This specification2 covers 8 and 9 % nickel-alloy steel forged or rolled flanges, fittings, valves, and parts intended for use in welded pressure vessels for low-temperature service. The specification is applicable to forgings with maximum section thickness of 3 in. [75 mm] in the double normalized and tempered condition and 5 in. [125 mm] in the quenched and tempered condition. Forgings under this specification are intended for service at operating temperatures not lower than −320 °F [−196 °C] for Type I or −275 °F [−170 °C] for Type II or higher than 250 °F [121 °C].
| Composition, % | ||
|---|---|---|
| Type I | Type II | |
| Carbon, max | 0.13 | 0.13 |
| Manganese, max | 0.90 | 0.90 |
| Phosphorus, max | 0.025 | 0.025 |
| Sulfur, max | 0.025 | 0.025 |
| SiliconA | 0.15–0.30 | 0.15–0.30 |
| Nickel | 8.5–9.5 | 7.5–8.5 |
A. When vacuum carbon deoxidation is used, the maximum silicon content shall be 0.10 %.
| Tensile strength, min, ksi [MPa] | Yield strength, min, (0.2 % off-set), ksi [MPa] | Elongation in 2 in. [50mm], min, % | Reduction of area, min, % |
|---|---|---|---|
| 100 [690] | 75 [515] | 22 | 45 |