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# Pipe Equations

## Calculate cross-sectional areas, weight of empty pipes, weight of pipes filled with water, inside and outside surface areas

### Cross Sectional inside Pipe Area

Cross-sectional inside area of a pipe can be calculated as

Ai = π (di / 2)2

= π di 2 / 4                                 (1)

where

Ai = cross-sectional inside area of pipe (m2, in2)

di = inside diameter (m, in)

### Cross Sectional Pipe Wall Area

The cross-sectional wall area - or area of piping material - can be calculated as

Amπ (do / 2)2 - π (di / 2)2

= π (do 2 - di 2) / 4                               (2)

where

Am = cross-sectional wall area of pipe (m2, in2)

do = outside diameter (m, in)

### Weight of Empty Pipes

Weight of empty pipes per unit length can be calculated as

wpρm Am

= ρm (π (do / 2)2 - π (di / 2)2

= ρm  π (do2 - di2) / 4                              (3)

where

wp = weight of empty pipe per unit length (kg/m, lb/in)

ρs = density of pipe material (kg/m3, lb/in3)

### Weight of Liquid in Pipes

Weight of liquid in pipes per unit length can be calculated as

wl = ρl A

= ρl π (di / 2)2

= ρl π di2 / 4                                   (4)

where

wl = weight of liquid in pipe per unit length of pipe (kg, lb)

ρl = density of liquid (kg/m3, lb/in3)

### Weight of Pipe filled with Liquid

Weight of pipe filled with liquid per unit length can be calculated as

w = wl + wp                          (5)

where

w = weight of pipe and liquid per unit length of pipe (kg, lb)

### Outside Surface Area of Pipes

Outside surface area of steel pipes per unit length can be calculated as

Ao = 2 π (do / 2)

=  π do                            (6)

where

Ao = outside area of pipe - per unit length of pipe (m2, in2)

### Inside Surface Area of Pipes

Inside surface area of steel pipes per unit length can be calculated as

Ai2 π (di / 2)

=  π di                             (7)

where

Ai = inside area of pipe - per unit length of pipe (m2, in2)

## Related Topics

• Dimensions - Sizes and dimensions of pipes and tubes, and their fittings - inside and outside diameter, weight and more

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Temperature

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Length

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Area

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Volume

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Weight

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Velocity

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Pressure

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Flow

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