shall constitute a reliable means for preventing degradation of the sealing surfaces must have the capacity to adapt to different widths of the radially extending sealing space section, and in this respect a closure device of the seal shown and described in US-A-2 615 740 is insufficient. Another drawback of the sealing device according to US-A-2 615 740 is the fact that the sealing element positioned in the cylindrical section of the sealing space betwen the spigot and the socket is of tubular shape and is of such axial dimensions that it substantially completely fills up the cylindrical section of the sealing space. This means that there is in the sealing device of US-A-2 615 740 no distance between the closure element and the sealing element providing for an extremely rigid joint which does not allow an angular position between the pipe end portions at the joint. This means that the concrete material of the pipes forming the joint are subjected to substantial stresses often causing that the concrete is broken. The object of the present invention is to provide a sealing device for concrete pipes having a reliable closure device for preventing mediums containing substances which are detrimental to the concrete from contacting the sealing element and the sealing surface portions positioned in the region of the sealing element, the sealing device being of a kind which permits an angular position between the concrete pipes without jeopardizing the tightness of the joint between the pipes. In order to comply with this object the sealing device according to the invention is of a kind comprising a sealing surface in a socket of one of the pipe end portions and a sealing surface on a spigot end of the other pipe end portion, the spigot end being introduced into the socket for forming between the sealing surfaces a sealing space which is connected with the interior of the pipe end portions and comprises a cylindrical sealing space section and a radially extending sealing space section which connects the cylindrical sealing space section with the interior of the pipe end portions and further comprising an elastic material sealing element which is compressed in the cylindrical sealing space section, and a closure element consisting of rubber-elastic material and positioned in the radially extending sealing space section for preventing a medium conveyed in the pipe end portions from contacting the sealing element as well as the sealing surfaces at least in the region of the sealing element, the closure element and the sealing element consisting of the same material and being connected with each other, the elastic material sealing element being compressed in the cylindrical sealing space section at an axial distance from the radially extending sealing space section, the closure element being connected with the sealing element by means of a wall which is thin in relation to the radial thickness of the elastic material sealing element and in relation to said axial distance and covering the sealing surface of the spigot end between the closure element and the sealing element and the closure element comprising at least one sealed, annular, gas-filled, compressible cavity. Preferably the closure device positioned in the sealing space is constituted by a rubber-elastic material closure element which for example consists of an annular hose filled with gas, preferably air or a closure element which defines a plurality of sealed cavities. Thereby it is suitable that the closure element is compressed in a section of the sealing space, which is defined by an end surface of the spigot and an opposite surface of the socket and extends radially from the interior of the pipe end portions to a cylindrical section of the sealing space. This means that the medium conveyed in the piping is completely prevented from entering the sealing space which in turn provides that the sealing device is maintained intact. Due to the fact that the closure element consists of a gas-filled annular element the closure device is capable of maintaining its function also after a substantial degradation of the concrete surfaces engaged by the hose. The fact that the closure element is filled with gas provides for a successive widening of the hose for maintaining its function so as to close the sealing space. The fact that the sealing element is positioned at an axial distance from the radially extending sealing space section and that the closure element is connected with the sealing element by means of a thin wall allows that the pipes are positioned at an angular position in relation to each other, the fact that the closure element comprises a gas-filled cavity providing a correct function of the closure element also in the angular position of the pipes. The sealing element of the sealing device according to the invention can be designed in different ways. In an embodiment of the sealing device according to the invention the sealing element comprises two sealing portions which are adapted at the axial displacement of the sealing surfaces taking place when the spigot end is introduced into the socket substantially indisplaceably to engage one of the sealing surfaces each and to slide against each other along two sliding surfaces contacting each other and preferably provided with a lubricant. Thereby one of the sealing portions can constitute the main body of the sealing element while the other sealing portion is constituted by a thin, so called sliding skin. It is also possible to design the other sealing portion as a closed hose which at the displacement of the sealing surfaces in relation to each other rolls up onto the main body of the sealing element as a caterpillar track. The invention is described in the following with reference to the accompanying drawings. Fig. 1a is an axial section of an embodiment of a sealing device according to the invention before the pipes have been jointed. Fig. 1b is an axial section of the completed sealing device shown in Fig. 1a. Figs. 2a-4a and 2b-4b are axial sections corresponding to the sections of Fig. 1a and 1b, respectively, showing other embodiments of sealing devices according to the invention. The sealing device according to the invention is intended for sealing two concrete pipe end portions in relation to each other. The pipe end portions are part of a piping for conveying waste water containing sulphurous gas or marsh gas. The sulphurous gas is detrimental to the concrete material and successively degrades the material. In order to increase the life of the piping the concrete walls of the pipes are manufactured with larger thickness. The sealing device according to the invention is intended for solving the problems appearing at the pipe joints by the fact that the concrete is degraded in the region in which the sealing device engages the concrete. One of the pipe end portions forms a socket 2 having at its inner surface a sealing surface 4 comprising a cylindrical portion 6 and an adjacent, annular portion 8 extending transversely of the axis of the pipe. The cylindrical portion 6 of the sealing surface 4 is somewhat conical with the smallest diameter at the inner portion which is positioned adjacent the annular portion 8 of the sealing surface. The cylindrical portion 6 of the sealing surface 4 is provided with a chamfer 10 at its outer, free end. The other pipe end portion forms a spigot end 12 having a sealing surface 14. The sealing surface 14 comprises a cylindrical portion 16 and an annular portion 18 extending transversely to the axis of the pipe and forming the free end surface of the spigot end 12. The cylindrical portion 16 of the sealing surface 14 merges through a shoulder 20 into a cylindrical portion 22 having larger diameter than the portion 16. A sealing and closure unit 24 consisting of rubber elastic material is positioned on the spigot end 12. The sealing and closure unit 24 consists of a sealing element 26, a closure element 28 and a connection portion 30 extending between the sealing element 26 and the closure element 28. The sealing element 26 has a radially projecting compression portion 32 having a conical outer surface 34 and further has a support portion 36, supporting against the shoulder 20 of the spigot end 12. The closure element 38 is constituted by an annular, tightly closed hose the walls 38 of which enclose an air-filled space 40. The outer surface of the wall 38 of the closure element is provided with annular beads 42. The connection portion 30 between the sealing element 26 and the closure element 28 is constituted by a wall having substantially the same thickness as the wall 38 of the closure element 28. The sealing and closure unit 24 is tensioned on the sealing surface 14 of the spigot end 12 with the sealing element 26 and the connection portion 30 contacting the cylindrical portion 16 of the sealing surface 14, with the support portion 36 of the sealing element 26 engaging the shoulder 20 and with the closure element 28 engaging the annular portion 18 of the sealing surface 14. In order to establish the pipe joint according to Fig. 1b the spigot end with the sealing and closure unit is connected with the socket by introducing the spigot end into the socket in the axial direction of the pipes. Thereby the compression portion 32 of the sealing element 26 is contacted by the chamfer 10 at the end surface of the socket, the sealing element being successively compressed with the compression portion turned down towards the support portion 36. At the continued introduction of the spigot end into the socket the closure element 28 is compressed between the portion 18 of the sealing surface 14 and the portion 8 of the sealing surface 4 while the sealing element 26 is concurrently further compressed by the engagement with the conically tapering portion of the sealing surface 4. In the final position shown in Fig. 1b the closure element 28 completely fills up the portion of the sealing space, which is defined by the portions 18 and 8 of the sealing surfaces 14 and 4 respectively, providing a complete closure of teh sealing space and completely preventing the sealing space from being influenced by the medium conveyed in the piping. This means that the portion of the sealing device consisting of the sealing surfaces 14 and 6 and the sealing element 26 and positioned inside the closure element 28 is completely protected from being degraded by for example sulphurous gas which degrades the concrete material forming the sealing surfaces 6 and 14 rapidly leads to a loss of the compression of the sealing element necessary for the tightness of the joint. In a piping provided with sealing devices according to the invention only the inner surface of the piping is accessible for being attacked which means that the piping does not become untight until the complete wall of the piping has from inside being degraded by the sulphurous gas. The closure element 28 is capable of adapting to great tolerances with regard to the distance between the portions 8 and 18 of the sealing surfaces, which are engaged by the closure element 28. Thus, the distance between the surface portions may without problems vary between 10 and 50 mm. In Figs. 2a and 2b, 3a and 3b, and 4a and 4b, there are shown embodiments of the sealing device according to the invention which are modified in relation to the embodiment according to Figs. 1a and 1b only in relation to the design of the sealing and closure unit. Thus, also the sealing devices according to this figures comprise a spigot end and a socket of the same design as the spigot end and the socket of the embodiment according to Figs. 1a and 1b. The socket and the spigot end as well as the sealing surfaces thereof are designated with the same reference numerals as in the embodiment according to Figs. 1a and 1b with the addition of "a", "b", and "c". Each of the sealing devices according to Figs. 2a and b - 4a and 4b comprises a sealing and closure unit 24a - 24c, comprising a sealing element 26a - 26c and a closure element 28a - 28c. The sealing elements 26a - 26c are of the same design as the sealing element 26 of the embodiment according to Figs. 1a and 1b and comprise a compression portion 32a - 32c having a conical outer surface 34a - 34c and a support portion 36a - 36c. The closure elements 28a - 28c are connected with their sealing elements 26a - 26c by means of connection portions 30a - 30c extending between the sealing elements 26a - 26c and the closure elements 28a - 28c. The closure elements 28a - 28c have substantially the same outer shape as the closure element 28 of the embodiment according to Figs. 1a and 1b while the interiors of the closure elements 28a - 28c are designed in different ways. In the embodiment according to Figs. 2a and 2b the closure element 28a is provided with four annular spaces 44 extending around the closure element and separated from each other by means of partitions 46 arranged as a cross. In the embodiment according to Figs. 3a and 3b the closure element 28 b is provided with a number of annular spaces 48 having a circular cross sectional shape and extending around the closure element. In the embodiment according to Figs. 4a and 4b the closure element 28c is provided with a number of annular spaces 50 having a longitudinal cross sectional shape and extending around the closure element. The spaces 44, 48 and 50 of the closure elements 28a, 28b and 28c in the sealing and closure units according to Figs. 2a and 2b, 3a and 3b and 4a and 4b are closed and contain air in the same way as the space 40 in the embodiment according to Figs. 1a and 1b. The spaces provide that the closure elements can adapt to large tolerances in respect of the distance between the surface portions of the sealing surfaces engaged by the closure element. The invention can be modified within the scope of the following claims.

Claims: A sealing device for sealing two concrete pipe end portions in relation to each other, comprising a sealing surface (4) in a socket (2) of one of the pipe end portions and a sealing surface (14) on a spigot end (12) of the other pipe end portion, the spigot end being introduced into the socket for forming between the sealing surfaces a sealing space which is connected with the interior of the pipe end portions and comprises a cylindrical sealing space section and a radially extending sealing space section which connects the cylindrical sealing space section with the interior of the pipe end portions and further comprising an elastic material sealing element (26) which is compressed in the cylindrical sealing space section, and a closure element (28) consisting of rubber-elastic material and positioned in the radially extending sealing space section for preventing a medium conveyed in the pipe end portions from contacting the sealing element as well as the sealing surfaces at least in the region of the sealing element, the closure element (28) and the sealing element (26) consisting of the same material and being connected with each other, the elastic material sealing element (26) being compressed in the cylindrical sealing space section at an axial distance from the radially extending sealing space section, the closure element (28) being connected with the sealing element (26) by means of a wall (30) which is thin in relation to the radial thickness of the elastic material sealing element (26) and in relation to said axial distance and covering the sealing surface of the spigot end betwen the closure element and the sealing element and the closure element (28) comprising at least one sealed, annular, gas-filled, compressible cavity (40; 44; 48; 50). A sealing device as claimed in claim 1, characterized in that the closure element (28) is constituted by a gas-filled, annular hose (38) defining the sealed cavity (40). A sealing device as claimed in claim 2, characterized in that the hose (38) is provided with annular projections (42) at its outer surface. A sealing device as claimed in claim 1, characterized in that the closure element (28a, 28b, 28c) defines a plurality of sealed cavities (44; 48; 50). A sealing device as claimed in any of the preceding claims, characterized in that the sealing element (26) has a radially projecting sealing portion (32) and a support portion (36) engaging a radially extending shoulder (20) on one of the pipe end portions. A sealing device as claimed in any of the preceding claims, characterized in that the sealing element (26) consists of a main portion (52; 62) and a sliding skin (54; 64). A sealing device as claimed in claim 6, characterized in that the sliding skin is constituted by a closed hose (62).

Inventors: JOERNHAGEN LENNART, JOERNHAGEN, LENNART, Jörnhagen, Lennart
Applicants: FORSHEDA AB
Application year: 1992
Main classification: F16L17
IPC codes: F16L17, F16L21