Alloy Steel Flanges
Alloy steel flanges are engineered for the most demanding environments. By incorporating elements like Chromium and Molybdenum (Chrome-Moly), these flanges offer superior resistance to scaling, high-temperature creep, and hydrogen attack.
Grades and Characteristics
- Standard Grades: ASTM A182 F5, F9, F11 (Class 1/2/3), F22, and F91.
- Performance: Excellent mechanical properties at temperatures exceeding 500°C.
- Common Uses: Power plant piping, heat exchangers, and refinery catalytic crackers.
- Surface Finish: Shot blasted and treated with specialized heat-resistant anti-corrosion oil.
Dimensional chart — ASME B16.5 (Alloy Steel)
While dimensions follow B16.5, alloy flanges are most frequently specified in higher pressure classes (600 and above).
| NPS | Class | Outside Diameter | Thk (t) | Hub Dia (X) | Bolt Circle | No. of Holes |
|---|---|---|---|---|---|---|
| 2" | 600 | 165 mm | 25.4 mm | 84 mm | 127.0 mm | 8 |
| 4" | 600 | 275 mm | 38.1 mm | 152 mm | 215.9 mm | 8 |
| 6" | 900 | 380 mm | 55.6 mm | 235 mm | 292.1 mm | 12 |
| 8" | 1500 | 470 mm | 92.1 mm | 311 mm | 368.3 mm | 12 |
Heat Treatment: All alloy steel flanges are supplied in the Normalized and Tempered (N+T) condition to ensure optimum grain structure and strength.