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An important element of what is un- doubtedly the most typical of marine watertube boilers is the header. Un- der the proposed rules, the manufac- ture of this element will not undergo any change. In viewing this proc- ess, one cannot fail to get the very de- cided impression that special equip- ment and production technique have been so admirably coordinated as to result in precision-like production of finished forgings. From the charging of the forging furnace with the stock, to the delivery of shaped header blanks at the outlet of the press that forges the headers to shape, every step in the process bespeaks the certainty of results attained in the production of thousands, even hundreds of thou- sands, of fundamentally duplicate parts during more than 40 years. Ends Spun Inward Although improvements in this proc- ess may be difficult to conceive, in one respect an improvement has been ef- fected in recent years. Formerly the open ends of the headers were closed with flat plates, forged in place. Now the ends are heated and rolled or spun inward, on a machine designed espe- cially for the purpose, thus providing ends that are integral with the main body of the header. At the center of the ends, where the spun metal might be porous, small plugs are inserted° these are shouldered inside and weld- ed at their outer ends, Incidentally, this is, on a small scale, the same method the company has used to close in, by spinning, the ends of larger headers and some boiler drums for land service. The next step in header manufac- ture is the testing of the blanks, which consists of subjecting these unma- chined parts to a hydrostatic test of twice the working pressure. The blanks are then machined in what may be described as two opera- tions. The one operation consists of trepanning the tube holes in a mul- ® One of the world’s largest stress relieving Eb EWG: es; Length 60 feet; inside width, 14 feet 6 inches. Used for stress relieving fusion welded pressure vessels ® ® This completely equipped mnmi- croscopical lab- oratory is an important. ele- ment im exact contral and su- pervision of boiler construc- tion and par- ticularly of welded con- struction ¢ tiple-spindle drilling machine that, as is the case with much of the equip- ment used in the plant, was especially designed and built for performing one operation. A typical machine for this purpose is capable of trepanning eight groups of four l-inch or 2-inch tube holes simultaneously. In the other operation, elliptical handholes are machined in the side of the header opposite the tube holes. This operation, because of the shape of the holes, is, of course, more com- FFICIAL adoption of the proposed new rules cover- ing marine boiler construction, now awaiting action by an ex- ecutive committee of the board of supervising inspectors, is ex- pected in the near future. What effect adoption of the new rules will have on the methods of marine boiler construction is dis- cussed in this article, the second part of which will appear in the July issue. MARINE REVIEwW—June, 1934 plex and consequently is performed on a machine more highly specialized than that used for the tube holes. It. will profile eight elliptical handholes in one operation. The header is chucked on a table or carriage under the spindles and is moved in an ellip- tical path by a cam mechanism while the eight profiling spindles cut the edges of the handholes to the required shape. Careful Installation of Tubes The tubes are expanded into the headers in the shop, to form tube sec- tions. In this operation the headers are mounted on racks, or what is termed a “header bench,” and securely held in place by a chucking arrange- ment that automatically sets the head- ers with respect to the tubes and each header with respect to the other, in a uniform and unvarying position, so that when the _ sections are later erected in place in the boiler, they will be interchangeable and _ accurately aligned with the other parts of the boiler to which they must be con- nected. Power-driven expanders are used, the operator at one end working two or more tubes in advance of the op- erator at the opposite end, to prevent any tendency towards the setting up of strains in the tubes—a refinement in operating methods that distin- guishes modern boiler-making from the methods that have earned for the old fashioned boilermaker his reputa- tion for crude workmanship. After the tube sections are com- pleted, each is hydrostatically tested to one and one half times the work- ing pressure, thus concluding one series of tests of materials and work- manship made to assure the accuracy and soundness of the sections. First, there are the tests of materials at the steel mill. These are followed by lab- oratory tests at the boiler works or tube mill, the spinning-in of header blanks—really constituting another test—the hydrostatic test of finished headers, a whole series of tests of 15: