CORRESPONDENCE Pipe Line Protection SIR: The article “Pipe Line Protection” by Stanley Gill
[IND. ENQ.CHEM.,25,49 (1933)] invades a field in which several commercial interests are engaged in competitive relationship and it thus has become difficult for Gill to preserve the neutrality from which he undoubtedly did not desire to depart. Nevertheless, certain portions of the article in question may well be reviewed in the light of more recent data as well as from the point of view of variant commercial practices. The article was presented by the author a t the New Orleans Meeting of the AMERICAXCHEMICAL SOCIETYa t the end of March, 1932, or substantially 10 months before its publication in ISDUSTRIAL A N D ENGISEERIKG CHEMISTRY.In the meantime there had been further reports in course of development by the American Petroleum Institute (4) and the American Cras Association ( 2 ) , as outcomes of the test programs being carried on, respectively, by Scott and Ewing in conjunction with the U. S. Bureau of Standards. These latter reports are not definitely referred to by Gill; they became available to the general reader as references only shortly after the article was published. It is stated by Gill that “by properly selecting asphalt and wrapper and by exercising care in application, coatings of good protective value can be obtained. Certain petroleum asphalts are entirely unsuitable for pipe-line protection * * * others have been found to be exceedingly stable * * * Asphalts should never be used without the protection of a wrapper.” Concerning coal-tar enamels Gill states, “Coal-tar enamel coatings will afford protection, under some conditions without the use of wrappers.” He further states, “The wrapped enamel coatings, which probably possess greater protective value than any currently available coatings of comparable cost, fall into two classes (bonded and unbonded wrap) * * * both, when the work is properly performed, will give coatings of high protective value.” The efitire implication therefore is that much more careful selection and application of asphaltic coatings are necessary than in the case of coal-tar enamel coatings, and the asphaltic treatment is definitely singled out as requiring a reenforcing wrapper. The preference for coal tar implied and expressed in Gill’s article is not justified by the reports of the American Petroleum Institute associate a t the Bureau of Standards. The American Petroleum Institute program of tests involved the burying in 1930 of pipe sections forming parts of actual pipe lines covered with nineieen types of treatments. Nine of the treatments were of coal-tar pitch origin; nine were asphaltic; one was a grease type. Some were thick and some were thin. Some were reenforced nith shields or wrappers and some were unreenforced. One, an asphaltic emulsion, was protected with includsand-cement mortar; one was an asphaltic mastic. TWO, ing the one above mentioned, %-ereasphaltic emulsions. It is presumed that each manufacturer of the coatings in this test sought to present his treatment in the most favorable light; that is, each treatment was the best of its kind a t the time. Any improvements in any ont’ since 1930 would be paralleled by presumed improvements in rill others. The over-all results shown in the 1931 (3)and 1932 examinations of the test sections were indicative of a low order of protection on the part of coal-tar treatments which had no wrappers. Of the ten treatments which in 1931 and 1932 showed a rating of 80 per cent or higher in effectiveness in prevention of pitting, only three were of coal-tar origin. The rest of the ten in the high effectiveness rating were asphaltic with the exception of one
treatment in 1932 which belonged to neither class. In both 1931 and 1932,l of the nine rating below 80 per cent in effectiveness, six were of coal-tar origin. On the basis of cost per ton (an item mentioned by Gill in the above quoted excerpt) asphalts have an advantage over coal-tar enamels. On the basis of thickness of treatment, asphalts have a further advantage as, weight for weight, asphalts will give a thicker treatment than coal-tar enamels. Gill’s article gives equal credit to loosely and closely bonded m a p s of reenforcing material over the covering. Yet the one unbonded wrap (asbestos paper) in the A. P. I. tests dropped in effectiveness rating from 0.97 in 1931 to 0.73l in 1932. Bonded and melted-in wraps with but one exception (again an asbestos wrap) retained their effectiveness ratings of the year before. The article by Gill favors asbestos papers in comparison with reenforcing materials of organic origin. But of the three asbestos treatments in the A. P. I. tests, two have a rating of 0.73l and 0.621 in effectiveness against pitting in 1932 (after having had ratings above 0.90 in 1931). Of the seven treatments having reenforcement of organic origin, all rated above 0.801 in 1932. The American Gas Association’s program of tests on underground-pipe protective coatings has paralleled the American Petroleum Institute tests in so far as duration of tests is concerned. However, the American Gas Association tests include no coatings applied t o lines in actual service. Conclusions drawn from the tests of the American Gas Association cannot be compared on an equivalent basis to those of the American Petroleum Institute obtained under conditions which bring about certain “long line effects.” A comparison indicates that there may be as much as a 1 to 3 difference in the severity of exposure of a coating on a short length of pipe as compared to exposure on a long line, soil conditions being equivalent. All manufacturers of protective treatments did not submit specimens in the A. P. I. test program. The manufacturer who had probably the longest history with reference to such treatments refrained from entering the test. The writer of this letter has been connected with corrosion protection work on underground pipe since 1905. It is probable that more severely corrosive soil conditions are met in California. than in any other part of the United States. Extensive applications of mechanically applied wraps to pipe, largely by a portable type of machine (5) as distinct from isolated local practices of the sort with mill-wrapped pipe, has a decidedly longer history in California than elsewhere. A noteworthy example of such a treatment is the 16-inch gas transmission line laid in 1929 northward from Buttonwillow, Calif., in the soil generally regarded as the most corrosive in the United States. An example of a similar protection is in t h e Lindsay-Strathmore and Terra Bella Irrigation Districts where 200 miles of riveted steel pipe ranging from 36 to 4 inches in diameter and from 12 to 16 gage in thickness were laid in 1916-17 in highly corrosive soil [some of this with a corrosion index (1) as high as 9 by the nipple and can method]. Not one foot of this pipe has ever been removed because of external corrosion. An example of this type of protection on the Atlantic Coast, employing the same asphaltic materials, is the 31 miles of 75-inch pipe in the Wanaque system of the Korth Jersey District Water Supply Commission, laid in 1928. Other installations embrace thousands of miles of gas, water, and oil trunk, distribution, and service lines. All of this work has been successfully carried out with asphaltic wrapping materials and asphaltic cementing 1 Effectiveness ratings in 1932 are not given in the report but may b e calculated from the reported data.
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compounds. In the outstandingly corrosive soil of the Pacific Coast there has been used for pipe protection only a negligible amount of the enamels made from coal-tar pitch.
paper, and found them to be strictly in line with the statements which I had previously made. It is an unfortunate feature of tests such as those being conducted by Scott for the American Petroleum Institute that test data can be readily misinterpreted LITERATURE CITED as a result of failure to consider all of the factors involved. A detailed refutation of Finley’s interpretation of these data would (1) Corfield, Western Gas, 6, No. 3, 25-27 (1930). (2) Ewing, Scott, Am. Gas Assoc., Distribution Subcommittee Rept. require a great deal of space, and would necessarily enter into on Specimens Removed in 1932 (1933). technical detail of little or no general interest. I can only reaf(3) Scott, G. N.,Am. Petroleum Inst., Development Production iirm the conclusions which have been quoted by Finley in his Eng. Bull. 208 (1931). discussion, both as regards the relative merits of coal-tar and (4) Scott, G. N., Ibid., 210 (1932). ( 5 ) Speller, “Corrosion, Causes and Prevention,” p. 532, McGraw- asphalt coatings, and of organic wrapping materials, as compared Hill, 1926. to asbestos felts. It is an unquestioned fact that The Paraffine DOZIERFINLEY Companies, Inc., with which Finley is associated, are entirely competent to exercise the care in selection and skill in application TEDPARAFFINE COMPANIBS, INC which are necessary to obtain good asphaltic coatings; but I do SANFRANCISCO, CALIF. April 10, 1933 not see that this fact alters in any regard my considered statement concerning the general merits of the various classes of coating materials. As Finley implies in his discussion, it is inevitable SIR: I have read Finley’s comments with a great deal of in- that a neutral observer should occasionally offend some of the terest, and can only say that none of the points which he raises “several commercial interests * * * engaged in competitive relaserves t o invalidate any of the extremely general conclusions tionship” in the pipe-line coating field, and I can only express my which were stated in my paper. Before the paper was finally regret that the interests with which Finley is connected should handed to you for publication, I was in possession of the data have been among the group which I offended. STANLEY GILL on the second year’s inspection of the American Petroleum InstiRUSKBUILDINQ tute specimens, and also of the latest data on the American Gas HOUBTON, TEX. Association tests. I considered these carefully in relation to my April 19, 1933
BOOK REVIEWS LATEX AND ITS INDUSTRIAL APPLICATIONS. By Frederick Marchionna. 1037 xxiii pages. Rubber Age Publishing Company, 250 W. 57th St., New York, 1933. Price, $15.00.
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THISvolume comprises an extensive and thorough survey of the patent and technical literature on rubber latex. Both patents and literature references are excellently abstracted. Although the author makes no claim for com leteness beyond July, 1929, pointing out that from that date t f e patent literature is either well briefed or fully reported, or translated in Rubber Chemistru and Technology, much of the patent literature has been covered up to and through 1932. The scope of the book is even broader than the title implies. I n the 11 chapters there is much information which is not strictly confined to latex. The chapters on rubber plauts, planting, and the cultivation of rubber not only contain references to Hevea brasiliensis, from which practically all the latex of commerce is derived, but also to guayule, which is not ordiiiarily considered a latex-bearing plant. I n the chapter on methods of preserving latex and rubber, nearly as much attention is given to the preservation of coagulated rubber as to the preservation of latex. A chapter on the behavior and characteristics of latex follows, with specific chapters on the coagulation and preparation of crude rubber from latex. The main section of the hook is concerned with the direct application of latex for the manufacture of rubber products. This section comprises nearly half the book and is the most valuable portion, since it brings together in one place the patent literature, well-abstracted, on the various industrial applications. Each section is introduced with a brief summary on the subject matter of that chapter. These were all written by the author, with one exception. The value of these brief introductory chapters would have been much enhanced had they been written b y specialists in the various fields, as in the latter case, and had literature references been given more consistently in discussing t h e work of the various investigators. Certain inaccuracies have crept into these introductory chapters, obviously as a result of the lack of specific knowledge or experience of the author. For example, acetic acid is given as the most common coagulant of latex. Formic acid had largely supplanted acetic acid for this purpose considerably before 1929. Again, the “superiority of
Para rubber” (to what and from what standpoint is not stated) is ascribed t o “the degree of the heat of the smoke, which is between 70’ and 80’ C.” This statement is ambiguous and the explanation is questionable. The style of the author and the clarity of his writing deserves especially favorable comment. The sentences are clear and concise, and the paragraphing is well done. The result is a book which is pleasant to read, in spite of the Fact that it is really a reference volume. The method of classification is less commendable. This, coupled with poor choice of type for the headings and poor spacing for these headings, makes consultation of this book for reference purposes annoying in some respects. The author has chosen to classify the patents under each heading under the country in which the patents were granted. This of course results in discontinuity. For example, instead of the United States, British, German, and French patents, issued on the same invention, being grouped together, they are far removed from each other. A further unfortunate procedure was the failure to place the abbreviation of the country before each patent number. The result is that the reader may find it necessary to thumb through many pages to find out to what country the patent number refers. Failure on the part of the publisher to use heavy type and sufficient spacing for the headings makes it difficult to find the subdivisions of the patents. A serious error was made when the names of the assignees of the patents were left out. Omission of the initials of the patentee is also disconcerting, especially where there are several investigators with the same surname. The subdivisions of the material in Chapter VIII, which covers the direct use of latex in industry, could have been much improved had the 8 arts been further subdivided. The material is listed under broad headings that one must cover many pages in looking up patent abstracts in any particular field. The placing of the abstracts is not always accurate. For example, in the section on adhesive and coating materials, “latex paints” are interspersed with “seal for containers,” “surgical dressings,” “aircraft coverings,” and “treatment of leather.” A subdivision on the compounding of latex would have been especially acceptable. The adoption of a unique and original set of abbreviations for use in referring to the journal literature seems unnecessary, in view of the fact that most rubber technologists who are interested in latex are thoroughly familiar with the accepted abbreviations
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