A 3-in. schedule 40 commercial steel pipe (with an actual inside diameter of 3.068 in.) carries \(210^{\circ} \mathrm{F}\) SAE 40 crankcase oil at the rate of \(6.0 \mathrm{gal} / \mathrm{min}\). The oil specific gravity is 0.89, and the absolute viscosity is \(6.6 \times 10^{-7} 1 \mathrm{~b} \cdot \mathrm{sec} / \mathrm{ft}^{2}\). Calculate the pipe size required to carry the same flow rate at approximately one-half the pressure drop of the 3-in. pipe. Both pipes are horizontal.