January, 1933
INDUSTRIAL AND ENGINEERING CHEMISTRY
amination of 2-chloroanthraquinone. The controls a t 195200’ C. without catalysts of any character appear to be about as good as those containing a copper compound alone. At lower temperatures (Table I), however, experiments containing a copper compound showed an improvement over controls. In Table IV are presented data relating to the ammonolysis of 2-chloroanthraquinone which show the effect of using potassium chlorate along with a copper catalyst.
compound. The data in Table V show that under optimum conditions a satisfactory product can be obtained. LITERATURE CITED (1) (2) (3) (4) (5)
A>lMONIUM SALTS
AXD
COPPER COMPOUNDS
When ammonium nitrate was used in conjunction with cuprous oxide in the ammonolysis of 2-chloroanthraquinone, the results were always better than when either one alone was used. I n fact, the addition of any ammonium salt to cuprous oxide by exerting a common ion effect contributes to an improvement in both the yield and purity of the amino
49
(6) (7) (8) (9) (10)
Arnold, U. S. Patent 1,799,722 (1931). Groggins and Newton, IND. ENG.CHEM.,21, 369 (1929). Groggins, Stirton, and Newton, Ibid., 23, 893 (1931). Hale and Britton, U. S. Patent 1,607,824 (1926); reissue 17,280 (1929). Hots, U. S.Patent 1,690,786 (1928). Imperial Chemical Industries, Ltd., French Patent 717,538 (1932). McMaster and Steiner, ISD.EXG.CHEY.,22, 547 (1930). Reppe, U. S. Patent 1,762,742 (1930). Schweitaer, U. S.Patent 1,806,714 (1931). Tobler, U. S.Patent 1,699,894 (1927).
RDCEIYED October 10, 1932. Part I is Contribution No. 214, and Part I1 No. 215 from the Color and Farm Waste Division, Bureau of Chemistry and Soils. Other parts will be printed in February and Marah
Pipe-Line Protection STANLEY GILL. Rusk Building, Houston, Texas
D
ET’ELOPMENT of irnNo attempt is made to present detailed data covering their p e r f o r m a n c e . This has been expressed as folproved coatings for the upon the application and performance of the protection against corrolows (4): several classes of coatings which are discussed. sion of buried pipe lines is a probThe general status of the art of pipe-line protecImpermeability to moisturelem of the utmost economic imwhich should not be confused with portance. Shepard (9)estimates tion is described. waterproofness-is the most imthat there are in the U n i t e d I n general, it may be stated that, although portant single requirement for a coating which will protect metal S t a t e s approximately 450,000 there are available coating systems make miles of buried pipe lines. At a against soil corrosion. A coating possible economical protection of pipe lines, there which positively prevents access of conservative estimate these lines moi ture to the metal’s surface will remains a large field f o r O f improved contain not less than 30,000,000 prejude the possibility of corromethods f o r preventing the great losses which corsion. If moisture is in contact tons of steel, all of which is exwith the metal surface, corrosion posed tomore or less severe cormrosion forces upon the pipe-line industry. may or may not proceed, dependsive attack. Approximately half ing upon other conditions. of the total mileage is in trunk In general, any coating which meets this condition, and line systems for the transportation of oil and gas, the remainder being in distribution systems within cities, etc. which continues to meet it after prolonged exposure to soil The trunk line systems consist almost entirely of large-size action will satisfactorily protect buried metal. It is not imsteel pipe, oil lines being made up of 4- to 12-inch pipe and possible that a satisfactory coating could be devised which gas trunk lines of 8- to 24-inch pipe. The distribution sys- would not satisfy this requirement, but it is certain that this tems are of smaller sizes, and considerable cast-iron pipe is has not been done up to the present time. Continued impermeability of pipe-line coatings depends used. Shepard (9)estimates that the annual loss by corrosion of these lines is $142,500,000. His estimate compares favor- upon the following factors: (1) resistance to deterioration ably with that prepared by Speller in 1927 (IO). It is prob- from chemical or bacterial action, (2) freedom from capillary able that these figures are considerably higher than the actual pores, and (3) resistance to mechanical distortion. Of these, loss of metal caused by the corrosion, but they are certainly the third is perhaps the most important cause of failure in lower than the actual total expense entailed by corrosion existing protective coatings. The principle of mechanical of pipe lines. distortion of pipeline coatings was developed by Scott (7) The tremendous economic loss arising from corrosion of and was termed by him “soil-stress action.” Scott’s work, buried pipe illustrates the importance of the problem which which has shown the prevalence and importance of soil stress confronts manufacturers of protective coatings for pipe in the destruction of pipe-line coatings, has been of the utmost lines. Although there are a t present coating systems which importance in establishing present methods of pipe-line can be depended upon to reduce greatly corrosion of buried protection, which almost universally incorporate means for lines, all are subject to certain objectionable features. The protecting the coating material against mechanical distortion. problem is by no means solved, and an extremely promising Fully as important as the ability of a coating to afford confield is presented to the coating manufacturer who can de- tinued protection are the limitations imposed by economic velop a protective method which will economically reduce considerations. Much work has been done to determine the soil-corrosion losses. extent to which the use of coatings is economically justified. Very little of this has been published, although the general REQ~IREXENTS FOR SATISFACTORY PIPE-LINECOATISGS principles were enunciated by Weidner ( I d ) in 1926. A later discussion of the economics of pipe-line protection has been Extensive investigation of the performance of pipe-line contributed by Truett (22) and by Weidner (IS). Obviously, coatings has served to develop but one general principle the justification for the use of coatings depends upon the
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I N D U S T 13 I A 1.
A h I1
li U
(;
severity of the corrosivc conditions and upoii tlic cost m d effectivenessof the coating system. Extended use of coatings is justified by increasingly severe corrosive conditions, by increased effectiveness of coatings, hy increased cost. of lines, by increased protection efficiency of coatings, and by decreased cost of coating systems. These factors must be carefully considered in the development of n pipe-line coating,
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c E1 li; hl 1 s T H Y
Vol. 25, No. 1
oil-paint films. This proposal is based upon the numerous obsersations of eases in which markings made in the mill ~ with white lead and red lead paints while the pipe w a still hot have remairied intact for many years of underground exposure. It is possible that the work being done on this line will produce worthwhile results, although as yet there are no conclusive data upon the performance of such coat,ings. It is also probable that the performance of certain classes of bituminous coating materials can be improved by using, in conjunction with them, corrosion-inhibitive oil-paint primers. Tests iif combined coatings of this type are now in pmgrem. ~IITUMINOUS"CUT-BACKS"
Of coatings which are applied cold, solutions of bitumens (both coal tar and asphalt) have been most xidely employed. Such coatings possess the advantages of cheapness and ease of application, and these considerations liave cairsed them to be used on many thousands of miles of pipe lines. Generally speaking, coatings of this class are of little or no value for the protec.tion nf pipe wliich is exposed to destructive soil corrosion. This statement applies with almost equal trutli to the comparatively few cut-hack coatings which have heon made with sonre degree of technical supervision, and to the far greater number of coatings which have been made of the cheapest material available, and sold merely with an eye to profit. The failure of bitunrinous cut-back coatiugs i8 caused almost entirely by their great permeability to soil moisture. I3y proper selcction of bitumen, they may he made to possess a satisfactory chemical stability; but all are more or less permeable to moisture, and even those which possess u relatively high initial impermeability are rapidly destroyed by soil-stre= action. The present tendency in pipe-line protection is to eliminate entirely thc use of bituminous cubhacks. This practice is warranted by their proven lack of protective value; but there remain many lines oii which, because of their temporary nature or a mild corrosive environment, cut-backs can be
must also the adaptability of the coatiiig to applicatimr under the rather difficult conditions which prevail during tlic construction of a pipe line. Within the scope of this paper i t is not. possible to consider in detail all of the types of p i p l i n e coatings which have been used, or which are now under consideration. A great amount of work is being done on the development of pipeline coatings, and rapid advances are being made. A c,onrprcheusivevien of the present status of this work is given by progress reports on the work of Scott (6') and 1i:wing ( 1 ) . The following description covers briefly t.he various cl es of coatings, and is intended to serve as a rapid siirvey of the field, rather than as a detailed description of the advantages and disadvantages of the various coating niatcrials &s
OIL PAiNTs Among the earliest attempts to protect buried pipe lines was the use of the usual types of metal protective paint, particularly red lead. Although occasional instances of satisfactory performance of such paints have been reported, they a,re, generally speaking, inapplicable for the purposes. Apparently their failure is caused by saponification of the oil film, although the permeability of the film may also contribute to their failure. The writer has observed cases of severe pitt,ing of pipe under apparently unbroken films of red lead paint. It has.been suggested by Speller and others that coatings of excellent protective value could Ire obtained by baking
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