Buying guide
How to specify Alloy 825 pipe fittings to ASTM B366 (WPNICMC)
Short answer
Alloy 825 buttweld fittings are ordered to ASTM B366, grade WPNICMC (UNS N08825), with dimensions to ASME B16.9 (or MSS SP-43 for light-wall). Forged socket-weld and threaded 825 fittings are made to ASTM B564 with dimensions to ASME B16.11.
What B366 covers
Fitting types
| Fitting | Dimensional standard | Page |
|---|---|---|
| Elbow 45° / 90° / 180° (LR & SR) | ASME B16.9 | 825 elbow |
| Equal & reducing tee | ASME B16.9 | 825 tee |
| Concentric & eccentric reducer | ASME B16.9 | 825 reducer |
| Cap | ASME B16.9 | 825 cap |
| Stub end (long & short) | ASME B16.9 · MSS SP-43 | 825 stub end |
| Socket-weld & threaded fittings | ASME B16.11 (material B564) | Socket weld fittings |
Seamless or welded?
Smaller sizes are normally seamless, formed from B423 pipe. Larger sizes and light walls are often welded from B424 plate. Welded fittings should have the seam radiographed where your specification requires it; say so on the order. The wall thickness of each fitting matches the schedule of the pipe it will be welded to.
Ordering checklist
- ASTM B366 WPNICMC (ASME SB-366)
- Type and angle, e.g. 90° LR elbow
- Size (NPS) and schedule, e.g. 3" Sch 40S
- Seamless or welded, with radiography if welded
- End preparation: bevelled to ASME B16.25
- Certificate EN 10204 3.1 / 3.2; NACE if sour service
Matching components
Fittings should match the rest of the line: 825 pipe to B423, 825 flanges to B564 and welding with ERNiCrMo-3 filler, which over-matches 825 in corrosion resistance.