P11 Buttweld Pipe Fittings
1¼Cr-½Mo / EN 1.7335 (13CrMo4-5) — the most widely used CrMo alloy steel for moderate-temperature refinery and power applications. Better creep strength than carbon steel, with good oxidation resistance to 500°C. ASME B16.9 and EN 10253-3 Type B. EN 10204 3.1 standard; 3.2 TPI on request.
½″–48″
Size Range
500°C
Max Service Temp
420 MPa
Min Tensile (EN)
EN 10204
3.1 Std / 3.2 On Req.
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P11 Grade Equivalents
| ASTM | EN W.Nr. | EN Name | DIN | UNS | ASME P-No. |
|---|---|---|---|---|---|
| A234 WP11 Cl.1/2/3 | 1.7335 | 13CrMo4-5 | 13CrMo4-5 | K11597 | 4, Gr 1 |
| A182 F11 (forged) | 1.7335 | 13CrMo4-5 | — | — | 4 |
| A335 P11 (pipe) | 1.7335 | 13CrMo4-5 | — | — | 4 |
| A387 Gr 11 (plate) | 1.7335 | 13CrMo4-5 | — | — | 4 |
Chemical Composition — P11 / 1.7335
| Standard | C | Cr | Mo | Mn | Si | P max | S max |
|---|---|---|---|---|---|---|---|
| ASTM A234 WP11 | 0.05–0.15 | 1.00–1.50 | 0.44–0.65 | 0.30–0.60 | 0.50–1.00 | 0.030 | 0.030 |
| EN 1.7335 (EN 10253-3) | 0.10–0.17 | 0.70–1.15 | 0.45–0.65 | 0.40–0.70 | ≤0.35 | 0.025 | 0.010 |
Note: The EN 1.7335 chemistry band is slightly different from ASTM WP11 — lower Si max, tighter S. Verify chemistry against the applicable standard when dual-certifying.
Mechanical Properties — P11 / 1.7335
| Standard | Min. UTS (MPa) | Min. YS (MPa) | Elongation (%) | Max. Hardness | HT Condition |
|---|---|---|---|---|---|
| ASTM A234 WP11 | 415 | 205 | ≥22% | 225 HBW | A or N+T |
| EN 1.7335 (EN 10253-3) | 420–600 | ≥220 | ≥22% | 225 HBW | N+T |
Available P11 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 & 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.
Welding & PWHT Requirements
⚠ PWHT Required — No Exemptions for Production Welds
ASME B31.3 and EN 13480 require PWHT for all P11 production welds above a minimum wall threshold (typically ≥13mm, but consult code edition). Even thin-wall P11 piping in critical service should have PWHT specified. Omitting PWHT leads to hard, brittle welds prone to hydrogen-assisted cracking.
Preheat Temperature
150–200°C minimum. Heat the entire joint area, not just the weld zone.
Inter-pass Temperature
Maximum 300°C. Maintain preheat throughout.
Filler Metal
ER80S-B2 (GTAW/TIG) or E8018-B2 (SMAW). Do not use carbon steel filler — it dilutes Cr/Mo below the minimum required for service.
PWHT Temperature
690–730°C (EN) / 675–760°C (ASME). Hold for minimum 1 hour per 25mm wall.
Cooling
Controlled cool in furnace to 300°C before air cooling. Chart-recorded temperature cycles required.
Post-PWHT Hardness
Weld and HAZ ≤225 HBW after PWHT.
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Specify size, schedule, fitting type, standard (ASME B16.9 or EN 10253-3 Type B), and required MTR. We respond within 1 business day.
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