After this line is radially cut, the branch maybe usedto locate the line of cut on the header, allowing for theintersection of the outer branch wall and inner headerwall as before. This line should be radially cut,followed by beveling.In making an eccentric branch connection theextreme case being where the side of the branch iseven with the side of the header, a similar procedureis followed, as shown in figure 3-53.THREE-PIECE Y CONNECTIONThe entire procedure for fabrication of an equaldiameter, three-piece Y connection is based onindividual operations already described. As the firststep, quarter the end of the three pieces of pipe andapply circumferential lines. When the three pieces arewelded together to form the Y, there will be threecenter lines radiating from a common point.The open angle between each pair of adjacentcenter lines must be decided, for each of these angleswill be the angle of one of the branches of the Y. Asshown in figure 3-54, these open angles determine theangle of adjoining sides of adjacent branches. Thushalf of the number of degrees between center lines Aand B are included in each of the adjoining cutbacksbetween these two branches. The same is true withrespect to the other angles and cutbacks betweenFigure 3-52.—Line of cut is first marked on branch with thismethod.Figure 3-53.—Marking cut on branch for eccentric branchconnection.Figure 3-54.—Three-piece Y connection.center lines, Moreover, each piece of pipe must havea combination of two angles cut on the end.To determine the amount of cutback to form anangle of the Y, set the protractor at one half of the openangle between adjacent branch center lines. Place theprotractor on the square, crossing the outside radiusmeasurement of the pipe on the tongue of the square,and read the cutback distance off the blade of thesquare. Mark off this distance on one side quarter lineon each of the two pieces that are to be joined. Thenmark the cutback lines. Repeat this procedure for theother two angles of the Y, taking care to combine thecutbacks on each pipe end. Three settings of theprotractor determine all cutbacks.An alternate method for determining each cutbackis to treat two adjacent branches as a simple miter turn.Subtract the number of degrees of open angle betweencenter lines from 180 degrees and set the protractor atone half of the remaining degrees. Cross the outsideradius measurement on the tongue. Mark one side ofeach adjoining pipe section. Repeat for the other twobranches. Take care to combine the proper cutbackson each pipe end. Set the protractor for each openangle of the Y connection.The computations and measurements for thelayout (fig. 3-54) are shown in table 3-1. The pipe is12 inches in diameter and has a radius of 6 inches (15cm)3-22

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