Create a new layer named "pipe2" with two child layers "inner" and "outer". Set "pipe2//inner" as the 'layer to use', and set off the layers "pipe1"
Choose Geometry->Create->Point and enter points (-20, 9) and (-20, 11). Press ESC to conclude the creation of points.
Change the layer of the second point to "pipe2//outer"
From the Copy window, select Points and Rotation. Enter an angle of 180 degrees and from the Do extrude menu, select Lines. Since the rotation can be done on the xy plane, choose Two Dimensions. The center of rotation is the coordinates (-20, 0, 0), and set Multiple copies to 2
Click Select and select the two points just created.
Create a surface: choose Geometry->Create->NURBS Surface->By contour and select the four lines. Press ESC twice.
From the Copy window, select Surfaces and Translation. In First Point and Second Point enter the points defining the translation vector. Since this pipe section must also measure 40 length units, the vector is defined by points (0, 0, 0) and (0, 0, 40).
From the Do extrude menu, select the Volumes option and set Multiple copies to 1.
Click Select to select the surface and press ESC to conclude the selection.

A rendering of the two overlapping pipes

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