If you want to cut the pipe lengthwise into halves, it is necessary to outline its diametrical plane. It’s easy to do and without any measuring devices by using a sheet of paper. Attaching it to the end of the pipe and outlining a circle with a pencil, then cut out the circle and fold in half. Now it is enough to make the paper semi-circle again to the face – bend will show exactly the line of the longitudinal section of the pipe.