1 inch refers to the inside diameter. So the cross sectional area is pi*radius² = 3.1416*(0.5 in)² = 1.5708 in². Multiply this by the length [5 ft = 60 inches]: 94.248 in³. If you wish: 1 US gallon = 231 in³, so this converts to 0.408 US gallons.
The volume is 70.685 cubic feet.
The volume of a 100-foot diameter x 200-foot long cylinder is: 11,750,400 US gallons.
If the pipe is round, with a 55-foot diameter, and 36 inches long, then its capacity is 53,317.3 gallons. If the pipe is round, with a 36-inch diameter, and 55 feet long, then its capacity is 2,908.2 gallons. Either way, we have no way of knowing how much water is in it. For all we know, it may even be empty.
A 14-inch diameter by 20 foot long pipe has a volume of: 21.38 cubic feet.
A four-foot diameter pipe that is five feet long has a volume of 470 gallons.
A pipe that is 30 inches in diameter and 12 feet long has a volume of: 440.6 US gallons of water.
Completely filled, (pi x radius squared x length in inches)/231 cu in per gallon = gallons = 13.06122449, if the inside diameter of the pipe is 2 inches. =========== Of course that assumes that the inside diameter is exactly 2 inches. For real pipes, the actual inside diameter of a pipe depends on the "schedule" of the pipe. For a "nominal" pipe diameter of 2 inches, the outside diameter will be 2.375 inches and the wall thickness could vary from .065 inches (schedule 5) to .343 inches (schedule 160) meaning that the actual inside diameter could vary from 2.245 inches to 1.689 inches.
Use the formula for volume on a cilinder that is 1' high and 3/4" in diameter and multiply by 4000 feet.
A 1,850-foot long pipe with a 16-inch inside diameter has a volume of 2,580 cubic feet. In terms of liquid volume, this section of pipe can hold up to about 19,300 US gallons.
Pipe is generally cylindrical and the dimension refers to the inside diameter. One cubic foot contains 7.48 gallons. The volume of a one foot long 20" diameter pipe is: pi(1.667/2)^2 = 2.18 cubic feet. At 7.48 gallons per cubic foot the total volume is 16.3 gallons.
The volume of a pipe that is 10mm diameter and 200 meters long is: 0.015708 m3
The volume in liters of a 100mm long by 50mm diameter cylinder is: 0.196 liters.