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H John W. Boardman—Self-Unloading Cement Carrier—Owned by the Huron Transportation Co., Detroit Know Your Service Conditions For Successful Performance of Equipment Satisfactory Results Are Ob- tained Only by Proper Installation and Operation of All Dependent Units N THE design of a superheater there are encountered variables which have a marked effect upon the final temperature of the steam. Before completing the final arrange- ment, the designer must decide for himself what the approximate condi- tions will be, including the percentage The author, L. M. Rakestraw, is a member of the staff of the marine department of the Foster Wheeler Corp. By L. M. Rakestraw of moisture in the steam, the per- centage of CO, in the flue gases and the temperature of the exit gases from the boilers. With the experi- ence now available it is possible to determine these conditions very close- ly. A typical example of what may happen when some of these factors diverge from the designer’s original estimates recently developed in the case of the S. S. JoHN W. BoARDMAN Deck of the Self-Unloader John W. Boardman in Winter 74 MARINE REVIEW—April, 1928 of the Huron Transportation Co. THE BOARDMAN is equipped with two scotch marine boilers, having two furnaces each, tubular air heat- ers and waste heat Foster super- heaters; the latter designed to pro- duce a superheat of 50 degrees un- der certain operating conditions. Early last spring it was found that the superheat produced was approxi- mately 22 degrees Fahr. and a pre- liminary inspection showed that al- though the vessel was fitted with in- duced draft and air heaters, the boilers were operated with the ash- pit doors open. It further developed that the reason for this was that the furnace grates burned out rap- idly when operating with the ash pit doors closed. Another interest- ing condition of operation was that the action of the triple expansion engine indicated the presence of a considerable amount of water in the cylinders in spite of the fact that the steam thermometer showed 22 de- grees superheat at the boilers. Service engineers studying the un- satisfactory performances of the su- perheaters recognized that the re- sults obtained were allied, in all probability, with other unfavorable conditions. Obviously the preheat of