CONTAINERS, METALLIC, a phrase describing cylin ders, tank cars, barrels, drums and cans, used to hold substances either in gaseous solid or liquid form at atmospheric or high pres sures.
Types.--Cylindrical containers are built to with stand rough usage and high pressure. Gases and liquids under pres sure that are likely to be explosive,highly combustible or poisonous are usually held in them. Increases in temperature due to weather or fire might easily double or treble the original pressure in the con tainer and if the strength of the container were insufficient, an explosion causing serious damage or loss of life might result. These containers or cylinders range in size from very small flasks containing only a few ounces of material to tank cars carrying a battery of tanks designed to carry several tons. The design of cylinders varies depending on the physical and chemical prop erties of the material to be shipped. Some are equipped with special safety devices which operate when the internal pressure increases to a point where further increase in pressure might rupture the container. Others are equipped with devices to per mit the escape of the contents when the temperature of the vessel and contents becomes excessive. Substances shipped in cylinders are oxygen, acetylene, hydrogen, nitrogen, chlorine, sulphur dioxide, nitrous oxide, ethylene, methyl chloride, ammonia, car bonic acid gas, liquefied petroleum gases, helium, argon, blaugas, pintsch gas and a number of others.
Containers designed to transport materials having considerable weight, or bulk, which are in suitable form to permit being shipped at ordinary atmospheric pressure are designated as tank cars, barrels, drums and cans (see CANNING).
These consist of railway cars equipped with one or more tanks, the total capacity being generally about 8,000 gal lons. They are equipped with piping for heating and liquefying viscous liquids, valves and vents to facilitate filling and emptying. Where large quantities of material are to be transported, and the existing regulations permit that material to be shipped in bulk, these tank cars offer a very economical service as containers. Barrels.—Because the number of consumers whose business warrants delivery of material in tank cars is limited, barrels, drums and cans play a large part in the distribution of many products to the consumer. Those containers having a bilged shape similar to the wooden barrel or keg, are termed barrels. They are made of heavy gauge steel and are designed to withstand extreme abuse. Their shape makes them easy to handle especially when filled with heavy materials, and because of their sturdy construc tion and long life they are treated as transport equipment, being depreciated on a basis of probable life and number of trips through which they are likely to remain sound. Records show that bilged steel barrels of the seamless type have a life of over 20 years with an average of eight trips per year. Bilged type containers of 3o and 5o gal. sizes are produced in the United States. Germany produces bilged steel barrels up to no gal. capacity. There are two distinct types of barrels, those fitted with threaded bung and vent for liquid substances and those equipped with removable plates or full removable heads to facilitate empty ing semi-liquids, paste or solid substances. These containers having straight sides and a capacity ranging from 1 o gal. up to no gal. are usually termed drums. They are made in a variety of designs depending on the product to be shipped. For liquid products they are provided with threaded bungs and vents. For semi-liquids, pastes and solid substances the drums are equipped with removable heads to facilitate the removal of the contents.
Drums.—Two distinct types of drums are produced in the United States. Heavy gauge drums are required for the shipment of substances which are combustible, explosive or corrosive. Those for highly corrosive substances such as acids, are specifically de signed to give service under cxtre ne conditions. Substances hav ing a low flash point, or those of the non-corrosive type may be shipped in very light gauge steel drums used only for one ship ment, the drum being destroyed after it has been emptied. When the material shipped is non-combustible or non-corrosive and where long distance shipments are made, or where the substances pass through several hands before reaching the ultimate consumer, the light gauge single trip drum is economical. Where return freight rates are not excessive and when marketing conditions are favourable the returnable type or heavy gauge drum and the bilged type steel barrel have proved themselves to be an economy over the light gauge single trip container of the drum type. • Cans.—The number of consumers who purchase smaller quan tities of materials than are contained in standard drum sizes, is legion. Also many substances are of such a nature that they are used in. small quantity by the consumer. For these substances cans of a variety of shapes and sizes varying from a few ounces to Io gal. capacity are manufactured. They are strictly of the single trip container type, are sold with their contents, are non returnable and are often made non-refillable. Tank cars, barrels, drums and cans are used for the distribution of vegetable, animal and mineral oils, gasolene, kerosene, turpentine, alcohol, soaps, ink, paint, varnish, shellac, lacquers, putty, lard and lard substi tutes, acids, medicines and many thousands of chemical com pounds.
The construction of the large majority of tank cars, cylinders, barrels, drums and cans is often (particularly in the United States) under Government supervision. (H. ME.)
