ASTM A234 WP91 Buttweld Fittings are made to ASTM A234 / ASME SA234 WP91 Type 1 for supercritical steam service. Elbows, tees, reducers and caps are dimensioned to ASME B16.9 and bevelled for welding into ASTM A182 F91 pipe.
Raaj Fittings manufactures ASTM A182 F91 buttweld fittings in-house at our two plants in India, seamless and welded, from ½" upwards, and exports them to EPC contractors, fabricators and stockists across the Middle East, Europe and the Americas, with full traceability and EN 10204 certificates.
| Material specification | ASTM A234 / ASME SA234 WP91 Type 1 |
|---|---|
| Construction | Seamless and welded |
| Dimensional standards | ASME B16.9; bevelled ends to ASME B16.25 |
| Size range | ½" to 48" NPS; larger sizes to order |
| Wall thickness | SCH 10 to SCH 160, STD, XS, XXS, or to the pipe wall thickness |
| Certification | EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 on request |
ASTM A182 F91 is a modified 9% chromium, 1% molybdenum steel micro-alloyed with vanadium, niobium and nitrogen. Its tempered martensitic structure gives far higher creep strength than conventional chrome-moly steels, allowing thinner walls in supercritical and ultra-supercritical power plant steam piping.
| Element, % | ASTM A182 F91 |
|---|---|
| Carbon (C) | 0.08 – 0.12 |
| Manganese (Mn) | 0.30 – 0.60 |
| Phosphorus (P) | 0.020 max |
| Sulphur (S) | 0.010 max |
| Silicon (Si) | 0.20 – 0.50 |
| Chromium (Cr) | 8.0 – 9.5 |
| Nickel (Ni) | 0.40 max |
| Molybdenum (Mo) | 0.85 – 1.05 |
| Vanadium (V) | 0.18 – 0.25 |
| Niobium (Nb) | 0.06 – 0.10 |
| Nitrogen (N) | 0.03 – 0.07 |
| Property | ASTM A182 F91 |
|---|---|
| Yield strength, min. | 415 MPa (60 ksi) |
| Hardness, max. | 248 HBW |
| UNS | Werkstoff Nr. | EN / DIN | Other |
|---|---|---|---|
| K90901 | 1.4903 | X10CrMoVNb9-1 | P91 / T91 (pipe / tube) |
Chrome-moly fittings are heat treated after forming to restore properties, and hardness is checked. Field welds need preheat and post-weld heat treatment to the piping code, and hardness testing after PWHT is common practice.
Every heat is PMI-verified and its chemistry and mechanical properties are confirmed against the material specification before the buttweld fittings are released. Each piece is marked with grade, size, rating and heat number for traceability to its EN 10204 3.1 mill test certificate. EN 10204 3.2 certification and inspection by the buyer's nominated third-party agency are available on request, as are PED 2014/68/EU compliance for European projects and IBR certification for Indian boiler applications.
Heat treatment records and hardness results are reported for each heat.
Its creep strength at 550–600 °C is far higher than F22, so steam piping can be thinner and lighter, which reduces cost and thermal fatigue in modern high-efficiency plants.
Yes. Smaller sizes are normally seamless and larger sizes welded, with weld examination as the specification and your order require. Tell us the size, schedule and any construction requirement.
Every order is supplied with EN 10204 3.1 mill test certificates showing heat chemistry and mechanical properties to ASTM A234 WP91 Type 1. EN 10204 3.2 certification and inspection by your nominated third-party agency are available on request.