Linear Thermal Expansion Calculator
Calculate how much a pipe, bar or vessel grows or shrinks with temperature, for expansion loops, thermowell and sensor mounting checks.
- ΔL = α × L × ΔT = 12 × 10⁻⁶ × 50 × 160 = 96 mm
Linear Expansion Formula
α is the mean coefficient of linear expansion over the temperature range. Values shown are typical for about 20 to 100 °C; they rise slightly at higher temperatures.
Worked example
A 50 m carbon steel steam line heated from 20 to 180 °C grows 12 × 10⁻⁶ × 50 × 160 = 96 mm.
Frequently Asked Questions
How much does steel expand per degree?
About 0.012 mm per metre per °C, so 1.2 mm per 100 m per °C.
Why do plastic pipes need more expansion allowance?
PVC expands about four times and HDPE more than ten times as much as steel for the same temperature change.
Does thermal expansion affect instruments?
Yes: it moves tank nozzles, changes the length of displacers and capillaries, and loads small bore impulse lines.
Learn more on the blog
Thermocouple and RTD installation precautions
A practical, field focused guide on instrumentationblog.in that explains the theory behind this calculator and how engineers apply it on real plants.
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