Approximate weight of a butt welding cap can be calculated based on its its wall thickness, outside diameter and end to end length. Please note that actual weight of a cap from a particular manufacturer may vary depending on manufacturing process. Dimensional standards like ASME B16.9 do not provide weights of butt welding fittings. 

Weight of a Butt Weld Cap as per ASME B16.9 is calculated as per following formula  :

Where :

1. W = Weight of Cap in Kg.
2. OD = Outside diameter of cap (mm)
3. E = End to end length of cap (mm)
4. T = Wall Thickness (mm)

Cap Size	1/2 3/4 1 1-1/4 1-1/2 2 2-1/2 3 3-1/2 4 5 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Wall Thickness	mm Inch