Boiler Tube Creep Rupture Life Calculator (Larson-Miller)
Estimate remaining creep life ($t_r$, operating hours) and Larson-Miller Parameter ($LMP$) for superheater and reheater alloy boiler tubes under thermal stress.
Tube Geometry & Steam Conditions
Creep Rupture Life & Overheating Margin
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High-Temperature Creep Rupture & Larson-Miller Theory
In utility boilers operating above $500^\circ\text{C}$ ($930^\circ\text{F}$), alloy steel superheater and reheater tubes undergo irreversible time-dependent plastic deformation known as creep. Under continuous internal steam hoop stress, atomic diffusion causes microscopic grain boundary micro-voids to form, coalesce into fissures, and culminate in violent "fish-mouth" rupture.
The 10°C Overheating Rule
The Larson-Miller parameter integrates temperature and time into an Arrhenius equivalence: $$\text{LMP} = T \cdot \left(20 + \log_{10} t_r\right) \times 10^{-3}$$ Because creep life scales inversely with temperature inside an exponential term, operating just $10^\circ\text{C}$ to $15^\circ\text{C}$ above design metal temperature cuts remaining tube life by more than $50\%$.