Cargoes of fuel oil as high as 15,000 barrels are taken on by some of the trans-Pacific steamers (See fig. 19). All of the -four oil companies mentioned maintain large storage tanks ad jacent to the water front at San Francisco, with receiving and discharge pipes leading to the docks. In addition to supplying oil to the(steamers in the bay, these barges de liver oil from the refineries operated by the various oil companies in the vicinity of San Francisco, to these oil storage tanks ad jacent to the water front. These tanks supply fuel oil to the smaller vessels that tie up at the oil docks. The Standard Oil and the Shell Oil each maintain such'storage tanks at the northerly end of the water front, from which point the numerous lumber schooners and fishing boats are supplied. At the southerly end of the water front, in the vicinity of 16th and 17th streets, such storage stations are maintained by the Standard Oil, Union Oil, and the Associated Oil Companies. In addition to supplying oil to the smaller vessels, these storage stations supply the oil trucks that deliver oil through the City of San Francisco. The Shell Oil Company operates barges which take on oil at the loading station at Martinez and are towed to the San Francisco water front by a steam tug used for this exclusive purpose. During the busy seasons gasoline tugs are rented from the local launch corn _ panics. These barges have a carrying capacity ranging from 1,030 barrels to 3,000 barrels. The barges are all of wooden con struction, being built especially for this type of service. Barge No. 4 is 148 feet in length, 35 feet in width and 6 feet 10 inches in depth. She draws 5 feet 6 inches when loaded and 3 feet 6 inches light. Barge No. 3 is 78 feet in length, 23 feet in width, and 6 feet 10 inches in depth, and draws 6 feet 6 inches when loaded and 2 feet 6 inches when light. Barge No. 1 is 116 feet in length, 32 feet in width and.10 feet 2 inches in depth, and draws 7 feet when loaded and 3 feet 6 inches light. She has a carrying capacity of 2,950 barrels of oil. The 250 horsepower steam tug Priscilla was built especially for tending these barges. They are operated on the tides, being towed from Martinez when the tide is going out and returned with the incoming tide. Approximately 140,000 bafrels of oil are handled monthly by these barges. Barge No. 4 is equipped with a gasoline-operated generator which pro vides electric current for lighting, which greatly facilitates night operations." The railroads are among the principal users of fuel oil in this country. For filling the fuel storage_ tanks of the railroads the oil is, transported in tank cars. Mr. Robert Clarke, Jr., de ' scribes the development of the tank car as follows :a "In 1865 the car tank, mounted on a railroad flat car, made its appearance. Mr. Lawrence Myers—who was represented as the patentee of this type of tank on wheels,—called it the "Rotary Oil Car." A number of the first tanks on cars were constructed of iron, but the majority were built of heavy pine plariks, a material more rt,". readily obtainable*d lower in cost. In shape these tanks were practically the same as the small iron-hooped wooden, tank in use at the wells, being round and of smaller diameter at the top than the bottom and holding from 40 to 50 barrels each. On each flat car two of these tanks were mounted—one at each end over the trucks—making the capacity of the car between 80 and 100 bar rels. The first of these "Rotary Oil Cars" arrived in Titusville, Pa., on November 1, 1865, where it received a cargo of oil at the Miller farm, the terminus of the first successful pipe line from Pithole. Miller farm was located four miles below Titusville on the banks of Oil Creek, Pa. This car was the property of the Eagle Transportation Company of Philadelphia, Pa., who owned the patent rights and who proposed to build and operate a tank line on all railroads for the transportation of crude and refined oils. With customary progressiveness we find the builders and users of tank cars soon making improvements in design and con of the original scar. Dillingham and Cole, a firm of machinists with shops located at Titusville, Pa., in 1866 received a contract for fitting 60 tanks on cars for the Oil Creek railroads— now a part of the Pennsylvania Railroad System—with a rather ingenious gate-valve or cock that could not be opened without having a wrench that was especially made for the purpose. These tanks were constructed of iron and mounted on flat cars at each end over the trucks, similar to those of the Eagle Transportation Company. The capacity of these cars was about 90 barrels. This new method of shipping was indeed a step in the right direction, for it eliminated a very considerable loss of oil resulting from leakage-in transit, reduced the liability of serious conflagrations and did away with the necessity of a return of thousands of bar rels to the producer, besides eliminating cooperage charges. Until 1870 this type of car, in which the iron-thooped wooden tank was employed, was used extensively in transporting crude oil to mar ket. In the late sixties, however, the forerunner of the present type of tank car was introduced—a design of car in which a horizontal cylindrical tank replaced the two small wooden ones The first of these cars was shipped to the Oil Creek region in 1868 and sidetracked at the Boyd farm for loading. A radical change was made in the designing of these new tanks in that they were fitted with a dome which allowed the oil to expand without injury:to the tank. These cars had a capacity of 80 to 90 barrels. Later this was increased to 100 barrels, which became the standard for that period. The. advantages of this new type of car were quickly recognized by both oil and railroad men ; in fact, its adoption was so general that by the end of 1872 the ma jority of the old type of cars had disappeared. About May 1, 1872, the Oil Creek and the Lake Shore Railroad companies issued orders that after that date none of the old type of tank cars would be accepted for transportation over their roads. With
few exceptions, this ruling was generally adopted by other rail ways, although even as late as 1876 they were still accepted by the Allegheny Valley Railroad, extending from Oil City to Pittsburgh. By 1880 the last of the early wooden tank cars had disappeared from service. It is particularly true of American progressiveness and business acumen that the introduction of a new process or new method of doing something in one field is soon applied with equal success to other fields and so it has been with the tank car. Today there are thousands of tank cars in service carrying other products than petroleum and its by-products. The Master Car Builders' Association state in their specifications covering the design and construction of tank cars that a tank car is "any car to which one 'or more metal tanks, used for the transportation of liquids or compressed gases, are permanently fastened," and in order that these tank cars may be designed and constructed to meet the service requirements of a wide range of products they have designated that there shall be five classes of tank cars, classi fied as follows : "Class 1.—Tank cars for general service, with steel under frames or without underframes, built prior to 1903.
"Class 2.—Tank cars for general service, with steel under frames, or without underframes, built between 1903 and May 1, 1917.
"Class 3.--Tank cars for general service, built after May 1, 1917.
"Class 4.—Tank cars for the transportation of volatile in flammable products whose vapor pressure at a temperature of 100° F. exceeds ten pounds per square inch, built after May 1, 1917.
"Class 5.—Insulated tank cars of specially heavy construc tion, built after January 1, 1918, for the transportation of liquid products whose properties are such as to involve danger or loss of life in event of any leakage or rupture of the tank." The importance of good, strong, sound and thorough con struction in tank car design cannot be overestimated. Upon these factors depends the life and efficient service of the car. A poorly designed and constructed tank car is not only a menace to the railroads hauling them, but also the shipper, consignee and the industrial centers through which the car may pass.
In general the storage tanks erected by the railroads are steel cylinders. The size of a storage tank will naturally be a little in excess of a multiple of 6,000 gallons, for the reason that 6,000 gallons is the capacity of a regulation tank car. So, then, storage tanks will properly have capacities greater than 6,000, 12,000, 18,000 and so forth, gallons. Fig, 23 shows a 20,003-gal lon fuel oil tank along the Mexican Railway,a and Fig. 24 shows locomotive loading tanks along the lines of the United Railways of Havana.b For the storage of fuel oil at small industrial plants and at hotels, apartment houses, and residences, the steel tank haS been in general use. Mr. S. D. Rickard, Consulting Engineer, Wayne Oil Tank & Pump Company, gives the following advice concern ing storage tanks: "ToO great care carrot be used in the selection of the oil storage tank, or tanks. It is a great deal more difficult to con struct .
an oil-tight tank than to a tank simply for the storage of water. It is very difficult and sometimes impossible to repair a leaking tank, and a great deal of oil may be lost before the leak is discovered. All tanks should be inspected and labeled by the Underwriters' Laboratories of the National Board of Fire Underwriters.
Fuel oil storage tanks should be cylindrical in shape and placed underground so that the top of the shell is at least two feet below ground. These tanks should be of sufficient capacity to allow for a working supply in case deliveries are delayed, and so that tank cars can be entirely emptied as soon as they are received, avoiding demurrage Charges. Where shipments are to be received in single carload lots, a 12,000-gallon tank is the smallest size that should be installed. However, many installations embody two or more tanks varying in capacities from 8,000 to 25,000 gallons.
It should be specified that the tank be fitted with all of the pipe flanges and the manhole at one end of the shell on top. In this way it is possible to build a box with a trap door over one end of the tank whereby all pipe connections and the manhole may be easily gotten at.
It is good practice to fit a fuel oil tank with the following flanges and manhole: one 10" x 16" manhole, one 372" suction flange, one 4" fill flange, one 172" vent flange, one 1y2" return pipe flange, and one 72" indicator flange.
Every fuel oil tank should be constructed with internal steam coils of proper design. Although it might be possible to obtain a light oil at the time the tank is installed, it may become neces sary of any time to burn a heavy oil, which would require heating.
Each storage tank should be fitted with a tank gallonage indicator. These indicators show at a glance the contents of the tank. ,They may be placed inside of the nearest building, outside of the building against the wall, directly over the tank, or on the side of aboveground 'tanks." When it is impossible to place the main storage tanks below ground or below the level of the burners, a small 5 or 10 barrel reservoir tank should be placed underground below the main storage. This reservoir tank is then fed by gravitjr from the overhead tanks. Just inside the small reservoir tank is placed a float valve, as shown in Fig. 25. This valve closes whenever the oil in the small tank reaches a certain level. The suction and return pipes should run from this small underground tank in the usual manner. In this way the danger of flooding a building with oil is avoided. Fig. 26 shows a typical steel storage tank for fuel oil.