This research was carried out, by the request of the Nippon Kaiji Kyokai, on the first all-welded dry combustion boiler with two furnaces in Japan, which was manufactured at the Innoshima yard. In order to obtain the data for the design, manufacturing, inspection and operation of such an all-welded boiler, authors measured the deformations and stresses of the boiler and also checked. whether it would yield under the test water pressure required by the rules or not. Although authors had not enough time to measure the all of the scheduled points of the boiler, because it was to be fitted to a new ship before long, authors could clear up several facts as follows. (1) Even under the required pressure, any sign of the yielding phenomenon was not noticed at any part of the boiler. (2) Therefore, as far as it concerns the boiler tested, it is not necessary to provide any longitudinal stay to strengthen the water-containing part formed by the flues and shell plate. (3) At the water-containing part above mentioned, it was observed that the ehd plate having a manhole reinforced by flanged plate was stronger in the elastic region than the other not having it, unless there were any other factors. (4) The stress which occurs at the flanged part of the end-plate edge shows the highest value at the center of the curved part, however this highest value of each curved section varies in accordance with the unsupported area of the flat plate to which the curved part joins. (5) It will be seen that holes provided for the water tubes of the rear end-plate do not affect the elastic stresses of the end-plate. (6) The welded longitudinal joint of shell plate, which is annealed after welding, is considered to be stronger than the riveted joint, unless the extreme change of curvature occurs in it while annealing.
