well you can find the volume by subtracting a cylinder(the hollow part) form a cylinder (the whole pipe fully filled)

the inner diameter of the pipe is d(inner) = (25-12)mm

= 13 mm

the volume of the hollow cylinder = 2*[pi(d(inner))^2]/4

= 0.000265464 m^3

the volume of the fully filled cylinder = 2*[pi(d(outer))^2]/4

= 0.000981747 m^3

therefore the volume of the pipe = 0.000981747 - 0.000265464

= 0.000716283 m^3