Pipes and Tubes - Temperature Expansion
Pipes expands when heated and contracts when cooled. The expansion of the pipes can be expressed with the expansion formula
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The temperature expansion of pipes depends on the start and final temperature of the pipe and the expansion coefficient of the piping material at the actual temperature. The general expansion formula can be expressed as:
dl = α Lo dt (1)
where
dl = expansion (m, inch)
Lo = length of pipe (m, inch)
dt = temperature difference (oC, oF)
α = linear expansion coefficient (m/moK, inch/inchoF)
Mean expansion coefficient may vary with temperature as:
| Mean Expansion Coefficient - α - (10-6 inch/inch oF) | ||||||||
| Material | Temperature Range (oF) | |||||||
| - 32 | 32 - 212 | 32 - 400 | 32 - 600 | 32 - 750 | 32 - 900 | 32 - 1100 | 32 - 1300 | |
| Alloy Steel (1% Cr. 1/2% Mo) |
7.7 | 8.0 | 8.4 | 8.8 | 9.2 | 9.6 | 9.8 | |
| Mild Steel (0.1 - 0.2% C) |
7.1 | 7.8 | 8.3 | 8.7 | 9.0 | 9.5 | 9.7 | |
| Stainless Steel (18% Cr. 8% Ni) |
10.8 | 11.1 | 11.5 | 11.8 | 12.1 | 12.4 | 12.6 | 12.8 |
Formula (1) can also be used with SI units. The expansion coefficient must be adjusted to oC.
- T(oC) = 5/9[T(oF) - 32]
- 1 in (inch) = 25.4 mm
- 1 ft (foot) = 0.3048 m
- Expansion coefficients for some common materials
Example - Thermal Expansion of Heated Alloy Steel
100 feet of alloy steel pipe is heated from 32 to 212oF. The expansion coefficient is 8 10-6 (inch/inchoF).
The expansion can be expressed as:
dl = (8 10-6 in/inoF)(100 feet) (12 in/ft) ((212 oF) - (32 oF))
= 1.728 inch
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