Laying out for boiler makers and sheet metal workers; a practical treatise on the layout of boilers, stacks, tanks, pipes, elbows, and miscellaneous sheet metal work . , the plate must be laid out with alength between the center lines of the rivet holes equal tothe circumference of a circle whose diameter is 48^ inches,or referring to Fig. 9, it will be seen that if t = the thickness ofthe material and D the inside diameter, then the neutral di-ameter is D + 2 X /^ t or D -j- t. Therefore the circumfer-ence corresponding to this diameter is X (D -j- t) D + t. That is, it
Laying out for boiler makers and sheet metal workers; a practical treatise on the layout of boilers, stacks, tanks, pipes, elbows, and miscellaneous sheet metal work . , the plate must be laid out with alength between the center lines of the rivet holes equal tothe circumference of a circle whose diameter is 48^ inches,or referring to Fig. 9, it will be seen that if t = the thickness ofthe material and D the inside diameter, then the neutral di-ameter is D + 2 X /^ t or D -j- t. Therefore the circumfer-ence corresponding to this diameter is X (D -j- t) D + t. That is, it is equal to the circumferencecorresponding to the inside diameter plus times thethickness of the plate. For ordinary work three times thethickness of the plate is generally used. The circumferencecorresponding to the outside diameter might have been found,in which case three times the thickness of the plate shouldhave been subtracted from it. When two rings or courses ofplates are to be joined together, one of which is an insideand the other an outside ring, the circumference correspond-ing to the neutral diameter of the inside ring may be found, T to L. FIG. 10. of the cylinder. The circumference of a circle is equal times its diameter. If the apprentice is not familiarwith the use of decimals, the same result may be obtained bymultiplying the circumference by 22 and dividing by 7. Innearly all engineers and boilermakers hand-books, tablesare given, in one column of which are values of diameters, andin another column the corresponding values of the circum-ferences of the circles, and in a third column the values ofthe areas of the circles. The area of a circle is equal to and then for the length of the outside plate six times thethickness of the material should be added to this. This willmake a close fit between the rings, as the exact amount to beadded is 2 times or about 6^ times the thickness ofthe material. For an easy fit, add a little more
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Keywords: ., bookcentury1900, bookdecade1900, bookidl, booksubjectsteamboilers
