IBR Approved · Alloy Steel (Grade 92)
ASTM A234 WP92 Buttweld Pipe Fittings
Grade 92 (9Cr-1.8W-Mo-V-Nb) tungsten-strengthened martensitic alloy steel — the highest-creep CrMo fitting grade, for ultra-supercritical power plant main steam and reheater piping to ~650°C. 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 WP92 — Grade 92 — is a tungsten-strengthened creep-strength-enhanced ferritic (CSEF) steel. It builds on Grade 91 by adding roughly 1.5–2.0% tungsten (with reduced molybdenum) plus boron, raising creep-rupture strength beyond WP91 and enabling thinner, lighter main steam and reheater piping in ultra-supercritical (USC) power plants operating up to about 650°C.
WP92 is supplied normalized and tempered with hardness controlled to about 250 HBW, IBR approved with Form III-C. Its EN counterpart is X10CrWMoVNb9-2 (material number 1.4901).
Critical: heat treatment & PWHT control
Like Grade 91, WP92 is unforgiving of procedure deviations. Fittings are supplied normalized & tempered. Weld PWHT is mandatory within a narrow 730–780°C window (below Ac1), with hardness controlled to ≤250 HBW. Only a matching Grade 92 (B91/B92-type) filler may be used, with tight preheat and interpass control. ASME P-No. 15E, Group 1. Heat-treatment and hardness records accompany every fitting.
Chemical Composition — A234 WP92
| Element | Requirement | Note |
|---|---|---|
| Carbon (C) | 0.07 – 0.13% | — |
| Chromium (Cr) | 8.50 – 9.50% | Oxidation & creep |
| Tungsten (W) | 1.50 – 2.00% | Key creep strengthener |
| Molybdenum (Mo) | 0.30 – 0.60% | — |
| V / Nb / N | V 0.15–0.25, Nb 0.04–0.09, N 0.030–0.070 | Microalloys |
| Boron (B) | 0.001 – 0.006% | Creep stability |
Mechanical Properties — A234 WP92
| Property | Requirement |
|---|---|
| Tensile Strength (min) | 620 MPa (90 ksi) |
| Yield Strength (min) | 440 MPa (64 ksi) |
| Elongation (min) | ≥ 20% |
| Hardness | ≤ 250 HBW |
| Heat Treatment | Normalized & Tempered (mandatory) |
Equivalent Grades
| Product Form | Specification |
|---|---|
| Buttweld fittings | ASTM / ASME A234 WP92 |
| Seamless pipe | ASTM A335 P92 |
| Forgings / flanges | ASTM A182 F92 |
| EN designation | X10CrWMoVNb9-2 (W.Nr. 1.4901) |
Fitting Types Available in WP92
- Elbows — 45° / 90° / 180°, LR & SR
- Tees — equal & reducing
- Reducers — concentric & eccentric
- Caps — buttweld end closures