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tubes at the mill, and finally, the hy- drostatic test of completed sections. In fact, there are separate series of tests and inspections, such as these, throughout the entire manufacturing process. The manufacture of drums would, under the proposed rules, undergo a complete change, because fabrication by welding would be permitted and, judging from the wide acceptance of this construction for land service, would soon be the prevailing method. However, this change should in no way work a hardship on a modern poiler shop, since the up-to-date manu- facturer is now employing welding for this purpose. For instance in the plant under consideration, more than 1400 boiler drums with fusion-welded seams have been produced to date. Length of seams in these drums and other pressure vessels is over 90,000 feet. Prior to that time, this manufacturer had done considerable research work in fusion welding, and, during the course of this investigation, had made over 10,000 laboratory tests, had carried out repeated-pressure tests of 31 drums and shells, which were subjected to hy- drostatic pressures varying from 0 to 11% times the working pressure, some of them through 2,000,000 cycles. Many Tests Carried Out This manufacturer had also tested to destruction, under hydrostatic pres- sure, four full size drums of different constructions, including riveted and welded, as well as one seamless drum, and had determined the endurance limit of the deposited weld-metal with rotating beam machines, whereby some specimens were given over 30,- 000,000 cycles of reversed bending stresses. Before the fusion welding process was finally used for the commercial fabrication of boiler drums and unfired pressure vessels, a complete study was made of nondestructive _ tests, whereby the soundness of welds in fin- ished products might be determined. This study included an investigation 16 of the practicability and reliability of the various well known _ physical, chemical and microscopic tests of cou- pons or test pieces taken from main welded seams, electromagnetic tests, and X-ray examination. As a result, a thoroughly satisfactory test proce- dure, definitely proving the quality of welds, was developed. Fusion Welding Dependable This brief mention of the research and development work carried out by this one company is made merely to emphasize the fact that fusion welding long ago pased the experimental stage and is today a process that can be relied upon. Later in our trip through this boiler plant, we not only shall see how welded seams are made, but also note the precautions taken, in the form of tests and examinations, to provide definite assuranecce that drums made by this process for ma- rine boilers will be safe and reliable. Drum plates are laid out and ma- chined to size. The edges of the plates that, when assembled, will be united by welding are planed to form a conventional U-shaped welding groove. The bending or rolling of the plates to cylindrical form is done in the same manner and by the same process as that used to shape plates for riveted drums—large and thick plates are formed cold in the process ® A view of part of the forge shop showing a forge furnace at the right and a hydraulic press used for dishing and flanging drum heads ® . 2 Tube holes of headers for watertube boil- ers are drilled on a mass pro- duction basis— with special machines such as this one A MARINE REVIEW—June, 1934 or, if they are of unusual thickness, they are hot pressed. Smaller plates are rolled. In witnessing the operation of roll- ing these great plates, one is im- pressed not so much by the ease with which the massive machines perform the operation as by the accuracy with which the prescribed curvature is at- tained. That this accuracy is accept- ed as a matter of everyday skill in modern boiler manufacturing is shown by the fact that the tolerance in cir- cularity allowed by the proposed ma- rine rules is one per cent. No diffi- culty, however is experienced in fabri- cating boiler drums to this tolerance. In viewing the equipment required for this work, the visitor cannot fail to be impressed by its magnitude. On the one hand is a gigantic roll capa- ble of bending plates 26 feet in length; nearby, a mammoth hydraulic press, capable of hot-pressing plates 414 inches thick, to form halves of a cylin- der of only 30 inches inside diameter, towers above the visitor. How Welding Is Done After the plates are formed, they are tack-welded together temporarily with steel strips at the bottoms of the grooves that are to receive the metal deposited during the welding process. The drum is then set up under an automatic welding machine that welds the plate edges together. Flux-coated metal electrodes are mounted in the welding heads of the machines and, as the molten metal from the elec- trode or rod is deposited in a longi- tudinal groove, the welding machine moves slowly along the drum, and, in the case of a circumferential groove, the machine remains stationary while the drum is revolved on a _ special cradle. The electrode, in each case, lays a thin layer of weld metal that is covered by the flux and is thereby protected from the atmosphere. Thus, layer by layer, the weld metal is de- posited in the groove, until the joint is completed. The coating on the electrodes, a re-