Chrome-moly alloy steel fittings for high-temperature, high-pressure service. Power plants, refineries, boilers, petrochemical piping. Every ASTM A234 grade in stock.
Chrome-moly (Cr-Mo) alloy steels are the backbone of high-temperature piping in power generation, refinery, and boiler industries. All major ASTM A234 grades with full heat treatment documentation.
Modified 9Cr-1Mo-V — the modern standard for ultra-supercritical power generation piping. Exceptional creep strength at 600–649°C. Higher allowable stress means thinner walls and weight savings over P22.
Next-generation over P91. Tungsten and boron addition improves creep rupture strength ~20%. Specified for the most demanding advanced ultra-supercritical plants targeting 700°C+.
The original chrome-moly grade (2¼Cr-1Mo). Long service history in boilers, heat exchangers, and hydrogen service. Massive installed base across global refineries. Available in Class 1 and Class 3.
1¼Cr-½Mo — the workhorse intermediate chrome-moly grade. Excellent balance of strength, toughness, and weldability. Extensively used in boiler superheaters and main steam lines.
9Cr-1Mo with higher chromium than WP22, providing better oxidation and corrosion resistance. Specified in hydrogen reforming service, sulfur-containing atmospheres, and older installations.
5Cr-½Mo bridging WP22 and WP9. Higher oxidation and sulfidation resistance than WP22. Used in refinery furnace tubing, catalytic cracking, and coker units with elevated sulfur conditions.
| Parameter | WP91 (P91) | WP22 (P22) |
|---|---|---|
| Alloy System | 9Cr-1Mo-V-Nb (Modified) | 2¼Cr-1Mo |
| Max Service Temp | 649°C | 600°C |
| Allowable Stress at 600°C | ~87 MPa | ~55 MPa |
| Creep Strength | Significantly higher | Moderate |
| Wall Thickness Required | Thinner — weight saving | Thicker |
| PWHT Required | 760°C ±15°C, min 2 hrs | Lower temp, more flexible |
| Cost | Higher material cost | Lower material cost |
| Best For | New USC power plants | Replacement, older plants |
| Grade | ASTM / ASME | Cr % | Mo % | Other | Max Temp. | Min Tensile | Application |
|---|---|---|---|---|---|---|---|
| WP91 | A234 WP91 | 8.0–9.5 | 0.85–1.05 | V, Nb, N | 649°C | 585 MPa | USC power, turbine |
| WP92 | A234 WP92 | 8.5–9.5 | 0.30–0.60 | W, B | 620°C+ | 620 MPa | A-USC boilers |
| WP22 Cl.1 | A234 WP22 Cl.1 | 2.0–2.5 | 0.87–1.13 | — | 600°C | 415 MPa | Refinery, boiler |
| WP22 Cl.3 | A234 WP22 Cl.3 | 2.0–2.5 | 0.87–1.13 | — | 600°C | 515 MPa | High-pressure boiler |
| WP11 Cl.1 | A234 WP11 Cl.1 | 1.0–1.5 | 0.44–0.65 | — | 550°C | 415 MPa | Boilers, steam lines |
| WP9 | A234 WP9 | 8.0–10.0 | 0.90–1.10 | — | 600°C | 415 MPa | H₂ reformers |
| WP5 | A234 WP5 | 4.0–6.0 | 0.44–0.65 | — | 600°C | 415 MPa | Refinery furnaces |
Every alloy fitting comes with N&T records, hardness test results, and impact test certificates as required by ASTM A234.
For Indian power and boiler projects requiring IBR compliance, we supply with IBR Form III-C and stage-wise inspection records.
XRF-based Positive Material Identification on every alloy shipment. No mix-up risk between WP91 and WP22 — a critical safety step.
WP11 and WP22 available in Class 1 (standard) and Class 3 (Q&T, higher strength). Confirm your class requirement at inquiry.
All alloy fittings packed with VCI protection, bevel-end caps, and wooden crates for long international shipments.
We understand P91 weld repair requirements, PWHT documentation, and the documentation needs for EPC and O&M projects.
Each chrome-moly grade has a dedicated page with full specifications, PWHT requirements, and application guidance.
Send grade, type, size, schedule, quantity. IBR and 3rd party inspection available. We respond within 4 hours.