STPA24
JPApproximate matchJIS · JIS G3458:2019
Family of chrome-molybdenum alloy steel pipes (roughly 1 to 2.25% Cr, 0.45 to 1.1% Mo) intended for high-temperature circuits (superheated steam, refinery reactors and lines, hydrocracking units), typically between 450°C and 600°C depending on Cr-Mo content. US reference: ASTM A335 P11 (1.25Cr-0.5Mo) and P22 (2.25Cr-1Mo), with equivalents in Europe (EN 10216-2), Japan (JIS G3458) and South Korea (KS D3573).
| Grade | Region | Standard | Re (MPa) | Rm (MPa) | Delta |
|---|---|---|---|---|---|
| STPA24 | JP | JIS G3458:2019 | 205 | ≥410 | reference |
| STPA23 | JP | JIS G3458:2019 | 205 | ≥410 | 0% |
| SPA23 | KR | KS D3573 | 205 | ≥410 | 0% |
| SPA24 | KR | KS D3573 | 205 | ≥410 | 0% |
| A335 Grade P11 (1.25Cr-0.5Mo) | US | ASTM A335/A335M (ASME SA-335) | 205 | ≥415 | 0% |
| A335 Grade P22 (2.25Cr-1Mo) | US | ASTM A335/A335M (ASME SA-335) | 205 | ≥415 | 0% |
| Neighboring grades — different strength | |||||
| 10CrMo9-10 (1.7380) | EU | EN 10216-2:2013 | 280 | 450–600 | +37% |
| 13CrMo4-5 (1.7335) | EU | EN 10216-2:2013 | 290 | 440–590 | +41% |
| Grade | C | Mn | Si | P | S | Cr | Mo |
|---|---|---|---|---|---|---|---|
| STPA24 | ≤0.15 | 0.3–0.6 | ≤0.5 | ≤0.03 | ≤0.03 | 1.9–2.6 | 0.87–1.13 |
| STPA23 | ≤0.15 | 0.3–0.6 | ≤0.5 | ≤0.03 | ≤0.03 | 1–1.5 | 0.45–0.65 |
| SPA23 | ≤0.15 | 0.3–0.6 | ≤0.5 | ≤0.03 | ≤0.03 | 1–1.5 | 0.45–0.65 |
| SPA24 | ≤0.15 | 0.3–0.6 | ≤0.5 | ≤0.03 | ≤0.03 | 1.9–2.6 | 0.87–1.13 |
| A335 Grade P11 (1.25Cr-0.5Mo) | 0.05–0.15 | 0.3–0.6 | 0.5–1 | ≤0.025 | ≤0.025 | 1–1.5 | 0.44–0.65 |
| A335 Grade P22 (2.25Cr-1Mo) | 0.05–0.15 | 0.3–0.6 | ≤0.5 | ≤0.025 | ≤0.025 | 1.9–2.6 | 0.87–1.13 |
| 10CrMo9-10 (1.7380) | 0.08–0.14 | 0.4–0.8 | ≤0.5 | ≤0.02 | ≤0.01 | 2–2.5 | 0.9–1.1 |
| 13CrMo4-5 (1.7335) | 0.08–0.18 | 0.4–1 | ≤0.35 | ≤0.025 | ≤0.01 | 0.7–1.15 | 0.4–0.6 |
Note: Equivalent to P22 (ASTM) and 10CrMo9-10 (EN) by Cr-Mo composition (2.25% Cr / 1% Mo nominal). Belongs to JIS G3458 (alloy steel tubes and pipes), not to be confused with the STBA series of JIS G3462 (boiler/exchanger tubes), which covers a neighboring but distinct grade range.
Values compiled from public sources for guidance only — always verify against the official standard before use in design or fabrication.