Metal Drums and Cvlinders J
Improved steel drums, plastic linings, and nonferrous metals and alloys are important developments in the shipping of chemicals. Work on standardization is lessening the confusion that has existed.
ROBERT H. LONG The Harshaw Chemical Go., Cleseland, Ohio
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IFTY years ago, a pioneering generation of packaging engineers, dissatisfied with the contemporary flimsv and ineffectual containers whose failures were causing deaths, injuries, and property destruction, designed a seiies of 12-, 14-, and 16-gage steel chemical d r u m which were masterpieces of strength and durability. I n modified forms, these drums are still manufactured for the shipment of extremely dangerous commodities. Because of their initial cost, it was necessary to use them as returnable containers. I n the early 1 9 3 0 ’ ~ a ~new and restless generation of chemical packaging men, encouraged b y improved metallurgical and container-production techniques, decided to design a lighter gage single-trip 55-gallon drum for moderately hazardous commodities which did not need the protection of heavier containers weighing 80 to 150 pounds. I n 1934, as a successful conclusion to their efforts, a drum made entirely of 18-gage steel, weighing about 50 pounds, was authorized for the shipment of certain hazardous liquids. The light-gage container, which is now identified as Specification ICC-l7E, is still the most widely used and staple drum for the shipment of flammable chemicals, paints, solvents, and petroleum products. Metal shortages during and following World Wai I1 forced industry to retest and use the ICC-17E container for more than one trip. Herice the drum which started out as a single-trip package can no longer be regarded as such. Several manufacturers of steel drums sensed the economic advantages of developing a true single-trip container for regulated liquids, using steel lighter than 18 gage. I n 1953 one of the producers, after experimenting with models made of 20-, 22-, and 24gage sheet, announced the successful development of a 55-gallon 24-gage drum having an empty weight of about 27 pounds. On July 14, 1954, in the presence of a technical group representing the Bureau of Explosives, Manufacturing Chemists’ Association, Petroleum Section of the Packaging Institute, Steel Shipping Container Institute, the armed forces, and others, a production lot of the new light-gage drums was subjected to the same series of physical performanee tests that the 18-gage ICC17E type is required to meet. A4irpressure a t 7 pounds per square inch admitted to the drum caused no leakage at the ends, called the chimes, or welded side seams. When filled with water and held a t hydrostatic pressure of 15 pounds per square inch for 5 minutes, no leakage occurred Pressures beyond test requirements were admitted and the drums eventually burst open a t the chime seams in the range of 38 to 44 pounds per square inch. Drums filled to 98% of their capacity with water (about 485 pounds) were dropped from a height of 4 feet onto concrete without rupturing or leaking. The features which impart stability to the new light drum might escape the notice of the casual observer. The chimes, which join the body of the druin to the heads at both ends, have a circular strip of 18-gage steel seamed into them. A cross section oE this vital seam shows eight thicknesses of metal, which account for its remarkable performance in pressure and drop tests. June 1955
The drum sides, which \Till withstand a vertical load of 4000 pounds or more, are strengthened by the presence of a series of circumferentially embossed ridges or beadings. The heads are embossed with radial as well as circumferential reinforcements. The bottom head has a flat central zone, called a drop panel, which distributes the load of the filled drum away from the chime rim. The container will accommodate all standard types of closure fittings in the usual choice of locations. Before final approval and authorization by ICC specification number assignment can become effective, the new drum must be proved adequate in actual service. It is expected that interested consumers will use the drum for shipping certain regulated commodities under special permits granted by the Interstate Commerce Commission. Indications are that the new drum will be priced attractively lower than a container made of 18-gage steel, and its 46% lower tare weight \Till compound its economy through pavings in freight charges. PLASTICS
Accompanying the revolutionary trend toward lighter but effective steel containers is an equally welcome invasion of the metal packaging sphere by plastics. Out in front is polyethylene. During shipment and use, the polyethylene containers, many of which are packaged in outer drums made of steel, are provided with a sturdy coat of armor. Sprayed or laminated plastic coatings applied to drum interiors have made possible the shipment of organic and inorganic solutions heretofore believed impossible in steel containers. For protection of a higher order than is necessary to prevent air rusting in transit, linings of modified alkyd lacquers, clear phenolics, epoxide resins, vinyls, vinylidene chlorides, plastisols, or organosols may be used. Phenol-formaldehydes are one of the best classes of lining materials, but cannot be used under strong alkaline conditions. Being linear compounds, vinyls are both thermoplastic and solvent-soluble, and these properties limit their applications, but they have excellent water resistance and resistance to mild alkalies and mild acids. The epoxide resins have more recently gained wide acceptance in lining compositions. They are more flexible than phenolics and they stand reverse impact and metal fabrications without damage. The alkyd resins are not much used for linings that are subject to continual contact with degrading materials, but are used to a great extent, particularly when modified by urea or melamine resins, to give coatings with excellent hardness and weather resistance. Polyamides (nylons) and polyesters (Dacrons) have not been used t o any great extent, possibly because of their hydrolyzable amide and ester linkages. The cellulosics, because of their water susceptibility, are not suitable for linings. The poly(viny1 alcohol) acetals such as poly(viny1 butyral) are being used in wash primers and in certain epoxide resin formulations to promote metal adhesion and to provide adherent base coats. Because the closure zone may be a potentially weak spot in an otherwise satisfactory plastic-lined metal drum, two manufac-
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Table I.
Drum Size and Type Nominal 55-gallon tight head Nominal 55-gallon open head Nominal 30-gallon tight head Nominal 5-gallon open head pail
Drum SDecifications
Former Nonstandard Drums Inside Diameter, Inches Inside Height, Inches Volume, Gal. Greatest Smallest Greatest Smallest Greatest Smallest 228/1( 22 338/r 321/8 57.8 54.9 221/1 22 348/4 3213/~e 58.9 56.0 18’/16 271/1a 32.6 30 3 1718/is 29’/r 111/4 12’/16 5.8 13’/8 5.2 11a / l E
turers of container accessories have designed and started producing closures made of polyethylene. These fittings present inner flange and plug faces and thread junction zones made entirely of the plastic, thereby eliminating possible contamination of the lading by contact with bare or imperfectly coated metal closure parts. One style of closure is made by coating the inner surfaces of a conventional 2-inch flange with molded polyethylene. This unit is pressed into the drum and is seamed into an embossed opening in the metal, making a liquid-tight seal. Thus installed, a 1.5inch opening of threaded polyethylene is presented for filling and emptying. A solid polyethylene plug having mating 1.5-inch threads is used t o seal the opening. Secondary protection is provided by application of a sheet metal seal which is crimped in place and covers the entire exposed flange and plug parts. During reconditioning of the drum after initial usage the polyethylene parts may be removed, but the inner metal core then becomes effective as a standard 2-inch metal closure flange. The other type of plastic closure is made entirely of polyethylene, with the exception of an outer rim of metal. When these are used, the container manufacturer furnishes drums with openings fitted with dustproof caps. After the drum is filled, a closure is placed in the opening and crimped tightly in place by an airpowered sealing tool. The body of the closure corresponding t o a flange has a polyethylene diaphragm which hermetically encloses the contents and must be cut open when withdrawal is desired. The zone above this has molded plastic threads to accommodate a 2-inch polyethylene plug, which has a centrally located 0.75-inch threaded polyethylene plug and underlying sealed diaphragm for venting or limited withdrawal purposes. During drum reconditioning, the entire closure is decrimped from the embossment on the container. After the drum is cleaned and refilled, the user inserts a new complete polyethylene closure and seals it in place. I n addition to extensive usage in lined containers, the polyethylene fittings may win preference as closures on the new 24gage 55-gallon drums which, in most cases, will be discarded rather than reconditioned after the first service trip. STANDARD DIMENSIONS
For years, the lack of standards for dimensions and volumes in certain types and sizes of drums has been a focal point of inconvenience and annoyance in chemical plants. Steel containers, especially those in reconditioned lots, procured from several sources usually have differences in diameters, heights, and volumes which complicate filling controls and palletizing or carloading practices. The Metal Packages Committee of the Manufacturing Chemists’ Association, collaborating with the Petroleum Section of the Packaging Institute, which made a survey of the troublesome construction variables, participated in the establishment of a rational series of standards with the full cooperation and sanction of the technical committees representing steel drum manufacturers. Although specifications for the new standards cover numerous detailed revisions, Table I shows a comparison of significant differences in dimensions and volumes in typical sizes of former nonstandard drums with those drafted for the standard units. Since December 1954 consumers have been able to order drums 1194
Standard diameter, inches 221/2 221/2 181/r 111/4
New Standards Standard Volume, Gal. height, inches Maximum Minimum 34 57.75 57.20 34 57.75 57.20 31.20 271b/16 31.50 5.20 1231~ 5.45
conforming to the new standmds. Drums made according to former specifications are still procurable, however. CORROSION
Perhaps the chemical industry can be accused of being fussy, b u t when it pays almost $100 each for stainless steel drums t o package nitric acid, it expects the containers t o hold the nitric acid. Up to several years ago, the high priced drums were developing mysterious leaks with chronic regularity. Industry, dissatisfied with the performance, referred the problem to the Manufacturing Chemists’ Association. A subcommittee of the Metal Packages Committee, undertaking a study of the relationship between the acid and the container metal, found that leaks and failures were most prevalent a t the welds in the body seams or closure zones. An experimental program revealed that selective corrosion was occurring in the welds and adjacent sheet due t o stressed conditions in the metals. Corrective measures recommended by the technical group made it optional to stress-relieve drums made of welded 304 stainless steel b y heat treatment or t o use columbium-stabilized 347 alloy, which requires no stress-relieving treatment. Another subcommittee for 6 years has been following a research program centered around the development of a satisfactory singletrip container capable of transporting aqueous hydrofluoric acid. Slight dissimilarities in the steels used in the bodies, heads, and closures have been sufficient t o promote slow corrosion and resultant hydrogen formation due t o bimetal coupling in the presence of the acid which acts as an electrolyte. By using polyethylene closures to eliminate one electrochemical reactant factor, and by recommending the venting of drums while in storage prior to use, the committee seems to be approaching a satisfactory conclusion to its task of selecting an adequate design. As with other new types of drums, a period of trial shipments will be required before regular use is authorized. STEEL DRUMS
Aggressive committee action is reshaping standards for steel drums used in the packaging of dry or solid regulated poisons, flammables, and corrosives. The finishing touches have been applied to two new specification drums: a full open-head drum which will be designated as ICC-37A, and a tight-head drum with a large central filling opening which will be called ICC-37B. These two new containers will replace four currently authorized types of drums in the ICC-37 series b y consolidating the desirable construction features of each and eliminating superfluous or duplicated details. One of the drums again reflects the trend toward lighter gage metals of construction. For example, an openhead ICC-37A drum made of 24-gage steel will be authorized for gross weights up to 350 pounds, whereas the present ICC-37D drum made of the same gage sheet may not exceed 80 pounds gross. The ICC-37B will fill a long-felt void in the ICC-37 class. Ita seamed, nonremovable heads will withstand more abuse without failing than any of the present drums having nonmandatory tight-head construction. Companies which depend for income on the shipment of cyanides, arsenicals, mercury and thallium compounds, dry insecticides, phenol, permanganates, chromic acid, and many other regulated dry commodities will be benefited by the new drum. The standardization crusade is not limited to containers as
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Vol. 47, No. 6
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Handling of Chemicals such. For several decades the lack of uniform closure parts on I C C d A drums, employed for the shipment of corrosive liquids which are compatible with steel, has been causing trouble. Plugs made b y one company would leak when installed on drums fitted with closure flanges produced b y several other manufacturers. After several years of negotiating with closure producers, a change in the I C C regulations mas drafted in February 1954, which will bring about nation-wide conformity of plugs and closure flanges under a single standard specification. NQ\FERRQUS
DRUMS
Various chemicals Fill attack steel and ferrous alloys vigorously. This circumstance does not rule out the advantage of using strong metal containers. Applying the same principles of construction as used for steel containers, drums fabricated of several nonferrous metals or alloys are giving excellent performance. Benzyl, benzoyl, thionyl I sulfuryl, and pyrosulfuryl chlorides and phosphorus tribromide are packaged with complete safety in drums made of refined nickel. lblonel containers are recognized as reliable for the transportation of bulk quantitie3 of dry liquid bromine and other brominated compounds. Magnesium has a high resistance to corrosive fluoride solutions and containers made of the metal are commercially available. Aluminum is an ideal metal for packaging such regulated commodities as 95 % nitric acid, hydrogen peroxide, and anhydrous mono-, di-, and hexafluorophosphoric acids. Drums made of aluminum are lightweight, resistant to corrosion, and nearly as strong as those constructed of steel. The largest demand for them today is in the shipment of beverages, fats, oil, glycerol, food additives, and pharmaceuticals.
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CYLINDERS
Seventy-five years ago cylinders resembled random lengths of gas pipe. Chronic epidemics of disastrous failures were finally ended by the development of seamless or welded cylinders constructed of manganese steel, the toughness of which is comparable to that of the metal used in railroad rails. I n normal use, manganese steel cylinders are practically indestructable because of the strength imparted by their thickness and weight. Again, World War I1 and its insatiable consumption of metals provided the incentive for metallurgists to find ways and means of reducing the weight of steel in cylinders without sacrificing safety. Prewar precedents set by companies which had tested cylinders for liquefied petroleum gases constructed of high stress alloy steels gave the reaearchers a head start. Ferrous alloys containing chromium, molybdenum, and sometimes boron, nickel, and zirconium, in addition to the usual carbon, silicon, sulfur, phosphorus, and manganese, were developed which increased the test pressure factor of safety on cylinders from 2:l to 4 : l . Seamless alloy steel cylinders of the ICC-3AA class weighing 105 pounds now do the same work as ICC-3A manganese steel gas containers n-eighing 130 pounds. Furthermore, cylinders made of alloy steel carry extra weights of oxygen, nitrogen, helium, and argon because of an existing regulation which permits compression of contents 10% in eccess of the cylinders’ rated service pressure. By slightly increasing the thickness of the metal in alloy steel cylinders, it is possible to charge them with gases a t 5000-pound pressure with complete safety, although current working pressures are limited to a practical maximum of 3000-pounds per square inch. Welded or brazed cylinders made of special ferrous alloys weigh 30y0 less than units of the same sizes made of manganese steel. These contaiders, which are authorized under specification ICC4BA, and are used extensively for the packaging of propane and butane, have a higher factor of safety at their test pressure than their manganese steel antecedents. The chemical industry employs them advantageouslv as containers for refrigerant gases of June 1955
the chlorofluoromethane type, and for the packaging of low boiling point liquids and corrosives such as inhibited vinyl chloride, anhydrous hydrogen fluoride, and boron trichloride. Since 1950 the producers of chemical gases have borrowed a technique from the manufacturers of oxygen, nitrogen, helium, and hydrogen. Boron trifluoride, which is assuming a major role as a polymerization catalyst, can now be ordered in 10,000-pound lots packaged in manifolded banks of cylinders, 21 feet in length, mounted on highway transport vehicles. One trailerload of gas, which is the equivalent of 160 cylinders of the conventional size, can be kept in constant operation until i t is empty, thereby permitting large volume consumers to take advantage of continuous processing economies. The same manifolded gas carrier is also being used to transport ethylene, and it is only a matter of time and the development of large volume demand until the manufacturers of other chemical gases will follow suit in choosing this efficient method of delivering their products. Nonferrous metals and alloys also play a part in cylinder construction. Nickel is one of the best construction materials for cylinders designed to hold elemental fluorine and other fluorinating agents, such as the halogen fluorides. For the first time in history, an experimental lot of cylinders, drawn from titanium metal billets, was produced during the summer of 1954. Germany is turning out aluminum cylinders for use in Europe, but American manufacturers are still skeptical concerning the reliability of this light metal for cylinder construction, because of its observed tendency to lose strength in the neck zone prior t o the completion of 10 years of service. Xonmetallic cylinders made of fiber glass bonded with plastics are being used experimentally in intraplant service for the storage of oxygen and nitrogen at pressures up to 2000 pounds per square inch. This lightweight container deserves t o be watched as a future contender for business in the commercial cylinder market. SAFETY
The Compressed Gas Association, through the work of its technical committees, has made a n outstanding contribution to the safety and welfare of the public. The adoption of a pin-index system on cylinder valves and outlet adapter yokes for medical gases is paying dividends in the reduction of deaths in hospital operating rooms. The pins and slots on the cylinder closure and withdrawal parts make it impossible to connect, accidentally, a carbon dioxide or nitrous oxide cylinder into an oxygen line. Each line, fitted with its proper pin-indexed adapter, can be coupled only t o a cylinder containing the gas intended to flow through the system. Similar protection to the users of commercial gases is afforded by a noninterchangeable series of outlet threads on valves and corresponding mating threads on adapters. Variables consist of different size diameters, internal and external threads, and right-hand and left-hand threads. The addition of the wrong gas to a line can cause a n explosion or ruin thousands of dollars worth of equipment. The CGA outlet thread standards deserve much praise for their mute guard duty in the protection of lives and property in our plants. Twenty years from now, many of the present-day containers and packaging practices will be outmoded, but a new and equally enthusiastic generation of packaging engineers, proud of their heritage, will be busy at work keeping chemicals flowing to consumers all over the world in packages designed for safe and economical service. ACKNOWLEDGMENT
T h e author wishes t o thank Edward E. Grosscup, Inland Steel Container Corp. , Chicago, Ill. for the information regarding plastic linings. RECFXVED for review October 15. 1954.
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ACCEPTEDMaroh 25, 1955.
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