AL'UMINUM ALLOYS H. W. FRITTS AND E. D. VERINK, JR. Aluminum Co. of America, New Kensington, Pa. tions where aluminum alloys are used in contact with concentrated n i t r i c a c i d . A n o t h e r item (11) points out how an aluminum drum and aluminum piping provided a satisfactory nitric acid cooler. Nitrogen Compounds. Typical uses of aluminum alloys in ammonia service are for refrigeration tubing, storage vessels, sprays and molds in contact with ammoniacal rubber latex, and heat exchanger tubing handling ammonia-carbon dioxide-steam mixtures as encountered in the soda ash industry (42). A thin, protective oxide film forms on aluminum alloys after exposure to ammonia and prevents further appreciable attack. Combining adequate strength and resistance to corrosion, aluminum alloy 61ST6 was chosen for the construction of a large welded ammonium nitrate prilling tower. It is an airtight, 22 X 32 foot rectangular tower, 155 feet high (16, SO). A former United States Navy LST has been converted by the installation of six large aluminum tanks, to carry nitrogen fertilizer solutions (56). Another nitrogen-containing compound, urea, is purified in aluminum equipment (55). Organic Acids. Acrylic acid (glacial) is shipped in aluminum alloy drums (4). Aluminum allnys are widely used in the production and handling of both acetic acid and acetic anhydride (41). In the production of citric acid by the fermentation of sugar, shallow aluminum pans, because of their nontoxicity, are largely responsible for the high yields obtained (24). A battery of high purity aluminum tanks store fatty acids at a large plant in England. Inert gas atmospheres are maintained in the tanks to protect the fractionated acids (26). Synthetic Resins. Because aluminum alloys protect the color quality of resins, they were selected as materials of construction for reaction vessels, storage tanks, and tower internals in a large petrochemical plant in England ( 4 6 ) . Water. The world's first heavy water moderated nuclear reactor, at Argonne National Laboratory, is housed in an aluminum tank filled with 61/* tons of heavy water. Aluminum tubes also house the safety and control rods (10). Aluminum storage and distribution systems for distilled, deionized, and demineralized water are becoming standard. Bryan (9) has attributed the resistance of aluminum and its alloys to the action of boiling distilled water to the formation of a tightly adherent, impervious film. This protective film of alumina monohydrate is inert and highly insoluble. The Downingtown Paper Co. of Downingtown, Pa., has installed an aluminum steam condenser for heating water on the roof of its plant. Advantages over using a standard cast iron condenser were threefold: the aluminum condenser was supplied a t a lower initial cost than a standard cast iron unit; the need for costly roof supports was eliminated since the condenser rn much as the cast iron unit it reweighs approximately placed; and no expensive rigging was required since two-section construction permitted the aluminum condenser to be moved to the roof on the freight elevator (58). Miscellaneous. Aluminum sheet is used in a plant in England as protection for thermal insulation on pipes and vessels. Heat exchanger tubes of aluminum alloys also are employed in this same plant to resist hydrogen sulfide and corrosive cooling waters in condensers (46).
Aluminum alloys continue to find new uses in the chemical and related process industries. In this review the authors discuss the applications of aluminum alloys in the chemical, petroleum, and food industries. The use of aluminum foil, particularly in the food industry, has increased during the past year. The first use of aluminum in this country in power plant operations (aside from aluminum electrical conductors) is discussed. The use of aluminum alloys for railroad tank cars for the transportation of chemicals continues to increase.
A
LUMINUM alloys, together with many other materials of construction, are in short supply this year, principally because of their expanded use in the national defense effort. Although many new uses are recorded in the literature, the majority of aluminum being used by the chemical and related process industries is for established applications mentioned in earlier articles (8, 43-45). DESIGN CONSIDERATIONS
Indicative of progress toward the acceptance of stronger aluminum alloys, 4s (ASTM alloy MGIIA) is now covered by case 1114 of the American Society of Mechanical Engineers code for unfired pressure vessels (25). The American Petroleum Institute also includes recommended practice for use of aluminum alloys in construction of tank roofs and top shell rings in its specifications for welded oil storage tanks ( 5 ) . CHEMICAL APPLICATIONS
Coal Chemicals. Shearon, Hall, and Stevens (54)in reporting on the production of fine chemicals from coal, point out that aluminum alloys are used for the construction of tanks handling benzaldehyde, benzyl alcohol, and a hopper for benzoic acid. Fluorine Compounds. A most interesting application is the use of aluminum alloy reactors for making fluophosphoric acids. These acids are formed by the interaction of anhydrous hydrofluoric acid and phosphorus pentoxide (12). Aluminum industrial building sheet was employed for the construction of a plant in which various fluorine chemicah are made. In spite of the presence of traces of hydrogen fluoride in the atmosphere, this building is in good condition after 2 years of service (4). Hydrogen Peroxide. Recent changes in regulations of the Interstate Commerce Commission (ICC) now provide for shipment of up to 52% hydrogen peroxide solutions in aluminum alloy drums (17). Latex Solutions. For many years aluminum alloys have been used by the rubber industry both in forming many rubber articles and in handling the crude latex solutions. A recent article (1) discusses the desirability of aluminum alloys in the construction of latex hand carts, latex storage tanks, acid mixer and coagulating tanks, latex bulker tanks, and containers of many varieties. Smoke houses built of aluminum alloy corrugated sheets take advantage of the high reflectivity for radiant heat and corrosion resistance characteristics of the metal. Mineral Acids. The advantages of aluminum alloy equipment for handling nitric acid above SO% concentration have long been recognized. Recent changes in the ICC regulations (18) now permit shipment in aluminum of this acid containing lower oxides of nitrogen. A number of high purity aluminum drums currently are used for shipping red fuming nitric acid (4). A recent article by Binger and Verink ( 7 )reviews many applica-
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Vol. 43, No. 10
Food Handling Equipment. A United Nations committee has recommended the use of aluminum-lined crates for handling fish. Aluminum-lined fish crates have been used for some time in England because they are light in weight and easy to clean ( I S , 29, S I ) . Bulk salt is handled and stored in largk welded 61s aluminum bins (28). A survey of handling equipment in the quick freezing industry in England points out that a number of firms are using aluminum equipment, such as trays and conveyor slats, for handling fish, fruit, and packaged products (14). Architectural Applications. A large meat processor in Boston recently lined a sausage packing room with aluminum to make it sanitary, rodentproof, fireproof, vapor tight, and corrosion resistant (49). ALUMINUM FOIL APPLICATIONS
Aluminum foil applications, particularly in the food industry, showed a marked increase this past year. Over Figure 1. Rich Oil-Lean Oil Heat Exchangers Utilizing Aluminum Alloy T u b e s 2000 tons of foil are used per year for Aluminum corrugated sheet protects the thermal insulation on these exchangers milk caps alone (16). It is estimated that 60y0 of the oleomargarine proPETROLEUAI APPLICATIOIVS ducpd in 1949 was packaged in aluminum foil (3). The foil outer wrap prevents rancidity of fats resulting from exposure to Handling Equipment. A large refiner is using an all-aluminum light, prevents loss of moisture, and retains the flavor. Large swing line to facilitate the loading of tank cars. The 12-foot long, quantities of butter are also packaged in aluminum foil. 4-inch diameter line, of all-welded construction, weighs only 42 Khite (48)summarized the advantages of foil over parchment pounds compared to 129 pounds for the steel line it replaced. in protecting the quality of butter. The advantages reported are greater ease of handling and reduced Aluminum foil is used for pie pans. It enables the pies to be maintenance costs ( 4 7 ) . Having successfully fulfilled all the reEornied, baked, and delivered without transfer to paperboard quirements of military field performance, 61ST aluminum pipe plates (93). soon will be standard Army pipeline equipment for handling gasoAnother interesting use of aluminum foil is for lining fiber line in the field (40). drums. Bergstrom (6) describes how foil laminated bet.ween two General Metal Work. Combining reduced maintenance and sheets of kraft paper lengthens the Me of fiber drums and inprotection for the thermal insulation, a number of petroleum recreases the range of chemicals that can be packaged. Aluminum finers have installed sheet aluminum covers over lease tanks, heat foil, as now manufactured in t,hicknesses above approximately exchangers, and large tar storage tanks ( 2 , 21, 36, 39). 0.0015 inch, is substantially free from pinholes and has zero vapor Tubing. A large gasoline manufacturer is using approximately permeability. 50,000 feet of 3/&ch aluminum instrument air tubing because of its loiv cost and resistance to corrosion by hydrogen sulfide gas. POWER PLAKT APPLICATIONS In t,he same plant, eight large rich oil-lean oil exchangers (Figure 1) use aluminum heat exchanger tubes ( 3 7 ) . Air Preheaters. I n 1950, aluminum air preheater tubes were Miscellaneous. Kerns and Raker ( 2 2 ) , in a paper presented used commercially for the first time in a steam boiler plant, thus before the American Petroleum Institute, have reviewed the use ma,rking the initial entry of the metal into power plant operation of aluminum in the petroleum industry. The results of some acin this country for ot,her than electrical or architectural servtual refinery installations of aluminum alloy tanks, heat exices ( 4 ) . Combining low cost, with good resistance to corrosion changers, instrument tubing, and insulation weatherproofing are by products of combustion, aluminum air preheater tubes are exsummarized. These authors state that aluminum alloys are of tremely promising. interest to the refining industry as a material of construction beCorrugated aluminum alloy sheet is used in a Ljungstrom air cause of their resistance to corrosives such as sulfides, organic preheater a t the Fulham, England, power station ( 2 3 ) . Alumiacids, and furfural. They are light and have good heat transfer num elements which were substituted for mild steel showed concharacteristics a t low cost. siderably superior resistance to corrosion. Three-year tests in COURTESY S I 0 W
FOOD PROCESS INDUSTRIES
Fruit. The cider and fruit juice industries in Switzerland are using considerable quantities of aluminum alloy containers, siphons, piping, and large anodized or enameled tanks ( 2 7 ) . Aluminum containers are employed in the modern processing of glac6 citrus peels for handling various lots of fruit (20). The French wine industry uses aluminum alloys to advantage in the condenser and heat exchange plant ( 3 2 ) .
RICHARDSON, I N C .
t,he cold end of the heaters indicate that aluminum elements will be reduced to half their original t,hickness after about 10 years, as compared with a t,otal mild steel life of about Z1/2 years. The aluminum elements also were much easier to clean. TRANSPORTATION O F CHEWICALS
The past year has seen a large increase in the use of aluminum alloys for railroad tank cars. Over 400 aluminum tank cars were
October 1951
INDUSTRIAL AND ENGINEERING CHEMISTRY
built during 1950 to handle a wide variety of chemicals including nitrogen fertilizer solutions, hydrogen peroxide, acetic acid, fatty acids, and a few miscellaneous commodities (4). LITERATURE CITED
(1) Aluminium News, 3, 11 (November 1950). (2) Aluminum Co. of America, Alcoa “Sluminuni Newsletter,” September 1950. (3) Aluminum Co. of America, private communication. (4) Aluminum Co. of America, unpublished information. ( 5 ) Am. Petroleum Inst., Specifications for Welded Oil Storage Tanks, A.P.I. Std. 12C, 9th ed., appendix D, October 1950. (6) Bergstrom, H. A., Chens. Eng. News, 27, 3566 (1949). (7) Binger, W. W., and Verink, E. D., Jr., Chem. Eng., 57, No. 11, 126 (1950). (8) Brown, R. H., and Verink, E. D., Jr., IND.ENG. CHEM.,39, 1198 (1947). (9) Bryan, J. M., J . SOC.Chem. Ind. (London), 69, 169-73 (June 1950). (10) Chem. Eng. News, 28, 4254-7 (1950). (11) Ibid., 29, 1882 (1951). (12) Chem. Inds., 67, No. 3, 380 (September 1950). (13) Food Manuf., 25, 98 (March 1950). (14) Hammond, A. E., Mechanical Handling, 36, 736-45 (December 1949). (15) Hardware Trade J., 219, 410 (January 1950). (16) Hockensmith, H. N., Welding J . ( N . Y,), 29, No. 9, 729 (1950). (17) Interstate Commerce Commission, Tariff 8, para. 73.266 (a-2), (b-3,4), page 64 (effectiveApril 15, 1951). (18) Ibid., para. 73.268 (c-I), page 66. (19) Iron Age. 162. 154 (December 9. 1948). (20) Jacobs, E. E.; Food Inds., 22, 1904 (November 1950). (21) Jones, H. H., and Cox, J. T., Ckem. Eng., 57, No. 7, 111 (1950).
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(22) Kerns, E. E., and Baker, W. E., paper presented before Am. Petroleum Inst., Tulsa, Okla., May 1, 1951. (23) Light Metals, 13,515 (September-October 1950). (24) McKee, A. B., Fitz, A,, and Fetchko, D. J., Chem. Eng., 58, No. 3,218 (1951). (25) Mech. Eng., 73, No. 4, 350 (1951). (26) Mfg. Chemist, 21, 78-80 (February 1950). (27) Modern Metals, 5, No. 2, 28 (March 1949). (28) Ibid., 6, 46-8 (October 1950). (29) Modern Packaging, 23, 77 (August 1950). (30) Oil’Gas J., 49, 51 (Nov. 2, 1950). (31) Packaging Rev., 69, 34 (January 1950). (32) Rev. aluminium, 27, 152-3 (April 1950). (33) Roosebroom, A,, Chem. Eng., 58, No. 3, 113 (1950). (34) Shearon, W. H., Jr., Hall, M. E., and Stevens, J. E., Jr., IND. ENG.CHEM.,41, 1812-20 (1949). (35) Sheet Metal Worker, 41, 39 (December 1949). (36) Shipbuilding and Shipping Record, 76, 8 (July 6, 1950). (37) Petroleum Engr., 23, No. 4, ‘2-24 (1951). (38) The Plant, 1, 94 (April 1950). (39) Thornton, D. P., Jr., Petroleum Processing, 5, No. 7, 715 (1950). (40) Treiber, K., Oil Form, 3,509-11 (November 1949). (41) Verink, E. D., Jr., Chem. Eng., 57, No. 11, 108 (1950). (42) Ibid., p. 110. (43) Verink, E. D., Jr., and Brown, R. H., IND.ENG.CHEM.,40, 1776 (1948). (44) Ibid., 41, 2095 (1949). (45) Verink, E. D., Jr., and Fritts, H. W., Ibid., 42, 1955 (1950). (46) Victor, M., Rev. aluminium, 27, 144-51 (April 1950). (47) Welding J., 29, No. 1, 81 (1950). (48) White, A. H., Can. Dairy Ice Cream J., 27, 27 (1948). (49) Ziemba, J. V., Food Eng., 23, No. 4, 109 (1951). RECEIVED July 7, 1951.
Carbon and Graphite W. M. GAYLORD, National Carbon Co., a Division of Union Carbide and Carbon Corp., Cleveland, Ohio engineering reference books (17, 4S, 61) now provide extensive data on dimensions and sizes of standard impervious graphite pipe and fittings, a p p l i c a t i o n s , corrosion resistance, and properties of c o m m e r c i a l l y available f o r m s o f carbon and graphite. Similar data are given for the porous and impervious forms of the element as aell as heat exchanger costs ( 5 2 ) . During the past 2 years, many reviews and summaries (4,11, l$,14, $1, .28,36,58,49,50) of the manufacture and applications of carbon and graphite in the chemical industries have appeared. Most of the authors of these reviews have restricted them to the materials generally available in their country.
Acceptance of carbon, graphite, and impervious carbon and graphite for fabrication of chemical equipment continues to grow as denoted by inclusion in standard reference works. Quantitative values have been published of the remarkable increase in high temperature strength of graphite. Applications are expandhg in the established mineral acid and inorganic chemical fields as well as the newer industrial chlorinated organic chemicals. New types of graphite heat exchangers have been introduced and conventional exchangers, spray nozzles, and steam jets have been standardized.
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HE tonnage consumption of electric furnace graphite in 1935 was as electrodes for electrothermic processes and as anodes in electrochemical processes, principally the chloralkali industry. However, in 1951, graphite as the base material for impervious graphite represents an important part of the present graphite production. The developments and applications of carbon, graphite, and impervious carbon and graphite in the chemical industry during the period 1947 through 1949 were summarized by Ford (20). This article provides a summary of the contributions to the literature and the more important developments during the past 2 years. While uses of carbon and graphite have expanded enormously in the chemical field in the past decade, it is expected that the next decade will see as great an increase as knowledge of the chemical inertness of this element becomes more widely diffused and taps new applications. Decreasing unit costs are accelerating the trend to carbon, graphite, and impervious carbon and graphite chemical equipment. As an example, 70.6 square foot standard impervious graphite heat exchangers are equivalent in first cost to stainless steel exchangers of the same surface, construction, and over-all dimensions. Standard chemical and
GEUERAL PROPERTIES
Malstrom, Keen, and Green ( 3 2 )have presented the results of a thorough study of some mechanical properties of graphite at elevated temperatures. They report that the short time tensile strength of the grades of electric furnace graphite they studied doubled in passing from room temperature to 2500’ C. The Young’s modulus increased 40% at 2000’ C. compared to room temperature measurement. I n coinparison to the best high temperature alloy available in 1945, pure alumina, PllgAlz.01, and beryllia, graphite is the only material having any useful strength above 1370’ C. I n the manufacture of impervious carbon and graphite, no new impregnant or base grades of graphite have come into general use during the past 2 years.
