EP0080130A1 - Sealing means for the annular space between a container wall and the floating roof of a large storage container - Google Patents

Abstract

1. Device for sealing the annular gap (3, 3') between a vertical container wall (1, 1') and a floating cover (4, 4') of a large storage container, especially of a floating roof tank or of a fixed roof tank with internal floating cover, consisting of a plurality of narrow spring strips (6, 6'), fixed at uniform intervals adjacent to one another to the periphery of the floating cover (4, 4'), which are orientated with their free ends resiliently against the tank wall (1, 1'), bridge across the annular gap (3, 3') while bending elastically and press an elastic sealing profile (14, 14') fixed to their free ends onto the container wall along a circumferential line, the annular gap being closed by a sealing apron (9, 9'), extending around the entire annular gap between the sealing profile (14, 14') and the floating cover (4, 4'), characterized in that, a plurality of adjacent spring strips (6, 6') are connected at their free ends to a seating profile member (10, 10'), open towards the tank wall (1), to form each spring unit, that the sealing profile is formed of a plurality of soft foam elements (14, 14') bearing against one another, around which the sealing apron (9, 9') is wrapped against the tank wall, and that each soft foam element (14, 14') is pressed onto the tank wall by a plurality of seating profile members (10, 10') situated closely against one another.

Description

The invention relates to a device for sealing the annular gap between the vertical container wall and the floating cover of a large-capacity container, in particular a floating roof tank or a fixed roof tank with an internal floating cover, consisting of a large number of narrow spring bands attached to one another at regular intervals on the circumference of the floating cover and resilient with their free ends are directed against the tank wall and press an elastic sealing profile fastened at their free ends along a circumferential line against the container wall, the annular gap being closed by a sealing apron which runs around the entire annular gap between the sealing profile and the floating cover.

Such annular gap seals are mainly used for the storage of volatile, liquid refinery products and chemicals to avoid evaporation losses and the accumulation of dangerous vapors. The annular gap required for the vertical movement of the floating cover between the vertical tank wall and the floating ceiling must be closed by an elastic sealing element which is capable of operating-related changes in the annular gap width as well as severe out-of-roundness leveling and bulging of the tank wall and thereby preventing the escape of product vapors or the ingress of rainwater as far as possible.

Another important task of the annular gap seal is to ensure that the free-floating cover is adequately centered, which is to ensure trouble-free vertical movement without local overloading or tilting. However, especially for use on lightweight floating ceilings with lower buoyancy, the frictional forces emanating from the annular gap seal must not become so great that there is a risk of the floating cover getting caught or being flooded by stored product.

Ideally, the annular gap seal should be able to exert a uniformly strong centering effect over the entire circumference of the tank, be able to easily compensate for deviations in the annular gap width by means of eccentricity, out-of-roundness and bumps with the help of sufficient spring travel, cover even smaller imperfections and unevenness of the tank wall by means of wide-area and elastic adjustment and as wear-resistant as possible have outer shell. In addition, the materials used should be extremely resistant, both to the storage media and to weather conditions.

In practice, these complex requirements are attempted to be met by attaching an elastic sealing element to the outer edge of the floating cover, which is adapted to the respective annular gap width by spring forces (DE-OS 27 30 546), by gravity (Bulletin No. 3200 from 1976 by Chicago Bridge &

Iron Company), by internal tension (US Pat. No. 3,795,339) or by hydraulic forces (US Pat. No. 3,173,291) and the gap is closed by a circumferential, flexible sealing apron or an elastic hose filled with liquid or plastic foam.

Annular gap seals for floating roof tanks are usually subdivided into a primary seal and a secondary seal, whereby the primary seal facing the stored product is intended to retain the majority of the product vapors and the secondary seal directed against the atmosphere is intended to prevent the ingress of rainwater in addition to improving the overall sealing effect. In contrast, annular gap seals for indoor floating ceilings in fixed roof tanks only have the task of limiting product emissions.

The following basic designs are known among the newer secondary seals for floating roof tanks: spring-pressed lip seals (US Pat. No. 4,116,358), spring-reinforced rubber aprons (DE-OS 28 32 978), lip seals made of polyurethane elastomer (publication EKT 0028-3-79 from Elastogran) and resiliently pressed foam pads with abrasion-resistant covering.

Lip seals have the disadvantage that they only seal along a narrow and relatively stiff lip, whereby sharp bumps, for example vertical weld seams, cannot be sealed and there is often the risk of being turned inside out, for example on horizontal weld seams. Spring-reinforced rubber aprons are also relatively stiff, so they cannot adequately seal vertical welds and are also at risk of being turned inside out. Resiliently pressed foam pads with an abrasion-resistant covering have the best chance of ensuring a seal with particular effectiveness and operational safety thanks to their high deformability, wide sealing surface and well-rounded outer shapes. Unsatisfactory in known designs of this type is the often insufficient corrosion resistance and long-term durability of the spring elements used and the resulting limitation of the possible spring travel.

To date, no optimal solutions have been known for sealing light indoor floating ceilings in fixed roof tanks. The known primary seals for floating roof tanks are too heavy for this application and result in excessive frictional forces. The frequently used lip seals made of polyurethane elastomer do not offer a sufficient sealing surface and cannot guarantee complete sealing and even centering of the floating cover due to the risk of being turned over, especially since the sealing is usually not turned over the entire circumference of the tank.

In a known annular gap seal of the type described at the beginning (DE-AS 23 58 636), leaf springs are provided as spring bands, which are arranged at large mutual distances, which means that thick spring bands are required. These thick spring bands are relatively stiff, offer considerable resistance to the elastic deformation and press the sealing profile at points onto the container wall. Due to the stiffness of the spring bands, the assembly of this known annular gap seal is very difficult. The outer ends of the spring bands are pointed at an acute angle to the tank wall, which means that the hard sealing profile, which has only relatively small cross-sectional dimensions, can easily get stuck during vertical movements of the floating cover. In addition, the known annular gap seal is designed only for the simultaneous primary and secondary sealing of a floating roof tank, the prestressing of the leaf spring legs lying up and down should be adjustable by a central fastening screw engaging in a vertical wall of the floating cover. The attachment of the mounting holes required for this in the vertical wall of the floating cover is undesirable because such holes can cause leaks in the floating body. In addition, the attachment points are no longer accessible after attaching the sealing apron, so that later spring settings only appear possible after removing the apron.

The invention has for its object to provide a preferably usable as a secondary seal for floating roof tanks and as an annular gap seal for internal floating ceilings of fixed roof tanks, which avoids the disadvantages of the known designs, especially with relatively low frictional forces, and uniform centering effect for the floating cover a maximum of flexibility, Sealing effect and operational safety with low corrosion sensitivity of the components used.

Starting from the genus mentioned at the outset, this object is achieved by the present invention in that the spring strips are formed from thin, closely spaced strips of a corrosion-resistant and permanently resilient material, with their ends facing the floating cover are fastened to this approximately horizontally and below elastic deflection span the annular gap so that a spring band at its free end or a plurality of adjacent spring bands (6, 6 ') is or are connected at their free ends to a receiving profile piece (10, 10') open towards the tank wall, and that along A plurality of foam elements are arranged along the circumference of the container, which are butted against one another, each foam element being pressed against the tank wall by a plurality of receiving profile pieces (10, 10 ') sitting closely next to one another.

The annular gap seal according to the invention has a permanently high spring elasticity and a uniform centering effect for the floating cover. The contact forces generated by the spring bands are evenly transmitted to the foam elements by means of the almost completely continuous receiving profile pieces.

The wide and soft elastic pressure of the outer sealing body ensures a high sealing effect with low frictional forces. Due to the spring bands that run practically parallel to the tank wall due to their deflection and the voluminous, soft and rounded outer sealing body, the risk of everting is eliminated. The individual spring straps are easily accessible without dismantling the sealing apron.

The arrangement is advantageously such that the receiving profile pieces have a substantially C-shaped cross section and an approximately perpendicular flange to the profile opening, to which the free ends of the spring strips are attached. The cross-sectional design of the receiving profile pieces allows easy attachment of the individual foam elements to be joined into a ring, the flange which adjoins the profile opening approximately vertically allowing attachment to the free ends of the spring bands such that the spring bands are aligned with these free ends practically parallel to the tank wall, whereby a considerable radially directed elasticity of the annular gap seal is achieved without the risk of being turned inside out or getting caught. For the attachment of the foam elements, it is advantageous if the free ends of the spring strips protrude into the profile opening of the receiving profile pieces and, together with an opposing profile bend, form a claw-like holder for the foam elements.

To achieve a defined contact of the foam elements on the container wall, the foam elements are preferably designed for use on a secondary seal in such a way that they are chamfered in cross-section on their side facing the tank wall in such a way that they have the shape of an upward direction when not pressed have blunt wedges. The chamfer ensures that the top edge of the outer sealing body is always pressed firmly against the tank wall, even when the gap narrows, and a sufficiently wide sealing surface is created. The free ends of two to six adjacent spring bands are expediently fastened to a receiving profile piece. Here, two to six spring bands and a receiving profile piece form a spring unit.

In the pursuit of the inventive concept it is provided that the spring strips are made of stainless spring steel sheet and the receiving profile pieces made of stainless steel sheet.

• Fig. 1 eine perspektivische Schnittansicht einer Ringspaltabdichtung als Sekundärdichtung eines Schwimmdachtanks.
• Fig. 2 einen Schnitt durch eine Ringspaltabdichtung an einer Innenschwimmdecke eines Festdachtanks und
• Fig. 3 einen Querschnitt durch das in;Verbindung mit der Sekundärabdichtung gem. Fig. 1 verwendete Schaumstoffelement.

Further details are explained in more detail below with reference to the drawings illustrating the exemplary embodiments. It shows:

• Fig. 1 is a perspective sectional view of an annular gap seal as a secondary seal of a floating roof tank.
• Fig. 2 shows a section through an annular gap seal on an inner floating ceiling of a fixed roof tank and
• Fig. 3 shows a cross section in accordance with; in connection with the secondary seal. Fig. 1 used foam element.

1 shows the vertical container wall 1 of a floating roof tank, which bears the annular gap seal, generally designated by the reference number 2, which bridges the annular gap 3 between the container wall 1 and the floating roof 4. The annular gap seal 2 is used above a conventional primary seal, not shown. On the horizontally inward Flange 5 of the floating roof 4, the thin and closely spaced spring bands 6 are fastened by means of screws 7 and with the interposition of a terminal block 8. The sealing apron 9, which runs endlessly around the entire annular gap, is fastened on the one hand to the receiving profile pieces 10, is knocked against the tank wall around the foam elements 14 and is fastened at the other end to the horizontal flange 5. The spring strips 6 consist of approximately 1 mm thick and approximately 100 to 200 mm wide sheet metal strips made of stainless spring steel.

In the example shown, three spring bands 6 are combined to form a spring element by a receiving profile piece 10 with a C-shaped cross section. The receiving profile pieces 10 have an approximately perpendicular to the profile opening flange 11, to which the free ends of the spring bands 6 are attached at 12 from the outside. The spring strips 6 are connected to the receiving profile pieces 10 in such a way that a short end piece 13 of the spring strips projects into the C-profile and holds the foam elements 14 in a claw-like manner in cooperation with an opposite profile bend 15.

The foam elements 14, each passing through a plurality of receiving profile pieces 10 and made from a flexible polyurethane foam, have an approximately square, rectangular or rhombic cross section, for example the cross section shown in FIG. 3. As can be seen from Fig. 3, the foam elements 14 are provided on their side facing the tank wall with a chamfer 16, so that the shape of an upward blunt wedge is formed. This ensures that the outer sealing body always rests with its upper edge on the tank wall 1 even when the gap has become narrower and that the water running down the tank wall in rain is pushed away from the tank wall without a larger storage space being able to form over the seal.

The sealing apron 9 is made of a fabric-reinforced rubber material or plastic with high flexibility and abrasion resistance. In addition to the attachment to the floating roof 4 already described, the sealing apron 9 is attached to the rear of the receiving profile pieces 10 by means of adhesive strips 17 at 18.

2 shows the annular gap seal 2 'between the vertical container wall 1' and the inner floating ceiling 4 'of a fixed roof tank, the fill level of which is indicated by the level line 19. Comparable components are designated with the reference numbers used for FIG. 1, which, however, are provided with an index line. The spring bands 6 'are bent downwards against the tank wall 1'. The foam elements 14 'have an approximately square cross section in the unpressed form. In this example, the sealing apron 9 'is clamped at the connection point between the flange 11' and the spring strips 6 'by means of clamping strips 17', folded down around the foam elements 14 'and below the spring strips 6' on the outer edge flange 5 ' Inner floating ceiling 4 'fastened by screws 7' and terminal strips 8 '.

Claims (7)

1.Device for sealing the annular gap between the vertical container wall and the floating cover of a large-capacity container, in particular a floating roof tank or a fixed roof tank with an internal floating ceiling, consisting of a large number of narrow spring bands attached to one another at equal intervals along the circumference of the floating cover, the free ends of which resiliently against the Tank wall are directed and press an elastic sealing profile attached to their free ends along a circumferential line against the tank wall, the annular gap. is closed by a sealing apron that runs around the entire annular gap between the sealing profile and the floating cover,
characterized,
that the spring strips (6, 6 ') are formed from thin, closely spaced strips of a corrosion-resistant and permanently resilient material, with their ends facing the floating cover (4, 4') at this approximately are fastened horizontally and span the annular gap (3, 3 ') with elastic deflection,
that a spring band at its free end or a plurality of adjacent spring bands (6, 6 ') is or are connected at their free ends to a receiving profile piece (10, 10') open towards the tank wall,
and that a plurality of foam elements (14, 14 ') are arranged along the circumference of the container, which are butted against one another, each foam element being pressed against the tank wall by a plurality of receiving profile pieces (10, 10') sitting closely next to one another. 2. Device according to claim 1, characterized in that the receiving profile pieces (10, 10 ') have a substantially C-shaped cross section and an approximately perpendicular to the profile opening flange (11, 11'), on which the free ends of the Spring bands (6, 6 ') are attached. 3. Device according to claims 1 and 2, characterized in that the free ends of the spring bands (6, 6 ') protrude into the profile opening of the receiving profile pieces (10, 10') (13, 13 ') and together with an opposite profile bend ( 15, 15 ') form a claw-like holder for the foam elements (14, 14'). 4. Device according to one of claims 1 to 3, characterized in that the foam elements - (14) for use on a secondary seal seen in cross section on their side facing the tank wall (1) are chamfered (16) that they are in Unpressed state in the form of an upward blunt wedge. 5. Device according to one of claims 1 to 4, characterized in that the foam elements (14, 14 ¹ ) are held non-positively by oversize in the receiving profile pieces (10, 10 '). 6. Device according to one of claims 1 to 5, characterized in that the free ends of two to six adjacent spring bands (6, 6 ') are attached to a receiving profile piece (10, 10'). 7. Device according to one of claims 1 to 6, characterized in that the spring strips (6, 6 ') made of stainless spring steel sheet and the receiving profile pieces (10, 10') are made of stainless steel sheet.

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