P22 Buttweld Pipe Fittings
2¼Cr-1Mo / EN 1.7380 (10CrMo9-10) — the workhorse alloy steel for refinery hydroprocessing, steam reformers, and high-temperature hydrogen service. Higher creep strength than P11 and a better position on the Nelson curve. ASME B16.9 and EN 10253-3 Type B. EN 10204 3.1 standard; 3.2 TPI on request.
½″–48″
Size Range
550°C
Max Service Temp
440 MPa
Min Tensile (EN)
EN 10204
3.1 Std / 3.2 On Req.
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P22 Grade Equivalents
| ASTM | EN W.Nr. | EN Name | DIN | UNS | ASME P-No. |
|---|---|---|---|---|---|
| A234 WP22 | 1.7380 | 10CrMo9-10 | 10CrMo9-10 | K21590 | 5A, Gr 1 |
| A182 F22 (forged) | 1.7380 | 10CrMo9-10 | — | — | 5A |
| A335 P22 (pipe) | 1.7380 | 10CrMo9-10 | — | — | 5A |
| A387 Gr 22 (plate) | 1.7380 | 10CrMo9-10 | — | — | 5A |
Chemical Composition — P22 / 1.7380
| Standard | C | Cr | Mo | Mn | Si | P max | S max |
|---|---|---|---|---|---|---|---|
| ASTM A234 WP22 | 0.05–0.15 | 1.90–2.60 | 0.87–1.13 | 0.30–0.60 | ≤0.50 | 0.025 | 0.025 |
| EN 1.7380 (EN 10253-3) | 0.08–0.15 | 2.00–2.50 | 0.90–1.10 | 0.40–0.70 | ≤0.50 | 0.025 | 0.010 |
Mechanical Properties — P22 / 1.7380
| Standard | Min. UTS (MPa) | Min. YS (MPa) | Elongation (%) | Max. Hardness | HT Condition |
|---|---|---|---|---|---|
| ASTM A234 WP22 | 415 | 205 | ≥22% | 241 HBW | A or N+T |
| EN 1.7380 (EN 10253-3) | 440–640 | ≥280 | ≥20% | 241 HBW | N+T |
N+T = Normalise and Temper. A = Annealed. EN 10253-3 requires normalising at 900–960°C, tempering ≥670°C.
Available P22 Fitting Types
90° LR Elbows
Long radius (1.5D). ASME B16.9 and EN 10253-3 Type B. ½″–48″.
45° LR Elbows
Long radius. ASME B16.9 / EN 10253-3 Type B.
Equal Tees
ASME B16.9 and EN 10253-3 Type B. All schedules.
Reducing Tees
All standard reducing combinations.
Concentric Reducers
ASME B16.9 / EN 10253-3.
Eccentric Reducers
ASME B16.9 / EN 10253-3.
End Caps
ASME B16.9 / EN 10253-3.
180° Returns
Long and short radius. ASME B16.9.
Stub Ends
Lap joint stub ends. MSS SP-43.
Critical Welding & PWHT Requirements
⚠ PWHT is Mandatory for All P22 Welds
P22 welds without PWHT exhibit high residual stresses and are susceptible to reheat cracking (stress relief cracking) at the coarsened-grain HAZ. PWHT is not optional — it is required by ASME B31.3, EN 13480, and all major piping codes regardless of wall thickness.
Preheat Temperature
150–200°C minimum before welding. Maintain throughout the weld.
Inter-pass Temperature
Maximum 300°C. Keep joint warm — do not allow cooling below preheat.
Filler Metal
ER90S-B3 (GTAW/TIG) or E9015-B3 (SMAW). Do not use P11 filler (ER80S-B2) — it will dilute the Cr/Mo content below specification.
PWHT Temperature
700–750°C. Minimum hold time: 1 hour per 25mm wall, 2 hours minimum for heavy wall.
Cooling
Slow cool in furnace to 300°C, then air cool. Temperature chart records required for all PWHT cycles.
Post-PWHT Hardness
Weld and HAZ hardness must be ≤241 HBW after PWHT. Hardness survey report required.
Nelson Curve — Hydrogen Service
P22 (2¼Cr-1Mo) sits above P11 (1¼Cr-½Mo) on the API 941 Nelson curve, allowing higher hydrogen partial pressures at a given temperature before high-temperature hydrogen attack (HTHA) onset. For hydroprocessing service above ~300°C with significant H₂ partial pressure, P22 is typically specified over P11. For service above ~450°C or very high H₂ partial pressures, step up to P91.
CrMo Grade Comparison
| Grade | Cr% | Mo% | Max Temp | PWHT °C | Primary Use |
|---|---|---|---|---|---|
| P11 / 1.7335 | 1.25 | 0.5 | 500°C | 690–730 | Steam headers, moderate refinery |
| P22 / 1.7380 | 2.25 | 1.0 | 550°C | 700–750 | Hydroprocessing, reformers, H₂ service |
| P5 / 1.7362 | 5.0 | 0.5 | 600°C | 720–760 | Refinery sulfidic service |
| P91 / 1.4903 | 9.0 | 1.0 | 650°C | 745–775 | Supercritical power, high-creep service |
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