The calculations are similar to the round bar. The only difference is that this is a hollow round pipe and the round bar is not hollow.

This pipe is better than the round bar because it provides more strength and has less weigh as compared to the round bar.

To calculate the mass, we must know the outer diameter and the inner diameter or thickness of the hollow round pipe.

Volume of the round = Sectional area x length

V= π ( R^{2} – r^{2} ) x L

Let us consider a 1m long round pipe of outer diameter, D = 60 mm and inner diameter, d = 50 mm. so the outer radius becomes, R = D/2 = 60/2 = 30 mm= 0.030 m and inner radius, r = d/2 = 50/2 = 25 mm = 0.025 m

Hence the volume, V = π (0.030^{2}– 0.025^{2} ) x 1 =0.0008639 m^{3}

Therefore, mass of round pipe = density x volume = 7900 x 0.0008639 = 6.8248 kg

In this way, you can calculate the mass of any round pipe which is hollow.