Identifier: americanschoolof01amer (find matches)
Title: American school of correspondence; a technical school for mechanics giving exclusive attention to steam and electrical engineering and the construction and operation of machinery
Year: 1898 (1890s)
Authors: American School of Correspondence
Subjects: Engineering
Publisher: Boston, Mass.
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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etal is so hardthat it is difficult to cut Avith steel tools. It welds with greatdifficulty but it can be forged. Its toughness increases by quench-ing from a yellow heat. It has a remarkable combination of greathardness, which cannot be lessened by annealing, great tensilestrength, toughness and ductility. The fact that it cannot be CONSTRUCTION OF BOILERS. RIVETED JOINTS. There are various forms and strengths of riveted joints. Itis obvious that in punching, or drilling, a plate is weakened to theextent of the sectional area cut out, and that if the holes arepunched the metal between the holes is weakened. In treatingthe strength of a joint it is customary to speak of it as a percent-age of the strength of an unpunched plate. If one plate overlaps another and is riveted to it, it is calleda lap joint. This joint has about 56% of the strength of a solidplate. If another row of rivets is added, it is called a doubleriveted lap joint as shown in Fig. 3, and has a strength of about 70%.
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Fig. 3. If the two plates are kept in the same plane and a cover orbutt strap riveted on, it is called butt riveting. Fig. 4, in which 52 CONSTRUCTION OF BOILERS. 23. What two ways are tubes fastened to the tube sheet? 24. Name some of the considerations that must be kept inmind when designing a boiler. 25. Upon what does the choice of type depend? 26. How many B. T. U. in a boiler horse-power? 27. Name four general requirements that a boiler must have ? 28. What is wire-drawing ? 29. Why is the length of a grate limited ? 30. Which is the more economical a slow or quick rate ofcombustion? (Other conditions the same). 31. If the boiler is to supply steam to a high speed engine,should the steam space be larger or smaller than if to a low speedengine ? 32. How do you find the volume of the steam space perH. P. per hour knowing the amount of coal consumed per H. P.per hour and the working pressure. 33. About what fraction of the volume of a multitubularboiler is the steam space ? 34. Abo

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