A METHOD FOR SEALING AN ELONGATED, HOLLOW CAVITY, AND A DEVICE FOR CARRYING OUT THE METHOD

Abstract: A method for sealing elongated hollow cavities (2), such as circular-cylindrical pipes, tubes, drill holes or the like, in which a body (1) is placed in the cavity in sealing contact with the inner surface (4) of the cavity. The method is characterized especially in that at least one essentially annular, elastic sealing element (3) sealingly mounted in a radially and circumferentially extending gap present in the body (1) is caused to be urged radially outwards into sealing abutment with the inner surface (4) of the cavity (2), by means of pressure (p) applied internally of the body. The invention also refers to a device for carrying out the method.

Description: A method for sealing an elongated, hollow cavity, and a device for carrying out the method The present invention relates to a method for sealing-off elongated, hollow cavities, such as circular-cylindrical pipes, tubes, drill holes and the like, in which a body is placed in said cavity in sealing contact with the inner defining surface(s) thereof. The invention also relates to a device for carrying out the method. There is often a need within, for instance, the fields of geotechnology and geology to seal off effectively tubes or pipes which have been installed in the ground or in holes drilled in a rock. The task of sealing off such cavities is often encumbered with considerable problems, such as when the seal is to be located at considerable depths, is required to be durable over long periods of time and is intended to withstand considerable pres¬ sures, for instance. The object of the present invention is to provide an effective and highly simple solution to this problem and one which will satisfy the aforesaid requirements. By way of example, the invention may be applied in connection with an arrangement or a system essentially of the kind disclosed in Swedish Patent Specification No 432 306. The invention thus relates to a method for sealing elongated, hollow cavi¬ ties, such as circular-cylindrical pipes or tubes, drill holes and like configurations, in which a body is placed in the cavity in sealing contact with the internal defining surface(s) thereof. The method is particularly characterized in that at least one substantially annular and elastic sealing element, sealingly arranged in a gap which extends radially and circumferentially of the body, is caused to be urged radially outwards into sealing abutment with the inside surface of the cavity, by means of pressure applied from within the body. The invention also relates to a device for sealing elongated, hollow cavi¬ ties, such as circular-cylindrical tubes or pipes, drill holes or like configurations, comprising a body which is intended to be placed in the cavity in sealing contact with the inner defining surface(s) thereof. The device is particularly characterized in that a substantially annular, elastic sealing element is sealingly arranged in a gap which extends radially and circumferentially in the body, and in that channels are provided through which pressure is applied internally of the body such as to urge the sealing element radially outwards and into sealing abutment with the inner defining surface of the cavity. The invention will now be described in more detail with reference to exemplifying embodiments thereof and to the accompanying drawings, in which - Figure 1 is a principle drawing of an inventive device intended for use in connection with a circular-cylindrical tube or pipe; Figures 2a-d are axial views which illustrate part of an inventive device in various stages of a cavity Bealing process; Figure 3a illustrates a structural element according to the invention from which an inventive device is obtained; Figure 3b is a sectional view taken on the line A-A in Figure 3a; Figure 4 is an axial sectional view of part of a first embodiment of a device constructed in accordance with the invention and based on the structural element of Figure 3; - Figure 5a is an axial sectional view of part of a second embod¬ iment of an inventive device Figure 5b is a view of the device illustrated in Figure 5a; Figure 6 illustrates schematically the use of a third embodiment of an inventive device; and - Figure 7 illustrates a fourth embodiment of an inventive device. In Figure 1 the reference 1 indentifies a substantially circular-cylindrical body which is intended to seal a circular-cylindrical pipe or tube 2 with the aid of a sealing element 3, such as an O-ring, via which the body 1 is intended to lie in sealing contact with the inner surface 4 of the pipe 2. The reference 5 identifies a nipple means which includes means for connection to a pressure line, not shown in Figure 2. The body 1, together with the sealing element 3, is intended to be inserted down into the pipe 2, which in the illustrated case consists of an elongated, hollow cavity 2, and be brought into sealing contact with the inner surface 4 of the cavity 2, by applying a pressure p_ within the body, Figure 2b, c, so as to urge the sealing element 4 radially outwards and into Bealing enga¬ gement with said inner surface 4. In the case of the Figure 2 embodiments, which in many instances is the embodiment preferred, the reference 3, as before, identifies a sealing element, which in this case is a radially outer sealing element, and reference 3' identifies a radially inner sealing element, the two elements 3, 3' being essentially concentrical with one another. The elements 3, 3' are arranged sealingly in a gap 6 located in the body 1 and extending radially and circumferentially therewithin. The gap 6 communicates with channels or passageways which are intended for the application of said pressure p_ and which in the case of this embodiment comprise a centrally located axially extending channel 7 and a radial channel 8 which connects the axial channel 7 with the gap 6. The reference 10 indentifies a slot which is located radially outwards of the gap 6 and which is connected to the gap through an opening a. which is narrower axially than the cross-sectional diameter, or thickness, of the outer sealing element 3 in its non-compreBsed state, so as to prevent said outer sealing element from re-entering the gap subsequent to having been pressed completely, or substantially completely, through said opening a, thereby to form herewith a permanent seal, in those instances when such a seal is desried. The gap 6 will preferably narrow outwardly. This narrowing of the gap 6 has been signified with the angles α and 2a in Figure 2. In this case, the cross-sectional diameter of the inner sealing element 3 ' may optionally be given a larger cross-sectional than the outer element, in the non- compressed state of said elements. Figure 3 illustrates a body element 1 ' which is intended to coact with an identical or a similar body element to produce a body 1. For the purpose of providing the gap 6 and preferably said channels, there are used two body elements, each of which has a substantially concave end surface 11, 12 and which are joined together, e.g. by means of a screw connection 13, Figure 2 for instance, such that the end surfaces 11, 12 will face towards one another and therewith form an outwardly narrowing gap 6. In the case of the illustrated embodiment, the slot 10 located adjacent the gap 6 is formed by means of a peripheral lip or flange which extends circumfer¬ entially around each of said concave end surfaces 11, 12. The body element 1" illustrated in Figure 3 is an example of an element 1' of standard design, where each element 1' of this kind has on one concave end surface 11 thereof a central, preferably screw-threaded recess 14 and on its other concave end surface 12 a central, preferably externally screw-threaded βtud 15 corresponded to said recess, so that the two elements 1' can be screwed together, thereby enabling a selected number of body elements to be joined sequentially and to build in pairs a gap 6 in the manner illustrated in Figure 4. Figure 5 illustrated schematically on embodiment which includes a bottom piece 16 which is intended for connection to the body 1 and therewith form a bottom closure 17, so as to enable pressure to be built up internally of the body and maintained therein. In the case of the illustrated em¬ bodiment, the bottom closure 17 is constructed so that it can be opened by means of said pressure applied internally of the body, to establish a connection 18 between the interior of said body 1 and said cavity 2 and includes closure devices 19 which in order to open require the application of a much higher internal pressure p_ than that required to establish a seal between the body 1 and said cavity, this seal being established by urging the sealing element radially outward into sealing abutment with the inner defining surface of the cavity. According to a preferred embodiment, the closure devices 19 include an internally mounted, elastic disc 20 which is supported around its rim by means of a support 21 which incorporates a central hole 22 through which the disc can be pressed out, by applying pressure internally of the body 1. In the case of the Figure 5 embodiment, the body 1, comprising body elements 1 ' , is used as a probe for taking samples of groundwater or the like for example. The reference 23 identifies a screw bushing which incorporates two radially pretensioned septa, i.e. rubber plates or washers 24, and an intermediate distance plate 25. The bushing is attached sealingly, by means of a seal 26, to a top piece 27 which incorporates an axial channel 28 and a radial channel 29 and which is connected to a first body element 1' by means of a screw connection of the aforedescribed kind. The two body elements 1' are screwed together and include an axial channel 28 and a radial channel 29 and are joined to the bottom piece 16 by a screw joint. The bottom piece, in addition to the closure devices 19, also includes an axial channel 28 and an external screw-thread 30 and an O-ring 31, which allow a filter device 32 or extension 33 to be fitted to the body, as shown in Figures 6 and 7. The disc 20 comprises a radially stretched or tensioned septum and the support 21 comprises a washer or round plate 21. One aspect of use is illustrated in Figure 6, in which the reference 34 identifies an evacuated sampling tube and the reference 35 identifies a double needle or cannula which is intended to pierce the two septa in the screwbushing and a corresponding septum closure 36 in the tube. Figure 7 illustrates an arrangement which includes two filter elements 32 and a plurality of extension elements 33. The inventive method and the modus operandi of the inventive device will be understood in all essentials from the aforegoing. The body 1, optionally complemented in accordance with Figures 5, 6 or 7, is inserted, normally lowered, into a cavity 2, such as a pipe, tube or drill hole. Pressure is applied in the interior of the body, via a pressure line connected to the nipple 5, the screw bushing 23 or the like. As the pressure increases progressively, the device undergoes the stages illustrated in Figure 2, in which the O-rings 3, 3' are displaced radially outwards until the outer ring has been pressed out in the slot 10. When the pressure is removed, the inner sealing element 3' will spring back, essentially to its original starting position in the gap 6, whereas the outer sealing element 3 will remain in the slot 10 and therewith retain the function of a permanent seal between the body 1, and the interior of the cavity 2, i.e. the pipe, tube, drill hole or the like. As will be perceived from the above, the invention provides a highly purposeful solution to the problem of sealing a cavity of the kind in question. The invention has been described in the aforegoing with reference to exemplifying embodiments thereof. It will be understood, however, that other embodiments and minor changes are conceivable within the scope of the inventive concept. For instance, any desired number of sealing elements, such as O-rings, can be used in each gap. It has been found, however, that two elements will normally suffice. Furthermore, the number of gaps 6 in each body can be varied in comparison with, for instance, the two gaps illustrated in Figure 2, so that a seal is obtained at a desired number of levels in each body. Naturally, more than one body can also be used in one and the same cavity. In addition to those embodiments in which a sealing element iβ pressed into a slot 10 and prevented from returning into the gap, embodiments are also conceivable in which a sealing element is held in permanent sealing contact with the inner defining surface of the cavity 2, at least at times or intermittently, by means of a continuously applied internal pressure. Neither need the elongated, hollow cavities or the body have a circular cross-section, since the invention can be applied effectively with other cross-sectional shapes. For example, a square-section tube can be used and βealed in accordance with the invention. The present invention is thus not restricted to the aforesaid embodiments, but can be modified within the scope of the following claims.

Claims: CLAIMS 1. A method for sealing elongated hollow cavities, such as circular- cylindrical pipes, tubes, drill holes or the like, in which a body is placed in the cavity in sealing contact with the inner surface of the cavity, characterized in that at least one essentially annular, elastic sealing element (3) Bealingly mounted in a radially and circumferentially extending gap (6) present in the body (1) is caused to be urged radially outwards into sealing abutment with the inner surface (4) of the cavity (2), by means of pressure (p) applied internally of the body. 2. A method according to claim 1, characterized in that two mutually concentric essentially annular sealing elements (3, 3') are urged radially outwards, such that the outer (3) of said elements is brought into sealing abutment with the inner surface (4) of the cavity (2). 3. A method according to claim 1 or 2, characterized in that a permanent seal is effected by urging an outer sealing element (3) essentially com- pletely into a slot (10) extending peripherally and externally of the gap (6) while compressing the sealing element (3) axially, the opening (a) between the gap (6) and the slot (10) through which the sealing element (3) passes being smaller than the cross-sectional diameter, thickness, of the sealing element (3) in its non-compressed state, so that the sealing element iβ prevented from reentering the gap (6). 4. A method according to claim 1, 2 or 3, characterized in that said gap (6) is formed by means of two body elements (1'), each of which have a substantially concave end surface (11, 12) and which are joined together with said end surfaces facing one another, such as to form an outwardly narrowing gap (6) . 5. A method according to claim 1, 2, 3 or 4, characterized in that pressure is applied internally of the body (1) via at least one axial channel or passageway (7, 28) and at least one radial channel or passageway ( 8, 29 ) connecting an axial channel and said gap (6). 6. A method according to claim 1, 2, 3, 4 or 5, characterized in that a bottom connection (18) with said cavity (2) is opened by means of an internally applied pressure subsequent to urging a sealing element (3) outward into sealing abutment with the inner surface (4) of said cavity, wherewith a considerably higher pressure is required to open said connection than that required to establish said sealing abutment. 7. A method according to claim 6, characterized in that said connection is opened by pressing an internally mounted and peripherally supported elastic disc or plate (20) out through a central hole (22) in the disc support (21). 8. A method according to claim 1, 2, 4, 5, 6 or 7 characterized in that an outer sealing element (3) is held in permanent sealing abutment with the inner surface (4) of the cavity (2) by continuously maintaining an internal pressure. 9. A device for sealing-off elongated, hollow cavities, such as circular- cylindrical tubes or pipes, drill holes and the like, including a body which is intended to be brought into sealing contact with the inner surface of the cavity, characterized in that a substansially annular, elastic sealing element (3) is arranged sealingly in a gap (6) which extends radially and circumferentially in the body (1) , and in that channels or passageways (7, 8, 28, 29) are provided for applying in the interior of said body a pressure which is effective in urging said sealing element (.3) radially outwards into sealing abutment with the inner surface (4) of the cavity (2) . 10. A device according to claim 9, characterized in that two mutually concentric, substantially annular elastic sealing elements (3, 3') are mounted in the gap (6), an inner sealing element (3') being located inwardly of the outer sealing element (3) . 11. A device according to claim 9 or 10, characterized in that the gap (6) has located externally thereof a slot (10) which is connected to the gap through an opening (a) which has a smaller cross-dimensional diameter, thickness, than the outer element (3) in the non-compresBed stated of said element, the sealing element therewith being prevented from passing back into the gap subsequent to having been pressed essentially completely through εaid opening (a) and therewith, in appropriate cases, providing a permanent seal. 12. A device according to claim 9, 10 or 11, characterized in that said sealing element (3, 3') comprises O-rings. 13. A device according to claim 9, 10, 11 or 12, characterized in that said gap (6) narrows outwardly, wherewith an inner sealing element (3') located radially inwards of the outer sealing element (3) has a greater thickness than the outer element in the non-compressed state of the element. 14. A device according to claim 9, 10, 11, 12 or 13, characterized in that the device includes at least one axial, longitudinal, channel (7, 28) and at least one radial channel (8, 29) connecting the longitudinal channel with said gap (6), through which said gap is placed under pressure. 15. A device according to claim 9, 10, 11, 12, 13 or 14, characterized in that said gap (6) and preferably also said channels (7, 8, 28, 29) are configured by means of two body elements (l 1 ) each of which has a sub¬ stantially concave end surface (11, 12) and which are joined together, for instance by means of a screw joint (13), with said end surfaces facing towards one another to form a gap (6), such as an outwardly narrowing gap. 16. A device according to claim 11, 12, 13, 14 or 15, characterized in that the slot (10) located radially outwards of the gap (6) is configured by a peripheral lip (9) which extends circumferentially around each of said concave edge surfaces (11, 12). 17. A device according to claim 15 or 16, characterized in that said body elements (I 1 ) are mutually identical and of standard construction, and in that each element Cl') has provided on one end surface (11) thereof a central, preferably internally screw-threaded recess (14) and on its other end surface (12) a central, preferably externally screw-threaded stud (15) corresponding to said recess, such as to enable said two elements to be joined together, thereby to enable a selected number of body elements to be joined together sequentially and pairwise form a gap therebetween. 18. A device according to claim 9, 10, 11, 12, 13, 14, 15, 16 or 17 characterized in that said body has attached thereof a bottom piece (16) which forms a bottom closure which enables pressure to be built up and sustained in the body (1). 19. A device according to claim 18, characterized in that the bottom closure is constructed so that it can be opened by means of pressure applied internally of the body, such as to establish communication (18) between the interior of said body and said cavity (2), and includes closure members (19) which in order to be opened require the application of a considerably higher internal pressure than that required to establish a seal between the body (1) and said cavity (2) by urging the sealing element (3) into sealing abutment with the inner surface (4) of the cavity (2). 20. A device according to claim 19, characterized in that the closure members include an internally mounted elastic disc (20) which is supported peripherally by a support (21) incorporating a central hole (.22 ) through which the disc (20) can be pressed by applying pressure to the body in¬ terior. 21. A device according to claim 9, characterized in that there is included an outer sealing element (3) which is intended to be held permanently in sealing abutment with the inner surface (4) of the cavity (2) by means of a continuously sustained internal pressure.

Inventors: TORSTENSSON BENGT-ARNE, TORSTENSSON, BENGT-ARNE
Applicants: TORSTENSSON BENGT ARNE, TORSTENSSON, BENGT-ARNE
Application year: 1989
Main classification: E21B33
IPC codes: E21B33, F16L55