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 . y of the weld in iron braces. Steelbraces may thus be made lighter and the factor of safety doesnot need to be so great as with iron braces. ^lany allowing on weldless steel braces 9,000 pounds per squareinch sectional area. Diagonal braces are not allowed the full value of t!iestrength of the brace, due to the fact that they do not strike 48 LAYING OUT FOR BOILER MAKERS the head at right angles. Thus, if a brace
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 . y of the weld in iron braces. Steelbraces may thus be made lighter and the factor of safety doesnot need to be so great as with iron braces. ^lany allowing on weldless steel braces 9,000 pounds per squareinch sectional area. Diagonal braces are not allowed the full value of t!iestrength of the brace, due to the fact that they do not strike 48 LAYING OUT FOR BOILER MAKERS the head at right angles. Thus, if a brace is allowed 9,000pounds in direct pull, it would be allowed less if set at 10degrees, and still less if set at 15 degrees. •li A :^ Area of brace in square inches. B = Stress per square inch, net section of brace. C = Length of line at right angles from the surface to be supported to the end of diagonal = Length of diagonal = Surface to be supported in square inches. A X B X C Then = pressure allowed per square inch. D X EAssuming that the brace is allowed 9,000 pounds per square inchin direct pull, and the length of (C) is 49 inches, with (D). FIG. 29.—BOILER HEAD BR.\CED WITH DIAGONAL BRACES. 50 inches and the surface to be supported 49 square inches,the pressure allowed would be found by substituting thesevalues in the above equation. 9000 X I X 49 = 180 pounds. 49 X 50 The photograph. Fig. 29, and the sectional view, Fig. 30show the manner of fastening diagonal braces, B and D, , representing the distjiiice C in the formula. From the dis-tances A and C and B and D in Fig. 30, the length of thebrace is determined. In Fig. 31 is shown a layout of diagonal braces for a 60-inchboiler head, in which there are 3>^-inch tubes. Au-thorities differ in regard to the area to be supported, butnearly all admit that a certain distance from the flange ofthe head is self-supporting. It is necessary, then, to determinehow far from the flange the head
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Keywords: ., bookcentury1900, bookdecade1900, bookidl, booksubjectsteamboilers
