stop making and selling propanil. If an injunction were issued, the companies could obtain licenses from Monsanto. However, Monsanto tells C&EN that it doesn't intend to grant licenses for propanil. The company says it has enough capacity at its plant in Luling, La., to supply the 6 million pound annual market for propanil with its trademarked product Rogue. Rice growers use propanil in about 90% of the cases of chemical weed control in rice fields. Propanil will be applied (primarily sprayed by aircraft) to about 1.5 million acres of the 2.25 million acres of rice grown in the U.S. this year, according to the U.S. Agriculture Department. The average rice yield is about 4100 pounds per acre, which makes the U.S. rice crop worth $512 million. For the farmer, use of propanil herbicide increases his net profit by at least $30 per acre, Monsanto says.
ASME pressure vessel code moving toward clearance It's been a long road for Section VIII, Division 2 of the American Society of Mechanical Engineers' boiler and pressure vessel code. The code, among other things, permits higher allowable design stresses for certain types of vessels under certain conditions. Following public hearings in St. Louis and Toronto, it is now clearing the last hurdles before publication late this year. Section VIII, Division 2 has been under development since 1963 by ASME's Boiler and Pressure Vessel Committee. It applies to unfired pressure vessels, and, as such, covers many vessels built for chemical and petroleum processing. As a whole, the new division provides an alternative set of rules for more stringent design of pressure vessels intended for use in more sophisticated applications than those covered by Division 1. Oral and written comments from manufacturers and users arising from the St. Louis and Toronto hearings will now be considered by the committee. The response, ASME says, was favorable, with no adverse criticism of any major portion. Those changes that are essentially editorial will be incorporated in the code immediately. Those that are more extensive, but which the committee feels to be significant, will be considered at a committee meeting in June. Publication of the division will thus broaden the entire code, which, ASME says, is being increasingly demanded. The new code division covers minimum requirements for design, fabrica24 C&EN MAY 20, 1968
tion, inspection, and certification of the pressure vessels falling within its scope. Compared to Division 1, Division 2 places greater restrictions on the choice of materials which may be used. However, it permits higher allowable design stresses in the range of temperatures over which the stresses are controlled by the ultimate strength or the yield strength. The division also requires more precise design procedures and prohibits some common design details. Also, it more specifically delineates permissible fabrication procedures and requires more complete testing and inspection. Division 2 places no limit on pressure. An introductory section explains that for very high pressures, some additions to or deviations from the code may be necessary. But only if the vessel still complies with all the code requirements after the additions or deviations can it be certified as meeting the code. As with Division 1, it is not intended that Division 2 cover all pressure vessels. Among those that are not within the jurisdiction of the division are pressure vessels subject to federal control and vessels with a nominal water-containing capacity of 120 gallons or less for containing water under pressure.
Synthetic cresylics to pace natural ones as supply source The next five years should see synthetic cresols and cresylic acids take over from the natural variety as a major source of supply. Synthetic material, which now accounts for less than 2% of the total demand (both natural and synthetic) of some 155 million pounds a year, may account for 115 to 120 million pounds (more than half) of the total 212 million pounds of expected annual demand by 1972. At least this is the outlook described by Ben Jones, vice president of Pitt-Consol Chemical Co., at the meeting of the American Coke and
Coal Chemicals Institute in Rye, N.Y. The overall U.S. supply of these products from natural sources—coal tar, gas works tar, and cresylates recovered from soda solutions used to remove aromatic sulfur compounds from gasoline at refineries—will drop over the next five years from about 152 million pounds in 1968 to about 93 million pounds by 1972. This gap will have to be filled by synthetics, Mr. Jones says. At present, the U.S. has only two synthetic o-cresol producers to meet this predicted demand. One producer, Pitt-Consol, has a 15 million pound-per-year plant at Newark, N.J. The other producer, Koppers Co., has a 10 million pound-per-year plant at Follansbee, W.Va. For many years, Mr. Jones says, the only sources of natural cresols and cresylic acid were coal tar, which was produced in coke ovens, and gas works tar. After World War II, however, petroleum refineries began to recover cresylics. Gasolines made from sour crudes had to be treated to remove aromatic sulfur compounds. This can be done by washing the cat cracker naphthas with aqueous caustic soda solutions. The spent soda solutions also contain cresylates. Recent trends in petroleum processing have been to operations which yield a naphtha of low sulfur content. The caustic soda treatment is no longer necessary, and the volume of cresylic acids from this source is decreasing. Recent changes in coke oven technology, too, will lead to reductions in supplies of cresylics from coal tar. Faster coking cycles and smaller coal sizes produce a more aromatic tar containing less cresylic acid. U.S. production from this source is expected to drop from about 60 million pounds in 1967 to 40 to 45 million pounds in 1972. Imports of cresylics come mainly from British gas works tar. However, recent discoveries of natural gas in the North Sea, Mr. Jones points out, will tend to dry up this natural source.
Demand for cresols and cresylic acids to increase Millions of pounds End use
1968
1969
1970
1971
1972
Phosphate esters Phenolic resins Wire enamel solvent Miscellaneous* TOTAL
63 50 17 25 155
68 54 22 26 170
74 57 24 28 183
80 61 25 29 195
87 65 29 31 212
* Includes disinfectants, exports, salicylaldehyde, herbicides, ore-flotation reagents, and metalcleaning formulations. Source:
B. W. Jones, Pitt-Consol Co.
