Hi Abati,

The pipe is a cylinder with radius $r$ units and length $l$ units and its volume $V$ is given by

\[V = \pi \; r^2 l \mbox{ cubic units.}\]

You have a diameter of 6 inches so the radius is $\large \frac62 \normalsize = 3$ inches. To use the expression above for $V$ the radius and length must be in the same units. To convert 3 inches to meters I suggest that you type What is 3 inches in meters? into the Google search window. Use the result to compute $V$ above in cubic meters.

One warning is that the calculation above uses 6 inches as the internal diameter of the pipe and a "pipe diameter of 6 inches" might mean the external diameter is 6 inches. If you access to the pipe you should measure the internal diameter in millimeters and use half this value as the internal radius of the pipe.

I hope this helps,
Penny