Field case · Condition monitoring
Thermography on a boiler feed pump discharge: rust and paint at the same temperature look different
Quick answer
On a pump discharge the infrared image showed rusted areas much hotter than painted ones, though the fluid was at one temperature. The reason is emissivity: oxidised and painted surfaces emit differently. A camera reads radiation, not temperature.
What the case covers
- The situation
- Why it happens
- Emissivity of a few common surfaces
- The misuse the author describes
- What to take from it
Takeaway. A thermal image shows surfaces, not just temperatures. Compare like finish with like finish, and write down the emissivity used.
Read the full case, with the data and the numbers