Claims
- 1. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks consisting essentially of,
- applying a layer of irreversably compressible inorganic particulate material to the surface of a layer formed from a plurality of cellular glass blocks each having a cut face forming a plurality of open hemispherical cells thereon, said plurality of cellular glass blocks forming a layer of said load bearing insulation,
- penetrating said plurality of open hemispherical cells with said layer of inorganic particulate material to completely fill said open cells, and
- compressing said layer of inorganic particulate material to form a substantially planar surface of said inorganic particulate material having a preselected thickness on said cellular glass block cut faces.
- 2. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 1 which includes,
- compressing said layer of inorganic particulate material under a preselected compressive force into intimate contact with said cellular glass block open hemispherical cells.
- 3. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 2 which includes,
- precompressing said layer of inorganic particulate material with a compressive force up to 42 p.s.i. to bring the inorganic particles into intimate contact with said open cells.
- 4. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 1 which includes,
- applying an inorganic particulate layer of vermiculite onto said cellular glass block cut face where a major portion of the particles have a spectrum of sizes in the range between about 8 to 50 Tyler standard screen mesh.
- 5. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 4 which includes,
- said cellular glass block with said vermiculite layer having a compressive strength in the range between about 90 p.s.i. to 180 p.s.i.
- 6. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 1 which includes,
- spreading said inorganic particulate material onto said cellular glass block cut face to form a capping layer having a thickness in the range between about 3/16 inch to 1/4 inch.
- 7. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 6 which includes,
- spreading said capping layer onto said cellular glass block cut face by rolling or screeding.
- 8. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 1 which includes,
- a plurality of layers of cellular glass blocks positioned in overlying relation to each other with layers of said irreversably compressible inorganic particulate material therebetween.
- 9. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks comprising,
- applying a layer of irreversably compressible inorganic particulate material to the surface of a layer formed from a plurality of cellular glass blocks each having a cut face forming a plurality of open hemispherical cells thereon, said plurality of cellular glass blocks forming a layer of said load bearing insulation,
- forming a plurality of layers formed from said plurality of cellular glass blocks positioned in overlying relation to each other with layers of said irreversably compressible inorganic particulate material therebetween,
- penetrating said plurality of open hemispherical cells with said layers of inorganic particulate material to completely fill said open cells, and
- compressing said layers of inorganic particulate material to form a substantially planar surface of said inorganic particulate material having a preselected thickness on said cellular glass block cut faces.
- 10. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 9 which includes,
- compressing said layers of inorganic particulate material under a preselected compressive force into intimate contact with said cellular glass block open hemispherical cells.
- 11. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 10 which includes,
- precompressing said layers of inorganic particulate material with a compressive force up to 42 p.s.i to bring the inorganic particles into intimate contact with said open cells.
- 12. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 9 which includes,
- applying inorganic particulate layers of vermiculite onto said cellular glass block cut face where a major portion of the particles have a spectrum of sizes in the range between about 8 to 50 Tyler standard screen mesh.
- 13. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 12 which includes,
- said cellular glass block with said vermiculite layers having a compressive strength in the range between about 90 p.s.i. to 180 p.s.i.
- 14. A method for capping cellular glass blocks for use as load bearing insualtion of liquefied gas storage tanks as set forth in claim 9 which includes,
- spreading said inorganic particulate material onto said cellular glass block cut faces to form capping layers having a thickness in the range between about 3/16 inch to 1/4 inch.
- 15. A method for capping cellular glass blocks for use as load bearing insulation of liquefied gas storage tanks as set forth in claim 14 which includes,
- spreading said capping layers onto said cellular glass block cut faces by rolling or screeding.
CROSS REFERENCES TO RELATED APPLICATIONS
This application is a division of copending application Ser. No. 547,754, filed on Feb. 6, 1975, entitled "A Method and Apparatus for Capping Cellular Glass Blocks for the Load Bearing Insulation of Liquefied Gas Storage Tanks", now U.S. Pat. No. 3,952,469.
1. Field of the Invention
This invention relates to a method and apparatus for capping cellular glass blocks utilized as a load bearing insulation for the base insulation of liquefied gas storage tanks and more particularly to the capping of the cellular glass block insulation with a layer of particulate vermiculite to provide a capping which results in improved compressive strength.
2. Description of the Prior Art
In the storage of liquefied gas such as liquefied natural gas (LNG) and liquid oxygen (LOX) in cryogenic storage tanks, cellular glass blocks are commonly utilized as a thermal insulation and a load bearing insulation for the tank base. To increase the compressive strength of the tank base, it is the practice to cap each course of the cellular glass block base insulation with a layer of capping material. This capping layer serves to increase the compressive strength of the cellular glass blocks. The capping material, however, should provide less than a 1/4 inch deformation of the total insulation system so that the tank base is not subjected to any major deformation when the tank is initially loaded. Also the capping should not be resilient so that the tank base is not elastically cycled when the tank is filled and emptied.
In the past, liquefied gas storage tank bases have been constructed with a layer of compressible material between the slabs of insulation. In the case of liquefied natural gas tanks, the capping layer is usually hot asphalt, an asphaltic based material or contains asphalt such as asphalt filled paper. In the base insulation of liquefied oxygen tanks, however, organic materials are not permissible, and asbestos paper is commonly used in place of asphaltic materials as a capping for the tank base insulation. Asbestos paper, however, as a capping layer presents a potential health hazard and is becoming less available. In addition to many conventional capping materials becoming commercially unfeasible because of high cost or unavailability, they exhibit properties which do not permit their use over a wide temperature range. Their properties are temperature sensitive, becoming brittle at cryogenic temperatures and fluid at elevated temperatures. Consequently, the use of such materials is restricted to the base insulation of tanks for the storage of liquids at cryogenic temperatures or at elevated temperatures, but not both.
Many of the conventional capping materials when applied as load bearing base insulation upon the surface of the cellular glass blocks tend to rebound from the surface of the blocks when compressed. The cellular glass blocks have a cut face that forms a plurality of open hemispherical cells. Preferably, the capping material should fill the cells to provide an effective capping layer between the courses of the cellular glass block base. Conventional capping materials having resilient properties may not effectively fill the open cells and subsequently the tank base is elastically deformed when the tank is filled and emptied. In addition, because these materials do not come into intimate contact with the cellular glass block surface, the compressive strength of such an insulation system is substantially reduced. For this reason they are ineffective as load bearing insulation.
There is need for an inorganic material for capping base insulation of liquefied gas storage tanks that completely fills the open hemispherical cells of the cellular glass blocks and comes into intimate contact therewith to form a capping layer that is irreversibly compressible to provide improved compressive strength for the base insulation. Furthermore, the inorganic capping material should be an effective loading bearing insulation at cryogenic temperatures and elevated temperatures as well.
In accordance with the present invention, there is provided a method and apparatus for capping cellular glass blocks for use as load bearing insulation for the base of liquefied gas storage tanks. The cellular glass blocks are prepared for capping by cutting a horizontal surface of the blocks to form a cut face having a plurality of open hemispherical cells. A layer of irreversibly compressible inorganic particulate material is applied to the surface of the cellular glass block cut face. The layer of inorganic particulate material penetrates the plurality of the open hemispherical cells to completely fill the cells. The layer of inorganic material is compressed to form a substantially planar surface having a preselected thickness on the cellular glass block cut face.
The irreversibly compressible inorganic patriculate material, preferably vermiculite, adheres to the cellular glass block cut base by precompressing the layer under a preselected compressive force. In this manner the vermiculite material is compressed into the open hemispherical cells of the cellular glass blocks to form a capping layer thereon having a compressive strength in the range between about 90 p.s.i. to 180 p.s.i. As each course of cellular glass block base insulation is constructed the vermiculite particles are applied by screeding or rolling the particles over the open hemispherical cells of the cellular glass block.
Precompressing the vermiculite capping layer with a compressive force of up to 42 p.s.i. completely fills the open cells of the glass blocks. Preferably, the capping layer has a thickness in the range between about 3/16 inch to 1/4 inch between each course of the cellular glass block.
Accordingly, the principal object of the present invention is to provide a method and apparatus for capping cellular glass blocks for use as load bearing insulation for the base of liquefied gas storage tanks where the capping material is an irreversibly compressible inorganic particulate material that completely fills the open cells of the cellular glass blocks to provide the cellular glass block insulation system with a capping having a high compressive strength independent of temperature.
Another object of the present invention is to provide a method and apparatus for capping cellular glass blocks for base insulation of liquefied gas storage tanks with an inorganic capping material that is easily applied to the cellular glass base insulation to provide improved compressive strength for the liquefied gas storage tank at cryogenic and elevated temperatures.
A further object of the present invention is to provide a method and apparatus for capping the cellular glass blocks of base insulation for liquefied gas storage tanks with vermiculite particles that increase the compressive strength of the base insulation by uniformly distributing the load applied to the cellular glass blocks.
These and other objects of the present invention will be more completely described and disclosed in the following specification, the accompanying drawings and the appended claims.
US Referenced Citations (11)
Divisions (1)
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547754 |
Feb 1975 |
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Patent Grant
4073976
