The weight-per-foot of a 4-inch steel pipe with an outside diameter of 4.5 inches and wall thickness of 0.237 is calculated as follows: m = 10.68 ((4.500 in) - (0.237 in)) (0.237 in), m=10.79 lbs/ft. The weight, wp, of an empty pipe per unit length (kg, lb) is given by w_{p} = ρ_{m} _{A}m

= ρ_{m} (π (d_{o} / 2)_{2} - π (d_{i} / 2)^{2})

= ρ_{m} π (d_{o}^{2} - d_{i}^{2}) / 4

The weight of liquid in a pipe per unit length is given by:

w_{l} = ρ_{l} A

= ρ_{l} π (d_{i} / 2)^{2}

= ρ_{l} π d_{i}^{2} / 4.

The weight of a pipe and the liquid in it per unit length is given by w_{p} + w_{l}.

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