MITERED ELBOWS UNDER AWWA C208

Mitered elbows are brecommended by AWWA

Ⅰ to< 22.5° , use 2 pieces to weld

Ⅱ 22.5°< to ≤ 45°, use 3 pieces to weld

Ⅲ 45° < to ≤ 67.5°, use 4 pieces to weld

Ⅳ 67.5° < to ≤ 90°, use 5 pieces to weld

From the above drawings,we could see AWWA C208 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.After welded together,the elbow looks like back of shrimp.

What is the characteristic for this kind of elbows？

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″.