Mitered Elbows

AWWA Recomends:

22.5< to ≤ 45, use 3 pieces
45 < to ≤ 67.5, use 4 pieces
67.5 < to ≤ 90, use 5 pieces

A)  The larger the O.D. of the fitting, the more competitive a mitered fitting will be.  Because of the ultimate use, most fittings 54″ and larger can be fabricated and will provide that competitive edge.
B)  AWWA C208-96 elbows are made from miter cut pieces of pipe.  The mitered pieces that make up the elbow are called gores.  In a 5-piece elbow, there are two end gores and three middle gores.  The dimensions of the end and middle gores are determined based upon formulas provided by AWWA on page 7 of C208-96.
C)  AWWA C208-96 recommends 2 and a half X diameter as an optimum radius, (centerline radius), for mitered elbows with 1 X diameter as the minimum.  Due to industry standards for elbows of other specifications, (e.g. A234 WPB), we set the normal radius at 1 and a half X diameter.
D)  However, other standards set the “center-to-face,” or the line originating 90 degrees from the plane of the face of one end of the elbow to the center line of the other end as equal to the center-line radius.  AWWA C208-96 DOES NOT FOLLOW THIS PRACTICE!  In the AWWA spec, the “radius” is a calculation based upon the formulas mentioned above.  The AWWA spec states the radius of a 60″ elbow is 90″.  The “center-to-face” is 92.065″.