MOBILE TANK WALL SEALING SYSTEM

Abstract: A mobile tank sealing system is provided between the immobile upright tank wall (1) and a floating tank roof (7) which floats upon the liquid within the circumference of the tank wall in a vertical direction, also including an annular collar, known per se, of flexible cloth material (8), the inner circumferential edge (10) being interconnected to the outer circumference at the upper side of the tank roof and of which the outer circumferential edge is located at a higher level near the tank wall. The inventive improvement consists of an endless sealing profile (5) which is pressed in a direction mainly radially from the circumference of the tank roof against the tank wall along the entire circumference in a horizontal direction while exerting a nearly permanent pressure force, such by means of a spring system consisting of a great number of separate spring elements (14), each one end of a spring element being interconnected to or with the circumferential edge of the tank roof whereas the opposite end of the spring element is in direct connection to the endless sealing profile, which all along the tank wall maintains the seal between the tank wall and the profile by a nearly permanent pressure force.

Description: Sealing system for a storage tank provided with a floating roof. The invention relates to a mobile tank sealing system between the immobi upright tank wall and a floating tank roof which floats upon the liquid within t circumference of the tank wall in a vertical direction, also including an annul collar, known per se, of flexible cloth material, the inner circumferential edge bei interconnected to the outer circumference at the upper side of the tank roof a of which the outer circumferential edge is located at a higher level or not near t tank wall. Such a sealing system which is mobile in a vertical direction and which provided between the circumferential edge of the floating roof and the upright ta wall is indispensable for the storage of easily evaporating liquids, especially in t event these may diffuse an unpleasant and/or penetrating odour. A tank sealing system provided with a double sealing is known, consisting of first endless hollow sealing body, containing a liquid, which is provided around t circumference of the floating tank roof and a second annular sealing skirt whic is provided between the circumference of the tank wall and the inn circumference of the floating roof structure. At the one hand this sealing bod itself or a flexible slab between the tank wall and the sealing body scrapes again the tank wall causing considerable damages in the long run, amongst others a result of passing across welding seams, at the other hand the wall of the sealin body is subject to leakages on the long run, which of course strongly affects th effectiveness of the sealing. Despite the presence of a second additional sealing, e.g. shaped as an upwardl pointing and against the tank wall scraping flexible rain water and sand preventin profile, nevertheless during operation for usually large tank diameters, e.g. of 8 m, it appears that as a result of deformations, rust formation, frost, wear an leaking of the sealing element filled up with liquid, much rain water passe between the tank wall and the floating roof causing in occurring events also muc losses of vapour or gas. Furthermore the pressure force of the first sealing element which is exerted alon the circumference of the tank wall remains unchanged, that is to say, it does n adopt itself to changing conditions and if leakage occurs, the pressure force i almost reduced to zero, whereas as a result of repeatedly occurring uneve distances between the circumferential edge of the floating roof and the tank wal a constantly adjustable pressure force would be required. This not being the case just this latter circumstance alone causes already a very undesirable slo (deviations, deformations and remaining tensions) for the free passage of drippin rain water and sand dust respectively, which still more furthers the rust formatio of the tank wall and so the entire wear, including these of the indicated wear o the welding seams. It is the purpose of the invention to remove the disadvantages which occur wit the usual double sealing system by an endless sealing profile which is presse in a direction mainly radially away from the circumference of the tank roof agains the tank wall along the entire circumference in a horizontal direction while exertin a nearly permanent pressure force, such by means of a spring system consistin of a great number of separate spring elements, each one end of a spring elemen being interconnected to or with the circumferential edge of the tank roof wherea the opposite end of the spring element is in direct connection to the endles sealing profile, which all along the tank wall maintains the seal between the tan waif and the profile by a nearly permanent pressure force. In another embodiment of the invention the spring system consists of a grea number of oblong springs, these may be leaf springs but more particularly wir springs provide for a still greater freedom of movement in more directions, each outer end of which being tensioned between a point upon the sealing profil that is pressed against the tank wall and another point upon the circumferenti edge of the tank roof. In order to provide for a permanent pressure force it is advantageous if each spring bridges in a radial sense, the direct distance between th circumferential edge of the floating roof and the tank wall and if the entire lengt of each spring being a number of times greater than the slot distance which i bridged, particularly if the total length of the spring amounts at least three to fou times said slot distance. This advantage is also obtained in the event that in its tensioned position a sprin contains at least one loop shaped winding directing downward from a point at th circumferential edge of the floating roof and than runs nearly parallel in an upwar direction to the tank wall against which it is pressed under force along a relativel greater part of its total spring length. The same pressure force so being exerted upon the sealing profile, the out circumferential edge of the annular collar may be provided with an endless thickened rim and the sealing profile may be provided with a cavity f accommodating said rim. If the sealing profile has a C-shaped cross section may upwardly end into a nose shaped protrusion for carrying away rainwater an the like easily in a downward direction streaming especially if the cavity provide for the thickened rim is situated at a lower level and rainwater may easily pass i way down to the collar. Further advantages of various preferred embodiments of e.g. wire spring elemen which moreover may be subjected to torsion forces, in conjunction with in endle sealing profile which is provided with a relatively long tongue, will follow from th drawing. Fig. 1 shows schematically and in a cross sectional view A-A of fig. 3 a fir embodiment of the new sealing system according to the invention between a tan wall and a circumferential edge of a floating roof; Fig. 2 shows the same sealing as shown in fig. 1 in another position, the mutu distance between the tank wall and the circumferential edge of the floating ro being enlarged; Fig. 3 schematically shows a partial view seen from the tank roof in the directio of the upright tank wall; Fig. 4 shows a cross sectional view of an endless sealing profile; Fig. 5 is a partial cross sectional view A-A of fig. 6 of a tank wall and a tank ro under the application of spring elements and a sealing profile of fig. 4; Fig. 6 is a partial view, seen from the tank roof, of the connections between th sealing profile and the spring elements; Figs. 7 and 8 each show a partial cross sectional view A-A of fig. 9 at differe distances between the tank roof and the tank wall of a double spring structur and a double collar structure; Fig. 9 is a partial view from the tank roof in the direction of the tank wall an shows the double spring structure of the figs. 7 and 8; Figs. 10 and 11 also show in a partially cross sectional view a double sprin structure in use for crude oil storage tanks in which a scraper element i connected to the lowermost wire spring; Fig. 12 shows in front view a bearer element for the sealing profile which i connected to the wire spring and Fig. 13 shows a side view of the final shape of the bearer profile according to fig 12. According to the invention the sealing system, figs. 1 and 2, consists of a endless flexible sealing profile 2, pressed against the tank wall 1, in a cros sectional view being provided with an obliquely upwardly pointing nose whic sealingly presses against the tank wall 1 , a recessed portion 4 lying back from th tank wall 1 and further a convex portion 5, being a single sealing profile maintaining the effective sealing between the tank wall 1 and the circumferentia edge 6 of the floating roof 7, simultaneously applying an annular flexible skirt 8 known per se. This sealing skirt 8 consists e.g. of a weather resistant polyviny cloth, the inner circumference 10 being engaged to the circumferential edge 6 o the floating roof by means of connectors 9 in a mechanically sealing way, wherea the outer circumferential edge 11 has been provided with a thickened rim 1 which is connected to the profile 2 by means of an elastic cavity 13 accommodating this rim 11 all along its length in a strong and permanent manner The sealing profile is e.g. shaped from an extruded polymer material. The actua pressure force of the sealing profile 2 against the tank wall 1 is effected by a lon leaf spring 14, the portion 15 thereof lying over a relatively long distance agains the tank wall 1 and at its top portion 16 passing over in a connector 17 to th sealing profile 2. Downwardly the leaf spring 14 continues, via a curved part 1 subjected to additional spring force, into an upwardly pointing portion 19, pivotall connected by means of a pivot 20 to the outer circumferential edge 6 of th floating tank roof 7 thereby using a connecting element clampingly held by connector element 9, which consists of a welded bolt and a nut. The upper en 16 of the leaf spring 14 penetrates via a flat slot 22 into the lowermost leg of th C of the sealing profile 2 and until it accommodates the cavity of the C and ther it is e.g. connected to the middle portion of a spring 24 running in a horizont direction, by means of a pop nail 23. The length of this spring 24 is suchlike th the ends of two adjacent spring elements 24 just overlap, creating also betwee both leaf springs 14 there were the ends do overlap each other, an addition pressure force, particularly if these spring elements 24 are provided with a radiu which is opposite to the tank wall 1 facing them. The special feature of th permanency of the circumferential pressure force upon the sealing profile 2 wit respect to the tank wall 1 is a result of the fact that changes in the slot distan S to S' do indeed induce changes in the mutual distance between the portion of the leaf spring 14 and the edge of the tank roof, however, due to t operational momentum of the leaf spring 14, scarcely none or no chan respectively may occur in the pressure force which is exerted upon the seali profile 2. This operation is clearly visible in the drawing and consequently t abovementioned advantages are so created. If there is a desire to keep the clo material 8 more or less under tension, such may be effected by means of a sprin spanner 25 which e.g. is fixed to the lower end of the portion 16. At the opposi end of the spring spanner 25 there is provided a thickening portion 26 to preve local wear. The cloth material 8 is circumferential sealingly connected to the ta roof 7 by means of a number of flat rings 27, possibly also performable circumferential sectors. In other embodiments, see figs. 4-11 , the endless sealing profile 102 shaped an oblong tongue is chosen in preference of the firstmentioned convex profile The nose portion 103 of the tongue profile 102 presses against the tank wall 10 see fig. 5, showing a socalled Horton seal 104 provided with the invention. To th purpose a wire spring element 105, provided with a number wire turns 106 i connected with its lower end 107 to the uppermost portion 108 of the Horton se at the tank wall side 101. At its upper end the wire spring element 105 i connected to the sealing profile 102 by means of a bolted connection 109 whil using a bearer 110 shown in figs. 12 and 13. The wire spring element 105 has greater freedom of movement than under application of a leaf spring and it ca absorb torsion forces and move within the free central space 111 of the beare In the embodiment of figs. 7, 8 and 9 application is made of wire spring element 205 and 205' respectively in a double structure for pressure against the tank w in an upward and downward direction. The sealing structure against the tank w 201 is further nearly identical to that in fig. 5, with the difference that the ends the wire spring windings 206 are fixed to the tank roof 207 and thereby creat a perfect seal having a constant permanent pressure force. In a downwar direction the second wire spring element 205' is at the one hand with wir windings 206'connected to the tank roof 207, e.g. by means of an identical bo connection 209 and the lower end of the wire spring 205' is connected to secondary sealing body which presses circumferentially all around against the tan wall. The primary seal is provided by the sealing profile 202 in cooperation with the usual collar 208 and downwardly a collar 208' also completes the seal between the tank roof 207 and the tank wall 201 thereby restricting vapour losses and odour leakages respectively to a minimum. Also in fig. 8 the position is shown of the spring elements 205 and 205' in which a relatively long portion of each spring element nearly runs parallelly to the tank wall 201 so maintaining, while using the spring windings 206 and 206', a permanent pressure force. Likewise to the upper end of the wire spring 205, also the lower end of the wire spring 205'is connected to a runner 212 sliding up and down along the tank wall 201. In the fig. a runner structure is shown which does not form part of the invention. These wire springs may also be subjected to torsion forces which, during operation appear very advantageous. In figs.10 and 11 a similar double spring structure is shown as in figs. 7 and 8, the lower end of the wire spring element 305' being provided with a scraper 312. This application e.g. is particularly adapted for sealing of crude oil storage tanks enabling the highly viscous oil easily to be scraped from the tank wall. In figs. 12 and 13 the bearer 110 for the endless sealing profile is shown in developed manner. The rectangular portion 112 has been ultimately bent, se fig. 13, and is provided with an opening 113 to put through a connecting bolt 10 for the connection between the sealing profile 102 and the wire spring 105 havin also sidewise and vertically freedom of movement within the recessed triangula opening 111 of the bearer in its shape shown in fig. 13. As a result of th available wire windings 106, e.g. two or three, provided for in the wire spring 105 the latter may absorb torsion forces resulting from the movements of the tan roof, thereby realizing under all circumstances the permanent pressure force. If necessary, the fixation of the two wire springs 405 and 405' respectively ma also find place upon the horizontal edge flange of the tank roof 407, creatin constructional advantages, e.g. in building height and/or in slot distance. Patent Claims

Claims: Patent Claims 1. Mobile tank sealing system between the immobile upright tank wall and floating tank roof which floats upon the liquid within the circumference of the ta wall in a vertical direction, also including an annular collar, known per se, flexible cloth material, the inner circumferential edge being interconnected to t outer circumference at the upper side of the tank roof and of which the ou circumferential edge is located at a higher level near the tank wall, characteriz in that an endless sealing profile is pressed in a direction mainly radially from t circumference of the tank roof against the tank wall along the entire circumferen in a horizontal direction while exerting a nearly permanent pressure force, such means of a spring system consisting of a great number of separate spri elements, each one end of a spring element being interconnected to or with t circumferential edge of the tank roof whereas the opposite end of the spri element is in direct connection to the endless sealing profile, which all along t tank wall maintains the seal between the tank wall and the profile by a nea permanent pressure force. 2. Tank sealing system according to claim 1, characterized in that the spri system consists of a great number of oblong springs, each outer end of whi being tensioned between a point at the sealing profile that is pressed against t tank wall and another point upon the circumferential edge of the tank roof. 3. Tank sealing system according to claim 2, characterized in that at least se in a vertical top view, each spring bridges in a radial sense, the direct distan between the circumferential edge and the tank wall and the entire length of ea spring being a number of times greater than the distance bridged. 4. Tank sealing system according to any one of the foregoing claim characterized in that the total length of the spring amounts at least three to fo times the said distance. 5. Tank sealing system according to anyone of the foregoing claims, characterize in that in its tensioned position a spring contains at least one loop shaped windin whereas the part of the spring which is connected to this winding and in th presence of a small slot distance, runs nearly parallel to the tank wall for relatively greater part of its total spring length. 6. Tank sealing system according to anyone of the foregoing claims, characterize in that each leaf spring at its connection to the sealing profile and/or an addition scraper element and at a changing slot distance and as a result of a nearl permanent lever arm and when the mutual distance between the tank roof and th tank wall radially becomes uneven, yet permanently exerts the same nominal valu of pressure moment. 7. Tank sealing system according to any of the foregoing claims, characterized i that the outer circumferential edge of the annular collar is provided with a endless thickened rim, the sealing profile being provided with a cavity havin resilient edge portions for accomodating and clamping the said thickened rim. 8. Tank sealing system according to claim 7, characterized in that the endles sealing profile is of C-shaped cross section and is further provided with a shape protrusion which points upwards for carrying away the rainwater streamin downward from the tank wall. 9. Tank sealing system according to claim 8, characterized in that the nos shaped protrusion is situated at a higher level upon the upper portion of the than the cavity including the rim thickening and which is situated at a lower leve in such a manner, that rainwater being collected on the upper side of the profil is enabled to stream over upon the annular collar. 10. Tank sealing system according to any of the foregoing claims, characterize in that the spring and consequently the loop shaped winding of its outer en which is connected to the tank roof can move between two extreme positions, t sealing profile being permanently pressed by constant force against the tank wa that is to say at either side of a vertical plane that perpendicularly intersects t radial plane which contains the axis of the leaf spring. 11. Tank sealing system according to claim 10, characterized in that the annu collar is kept in a tensioned position by means of a number of spring spanne each being fixed upon the spring at the location of the sealing profile and bringi the collar under tension in a direction away from the tank wall in the event o change in the distance of the slot between the tank wall and tank roof. 12. Tank sealing system according to any one of the foregoing claio characterized in that at the inner side of the C there is provided a spring spann strip which exerts a horizontal pressure force in horizontal direction and ea spring spanner strip having such a length that spring spanner strips of ea adjacent pair of springs to which they are fixed, do overlap partially. 13. Tank sealing system according to claim 12, characterized in that the length the spring portion which is in close contact with the tank wall, is greater or at t most equal to the remaining length of the spring which is located between t point of fixation upon the tank roof and its lowest point of contact with the ta wall. 14. Sealing profile to be used for a mobile tank sealing system, consisting of a characterized by an endlessly connectable elastomere sealing profile which provided at least at its upper side facing the tank wall with a nose-shap protrusion which in a downward direction merges into a convex portion whic likewise to the protrusion, should press against the tank wall while in operati with a nearly constant pressure force during the upward and downward moveme respectively of the tank roof. 15. Sealing profile according to claim 14, characterized in that means are provid along a great number of locations along the inner circumference of this profile f interconnecting each time the one outer end of an oblong leaf spring element a direction perpendicular with respect to said profile and the other outer e thereof while creating a spring loop to the tank roof. 16. The combination of a sealing profile according to any one of the claims 14 15 and an annular collar known per se, characterized in that there is provided hollow cavity in the inner circumferential side of the sealing profile for clampingl accomodating a thickened rim collar. 17. Sealing profile according to any one of the foregoing claims, characterized i that along the inner circumference of the sealing profile there are provided number of partially and longitudinally overlapping prestressed spring element which are each fixed upon the upper end of a spring. 18. Spring element in use for a tank sealing system according to any of th foregoing claims, characterized in that it is performed as an oblong leaf sprin element which in its operational position is mounted while creating a loop. 19. Spring element in use for a tank sealing system according to any one of th foregoing claims 1-18, characterized in that it is performed as an oblong threade spring element which is at least provided at one end with a number of sprin windings, preferably two or three. 20. Tank sealing system according to any of the foregoing claims, characterize in that the spring elements for exerting a pressure force upon the sealing profil and the scraper profile are alternately pointing in an upward and downwar direction with respect to the edge of the tank roof. 21. Method for sealing of a changing slot between a fixed tank wall and a floatin tank roof while additional use is made of an annular collar of flexible materia known per se, characterized in that the collar is stretched between its fixatio along the inner circumference of the tank roof and its clamped accomodatio along the outer circumference in a mobile and along the tank wall in an upwar and downward direction moving sealing profile and upon this sealing profile b exerting a moment having a long lever arm via springs which are provided of least one loop shaped winding, in such a manner that in a radial direction to th tank wall a nearly permanent and constant force pressure is exerted upon th sealing profile and/or a wall scraper profile which pressure is permanent maintained despite a change in the slot distance.

Inventors: FABER ALEXANDER, VAN DER KUIL PIET HUGO ALPHONS, FABER, ALEXANDER, VAN DER KUIL, PIET, HUGO, ALPHONSUS
Applicants: FABER ALEXANDER, KUIL PIET HUGO ALPHONSUS V D, FABER, ALEXANDER, VAN DER KUIL, PIET, HUGO, ALPHONSUS
Application year: 1990
Main classification: B65D88
IPC codes: B65D88