locate two points and hence the center line. By thissame method, the quarter points also may be locatedThis operation is a must before any layout with thefield method.If you are using a long piece of pipe and are goingto cut both ends in addition to the square, you wiIl needa piece of carpenter’s chalk line with a plumb bob oneach end and two 24- or 36-inch (60- or 90-cm)-flatsteel rules (depending on the diameter of the pipe) tolocate the top and the bottom center lines. Figure 3-43shows a plumb bob and rules being used to locate thetop and the bottom center lines.Another one-shot method of quartering pipe is totake a strip of paper and wrap it around the pipe andtear or cut the part that overlaps. The ends shouldtouch. Remove the paper from the pipe and fold it inhalf, as shown in figure 3-44, view A. Then double thestrip once again, as shown in view B. This will divideyour strip into four equal parts. Place the strip of paperaround the pipe. At the crease marks and where theends meet, mark the pipe with soapstone and your pipewill be quartered.TEMPLATE FOR TWO-PIECE TURNThe fact that a length of pipe with square ends canbe fabricated by wrapping a rectangular section ofplate into a cylindrical form makes available a method(known as parallel forms) of developing pipe surfaces,and hence developing the lines of intersection betweenFigure 3-43.—Locating the top and the bottom center lines.Figure 3-44.—Folding a tip of paper for use in quarteringpipe.pipe walls. Based on this principle, wraparoundtemplates can be made for marking all manner of pipefittings for cutting preparatory to welding.The development of a template is done in practiceby dividing the circumference (in the end view) of thepipe into a specific number of equal sections. Thesesections are then projected onto the side view of thedesired pipe section. The lengths of the varioussegments that make up the pipe wall may then be laidout, evenly spaced, on a base line. This line is, ineffect, the unwrapped circumference (fig. 3-45). If thetemplate developed in figure 3-45, view C, is wrappedaround the pipe with the base line square with the pipe,the curved line, a-b-c-d-e-f-, and so forth, will locatethe position for cutting to make a 90-degree, two-pieceturn. Draw a circle (fig. 3-45, view A) equal to theoutside diameter of the pipe and divide half of it intoequal sections. The more sections, the more accuratethe final result will be. Perpendicular to the centerlineand bisected by it, draw line AI equal to the O.D. (viewB). To this line, construct the template angle (TA)equal to one half of the angle of turn, or, in this case,45 degrees. Draw lines parallel to the centerline frompoints a, b, c, and so forth, on the circle and mark thepoints where these lines intersect line a-i withcorresponding letters. As an extension of AI but a littledistance from it, draw a straight line equal to the pipecircumference or that of the circle in view A. This line(view C) should then be divided into twice as manyequal spaces as the semicircle, a-b-c-, and so forth, andlettered as shown. Perpendiculars should then beerected from these points. Their intersections withlines drawn from the points on a-i in view B, parallelto the base line in view C, determine the curve of thetemplate.SIMPLE MITER TURNAfter quartering the pipe, proceed to make asimple miter turn. Locate the center of the cut (fig.3-46, point c) in the general location where the cut isto be made. Use a wraparound to make line a-bcompletely around the pipe at right angles to the center3-17