IBR Approved · Alloy Steel (CrMo)
ASTM A234 WP22 Buttweld Pipe Fittings
2.25Cr-1Mo chromium-molybdenum alloy steel fittings — the hydroprocessing workhorse for refinery hydrogen service and high-temperature steam piping. Elbows, tees, reducers and caps to ASME B16.9 / B16.28, IBR approved with Form III-C, EN 10204 3.1 / 3.2 traceable.
Grade Overview
ASTM / ASME A234 WP22 is a 2.25Cr-1Mo chromium-molybdenum alloy steel — the most widely used CrMo fitting grade in refinery and petrochemical service. Its higher chromium and molybdenum content (versus WP11) give greater creep strength and, critically, superior resistance to high-temperature hydrogen attack (HTHA) per the API 941 Nelson curves.
WP22 is specified for hydroprocessing units, hydrogen reformers, catalytic reforming and high-temperature steam headers to around 580–650°C. For boiler service it is supplied IBR approved with Form III-C. Its EN counterpart is 10CrMo9-10 (material number 1.7380).
PWHT is mandatory
All WP22 welds require post-weld heat treatment, typically 700–750°C, to temper the hardened heat-affected zone and avoid hydrogen cracking. Post-PWHT hardness and the time-temperature record are reported on the EN 10204 3.1 certificate. Filler metal: ER90S-B3 (GTAW) / E9018-B3 (SMAW). ASME P-No. 5A.
Chemical Composition — A234 WP22
| Element | Requirement | Note |
|---|---|---|
| Carbon (C) | 0.05 – 0.15% | Weldability |
| Manganese (Mn) | 0.30 – 0.60% | — |
| Silicon (Si) | ≤ 0.50% | Low Si (vs WP11) |
| Chromium (Cr) | 1.90 – 2.60% | HTHA / creep resistance |
| Molybdenum (Mo) | 0.87 – 1.13% | Creep resistance |
| P / S | ≤ 0.030% each | Impurity limits |
Mechanical Properties — A234 WP22 (Class 1)
| Property | Requirement |
|---|---|
| Tensile Strength | 415 – 585 MPa (60 – 85 ksi) |
| Yield Strength (min) | 205 MPa (30 ksi) |
| Elongation (min) | ≥ 20% (per specification formula) |
| Heat Treatment | Annealed or normalised & tempered; PWHT after welding |
Equivalent Grades
| Product Form | Specification |
|---|---|
| Buttweld fittings | ASTM / ASME A234 WP22 |
| Seamless pipe | ASTM A335 P22 |
| Forgings / flanges | ASTM A182 F22 |
| EN designation | 10CrMo9-10 (W.Nr. 1.7380) |
Fitting Types Available in WP22
- Elbows — 45° / 90° / 180°, LR & SR
- Tees — equal & reducing
- Reducers — concentric & eccentric
- Caps — buttweld end closures