| Analysis Region | Microstructure |
| Elbow | Pearlite + Ferrite(a) |
| HAR | Proeutectoid pearlite + fine pearlite |
| Welding joint | Proeutectoid pearlite + dendrites |
| HAR | Proeutectoid pearlite + fine pearlite |
| Tube | Pearlite + Ferrite(b) |
| Tube in corroded region | Pearlite + Ferrite |
| Elbow in corroded region | Pearlite + Ferrite |