A 3 -in. schedule 40 commercial steel pipe (with an actual inside diameter of 3.068 in.) carries 210 degree F SAE 40 crankcase oil at the rate of 6.0 gal/min. The oil specific gravity is 0.89, and the absolute viscosity is 6.6 times 10^77 lb middot sec/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.