The Babcock formula for pressure drop can be found at the following website:
www.ruffneck.com
Here it is for your info;
Pressure Drop (PSI)= .000130W^2*L/pd^5 *(1+3.6/d)
Where:
W= Steam Flow Rate, lb/min
L = Length pf Pipe, ft
p =.0434 for 2 PSIG Steam
.0612 for 10 PSIG Steam...