support saddle for large steel pipe

huangyhg

support saddle for large steel pipe
i'm calculating / specifying the minimum requirements for large (>24") steel pipe support saddles. this is not the first time i've done this but there's a couple of things i just can't find any documentation and/or explanation for.
when calculating the saddle support (not the pipe shell) the awwa m11 manual and pressure vessel handbook give a formula for the minimum horizontal force (f). this force f is a product of the maximum vertical reaction multiplied by a constant (k). the constant k is based on the saddle to pipe contact angle (charts provided for angles from 120 to 180 degrees).
my two questions are; 1) what is this constant k and where is it derived from (i always assume it to be a minimum when compared to wind or seismic) and, 2) localized pipe stresses at the support have constants based on contact angles from 90 to 180 degrees. what is the minimum contact angle?
my client wants to use a contact angle of 60 degrees and i'm having problems backing up saying "no" and if i cant't back it up, now what?