US2108017A - Method of coating containers - Google Patents

Description

Feb. 8,` 1938. J. LIT-HGow 2,108,017-

METHOD OF COTING CONTAINERS Feb. 8, 1938. J. LlTHGow 2,108,017

METHOD 0F COATING CONTAINERS Filed Feb. 27, 1956 2 Sheets-Sheerl 2 Patented Feb. 8, 1938 UNI-TED STATES PATlezrrr OFFICE METHOD OF COA'IING CONTAINERS James Lithgow, Chicago, Ill., assignor to Lithgow Corporation, Chicago, Ill., a corporation of Del- Application February 27, 1936, Serial No. 65,978

y6 Claims.

large tanks such as tank cars, and tanks mounted in position for permanent installation as in breweries, factories, or the like.

Heretofore several methods have been used or proposed for lining such tanks or containers. One of these methods contemplates the use of glass or vitreous enamel which can only be applied at the factory where the container is made and requires high temperatures or around 1700 Fahrenheit to apply the same. Another method consists in the relatively cold application o f pitch or base coatings in which small sections of the surface of the container are treated at a time. Another method 'contemplates spraying nonferrous metals on the inner surface but all of these different processes have been found objectionable for various reasons which are familiar to those having to do with this art.

In accordance with the present invention I provide a novel method of coating or lining containers of the character indicated wherebythe contents such as various foods, drinks, or bulk liquids may be maintained in a sterile condition and will be protected from contamination or discoloration through contact with the material of the container. My improved process involves the use of a suitable lining material such as low temperature baking enamel or lacquer which is inert, when properly cured or baked, to food products or other contents to be placed or kept in the container. There are a large variety of types or kinds of paints, enamels or lacquers which are adapted to be used for the present purposes to meet the particular conditions as respect to the food or materials to be placed in the container and the present invention contemplates the use of any suitable coating material which may be adapted for the particular use for which the tank or container is intended.

l The principal object of the present invention is to provide a method of lining or coating containers, tanks, or the like, particularly after the r same have been mounted or installed in operatparticularly from the following description taken in connection with the accompanying drawings in which l Figure 1 is a longitudinal sectional view of a tank car'illustrating an application of my im proved method;

Figure 2 is a cross sectional view of the same showing the heating apparatus;

Figure 3 is a longitudinal sectional view illustrating any ordinary or preferred form of processing tank which is being lined or coated; l0

ceiving the coating or lining l on material which is capable of being hardened by baking at a relatively low temperature, such as paint, enamel or lacquer which may be applied in any suitable manner but preferably by means of a brush. This coating will ordinarily be allowed to air dry for about three hours or-more and is then baked on in accordance with my improved system` Any `number of coats may then be applied and baked on in accordance with the followingmethody but it will only be necessary to describe the operation for the first coat.

The tank which will ordinarily be made of steel or similar metal is enclosed or coveredwith a sectional insulating blanket 8 of any suitable 35 material such as mineral wool, 0r other material which will lend itself to being formed into portable sections so that they may be transferred from tank to tank and connected together in any suitable manner or fastened onto the outer surface of the tank to suit the4 various sizes and shapes thereof.

It is necessary or desirable to be able to determine .the temperature of the metal of all parts of the tank or container which is being treated 4- which may be done by any suitable temperature measuring apparatus such as thermometers, pyrometers, or the like. As a convenient method of determining the temperatures at dierent parts of the tank I provide wires or thermo-couples such as shown at 9 which are suitably connected with the tank and which may lead to the measuring instrument such as a portable potentiometer, thermostat, pyrometer or the like. These wires are preferably arranged so that the difdisconnected with'the instrument so that any desired number of temperature reading may be made for the different portions of the container. It is necessary to determine the temperature of the metal of the container as the bonding of the coating to the inner surface of the metal is quite critical as respects to the temperature. If the temperature is too low the lacquer or coating will not be properly cured and baked and if the temperature becomes too high the coating is apt to become brittle. It is necessary to take the temperatures of the metal at various points throughout the tank or container in order to have all parts thereof heated to the proper degree. This will be more readily understood when it is 4considered that tank cars which I have treated in accordance with this method are approximately seven feet in diameter and thirtytwo to thirty-eight feet long. Storage or other tanks which I have lined in accordance with this process have been upwards of twelve feet in diameter and seventy feet lo'ng. The tendency of heat is to rise and accordingly it is necessary to provide means for properly determining the temperature at different portions of the tank and particularly along the bottom in order to insure proper curing and baking of the coating throughout the interior surface.

The heat for baking may be derived from any suitable source but I have shown a portable furnace or heater Il which may be heated by the combustion of gas, oil, solid fuel, or the like. The furnace is directly connected to a fan I2 which is driven by a motor I3 which may be of the variable type in order to regulate the air supply. A conduit or pipe I4 leads from the'furnace into the tank or container 6 where it is provided with discharge means for equalizing the distribution of the hot air throughout the container. As shown in Figure 1 the pipe I4 has two lateral discharge branches I5 directed toward the ends of the tank and a down discharge branch I6 directed toward the bottom and outlet I1 of the tank. 'Ihese outlets are preferably provided with screens I8 to prevent any objectionable particles being blown into the container. After the heating apparatus has been arranged as shownv the curing and baking are accomplished by blowing a sumcient volume of hot air or gas into the tank to reach all interior surfaces and to raise the temperature to any desired degree. For instance with some lacquers the temperature is gradually raised forthree or four hours; until the temperature of the metal of the container reaches approximately 250 F. to 275 F. ,and thevtemperature is held at this point for. about one hour.

Of course the time and amout of heat will be dependent upon the character of the coating material as above suggested. The hot air or gases forced into the container from the furnace I I are permitted to escape through any suitable openings in the container and as shown in Figure 1 the outlet pipe or connection I1 which is also lined or coated will serve as an escape and at the same time will become sufficiently heated to bake the lacquer applied therein. The distribution of the air throughout the tank may also be con. trolled by arranging the outlet openings in order to suit the type or shape of the tank. After the desired number of coatings have been applied the heating equipment may be removed and the tank will be in condition for use. The sectional or removable insulation 8 and the portable heating ferent pairs may be conveniently connected and apparatus may be readily moved from one tank to another as will be readily understood.

The tank I9 shown in Figure 3 may represent a horizontal type of container intended for industrial purposeswhich is shown with a coating 20. The inlet pipe 2| for conducting heat from the furnace or source of heat supply is preferably stepped ldown or reduced in diameter to provide sections 22 and 23 and this discharge portion is provided with holes 24 which are arranged along the same as indicated in order to direct the heat or hot air to the different portions of the tank. The pipe 2| may be supported in the tank by means of hangers or supports 25 or in any other suitable manner. In this arrangement the tank is also provided with temperature measuring means or thermo-couples the same as in the form shown in Figure 1.

The upright tank 26 shown in Figure 4 is provided with a lacquer lining 21 which is applied as above described. In this instance the inlet pipe 28 has a vertical branch 29 with holes 30 in the sides thereof. 'I'he upper end of the branch 29 may be provided with a deilector 3| and a hole or opening left in the lower end, the entire arrangement being such that the heat will be spread uniformly throughout the tank in order to give an even or uniform baking of the coating throughout the tank.

Figure 5 shows a tank 32 having an upper portion made of wood and a bottom or base 33 formed of metal such as cast iron, which type of tank is in more or less common use. While it is not necessary to coat the main part of the tank it is desirable to coat or line the bottom 33 with a lining 34 as shown. The heat is introduced as above described through a pipe 35 from any suitable source of heat supply, this pipe being conveniently introduced at the ,bottom and provided at its upper end with a deilector 36 for distributing the gases which escape through openings 31. In order to conne the lining to the cast iron or metal bottom I provide a floor or partition 38 which is arranged above the upper end of the bottom and which has a lower insulating surface 39 for retaining the heat. This partition is preferably made in sections for easy insertion and so that it may be used for different tanks if desired.

The application of the heat to these different forms of tanks will be apparent from the above description. 'I'he amount of heat and regulation thereof may be controlled in any well known manner as by regulating the amount of fuel supplied to the furnace or heater and by varying the speed of the fan motor and the heat supplied to diierent portions of the tank may be .regulated by moving the inlet pipes or changing the outlet openings. After the one or several layers of lacquer or coating have been applied and baked on, the heat conducting and distributing devices and the temperature measuring apparatus and other parts may be removed and the tank or container will be ready for use.

In the actual application of this invention for commercial purposes I have found that by using a lacquer which can be applied at room temperatures a perfect bond will be made withv the steel and an even coat provided over all surfaces. My

improved method of baking provides full temper l tively low temperatures I am able to bake vessels 7s of irregular shape without distortion and can also operate on tanks in places such as brewery cellars which must be maintained at temperatures not over 40 F. without interfering with the regular plant operation. 'I'his process also provides means for recoating or lining old tanks which would otherwise have to be replaced at great expense and with resulting loss of operation while the tanks were transferred and which might also require the demolition of building walls to permit exit and entry of the tanks. The use of my method for lining the bottom cones or bases of wooden tanks is also highly desirable as it may be done without injury to the wooden staves and this lls a long felt Want of several chemical industries in which products are handled which affect metal but which nevertheless require the use of metal bottoms in order to make the necessary pipe connections.

While l have outlined various uses and advantages of my invention it may also be applicable to other containers and other advantages may be apparent to those familiar with the art. Any invention or subject matter herein shown and described but not claimed, is not intended to be dedicated to the public, insofar. as such subject matter is shown, described and claimed in my copending application for Metal coating, illed December 2, 1937, Serial No. 177,781. Accordingly I do not wish to limit my claims to the particular method or apparatus herein shown or described except as specified in the following claims in which I claim.

1. The method of lining a metal tank which comprises rst covering the tank with a covering of heat insulating material, then coating the inner surface of the tank with a suitable coating material which is adapted to be baked on, permitting said coating material to air dry, then introducing a conduit into the tank and forcing gases heated to the necessary temperature for baking the coating material, after it has become dry, through the conduit into the tank for a sufficient length of time to bake the coating to a uniform hardness, said gases being permitted to escape from the tank as the baking progresses.

2. 'Ihe process of coating relatively large metal tanks mounted in position for permanent insullation, which comprises applying a lining of a materialwhich is capable ofbeing" baked at a relatively low temperature to harden the same, then providing a portable furnace having a pipe adapted to lead therefrom into the container and having means for blowing air therethrough, then driving the heated air through said pipe into the container for a sulcient length of time to bake the lining applied thereto to obtain a lining of uniform hardness.

3. The process of coating the interiors of relatively large metal tanks mounted in position for permanent installation, which includes placing a y 4. The method of coating the metal portion of a tank, which comprises closing off said metal portion from the remainder of the tank, then painting the inner surface of said portion with a material which is capable of being hardened by baking at av relatively low temperature, temporarily covering the exposed outer surfaces of said portion with insulating material to be kept thereon during the baking process only, then directing gases which are heated to a baking temperature into said portion, said gases being directed into said portion a suflicient length of time to bake said material to a uniform hardness, and finally removing the insulation from said portion.

5. The herein described method of applying durable and substantially permanent linings to large metal tanks, metal tank cars, or the like, which comprises covering the tank temporarily with insulating material to prevent loss of heat during the baking operation, then coating the inner surface of the tankwith a suitable lining material which is capable of being hardened by baking at a relatively low temperature, allowing said lining to dry, then directing into the tank, gases which are heated sumciently to harden the lining material, and nally removing the insulating material, leaving said tank with a suitably hardened lining as Aandfor the purposes described.

6. The herein described method of protecting the interiors of metal containers of large size from the action of material placed therein, which comprises covering the container with a heat insulating cover, cleaning the inner surfaces of the container by sand-blasting, then applying a layer of coating material in liquid form, which material is of a nature that it may be hardened to the desired consistency by baking, allowing the layer to air dry until thoroughly dried, then forcing heated gases under pressure into the container. and gradually raising the temperature of the metal ofi-the container until it reaches approximately 250 F. to 275 F. and holdingthe 55 temperature at approximately this heat until the layer is suiliciently hardened, then permitting the tank to cool, and removing the insulation from the outer surface thereof.

- JAMES LITHGOW.

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