Pipe Formulas
Pipe and Tube Equations - moment of inertia, section modulus, traverse metal area, external pipe surface and traverse internal area - imperial units
Online Pipe Formula Calculator
outside diameter (in)
inside diameter (in) - (default values: STD 4 inches - Carbon, Alloy and Stainless Steel Pipes - ASME/ANSI B36.10/19
The calculator is based on the piping formulas and equations below.
Moment of Inertia
Moment of inertia can be expressed as
I = π (do4 - di4) / 64
≈ 0.0491 (do4 - di4) (1)where
I = moment of inertia (in4)
do = outside diameter (in)
di = inside diameter (in)
Section Modulus
Section modulus can be expressed as
S = 0.0982 (do4 - di4) / do (2)
where
S = section modulus (in3)
Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members.
Transverse Metal Area
Transverse metal area can be expressed as
Am = π (do2 - di2) / 4 (3)
where
Am = transverse metal area (in2)
External Pipe Surface
External pipe or tube surface per ft of length can be expressed as
Ao = π do / 12 (4)
where
Ao = external pipe surface area (ft2 per ft pipe)
Internal Pipe Surface
Internal pipe or tube surface per ft of length can be expressed as
Ai = π di / 12 (5)
where
Ai = internal pipe surface area (ft2 per ft pipe)
Transverse Internal Area
Transverse internal area can be expressed as
Aa = 0.7854 di2 (6)
where
Aa = transverse internal area (in2)
Circumference External
External circumference can be expressed as
Ce = π do (7)
where
Ce = external circumference (in)
Circumference Internal
Internal circumference can be expressed as
Ci = π di (8)
where
Ci = internal circumference (in)
Estimating Pipe Circumference and Section Area
| Nominal Pipe Size (in) | Circumference (in) Load Calculator! | Section Area (sq.in.) Load Calculator! |
|---|---|---|
| 1/4 | 0.785 | 0.049 |
| 3/8 | 1.178 | 0.110 |
| 1/2 | 1.571 | 0.196 |
| 3/4 | 2.356 | 0.442 |
| 1 | 3.142 | 0.785 |
| 1 1/4 | 3.927 | 1.227 |
| 1 1/2 | 4.712 | 1.767 |
| 2 | 6.283 | 3.142 |
| 2 1/2 | 7.854 | 4.909 |
| 3 | 9.425 | 7.069 |
| 3 1/2 | 11.00 | 9.621 |
| 4 | 12.57 | 12.57 |
| 5 | 15.71 | 19.64 |
| 6 | 18.85 | 28.27 |
| 8 | 25.13 | 50.27 |
| 10 | 31.42 | 78.54 |
| 12 | 37.70 | 113.1 |
| 15 | 47.12 | 176.7 |