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

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, inches)

Lo = length of pipe (m, inches)

dt = temperature difference (oC, oF)

α = linear expansion coefficient (m/moK, in/inoF)

Mean expansion coefficient may vary with temperature as:

Mean Expansion Coefficient - α - (10-6 in/in 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 an Alloy Steel Pipe

An alloy steel pipe with length 100 feet is heated from 32 to 212oF. The expansion coefficient is 8 10-6 (in/inoF).

The expansion of the pipe can be calculated as:

dl = (8 10-6 in/inoF) (100 ft) (12 in/ft) ((212 oF) - (32 oF))

    = 1.728 inches

• Temperature Expansion of Pipes - Excel Template