The Alaskan pipeline was designed to carry crude oil at a rate of 1.2 million $\mathrm{bbl} / \mathrm{day}(1 \mathrm{bbl}=$ $42 \mathrm{gal})$. If the oil is assumed to be Newtonian, with a viscosity of $25 \mathrm{cP}$ and an $\mathrm{SG}$ of 0.85 , the cost of energy is $\$ 0.10 / \mathrm{kWh}$, and the pipe grade is 600 \# ANSI, what would be the most economical diameter for the pipeline? Assume that the economic lifetime of the pipeline is 30 years.