Creating the end of the pipe

From the Copy window, select Surfaces and Rotation. Enter an angle of 180 degrees. Since the rotation may be done in 2D, choose the option Two Dimensions. The center of rotation is the upper right point of the pipe elbow. Make sure the Do Extrude menu is set to No.
Click Select and select the surfaces that join the two pipe sections and press ESC.
Select Utilities->Move window, select Surfaces and Translation. The points defining the translation vector are circled in next figure.

The circled points define the translation vector.

Click Select and select the surfaces created in point 1. Press ESC. The result should be as is shown.

The final position of the translated elbow.

To create a ring surface, choose Geometry->Create->NURBS Surface->By contour and select the four lines that define the opening of the pipe (see next figure). Press ESC twice.

Opening at the end of the pipe
From the Files menu, choose Save in order to save the file. Enter a name for the file and click Save.