HIGH-PRESSURE LEADTHROUGH APPARATUS

Abstract: A high-pressure leadthrough apparatus for leading conductors (1) into pressurized systems. The apparatus comprises a housing member (2), which contains a conductor duct (3) connected to the pressurized space and opening onto the surface of the housing member; a screw unit (5) which closes the duct and is provided with threadings and a hole (4) for the conductor; as well as a screw unit chamber (6) larger in diameter than the duct, into which chamber the screw unit can be tightly screwn. According to the invention, the screw unit (5) is formed of a structure combination comprising a threaded bolt (7) which can be screwed into the screw unit chamber (6); a slip plate (8) supported against the bottom of the bolt and reducing tensional friction; a top support plate (9) supported against the slip plate; a bottom support plate (11) resting against the bottom (14) of the screw unit chamber (6), the bottom (14) being perpendicular to the conductor duct (3); as well as sealing (10) provided in between the top and bottom support plates; all of which are provided with holes (4) essentially corresponding to the diameter of the employed conductor.

Description: HIGH-PRESSURE LEADTHROUGH APPARATUS The present invention relates to a high- pressure leadthrough apparatus, defined in the introductory statement of the patent claim 1, for leading conductors, measuring sensors and the like into spaces under high pressure (over 500 bar). The published patent application PCT/US82/01024 introduces a stuffing tube to be used in ships for extending cables in a waterproof fashion through the bulkheads of ships. The apparatus described in the publication is not suited for leadthroughs into pressurized facilities owing to its asymmetric sealing structure and its tensioning arrangement, which does not allow for a sufficiently high tension required by high pressure. Similarly, the apparatus is not suited for single conductors and sensors, but is mainly designed for thick cables. The Finnish patent 70349 and the German publication prints 3 002 127 and 3 136 370 disclose various leadthrough arrangements, whereby conductors and the like can be compactly extended to pressurized areas. However, these have their drawbacks when using the equipment under high pressure (e.g. over 500 bar). Although the said apparatuses are self-tensioning along with the growing pressure, it is possible that minor leakages may occur in high pressure, and these must be immediately blocked or else the leakage may bite a larger hole and a thus cause more serious damage. The apparatuses introduced in the said publications are, however, either troublesome or outright impossible to be retensioned under high pressure, because - due to many adjuster bolts - in high pressure they may develop slanted loads, which may damage or even break the adjuster bolts. Another drawback in the above mentioned apparatuses is the fact that the sensitive conductors and sensors may be bent under high pressure and therefore damaged. Yet another drawback is the difficulty in leading through conductors and sensors with varying diameters and sizes. Yet another drawback is that a possible leakage or other defect occurring in a single leadthrough or conductor affects the use of the whole leadthrough system. The object of the present invention is to eliminate some of the aforementioned drawbacks. A particular object of the invention is to introduce a leadthrough apparatus for conductors, by means of which one or several conductors can reliably and safely be extended into pressurized facilities, and by means of which any malfunctions occurring in one single conductor can be eliminated without disturbing other conductors, and by means of which in principle an unlimited number of conductors of varying thicknesses can be lead into pressurized spaces. As regards the characteristic novel features of the invention, the appended patent claims are referred to. The high-pressure leadthrough apparatus of the invention comprises a housing member provided with a conductor duct connected to the pressurized space and opening onto the surface of the housing member. The end of the duct is provided with a screw unit chamber, larger in diameter than the duct itself, whereinto a threaded screw unit can be screwed in order to close the duct. In the middle of the screw unit, there is provided a hole, essentially corresponding to the employed conductor in diameter, wherethrough the conductor can be inserted. In accordance with the invention, the screw unit is formed by a combined construction comprising a threaded bolt which can be screwed into the screw unit chamber; a slip plate supported against the bottom end of the bolt and reducing tensional friction; a bottom support plate resting against the bottom which is perpendicular to the conductor duct of the screw unit chamber; and sealing provided in between the slip plate and the bottom support plate. All of the above mentioned members are essentially provided with holes corresponding to the diameter of the particular conductor in question. Advantageously the sealing is formed of several sheet-like superposed sealing plates to be installed tightly on top of each other, which in the rest position are evenly in contact with the walls of the screw unit chamber, while the conductor passing through them is in contact with the sealing plates in an essentially compact fashion, the diameters of the holes corresponding to the diameter of the conductor. Thus a slight winding of the screw unit causes a tight grip, so that the sealing is pressed both against the conductor and the screw unit chamber walls. In between the slip plate and the sealing, there is advantageously provided a top support plate corresponding to the bottom support plate, in which case the sealing is compressed in between two strong support plates while the bolt is being screwed. The slip plate arranged between the screw unit and the top support plate is advantageously a teflon ring, which enables the screw unit to be wound and the leadthrough to be sealed even with high pressures so that the conductor and the sealing are not subject to winding and damaging strains. In a modification of the invention, the slip plate is formed by a coating provided on the bottom surface of the bolt and/or on the top surface of the top support plate, for instance a teflon layer, which functions in the above described manner. In a preferred embodiment of the invention, the housing member comprises several conductor ducts, each provided with a screw unit construction according to the present invention, so that the conductor ducts are in the housing member connected into one common main duct leading to the pressurized space. Advantageously the housing member comprises a conical outer surface narrowing in the direction away from the pressurized space, onto which surface the conductor ducts are vertically opened, so that within the housing member they are united radially and in a rounded fashion to the common main duct, which leads to the pressurized space. One housing frame may advantageously contain several superposed conical surfaces, in which case one conical surface may contain, depending on the radius thereof, for instance six screw units, while the conductors of possibly different diameters pass through separate screw units of separate conical surfaces and through the common main duct into the pressurized space. Among the advantages of the present invention with respect to the prior art, let us point out the simplicity in construction, the security in operation as well as the possibility to employ, in one and the same leadthrough, conductors and sensors of different diameters only by replacing the screw unit chamber parts with ones that have holes of the correct size. Another advantage is that the conductors to be lead through proceed in a straight line without the bends and curves occurring in the apparatuses of the prior art, which curves may cause damage to the conductors in high pressure. Yet another advantage is the possibility to readjust and increase the tension even under high pressure in a symmetrical and even fashion, without creating slanted and asymmetrical forces that cause damage to the apparatus and the conductor. If the sensor or the conductors are damaged or otherwise made inoperable, the apparatus can be tensioned even to such degree that the conductor is cut and the conductor duct closed, in which case it does not interfere with the rest of the leadthrough arrangements in use. Yet another advantage is the small diameter of the conductor duct, which is possible owing to the apparatus of the invention, so that the force affecting the screw unit is reduced to the minimum, and consequently the pressure endurance is further increased. In addition to these, yet another advantage is the nearly incompressible support plate - sealing - support plate structure, where the employed sealing is made of some nearly incompressible material, which under the pressure is tightly pressed against the conductor and the screw unit walls. Thus the tensioning of the bolt can be carried out at a short distance and takes place quickly, which is important in repair and leakage situations. In the following the invention is explained in more detail with reference to the appended drawings, where figure 1 illustrates a leadthrough apparatus according to the invention, and figure 2 illustrates another leadthrough apparatus of the invention. The leadthrough apparatus of the invention comprises the conductor duct 3 provided in the housing member 2, at the end of which duct there is provided the screw unit chamber 6, larger in diameter than the conductor duct 3, which screw unit chamber 6 is provided with threadings so that the bolt 7 can be screwed therein. The bottom 14 of the screw unit chamber 6 forms a vertical, planar surface with reference to the conductor duct, and in between the bottom and the bolt there is provided the following structure. Against the bottom lies the bottom support plate 11, advantageously a metal plate, whereupon lies the sealing layer 10 composed of several similar sealing plates 13. On top of the sealing, there is provided the top support plate 9, advantageously a metal plate, and in between this plate and the bolt there is fitted the slip plate 8, which can be made of for instance teflon, and the purpose whereof is to reduce friction in between the sealing layer and the bolt so that the bolt can be screwed even under high pressure without damaging the sealing by the winding. The members 8, 9, 10 and 11 are matched so that they are arranged in the screw unit chamber in an essentially close contact with the chamber walls, and that all of them as well as the bolt are provided ln the middle with a hole which has a diameter corresponding to the diameter of the employed conductor to be inserted through them, so that the conductor is just passable therethrough and sets tightly in the hole 4. The members 7 - 11 can then be replaced according to the needs of the situation so that the holes provided in them correspond to the conductor in use. The screw unit 7 advantageously comprises a hole 12 which extends towards the stem, so that only the bottom part 17 thereof is provided with the smaller hole 4 corresponding to the employed conductor 1. This arrangement is advantageous both as regards manufacturing techniques and from the point of view that it allows a flexible and slight bending of the conductor and prevents the conductor from breaking at the compact edge 18, which damage would be obvious if the tight hole would continue up to the end of the bolt. The leadthrough apparatus of the present Invention illustrated in figure 2 comprises the housing member 2, which contains two conical outer surfaces 16 narrowing in the direction away from the pressurized space, both of which surfaces are provided with six leadthrough devices illustrated in figure 1, each of the conductor ducts 3 thereof being connected in a downwards inclined and rounded fashion to the main duct 15 provided in the middle of the housing member. Thus even a high pressure effective in the thin conductor ducts 3 does not cause strong forces to be directed against the screw unit structures, and each conductor is successfully lead into the pressurized space essentially straight and free of slanted and bending pressure forces . The housing member can be provided with several superposed conical surfaces according to the needs of the situation and/or the diameter of the conical surface can be enlarged so that more leadthroughs can be fitted in one and the same surface. In practice the apparatus of the present invention was tested under the pressure of 1000 bar and with housing members provided with 3 conical surfaces, each surface with 6 leadthroughs. Several similar housing members were connected to a pressurized space, the total amount of the leadthroughs was over 150, and the test measurements did not reveal any leakages or damages with different conductors and sensors of varying thicknesses . In the above specification, the invention has been explained in detail with reference to a few preferred embodiments thereof, which dp not in any way limit the invention, but the various modifications thereof may vary within the scope of the inventional idea defined in the appended patent claims.

Claims: PATENT CLAIMS 1. A high-pressure leadthrough apparatus for leading conductors (1) into pressurized systems, which apparatus comprises a housing member (2) containing a conductor duct (3) connected to the pressurized space and opening onto the surface of the housing member; a screw unit (5) which closes the duct and is provided with threadings and a hole (4) for the conductor; as well as a screw unit chamber (6) larger in diameter than the duct, whereto the screw unit can be tightly screwed, c h a r a c t e r i z e d in that the screw unit (5) is formed of a structure combination comprising - a threaded bolt (7) which can be screwed into the screw unit chamber (6); - a slip plate (8) which is supported against the bottom of the bolt and reduces tensional friction; - a bottom support plate (11) which rests against the bottom (14) of the screw unit chamber (6), the bottom (14) being perpendicular to the conductor duct (3); - a sealing (10) fitted in between the slip plate and the bottom support plate; - all of which are essentially provided with holes (4) corresponding to the diameter of the employed conductor. 2. The apparatus of claim 1, c h a r a c ¬ t e r i z e d in that the sealing (10) is composed of several superposed sealing plates (13). 3. The apparatus of claim 1 or 2, c h a ¬ r a c t e r i z e d in that in between the slip plate (8) and the sealing (10) there is provided a top support plate (9). 4. The apparatus of any of the claims 1 - 3, c h a r a c t e r i z e d in that the slip plate (8) is a teflon ring. 5. The apparatus of any of the claims 1 - 4, c h a r a c t e r i z e d in that the slip plate (8) is formed of a coating provided on the bottom surface of the bolt (7) and/or on the top support plate (9). 6. The apparatus of any of the claims 1 - 5, c h a r a c t e r i z e d in that the housing member comprises several conductor ducts (3) which are combined into one common main duct (15) leading to the pressurized space. 7. The apparatus of claim 6, c h a r a c ¬ t e r i z e d in that the housing member (2) comprises a conical outer surface (16) narrowing in the direction away from the pressurized space, whereto the conducter ducts (3) are opened while they are combined in a radial and rounded fashion to the main duct (15).

Inventors: SELIN LAURI, SELIN, LAURI
Applicants: VALTION TEKNILLINEN, VALTION TEKNILLINEN TUTKIMUSKESKUS
Application year: 1987
Main classification: H02G3
IPC codes: H01B17, H01R13, H02G3