Dear all,

I've read the ring girders design example in Chaptor 7 'Supports for Pipe' of the AWWA M11, 2004, 4th ed. through and wonder about the value of the allowable stress in the Step 4 on page 99, why they use the allowable stress of 25,600psi instead of 20,000psi which is the allowable stress for ASTM A516, Gr60.

Your kind helps are very appreciated.

Regards
TWC