Handling of ChemicalsEthylene glycol, methanol, benzene, cyclohexane, toluene, alcohol, and propylene polymer are handled in skin-type barges with capacities from 8000 t o 15,000 barrels and load from 1000 t o 2200 net tons. The newer barges being built for this service are of the 15,000-barrel capacity. Some barges are equipped with stain-
less steel tanks; others have tanks lined with rubber or other suitable materials; and the latest will be aluminum. Styrene is now moving in appreciable quantities in special barges; here, the temperature must be held down a t timea, rather than kept up.
(Tank Transportation)
TANK TRUCKS W. E. MORGAN Union Carbide and Carbon Corp., New York, N . Y .
T
HE tank truck industry has had the same percentage in-
crease in growth during this postwar period as has the chemcal industry. This coincidence is understandable when one realizes that the chemical industry has been, by far, the most dynamic of industries and the tank truck was the most dynamic development in the transport field during the same period. The tank truck was one of the many factors which assisted the chemical industry t o achieve its remarkable growth. The chemical industry, by its expanded use of tank truck services, has helped the tank truck to achieve its current stature. Much has already been published about tank truck transportation of chemicals. I n 1941 there were 4653 for-hire tank trucks with a capacity of 20,159,000 gallons. I n 1951, this figure was up to 15,546 tank vehicles with a standing capacity of 82,888,000 gallons. The average size of tank trucks has increased from 3000 gallons in 1941 to about 4500 gallons today. I n addition t o common carrier equipment, there are approximately 7000 tank trailers in private operation. There is no certain method of determining how much of this equipment is in petroleum service and how much in chemical service. However, a conservative estimate is that 10% of this equipment is in chemical service. Most of the carriers hauling chemicals today started out as petroleum haulers and many of them still transport both chemicals and petroleum products. These operators began to eye chemicals transport in the years immediately prior to World War I1 as a result of the extension by the oil companies of their pipelines and expansion of their marine terminals. Probably more important, however, was the experience these operators gained during the war years, when tank cars could not be used for hauls under 200 miles without special permits from the Government. Both industry and carriers were pleasantly surprised a t the compatibility of the tank truck and most chemicals. Accordingly, after the war many chemical companies moved in the direction of expanded tank truck service. One problem presented itself immediately. Before a carrier can operate for hire in interstate commerce, i t must obtain a certificate of operating authority from the Interstate Commerce Commission. Many chemical producers had traffic representatives appear a t hearings all over the country in support of carrier applications for authority to perform this new service. They pointed out to the hearing examiners that there was a public need for this service for many reasons, most important of which were: Elimination of the drum, its cost, and the cost of handling it. This factor is the most obvious; the economies realized in eliminating the container were the basis for t h e establishment of a bulk pricing system in tank cars which was later extended t o include tank trucks. The tank truck will arrive a t destination much sooner than a tank car. A truck will deliver the same day within 100 miles, the next day within 250 miles, the second morning up t o 500 miles, and the third morning within 750 miles. The rails may take a t least 3 days for the shortest haul and up t o 10 days for 750 miles. June 1955
The shipper does not have t o rent tank trucks as he does tank cars. The tank truck rate includes the use of the tank truck. Because of its speed, a single tank truck can replace several tank cars, particularly on short-haul traffic. There are cases reported where two or three tank trucks replaced fleets of 10 t o 20 cars on a short-haul, 24-hour operation. Tank trucks range in size from 3000 t o 6000 gallons. I n certain states, combinations of a straight tank truck and a trailer, or trailer and trailer, permit shipment of quantities as high as 7500 gallons. A number of tank trucks are compartmented, some having as many as five or six compartments, permitting the transportation of several diffeient commodities a t once, or deliveries t o more than one customer or t o more than one destination. The customer does not have to be located on a rail siding and does not need as much storage area. All chemicals users can benefit from bulk deliveries from plants and bulk stations located in the industrialized sections of the country without the capital expenditures required for large bulk storage installations. Inventory Control. With same-day or overnight delivery in smaller quantities, the customer can exercise greater inventory control. Producers too, can work on tighter schedules without as much concern over the storage of production pending receipt of orders. Both the buyer and seller have a closer control of the product flow. The tank truck becomes part of the production line. On most of the carrier applications for tank truck authority that Union Carbide supported, the Interstate Commerce Commission found that these factors justified granting the authority. As a result, today, the company can supply virtually every part of the country by tank truck from one or more of its plants or bulk stations. PROBLEMS OF TANK TRUCK TRANSPORTATION
As the tank truck was used more, all was not sweetness and light. First, a large part of plant facilities had been built long before anyone gave much thought t o the idea of a tank truck. Proper tank truck-loading facilities had to be set up, t o avoid payment of heavy demurrage. The tank truck operators allow only 1 to 1.5 hours for loading and the same time for unloading. If more time is required, the detention charge ranges from $4 to $6 per hour. Secondly, some tank truck operators had pretty weird ideas as to what was meant by a clean tank. Most of these operators were relying on their petroleum experience. This did not work out very well in handling chemicals, with their varying characteristics coupled with the absolute requirement for delivery of a pure product, free from contamination. The carriers have since spent much time and money in training their personnel in the proper handling of chemicals. With several of the larger companies, the chemicals operation was divorced entirely from the petroleum. The carriers hired men with chemical training. They met with plant personnel and worked out procedures which assured the safety of personnel and quality of product. Supervisory employees became real specialists in the transportation of chemicals.
INDUSTRIAL AND ENGINEERING CHEMISTRY
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Even with all this commendable effort, the company felt it was expedient t o have its own tank-cleaning facilities and i t still does a great deal of cleaning today t o make sure t h a t customers get specification material when they buy in tank trucks. Because the tank truck usually has t o return to the plant empty, the area for economical tank truck movement of chemicals is somewhat restricted. Generally, movements beyond a 250or 300-mile radius of plant meant paying a higher rate than for movements by tank car. Material is shipped in tank trucks up t o 750 miles and over, but these shipments are generally in the emergency category or involve special products. Sometimes customers complained about the free time allowance for unloading and the high detention charges. It took a while for some of them t o realize that when a truck pulled in, it had t o be unloaded promptly. The tank truck operators developed a n allergy t o carrying all of the proper type, size, and amount of hoses and fittings for unloading. This is still the bane of existence with tank truck operators. Even after 6 years, trucks sometimes arrive without hose, coupling, adapter, or something else. I n addition to the Interstate Commerce Commission, state and municipal regulations and requirements had to be considered. The 48 states have 48 separate l a a s covering the size and weight of motor carrier equipment, all of which embody ideas which are dissimilar from each other in a t least one respect. Maximum gross weights imposed by the various states range all the way from 42,000 to 77,000 pounds. This complicates both the ship per's and carrier's operations. Deliveries to one state in the East cost about 16% more than they should because of the unusuallv low maximum weight allowed. A number of municipalities, like New York City, also involve themselves to some extent by means of restrictive ordinances, particularly on red label or flammable materials. SPECIALIZED EQUIPMENT
I n meeting these problems, it was discovered t h a t the carriers could do a lot in the way of supp1,ving specialized equipment. Generally no operator is going to invest $10,000 to $20,000 in a single piece of equipment, unless he is reasonably sure t h a t the equipment will be kept busy over a period of time. However, common carriers in the larger industrial areas maintain fleets of standard equipment on which a shipper can call without making any commitments in advance. Tank trucks are moving everything from alcohol to zinc chloride, from liquid chocolate to penicillin. There are more than 500 different chemicals and chemical combinations moving in tank trailers. With tank trucks, product temperature is controlled by insulation, refrigeration, heating, or combinations of these methods. I n the case of aluminum sulfate and phthalic anhydride, two classic examples of tank truck fleuibility, one entire process a t production end and again on the consumer's receiving line was eliminated. I n order to accomplish this in the case of phthalic
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a.nhydride, i t was transported safely in molten form a t a temperature of 270' F. Low t,emperature chlorobutadiene, a-hich is loaded a t - 15' F. with a critical temperature of 0' F., is moving safely in tank trucks distances !a far as 600 miles. Products like nitric acid, sulfuric acid, hydrochloric acid, tetraethyllead, liquid alum, and molten sulfur do not excite comment today when shipped in tank truck. The Interstate Commerce Commission regulates the construction and design of equipment used to transport so-called dangerous articles, which generally include flammable liquids, corrosive liquids, poisonous liquids, and compressed gases. The various specifications set forth in the regulations are referred to as MC-300, 301, 302, 303, 310, 311, 330. MC-303, 310, 311, and 330 are used most frequently. MC-303 is a high tensile steel tank which is more or less a n all-purpose tank. MC-310 is constructed of 8/6-inch st,eel plate and is designed for the movement of corrosives. MC-311 is a new, lighter tank for hauling corrosives. MC-330 is used for compressed gases. The traffic departments of chemical producers and the carriers . are const,antly working together t o maintain that sttme dynamic pace which has gotten us this far. Now t h a t tank truck movement. of chemicals has become standard procedure, they are concentrating on the transportation of many dry products in bulk and on bulk shipment of liquids in different types of containers. .4 number of .companies, including Union Carbide, are giving considerable thought to the use of equipment like hopper trucks, which are designed along the same lines as a hopper car and are excellent for the movement of synthet,ic resins, powdered and granular chemicals, and similar products. The dump truck with its snmller size, smaller load, and self-unloading features can deliver certain types of material into many parts of a plant area which are inaccessible to rail car and thus offer the maximum in maneuverability and efficiency. Shipment in detachable bulk containers such as the transit tank which, as the name implies, is a removable, mobile tank, is becoming a reality. Large, collapsible containers and units like the Sest-a-Bin offer considerable promise. The Nest-a-Bin, in particular, seems to have conquered t h a t age-old problem of returning the empty container and appears adaptable for both liquid and dry products. Much thinking is directed along the lines of combining the best in transport container and transport agency t o achieve the most effective type of delivery a t lowest possible cost. Recently, the railroads have indicated some interest in regaining the short-.haul traffic they have lost to the highway carrierp, particularly t o the t a n k trucks. If the rails should make a constructive effort in this direction, it will pose a real problem for the traffic managers of industry. .4s the chemical industry continues to grow, transportation agencies offering the most and best in the way of effective, progressive transportation will grow with it. RECEIVED for review October 15, 1954.
INDUSTRIAL AND ENGINEERING CHEMISTRY
ACCEPTED Aparch 2 5 , 1955.
Vol. 47,No. 6
