H. B. B O M B E R G E R
CHEMICAL PROCESS0 R S USE MORE T I T A N I UM Potential of titanium in chemical pjfocess equipment is intriguing-one
large company j n d s that
ihis material is usable in 95% o f its environments These titanium steam-heating coils are used in 25 to 30y0 sulj%ric acid at 277‘ F. Corrosion is inhibited by metallic sulJates in the solution. The Saffran Engineering Co. made 45 such units
forecasts predict that by R ecent 1970 annual consumption of titanium mill products will reach 40 to 50 million pounds. Even as early as this year, domestic shipments are expected to reach a record of 12 million pounds compared to 11.2 million for last year. This is remarkable, considering the fact that titanium has been in commercial production for only about 12 years. Responsible for this increased usage are titanium’s inherent advantages combined with decreasing cost, increased fabrication knowhow, confirmed reliability, and new uses. Military aircraft continue to consume the most, but use in missile, space, and chemical applications is increasing. Also, the chemical industry is using more470 of the 1962 market compared to 3y0 in 1961. I n terms of per cent, the last year’s market was: Military aircraft Commercial aircraft Missiles and space hardware Chemical equipment Ordnance and miscellaneous uses
57 20 75
3 5
Titanium alloys are attractive in the aerospace industries because of their important strength-to-weight advantages. By using 1000 pounds of titanium in the DC-8 Jetliner airframe, five extra passengers with baggage can be added on each flight. The highly successful Minuteman marks the first large-scale use of titanium in solid-fuel rocketry. Reliability of titanium was also highlighted with the unqualified success of the Project Mercury space capsule and the X-15 research vehicle. The Mercury capsule, and the Apollo which will land men on the moon, are largely of titanium. About 18y0 of the weight of the X15 consists of titanium. The Ti-6A1-4V alloy is the workhorse of the titanium industry; it responds to heat treatment and offers a good combination of strength, toughness, and weldability. Ti5A1-2.5Sn is next in total usage; it has lower room temperature strength than Ti-6A1-4V but better weldability, creep resistance, and low-temperature ductility. The alloy has excellent strength and toughness at cryogenic tempera-
tures and is finding increasing usage in liquid hydrogen. New alloys, such as Ti-8Al-lMo-lV, are expected to be used extensively in the new supersonic transports. Unalloyed titanium grades are employed most widely in the chemical industry where a Combination of good workability, moderate strength, and excellent corrosion resistance is required. An alloy of Ti-.2Pd is used under reducing conditions for more corrosion resistance. The chemical process industries loom as major beneficiaries of titanium’s properties. These industries have had the metal under close surveillance for several years and have established a firm background of reliable performance. A spokesman for one of the largest chemical companies recently stated that titanium is suitable for more than 95% of their environments and is now considered the long-sought universal material for their operations. Thus, specific equipment for different processes can be used, and only a minimum of standard titanium components need be held in reserve. (Continued on next p a g e ) VOL. 5 5
NO. 1
JANUARY
1963
53
Titanium mill products sell at an average price of about $5 per pound. However, the price is more realistic when based on metal volume rather than weight-density of titanium is only about 5870 that of steel. Also, further downward adjustments in prices and fabrication costs have been reported. In 1962 the price of titanium tubing, so important to the chemical process industries, decreased more than 35YG. Many of the common fabrications now cost no inore for titanium than for stainless steel and less than for superalloys. Titanium heat exchangers cost about 30Yc as much as equivalent glass units. Some plants have saved money by basing titanium equipment designs entirely on service loads. This is possible in many cases because of the metal’s excellent corrosion resistance. Large diameter ducts, with just enough wall thickness to support their own weight, are being used successfully for transporting wet chlorine gas. These ducts are competitive in cost but do not have the temperature limitations of other materials. Thin loose titanium liners are also used economically in distillation tower sections, and the development of efficient installation techniques has now made the lining. of large tanks practical. Corrosion Properties and Applications
During 1962, a number of new applications were either developed, or are under development, but published details are not available in most cases. However, corrosion properties and typical applications are described (2, P, 14). The largest industrial use of titanium was made by the Celanese Corp. at its Bay City, Tex., facility for the production of acetaldyhyde from ethylene. The metal is used as piping, pumps, valves, heat exchangers, and liners for vessels up to 32 by 10 feet.
H . B . Bombergcr is tire Supervisor of T i t a n i u m Research for the CrucLble Steel Co. of America. For the !last seven years, he has authored I@EC’s annual review on titanium. AUTHOR
54
A titanium-lined column made by P’uudler-Permutit,
Performance of titanium and other materials in a variety of chemical plant environments is described (77). This work confirms earlier reports that titanium has excellent resistance to wet chlorine, chlorinated brine, chlorine dioxide, hypochlorous acid, a wide variety of other chloride compounds, 62Y0 sulfuric acid saturated with chlorine, nitric acid, and alkaline solutions. The metal is not recommended for dry chlorine, solutions containing fluoride ions, hot or concentrated reducing acids, hot 73% CaC12, 30% AlCls, and certain hot alkali solutions. However, small amounts of oxidants and heavy metal ions tend to inhibit corrosion in otherwise corrosive solutions. Titanium alloyed with 0.2% Pd. 23 to 29y0M o , and combinations of Pd and h l o performs well in hot concentrated calcium chloride and hydrochloric acid solutions and also in environments which have little effect on the unalloyed metal (17). This agrees with earlier work which demonstrated that palladium and molybdenum additions greatly improve the performance of titanium in most of the reducing-acid environments where the metal has limited resistance. Molybdenum is the more effective allo) ing element but, unlike palladium, it lowers resistance to oxidizing solutions. More recent work indicates that tantalum is also an effective alloying element for improving resistance to sulfuric, hydrochloric, oxalic. and phosphoric acid solutions ( 3 ) . Chlorine producers and industries such a5 paper. plastics, and deter-
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Inc.
gents which utilize wet chlorine provide a rapidly growing market for a full line of titanium equipment. The metal is generally considered to have unsurpassed resistance to wet chlorine and most chlorine compounds (70). Recently, however, a few isolated cases of corrosion have been reported, where chlorine gas attacked titanium in certain deep crevices (5). The conditions required for attack appear to be restricted gas circulation and a high ratio of surface-area to gas-volume. I t is believed that the normally imperceptible reaction of wet chlorine with titanium dries the entrapped gas until it becomes reactive. The reaction rate then increases as acidic, hygroscopic titanium salts accumulate. Damage of this kind has been observed at taped duct joints where chlorine gas disbonds the tape and thereby produces restricted crevices. It has also been reproduced in the laboratory in deep all-titanium crevices. Thus, in chlorine equipment, restricted crevices should be avoided. Although the thermal conductivity of titanium is only about 570 of that for copper, field expericnce demonstrates that the metal has relatively good heat transfer characteristics. “bo, direct laboratory experiments indicate that titanium is more efficient than copper, glass, and other materials in vapor condensation ( 4 ) . This surprising behavior is believed to be associated with the lionwetting nature of the titanium surface which permits rapid drainage of the condensate. Also, R heat transfer barrier in the form of
a corrosion film doeq not form. Other properties of titanium, such as erosion resistance, high strength, and less tendency to foul, should also result in more efficient heat exchanger designs. The integrally finned titanium tubes developed by Wolverine Tube should result in still better heat transfer ( 7 7 ) . At least two soda ash plants are using titanium equipment. Cast iron units normally employed in the ammonia stills of the Solvay process must be replaced after about two years. Titanium tubes, however, have now been tested under the same conditions for more than five years without failure. The heat exchangers in the ammonia stills usually contain as many as 800 tubes per bundle. One plant realized a production increase of more than 25y0 after retubing a still with titanium. Thus, titanium units have been considered entirely on the basis of heat transfer rather than corrosion resistance. For cooling wet chlorine, titanium units compared with glass equipment under typical conditions offer significant savings in both capital investment and operating costs (18). Also, titanium for oil field pump and valve parts has excellent resistance to the corrosive and erosive effects of fluids such as sand-laden hydrogen sulfide brines (72). The metal performed well in gas lift valves and tubing but it appeared to be too soft for good durability as pump valve parts. Hardening may correct this shortcoming since a nitrided alloy (Ti-6A1-4V) is used successfully as fuel line valves in Navy aircraft. Hardened valves and connecting rods are also being studied for use in internal combustion engines. Better performance \vas reported for the lower inertial forces of the titanium parts. Some of the largest potential uses for titanium are in the electrochemical field. Thin titanium anodes clad with about 1 mil of platinum are performing well in cornmercial production of perchlorates. Similar anodes plated with from 0.05- to 0.10-mil of platinum have been tested extensively in chlorine cells (7, 13). The performance and
Pressure a n d vacuum gauges in five case styles and five Bourdon tube materials
Dial indicating thermometers in 'our case sizes Nith four actuatng media, vapor ension, mercury, iquid and gas
e
L i q u i d-i n-GI a ss i n d u s t r i a l thermometers in four :use sizes a n d f o u r types w i t h rigid stem, adust-angle, a d just-all, a n d dual scale styles
Recording instruments in four case sizes with up to four pens
Bi-metal dial thermometers in three case sizes, with three stem styles. Straight and angle forms
WRITE FOR LITERATURE ABOUT THE WEKSLER INSTRUMENTS WHICH INTEREST YOU
INSTRUMENTS
INDICATING. RECORDING P CONTROLLING INSTRUMENTS fOR T W E R I T U R I PRESSURE & HUMIDITY
i: WEKSLER INSTRUMENTS .
-
CORPORATION
195 E A S T M E R R I C K R O A D . F R E E P O R T , L . I . , N . Y .
"Originators o f World Renowned Adjust-angle Thermometers" Circle
No. 15 on Readers' Service Card VOL. 5 5
NO. 1
JANUARY
1963
55
reliability of such anodes is now well established on a laboratory scale and commercialization is expected to begin early in 1963. I n most cases the anodes will probably be used with new, more efficient cell designs which may also employ newly developed titanium cell covers and liners and titanium-sheathed copper conductors. Platinized titanium anodes have a number of important characteristics. Conducting, noncorroding titanium provides an excellent and inexpensive base for supporting a minimum amount of platinum. T h e combination anode is inert and it has the low chlorine overvoltage of platinum. Indicated benefits are high product quality, close permanent electrode spacings, major power savings, less maintenance, and greater versatility in anode and cell design than possible with conExventionally used graphite. panded titanium mesh appears ideally suited for the horizontal anodes in mercury cells because the pores permit convenient escape of the chlorine gas. Platinized titanium anodes are also used extensively in cathodic protection service for a variety of industrial and marine applications (20, 27). Rod-shaped anodes are used successfully in nearly inaccessable places such as heat exchangers, water lines, pump manifolds, other process equipment, and domestic water heaters. Platinumplated titanium-sheathed copper wire was developed for protecting large marine equipment. I n this case the thin platinum plate provides the desired anode properties, the titanium supports the platinum and protects the copper, and the copper provides high electrical conductivity. Platinized titanium is also used as insoluble anodes in electroplating, recovery and refining of rhodium, gold, platinum, silver, chromium, nickel, and other metals. Such anodes have been in continuous service for more than two years yielding deposits of excellent purity. Similar electrodes are finding limited but important applications in electro-organic reactions, water purification, and experimental fuel cells. Circle
56
No. 7 on Readers’ Service Card
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
A recent patent describes thc development of a nitrided titanium electrode which is said to have good corrosion resistance and electrical conductivity and to be useful as an anode in electrolytic processes where no fluorine is involved ( I ) . Unplated titanium is used extensively in the form of anode baskets for nickel purification and plating. The barkets permit the convenient use of less expensive nickel pellets and random pieces for anode dissolution. They replace shaped nickel anodes and 100% of the nickel is utilized ( 9 ) . ,4n automobile manufacturer who purchased 500 anode baskets reported that the savings in one year will more than pay for them. T h e same concept is applicable to the purification and plating of other metals. However, in winning or recovery operations where the metal is already in solution (such as the recovery of silver from photographic solutions), platinum-plated anodes are recommended. Unplated anodes develop a thin but noticeable oxide film which resists current flow from the titanium to the electrolyte, but this film does not interfere with current flow to metals such as the nickel in the anode baskets or to aluminum during anodizing. Unplated titanium is also used as cathodes in the electrolytic production of manganese and possibly other metals. T h e manganese is readily deposited on the titanium cathodes but it is not strongly adherent. T h e deposit can be readily stripped by hammering or flexing. However, occasional reconditioning of the cathodes appears necessary to avoid poor stripping and also embrittlement of the cathodes. Thin oxide films on titanium are responsible for the good corrosion resistance and electrochemical characteristics of the metal. Recent studies and earlier work indicate that the highest titanium oxide (TiO?) forms on titanium surfaces under extreme conditions of oxidation, such as exposure to air at elevated temperatures, oxidation in boiling solutions, and anodic reactions a t high positive potentials. Under more moderate conditions,
such as passivation in solutions a t room temperature and anodizing at low potentials, a lower oxide of composition [Ti203 a n d (3, 5 ) Ti021 was obtained. T h e oxide, Ti306, was detected on titaniurn after exposure to sulfuric acid a t room temperature, whereas a thin layer of T i 0 appears to form on the metal on exposure to air a t room temperature (79). Etching the metal with Hi304 caused a film of titanium hydride (6). Titanium oxides have interesting optical (15) and electronic (10, 76) properties. High oxides are resistive but lower oxides are conductive or semiconductive. Anodizing can produce desired resistive or dielectric properties. Thin film circuits of titanium a r e being developed to improve electronic performance. Titanium capacitors are also being developed and may replace tantalum capacitors in Japanese equipment. LITERATURE C I T E D (1) Amalgamated
W i t h the addition of only .OS% to 3.0% of Marasperse (based on the weight of the solids) a viscous pasty mass becomes an easy-to-handle freeflowing liquid. Only the state of the mass is changed. T h e volume is MARACARB is also a highly effec- unaffected because the Marasperse is tive dispersant and the redispersion taken into solution by the availaof the dyestuff pastes is greatly im- ble water. proved “Far superior to other T h e versatility of Marasperse types of humectants,” say the experts. dispersants is best described MARACARB - combination humecby the variety of applications tant, dispersing and redispersing agent in use, such as oil well drilling for dyestuff pastes, is one of the series of lignin chemicals produced by the muds, gypsum slurries, ceramChemical Department of M a r a t h o n . ic slips, pesticides, dyestuffs, Other Marathon lignin chemicals are industrial c l e a n e r s , concrete, used in such applications as preparation of oil well drilling muds, gypsum pigment, c a r b o n black and slurries and ceramic slips. I n the forclay dispersions, ore flotations, mulation of pesticides and industrial and many others. cleaners. In pigment, carbon black, and
Because of its s u p e r i o r humectant properties, Marathon’s MARACARB is being used to completely replace glycerine, glycols and other types of (more costly) h u m e c t a n t s in the manufacture of dyestuff pastes.
Curacao Patents Co. N.V., Brit. Patent 886, 197 (Jan. 3, 1962). (2) Anti-Corrosion Manual, 4th ed., 157-67, 1962. (3) Bishop, C. R., Powell, R. L., Corrosion 18, 205-210t (June 1962). (4) Bomberger, H. B., Crucible Titanium Rev. 9, 2-8 (November 1961). (5) Zbid., 10, 1-5 (August 1962). (6) Burinda, S. M., Samartsev, A. G., Zh. Prikl. Khim. 34, 2566-8 (November 1961). (7) Chem. Eng. 69, 68-9 (Jan. 22, 1962). (8) Zbid., 154-5 (April 30, 1962). (9) Electroplating Metal Finishing 15, 66 clay dispersions. As water reducing ad(February 1962). mixtures for concrete. Marasperses are water-soluble, free(10) Fuller, W. D., Nut. Electronics Conf. Proc. 17, 32-43 (1961). Return the coupon below for addi- flowing powders. Return the coupon (1 1) IND. ENG.CHEM.54, 69 (May 1962). below for additional information. tional information. (12) Jessen, F. W., Molina, R. J., Corrosion 17, 16-20, 22, 24, 26, 27, 30 (November 1961). (13) J . Electrochem. Soc. 109, 103C (March uu/u A D l v i s l o n o f A m e r l o a n Can Company 1962). CHEMICAL SALES DEPARTMENT (14) McPherson, R. J., Chemistry in CanMENASHA, WISCONSIN ada 14, 22-3 (February 1962). (15) Menard, R. C., J . Optical SOG. *Registered U. S. trademark, *Registered U. S. trademark. Am. 52,427-31 (April 1962). (16) Quinn, R. A., J . Electrochem. Snc. MARATHON e A Division of American Can Co. MARATHON A Division of American Can Co. CHEMICAL SALES DEPT. MENASHA, WIS. CHEMICAL SALES DEPT. MENASHA, WIS. 109, 64C (March 1962). (17) Sheppard, R. S., others, Corrosion 18, Send additional information on Maracarb Please send Information File NO. 1-13 0, Samples of MARASPERSE for use in 211t-8t (June 1962). to: (18) Titanium Metals Corp., “New Economies in Cooling Chlorine,” 1961. (19) Tomashov, B. D., Al’tovskii, R. M., Kushnerev, M. Y.,Akad. Nauk S.S.S.R. Dokladv 141, 913-6 (December 1961). (20) Walkiden, G. W., Corrosion Technol. ................................ ..... ..... ................ ............................. ..~ ...............-----------........ ................. ... . ~ ~ ...~ ..........~.....~ ~ . . .... 9,14-6 (January 1962). P l e a s e a t t a c h t o your c o m p a n y l e f t e r h e a d . P l e a s e a t t a c h to your c o m p a n y letterhead. (21) Zbid., 38-40, 44 (February 1962). 1-13 Circle No. 58 on Readers’ Service Card Circle NO. 57 on Readers’ Service Card V O L . 5 5 NO. 1 J A N U A R Y 1 9 6 3 57
...
MARATHON r;llO
------------------ ------------------
~
~~
~
~
~
