Inconel 690 Seamless Pipes/Welded Pipes (UNS N06690, 2.4642, Alloy 690)
General Description
Inconel 690 has the highest chromium content (29% Cr) among nickel alloys suitable for fabrication of pressure equipment, which confers exceptional resistance to oxidizing media. It is used for hot sulfuric acid, nitric acid, and nitric/ hydrofluoric acid mixtures, as well as for oxidizing salts. The high chromium content also improves resistance in hot sulfidizing environments.
Inconel 690 has good resistance to oxidizing chemicals, such as nitric acid, and to sulfur-containing gases at high temperature. Inconel 690 has a superior stress cracking resistance than Inconel 600 in steam generation nuclear reactors for piping, separators and weldments.
Applications involving nitric acid or nitric-plus-hydrochloric acid. Examples are tail-gas reheaters used in production of nitric acid and steam-heating coils in nitric- plus-hydrochloric acid solutions used for pickling stainless steels and reprocessing nuclear fuels. Inconel 690 is also useful for hightemperature service in gases containing sulfur.
Chemical Composition
| Grade | Ni% | Cr% | Fe% | Ti% | Mn% | Si% | C% | Cu% | P% | S% | Cu% | RE% |
| Inconel 690 | Min 58 | 27-31 | 7-11 | Max 0.5 | Max 0.5 | Max 0.5 | Max 0.05 | Max 0.5 | Max 0.030 | Max 0.015 | Max 0.5 | Max 0.1 |
| Grade | UNS | Werkstoff Nr. |
| Inconel 690 | N06690 | 2.4642 |
| Grade | Density | Melting Point |
| Inconel 690 | 8.2 g/cm3 | 1340°C-1377 °C |
| Alloy | Tensile Strength | Yield Strength | Elongation | Brinell Hardness (HB) |
| Inconel 690 Annealed | >580 MPa | >260 MPa | 30% | 150-240 |
