Figure 3-49. - 90-degree tee.

To make the template for the hole in the header, divide the circumference of the header into equal parts, as at points 1, 2, 3, and so forth. Next, project these points across to view A (fig, 3-49), as shown. As in view C, lay off the line 1-5-1 equal to one half of the circumference of the header, and divide it into the same number of equal parts as was done on the header. Locate point P, a distance from 1 in view C equal to 1-P in view B. With this point P and the distances 5-5, 4-4, and so forth, in view A, plotted as shown in view C, the curve of the template is located.

BRANCH CONNECTIONS

Branch to header connections (fig. 3-50) at any angle of 45 degrees to 90 degrees can be fabricated in equal diameter pipe by the following procedures. (Note that angles less than 45 degrees can be made, but a practical limitation is imposed by the difficulty of welding the crotch section.)

First, quarter both sections of pipe as before. hen locate the center line of the intersection (point B) on the header and draw line GF around the pipe at this