Seal material

Abstract

To provide a sealing material for flange connection, a method for manufacturing the sealing material, and use thereof.SOLUTION: The seal material comprises a layer of impregnated and coated graphite foil, or the seal material comprises a composite of two or more layers of graphite foil with a reinforcement material provided between the layers of graphite foil, wherein an outer surface of the composite has an impregnating material and a coating material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a seal for flange connections, and to the manufacture and use of such a seal. [Background technology]

[0002] Graphite foil seals and laminated composite seals containing graphite foil have been used in the prior art, for example, in pipelines and equipment in the chemical industry, and steam lines in power plants and heating systems. Graphite foil is produced by the thermal expansion of graphite intercalation compounds and the resulting accordion-like particles. These particles can bond together during compression under pressure to produce a stable, flexible foil- or sheet-like flat structure without the need for additional binders. Graphite foil is characterized by its resistance to high temperatures and aggressive media, relatively low permeability to fluids, high compressibility, good recovery, and very low tendency to creep under pressure. These characteristics make graphite foil suitable for use as a seal.

[0003] The mechanical stability of graphite seals can be improved by inserting a metallic reinforcing insert (metal sheet or foil) between two graphite foils. Thus, for prior art seals with a total thickness of 1-4 mm, a laminated composite of several hundred graphite foils with intervening metal inserts is typically used.

[0004] A method for producing a laminated composite with alternating metal and graphite layers is known from US Pat. No. 5,623,999. An inseparable, adhesive-free composite is produced between the metal and graphite layers by applying a thin layer of a surface-active substance from the group consisting of organosilicon compounds, perfluorocompounds and metal soaps to at least one of the surfaces to be bonded, bringing the surfaces to be bonded together and subjecting them to pressure and heat.

[0005] A drawback of the seals described in this prior art is that the adhesive effect of the seal during use, for example in a flange, can make replacement difficult. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent No. 0616884 [Patent Document 2] German Patent No. 10003927 Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide a sealant that is non-adhesive during application, and to provide a method for producing the non-adhesive sealant. [Means for solving the problem]

[0008] This object is achieved by a seal for flange connections, which comprises a layer of impregnated and coated graphite foil or a composite of two or more layers of graphite foil, with reinforcement material provided between the graphite foil layers, and the outer surface of the composite carrying the impregnation material and the coating material.

[0009] In an advantageous embodiment, the graphite foil comprises expanded graphite. To produce the graphite foil, expanded graphite having a worm-like structure must first be produced, typically by mixing graphite, such as natural graphite, with an intercalating agent (e.g., nitric acid or sulfuric acid) and heat-treating the mixture at high temperatures, e.g., 600°C to 1200°C (Patent Document 2).

[0010] The graphite constituting expanded graphite is expanded, for example, by 80 times or more in a plane perpendicular to the hexagonal carbon layers compared to natural graphite. Due to this expansion, expanded graphite is characterized by good moldability and good cuttability. Expanded graphite can be pressed into a foil by applying pressure.

[0011] Graphite foil has high resistance to temperature and media.

[0012] The impregnating material according to the present invention is selected from the group consisting of paraffins, long-chain hydrocarbons and mixtures thereof, preferably petrolatum. Petrolatum is preferred because it has the property of being less sticky, but does not prevent adhesion. In the context of the present invention, long-chain hydrocarbons are, for example, those having the general molecular formula C n H 2n+2 In the formula, n is 18 to 32, and therefore, it is understood that the molar mass is 275 to 600 g / mol.

[0013] The coating material according to the present invention is selected from the group consisting of fatty acid soap, mica, graphite powder, talcum, and mixtures thereof, and is preferably fatty acid soap.

[0014] In the context of the present invention, fatty acid soaps are understood to mean sodium or potassium salts of fatty acids, but also include metallic (Li, Ca, Mg) fatty acids. The fatty acids have the molecular formula C n H 2n+1These are understood to be saturated monocarboxylic acids with COOH, such as palmitic acid and stearic acid, with carbon chain lengths of C7 to C21 being preferred. Magnesium stearate is particularly preferred because it is non-toxic and a highly effective release agent. The coating material is applied as an active release agent without adhesive, preventing adhesion of the seal material. This has the advantage of preventing flange adhesion without the application of adhesive. A mixture of fatty acid soap and graphite powder is particularly advantageous because it provides an even higher separation effect and the graphite powder provides a separation effect even when the seal material is used at high temperatures.

[0015] The reinforcement is advantageously a metal insert.

[0016] The metal insert according to the present invention is selected from the group consisting of sheet metal, gasket sheet and expanded metal.

[0017] The metal insert advantageously has a thickness of between 50 μm and 150 μm.

[0018] The metal insert according to the present invention is selected from the group consisting of stainless steel, steel, iron, aluminum, nickel, copper, titanium, zinc, nickel alloys, copper alloys, aluminum alloys and zinc alloys, preferably stainless steel.

[0019] Another subject of the invention is a method for manufacturing a sealant, comprising the following steps: a) providing a graphite foil; b) providing an impregnating material and a coating material; c) dispersing the coating material in the impregnating material; d) applying the dispersion obtained in step c) to the outer surface of the graphite foil provided in step a); e) maintaining the graphite foil obtained in step d) at a temperature between 80°C and 180°C, preferably at a temperature of 105°C, for a period of 2 hours to 24 hours.

[0020] The graphite foil provided in step a) can be a plate or roll stock of graphite foil, which, if roll stock is used, is cut or stamped into plates of any size after step c).

[0021] In another advantageous embodiment, in step a) a reinforcement material is further provided, in step d) a dispersant is applied to only one outer surface, and step e) is followed by the following steps: f) stacking the graphite foils obtained in step e) so that the coating material is present on each outer surface of the stack and so that the reinforcement material is located between two graphite foils; g) pressing the laminate obtained in step f) to a thickness of 20% or less;

[0022] The impregnation and coating, followed by holding, can be a batch process (individually cut layers) or a roll-to-roll process (i.e., continuous process). In the roll-to-roll process, cutting into individually cut layers occurs after holding. The graphite foil is held at a temperature of 80°C to 180°C for 2 to 24 hours, allowing the impregnating material to penetrate the graphite foil and become uniformly distributed throughout the foil, while the coating material remains on the surface of the graphite foil.

[0023] The impregnating material provided in step b) according to the present invention is selected from the group consisting of paraffins, long-chain hydrocarbons and mixtures thereof, preferably petrolatum.

[0024] In a further advantageous embodiment, the coating material provided in step b) is selected from the group consisting of fatty acid soaps, mica, graphite powder, talc and mixtures thereof, preferably fatty acid soaps.

[0025] The layer or layers of graphite foil provided in step a) according to the present invention may have a density of 0.7 g / cm 3 ~1.3g / cm3 density, preferably 0.7 g / cm 3 It has a density of 1.3 g / cm 3 At densities above 0.7 g / cm, the flexibility of the graphite foil is not present to compensate for non-uniformities. 3 At densities below 0.7 g / cm the foil is not stable enough. 3 is preferred because at this density the graphite foil is particularly flexible and the foil compensates for non-uniformities particularly well during use.

[0026] At least one reinforcement provided in step a) according to the present invention is a metal insert.

[0027] The metal insert advantageously has a thickness of between 50 μm and 150 μm.

[0028] This sealing material is used for pipe flange connections in chemical plants.

[0029] The present invention will be described below with reference to the drawings, but is not limited thereto. [Brief explanation of the drawings]

[0030] [Figure 1] 1 shows a seal for a flange connection. [Figure 2] 1 shows a seal for a flange connection. DETAILED DESCRIPTION OF THE INVENTION

[0031] FIG. 1 shows a graphite foil (1) with an impregnating material (2) and a coating material (3) on both sides of the graphite foil.

[0032] FIG. 2 shows two layers of graphite foil (1) with a reinforcement (4) between the layers of graphite foil (1) and the outer surface of the composite with an impregnation (2) and a coating (3).

[0033] The present invention will now be described with reference to exemplary embodiments, which do not represent limitations of the present invention.

[0034] Exemplary Embodiments 0.7g / cm 3 Two layers of graphite foil (1000 mm x 1000 mm) with a density of 1000 μm each are coated on one side with a dispersion of petrolatum and magnesium stearate (2% by weight magnesium stearate in petrolatum), with 1-10% by weight of petrolatum / magnesium stearate applied to the graphite foil. The coated graphite foil is then heated to 105°C for 24 hours. The two layers of coated graphite foil are then laminated with a 100 μm thick gasket sheet, with the gasket sheet layer positioned between the two layers of graphite foil and the coating of the two layers of graphite foil facing outward when the single gasket sheet layer is placed.

[0035] The graphite foil and gasket sheet stack is pressed to a thickness of 2 mm. [Explanation of symbols]

[0036] 1 graphite foil 2 Impregnating material 3 Coating materials 4 Reinforcement

Claims

1. 1. A seal for a flange connection, the seal comprising a layer of impregnated and coated graphite foil, or the seal comprising a composite of two or more layers of graphite foil with a reinforcing material between the layers of graphite foil, the outer surface of the composite comprising an impregnated material and a coating material.

2. The seal of claim 1 , wherein the graphite foil comprises expanded graphite.

3. 2. The seal of claim 1, wherein the impregnating material is selected from the group consisting of paraffins, long chain hydrocarbons, and mixtures thereof.

4. 2. The seal of claim 1, wherein the coating material is selected from the group consisting of fatty acid soap, mica, graphite powder, talc, and mixtures thereof.

5. The seal of claim 1 , wherein the reinforcing material is a metal insert.

6. 6. The seal of claim 5, wherein the metal insert is selected from the group consisting of sheet metal, gasket sheet, and expanded metal.

7. The sealing material according to claim 5, wherein the thickness of the metal insert is 50 μm to 150 μm.

8. 6. The seal of claim 5, wherein the metal insert is selected from the group consisting of stainless steel, steel, iron, aluminum, nickel, copper, titanium, zinc, nickel alloys, copper alloys, aluminum alloys, and zinc alloys.

9. A method for manufacturing the seal material of claim 1, comprising: Step a. providing a graphite foil; Step b. providing an impregnating material and a coating material; Step c) dispersing the coating material in the impregnating material; Step d) applying the dispersion obtained in step c) to the outer surface of the graphite foil provided in step a); and step e) maintaining the graphite foil of step d at a temperature of 80°C to 180°C for 2 hours to 24 hours.

10. In step a), a reinforcement material is further provided, and in step d), only one of the outer surfaces is coated, and following step e), step f) of stacking the graphite foils obtained in step e) so that the coating material is present on each outer surface of the stack and the reinforcing material is disposed between two graphite foils; 10. The method of claim 9, further comprising a step g of pressing the laminate obtained in step f to a thickness of 20% or less.

11. 11. The method according to claim 9 or 10, wherein the impregnating material provided in step b is selected from the group consisting of paraffins, long chain hydrocarbons, and mixtures thereof.

12. 11. The method of claim 9 or 10, wherein the coating material provided in step b is selected from the group consisting of fatty acid soap, mica, graphite powder, talc, and mixtures thereof.

13. The graphite foil provided in step a) has a thickness of 0.7 to 1.3 g / cm ３ 11. The method of claim 9 or 10, wherein the granules have a density of

14. The method of claim 10, wherein the reinforcement provided in step a is a metal insert.

15. 9. Use of a sealing material according to any one of claims 1 to 8 for flange connections of pipes in a chemical plant.

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