Preheat Temperature Calculator
Determine preheat and interpass temperatures based on carbon equivalent (CE) and material thickness using the IIW formula.
Inputs
%
%
%
%
%
in
Results
Carbon Equivalent (CE)
0.33
Preheat Temperature
0 °F
Preheat Temperature-18 °C
Max Interpass Temperature200 °F
Weldability Rating1 (1=Good, 2=Fair, 3=Difficult)
How to Use This Calculator
- Enter the steel chemistry percentages: carbon (C), manganese (Mn), chromium (Cr), molybdenum (Mo), and nickel (Ni).
- Enter the material thickness at the joint in inches.
- Read Carbon Equivalent (CE) — values above 0.42 indicate higher preheat requirements.
- The required preheat temperature is calculated from CE and thickness; apply this temperature to the joint before welding.
- Maintain the preheat temperature as the interpass temperature throughout the weld to prevent cracking.
- If CE is very high (>0.70) or thickness is large, consider using the PWHT Calculator for post-weld heat treatment requirements.
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