The formula for calculating pipe weight is m=10.68 (do – tw) tw , where m is weight per foot (lbs/ft), do is outside diameter in inches, and tw is wall thickness in inches. The outside diameter and wall thickness of the pipe are required to calculate the weight per foot. The formula doesn’t take into account weight alterations after end finishing, e.g., upsetting or threading.
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 wp = ρm Am
= ρm (π (do / 2)2 - π (di / 2)2)
= ρm π (do2 - di2) / 4
The weight of liquid in a pipe per unit length is given by:
wl = ρl A
= ρl π (di / 2)2
= ρl π di2 / 4.
The weight of a pipe and the liquid in it per unit length is given by wp + wl.