The volume of a pipe is found by multiplying pi by the height by the radius squared. This is the common equation for a cylinder.
Finding the volume of a pipe is simple with the proper tools. First, the length (in the equation this is denoted an 'h' for height) of the pipe. Once the length is known, the area of the pipe needs to be found next. This can be done with or without a calculator.
The area of the pipe is measured by finding the area of the circular opening (base) on either end of the pipe. The standard equation for the area of a circle is "area = pi multiplied by radius squared." The radius is the distance from the center of a circle to its perimeter. If a calculator is unavailable, the average number for pi is 3.142.
After the area of the pipe has been calculated, the volume of the pipe can be determined by multiplying the area of the circle (base) by the height of the pipe. This is the volume of the pipe under closed system circumstances. A closed system means that there is no water flowing through the pipe.
The metal that the pipe is made out of has no bearing on the volume of the pipe.