C = (3D*P*F)/1000) in inches; (C = (3D*P*F*)/6,895) in millimeters
in which:
C = Minimum clearance between pipe containers or bottles in inches (millimeters).
D = Outside diameter of pipe containers or bottles in inches (millimeters).
P = Maximum allowable operating pressure, psi (kPa) gauge.
F = Design factor as set forth in § 192.111 of this part.
49 C.F.R. §192.175