Flat packing.

The invention relates to a flat seal consists of an annular core and a coating surrounding the core, the core being made of a more solid material than that of the coating.

Such seals have been in use for a long time. These consist essentially of flat or curved, vulcanised rubber washers on the basis of natural or synthetic elastomers with or without core as insert of a more solid material, such as steel. Other sealing variants O-rings are known to produce the necessary sealing forces in their shape to the flange.

is a prerequisite for all these seals that the necessary sealing forces may be incorporated into the design of the flanges.

but now the condition mentioned in those known and important flange that are applied in the case of corrosion and / or erosion, not given. This with a protective material (lining of hard and / or soft rubber, thermosets, thermoplastics and the like) provided flange are namely particularly at higher temperatures is no longer able to absorb the required sealing forces and be able to transmit. So flanged on pipelines are required in desulphurization plants, which are corrosion properly protected on the flange by hard rubber (hardness about 65 to 85 Shore D) and, as protection against erosion a covering soft rubber (hardness about 40 to 70 Shore A) in the tube.

On this problem is where the present invention. It should in particular be provided a seal with which it is possible without destroying the bond securely receive the sealing forces in the aforementioned transition between hard and soft rubber while maintaining a required higher sealing force to change.

It has surprisingly been found that said object can be achieved with a flat seal, which is designed such that the core is a circular ring plate and is located around this a soft-material seal having two half O rings that the required sealing forces in two corresponding grooves absorb and thus relieve the protective material as a lining. thus found was a flat seal consists of an annular core and a surrounding the core coating, the core being made of a harder material than the coating, which is characterized in that the core is a circular annular plate whose circular surfaces each having at least one concentrically running groove, and the coating is formed as a cross-sectionally U-shaped and the annular plate to enclose their curved narrow outer surface plastic sheath whose inner surfaces are provided with engaging in the grooves of the annular plate and from releasable beads.

The annular plate is according to the invention preferably made of hard rubber or metal. In the case of metal steel is the preferred material. In the case of hard rubber plates, preferred are those which have a hardness from 75 to 95 Shore D. The circular ring plate of the invention, whose thickness is generally in the range of 2 to 8 mm, has. At the two (planar) circular surfaces usually each have a concentrically arranged groove, which is preferably substantially in the middle of the area The ratio of the width of a slot opening to the width of the circular surface may vary within wide limits. It is generally from about 1: 3. The relationship between groove depth and thickness of the annular plate is generally selected so that a minimum ratio of about l: 2.3 exists.

As for the groove shape, various geometrical designs are suitable, for example square, rectangular, trapezoidal or rounded, the latter being preferred. A particularly advantageous shape of the groove is semicircular.

The circular ring plate grooved as sealing core according to the invention with a cross-sectionally U-shaped plastic shell, preferably based on natural or synthetic elastomers, surrounded representing the other part of the new seal. This case is designed so that it can be non-destructively removed from the circular annular plate and applied again, so is replaceable. In the plan view, the plastic casing as well as the gasket core, a circular ring plate, which fall on three sides of U-shaped or pocket-like so encloses the core, that only its curved narrow outer surface (outer face) is uncovered. The exterior more or less smoothly formed plastic casing of the invention (plastic casing) is further internally provided with beads, also known as surveys or springs, which fix the sleeve to the annular plate and on the other hand, the grooves of the circular ring plate correspond such that it is inserted into this and also detached from it can be. Which, like the grooves running concentrically beads are thus located on the two inner sides of the two circular surfaces of the core plate covering the U-shaped shell. The plastic from which the casing of the invention is formed, will be adapted to the sealed case, so that the various types of plastic are suitable. Due to its special properties, rubber is the preferred plastic. Therefore, the casing of the invention is preferably made of soft rubber. It has a hardness of 50 to 80 Shore A, preferably from 60 to 75 Shore A, has proved advantageous. The soft rubber case of the seal of the invention is in the case of the aforementioned flange connections of pipes for desulphurization harder than the overlying soft rubber (erosion protection) in the tube, whose (which) is hardness generally from 40 to 70 Shore A. The plastic casing of the invention may be formed as well as the known coatings flat or convex (lenticular) and the like. The thickness of the outer surfaces or circular surfaces of the cross-sectionally U-shaped envelope is placed as well as those of the known coatings generally in the range of 0.5 to 5 mm, wherein the casing bottom is preferably stronger than the circular areas, and thus designed as erosion protection.

It has been found that the seal of the invention is particularly effective and all requirements for seals withstands if between the size of the groove and the size of the bead is a certain relationship is maintained. Thus, the cited properties are especially achieved if the depth of the groove 10 to 40%, preferably 20 to 30%, smaller than the height of the bead and the volume of the groove is equal to or up to 20%, preferably up to 10 %, is smaller than the volume of the bead.

To produce the seal of the invention, first the two parts are manufactured, namely the circular annular plate with the annular grooves and the U-shaped plastic shell with the annular beads. The production of the disc needs in each well not be further described. The plastic sleeve is expediently manufactured by press vulcanization and in the case of rubber. In the case of other plastics, the injection molding process may be the appropriate solution. The two parts are then joined together to produce seal by the plate is introduced into the sheath.

The flat gasket according to the invention has a number of advantages. It is particularly suitable for sealing flange joints, as are present in piping, equipment, autoclaves, tank covers and the like, which must be corrosion- and erosion properly protected. By the contour of this seal, the seal forces are absorbed in the core of the circular annular plate across the grooves and the bead, without the thrust forces to the previously mentioned lining of the flanges, especially in the said transition area between the hard and soft rubber, to be transmitted. With an appropriate choice of the gasket inner diameter, ie the thickness of the bottom of the U-shaped casing of the invention, and of the soft rubber of the sheath also erosive stresses can be easily collected. Likewise, the sealing pressure can be reduced to that at issue erosion protection material for pipes of desulphurization by appropriate hardness and fabric choice or by reducing the thickness of the seal in the region of the casing soil; by this so-called minimum tolerance of the thickness of the seal of erosion control (the soft rubber on the flange) is considerably relieved.

In the following the invention will be explained in more detail with reference to an embodiment shown in the drawing.

The figure shows a flat gasket according to the invention, which is shown in perspektivischer- and in cross-sectional shape for a pipe flange. The gasket illustrated consists of a flat-shaped in cross-section circular ring plate 1 made of steel, which is provided on both sides with an annular groove 2, and a soft rubber coating 3, which encloses the circular annular plate 1 is U-shaped from inside to outside. The two annular grooves 2 are located on the two circular surfaces of the circular ring plate 1 respectively in the surface center. The concentric grooves 2 are formed semi-circular. The steel annulus plate 1 is 5 mm thick and their circular surfaces are 24 mm wide. The width of the opening of the annular grooves 2 is 8 mm and their depth 1.5 mm. The ratio of the width of the groove opening to the width of the circular surface of the plate l ie 1: 3, and that of the groove depth to the thickness of the plate 1 1: 3.3. The cross-sectionally U-shaped soft rubber shell 3 which encloses the circular annular plate 1 on its outer face and has a hardness of 65 Shore A is designed to be smooth on their outer surfaces. are the annular beads or annular springs 4 that are adapted to the grooves 2 and extending it to the two, the circular surfaces of the plate 1 covering inner surfaces of the case. 3 The depth of the grooves 2 is 25% less than the height of the bead 4, and their volume 10% less than that of the bead 4. The sealing outer surfaces of the soft rubber casing 3 are designed flat. The thickness of the outer surfaces is less than the thickness of the bottom of the U-shaped sheath third