ERROL B. SHAND Corning Glass Works, Corning,N. Y.
As a result of developments begun during World War I and of accumulated experience, industrial glass piping has become an accepted product in various branches of industry. It is giving satisfactory service in handling acids and other corrosive chemicals, often at temperatures of 250’ F., in protecting the quality of pharmaceutical and fine chemicals, and in maintaining sanitary conditions for milk, wine, and other food products.
T
H E use of glass as a material for industrial piping can be considered as an outgrowth of the glass tubing of the chemical and biological laboratories. E4RLY WORK ON GLASS PIPING
Probably the first serious thought was given to this matter of glass piping during TTorld War I, when the production of chemicals in this country, both in quantity and in variety, was increasing rapidly. This condition developed needs for piping material with better corrosion-resisting properties. During this same period, Corning Glass Works had been developing new types of borosilicate glasses, which had not only good chemical durability, but also coefficients of expansion with temperature which were only 35 to 40% those of the glasses then in general use. Both properties are essential in any glass considered for piping and various other industrial uses.
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The transition from laboratory tubing to industrial piping means a great deal more than simply increasing the dimensions of the tubing. One problem-the effects of higher thermally induced stresses resulting from the thicker glass sections-had been overcome with the use of the new low-expansion glasses, but other problems remained. At this time the use of glass as a structural material was somewhat limited, and experience in the design and application of glass for such purposes was not sufficient to make the best use of itsinherent properties. The glass manufacturer was not thoroughly conversant with the conditions existing in industrial plants, which imposed certain requirements for the successful operation of the piping. Finally, no equipment was then available in glass plants for the mechanical production of tubing of suitable sizes and lengths for this product. In order to correct these deficiencies, in 1924 Corning Glass Works retained the services of the late A. E. Marshall, an experienced chemical engineer, to guide the development of glass products including piping for industrial use. His efforts were later augmented by those of younger engineers. The experimental development of mechanical drawing equipment for glass tubing of larger sizes was initiated some time later. Other developments were also being carried on, which later had their effects on glass piping. One of these was the strengthening of glass by a process of heat treatment called tempering.
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Figure 1. Flanged Joint Assembly 2-inch Pyrex pipe, early type of 1927
An entry into this general field of application occurred with the placing in service of an acid cooler constructed from socket pipe sections blown from this new type of glass. Several other small installations were made of tubing or cylinders for conveying or cooling corrosive chemicals in the years directly following the war. These were largely of an experimental nature, and were crudely designed and installed. For this reason their operation left something to be desired, although the corrosion-resisting properties of the glass itself kept alive an interest in the material for chemical plant use. January 1954
Figure 2.
Flanged Joint Assembly
%inoh Pyrex pipe, present type
A demountable pipe joint comprising pressed glass flanges sealed to the hand-drawn tubing then available was designed and tested. The seal was effected by an interface gasket placed between the two glass flanges, which were then drawn together by
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Single sections of 10 feet or more were regularly produced. This product was marketed under the name of “Pyrex industrial glass piping.” Experimental tests showed that if the wall thickness of the tubing was reduced, specific rates of heat transfer were entirely satisfactory for many chemical applications. A number of tubular-type heat exchangers were consequently tried out in service. One of the early applications of glass tubing for heat-exchange purposes mas a cascade-type cooler, each unit consisting of two horizontal banks of tubing 19 feet long and 36 tubes high connected into vertical headers of metal. Sea water flushed over the tube banks was used to cool ammonia gas and ammonia liquor. Other installations of cascade and concentric tube coolers were made for wet chlorine gas and hydrochloric acid. Large units were also used for cooling a combination of hydrochloric acid and ethyl chloride in the process of making tetraethyllead for antiknock gasolines. Piping applications were made for conveying various corrosive chemicals including sulfuric, hydrochloric, nitric, and acetic acids, and other materials such as chlorinated hydrocarbons, hydrogen peroxide, bromine, and brines. Glass piping also was found t o , give excellent service as drain lines for handling the wastes of chemical laboratories and of chemical processes. In the field of fine chemicals, glass piping was handling chemical products of high purity such as nitric acid and a number of pharmaceutical products (Figure 3). In one instance, the prevention of contamination was of sufficient importance to dictate the fusion sealing of glass sections into long lines in order to eliminate contact between the gaskets and the product. For the handling of food products, where sanitation is an important factor, piping was installed in wineries and in a number of food packing plants (Figure 4). In this prewar period, glass piping was installed and operated successfully as a milk line in a dairy plant.
Figure 3.
Installation for Production of Pharmaceuticals Westburg Chemical Co., Inc.. Jersey City, N. J.
two split metal flanges. The general arrangement of this joint is shown in Figure 1. Elbows and tees were fabricated from glass tubing using this same flange construction. The first installation of this piping of any considerable extent was made a t the Hoffman Beverage Co., Newark, S. J., in 1927. These lines were used to convey fruit juices and carbonated beverages. The initial installation consisted of 2-inch piping. Later some 3-inch lines were added. The maximum length of straight sections of pipe was limited to approximately 70 inches, although most sections were prefabricated to shorter lengths in accordance with the piping layout. Among other installations of this same piping was one made a t the Taylor Winery in New York State. Experience gained in these and other installations led to the design of a more convenient and satisfactory pipe joint in 1931, one which is still used with minor modifications. This joint consists of a pressed glass conical flange, fusion-sealed t o the ends of glass tubing. The metal flanges are solid for pipe sizes up to and including 3 inches, being held in place by inserts cut from sheet asbestos packing. These inserts also have the function of distributing the clamping forces more uniformly around the glass. T h e structure of this new joint is shown in Figure 2. In 1934 the development of tube drawing equipment had progressed sufficiently to permit the mechanical drawing of pipe tubing of both 2-inch and 3-inch sizes. Not only was the piping drawn continuously in volume, but the dimensional variations were less than was practicable with hand-drawing methods.
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Figure 4.
Installation at Winery
Woodbridge Vineyard Association, Lodi, Calif.
The above summary represents briefly the status of glass piping a t the advent of World War 11. The properties of the glass in resisting and in preventing contamination had been demonstrated over a fairly wide field of application. The operation of glass piping under plant conditions was found to be practicable. Piping then available with common fittings included
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 46, No. 1
and Glass
-Ceramics
Figure 5. Part of Large Glass Heat Exchanger for Production of Magnesium Metal
&a of 1, 1.5, 2, 3, and 4 inches, together with heat-exchanger tubing sizes of 1.5, 2, and 3 inches. EXPANSION DURING WORLD WAR I1
World War I1 saw a second expansion of the chemical industry with greatly increased demands for glass and glass piping. Existing cooler installations used in the production of tetraethyllead were increased in size. The nuclear plant a t Oak Ridge, constructed under the Manhattan Project, utilized 7.5 miles of glass piping. The conditions under which this construction was carried out made it impracticable to prefabricate many of the special lengths and fittings a t the glass plant. These special parts were fabricated a t the Oak Ridge Plant by fusing the glass end flanges to the tubing with an electrical method developed by Corning Glass Works. With suitable equipment, workmen who had never handled glass previously were quickly trained to perform the operations of sealing and annealing as a part of the installation work. Although fabrication on the job proved to be more costly than a t the glass factory, the results proved that this was a satisfactory solution for the special conditions imposed in this case. The details of these operations and results obtained have been discussed (2, 4). Another important wartime installation was that of a cascadetype tubular cooler for a slurry of magnesium chloride and hydrochloric acid used for the production of magnesium metal a t Las Vegm, Nevada. Some 27 miles of glass piping were used in this installation, which was made up of units consisting of a bank of 13 tubes, 20 feet long, interconnected with glass U-bends (Figure 5 ) . Other wartime applications of heat exchangers included several installations for cooling arsenictrichloride used for munitions.
straight lengths and fittings. This greatly facilitates the erectiom and maintenance of the piping. Improved methods of fusing the glass flanges to the piping with the use of electric power were introduced on a larger scale. 4 very important development was that of tempering the fittings and also the flanged end of straight lengths. These parts are subjected to higher stresse~ when assembled in a pipeline, so that this improvement represented an increase in the strength level of the piping of the order of 100% ( 3 ) . One additional size, 6-inch, was also developed as a part of this program. The matter of providing the user with means of filling in special lengths of pipe was also given serious consideration. Several methods are now available for this. For sizes up to 3-inchJ inexpensive equipment m s developed for making up special lengths in the user's plant. This equipment includes a cutting device for the pipe, and gas burners for forming a rounded bead on the cut end. These beaded flanges can then be joined together or to the standard flanges with the regular metal flangeB.
RECENT DEVELOPMENTS
Manufacturing facilities and available skill in fabrication had been severely taxed by the increased demand for glass piping products imposed by the war. With cessation of hostilities a program was begun for a new plant and for the improvement of the product. Special equipment and fixtures were installed for the more accurate alignment and spacing of the flange faces of both
January 1954
Figure 6.
'
Glass Pipeline
Producers Creamery Co.,.Springfield, Mo.
INDUSTRIAL AND ENGINEERING CHEMISTRY
181
,
Figure 7.
Outdoor Pipeline
Bakelite Co., Marietta, Ohio
While not equal in strength to the standard tempered flanges, joints made in this way have performed very satisfactorily under exacting operating conditions. The restrictions placed on stainless steel during the war had
raised serious problems in expansions of dairy plants, In 1942 Corning Glass Works was requested to investigate the use of glass piping for fluid milk in order to relieve this situation. The cleaning and sanitizing of milk lines were then carried out entirely by dismantling the piping for washing and brushing. As methods of cleaning in place are essential in the operation of glass piping, such methods were investigated thoroughly to test their effectiveness in meeting every sanitary requirement. This work was carried out by the New York College of Agriculture a t Cornel1 University (1). Based on this and other work of a similar nature, the current revision of the U. S. Public Health Service Sanitary Code recognizes this method of cleaning pipelines for fluid milk, which has resulted in the removal of restrictions of the use of glass pipe in dairy plants (Figure 6). Previous to this code revision a number of installations of glass pipelines were operated under special sanitary supervision. A notable example of this was a t the plant of H. P. Hood and Son, Charlestown, Mass. At the pres& time this application of glass piping is expanding not only in dairy plants, but also in dairy barns in connection with bulk handling systems used for milking. PRESENT STATUS O F GLASS PIPING
Industrial glass piping of today is the result of 25 years of evolution. Its performance differs greatly from the early glass piping of 1927, and even from that of 5 years ago. Further develop ments are still in progress. As an instance of this, a glass pipeline having an outer reinforcement of glass fibers and plastic will shortly be installed in order to meet an unusual service condition. Over these years of evolution, glass has made a definite place for itself among materials for corrosion-resisting pipe. It is now successfully handling some of the most corrosive chemicals produced, often a t elevated temperatures (Figures 7 and 8); for some of these applications it is outstandingly superior to other materials. Not only does glass resist corrosion, but because of the inertness of its constituents, any effect of contamination is further reduced to a minimum. In the handling of food products, glass has the advantage of being more readily cleaned and sanitized than metals. Industrial glass piping with accessory fittings is now a well standardized product available in sizes from 1 inch to 6 inches. Tubular heat exchangers are obtainable with tubes of 1.5- 2-, and 3-inch sizes. It is reliable in operation, readily serviced by plant personnel, and economical when compared with other corrosion-resisting materials, Industrial glass piping has come of age. LITERATURE CITED
(1) Fleischman, F. F., White, J. C., and Holland, R. F., Food Inds., 22, 1686 (1950). (2) Schrader, R. J., and De Haan, A., Chem. & M e t . Eng., 53, No. 11, 96-101 (1946). ( 3 ) Shand, E. B , Heating & Ventilating, 47 ( l l ) ,68-82 (1950). (4) Whitehurst, B. W., Chem. & Met. Eng., 53, No. 7, 112-15 (1946). RECEIVED for review March 6, 1953.
Figure 8.
.4CCEPTED
October 4, 1953.
Glass Pipe Assembly
Hercules Powder Co.
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I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
Vol. 46, No. 1
