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Incoloy 825 Seamless Pipe and Tube (SB-423, UNS N08825)
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Incoloy 825 is a nickel-iron-chromium alloy with molybdenum and copper additions, supplied as seamless pipe and tube for sulphuric acid service, pickling, and copper smelting environments. This page covers the seamless product form manufactured to ASME SB-423 for UNS N08825 and UNS N08221, and how to specify it correctly on a purchase order.
Specification Coverage
SB-423 covers nickel-iron-chromium-molybdenum-copper alloys UNS N08825 and UNS N08221 in the form of cold-worked and hot-finished seamless pipe and tube intended for general corrosive service. General requirements for pipe and tube dimensional tolerances are governed by ASME B829. Buyers who also need a welded alternative should note that SB-705 covers welded UNS N06625, N06219 and N08825 pipe in the annealed condition, and SB-704 covers welded tubes of the same grades. For material that must be forged rather than rolled, SB-564 and SB-462 are the applicable forging and forged-fitting specifications.
Grade Comparison
| Grade | UNS | Ni | Cr | Mo | Cu | Fe | Typical Use |
|---|---|---|---|---|---|---|---|
| Incoloy 825 | N08825 | 38.0-46.0 | 19.5-23.5 | 2.5-3.5 | 1.5-3.0 | 22.0 min | Sulphuric acid, pickling |
| Incoloy 825 (alt.) | N08221 | 39.0-46.0 | 20.0-22.0 | 2.5-3.5 | 1.5-3.0 | 22.0 min | Lower Cr, tighter control |
| Incoloy 800 | N08800 | 30.0-35.0 | 19.0-23.0 | – | – | 39.5 min | High-temperature strength |
| Inconel 625 | N06625 | 58.0 min | 20.0-23.0 | 8.0-10.0 | – | 5.0 max | Mo-rich, lower Ni |
The distinguishing feature of Incoloy 825 against Incoloy 800 is the copper addition, which improves resistance to reducing acids such as sulphuric acid, combined with molybdenum for oxidising-acid and chloride resistance. Against Inconel 625, Incoloy 825 carries substantially more iron, which is deliberate: it raises the yield strength in a lower-strength application class where the driving requirement is acid resistance rather than chloride pitting resistance.
Chemical Composition (ASME SB-423 Table 1)
| Element | UNS N08825 (%) | UNS N08221 (%) |
|---|---|---|
| Nickel | 38.0-46.0 | 39.0-46.0 |
| Chromium | 19.5-23.5 | 20.0-22.0 |
| Iron | 22.0 min | 22.0 min |
| Manganese | 1.0 max | 1.0 max |
| Carbon | 0.05 max | 0.025 max |
| Copper | 1.5-3.0 | 1.5-3.0 |
| Silicon | 0.5 max | 0.5 max |
| Sulfur | 0.03 max | 0.03 max |
| Aluminum | 0.2 max | 0.2 max |
Where a product (check) analysis is performed by the purchaser, the material shall conform to the product analysis variations of ASME B829.
Mechanical Properties (ASME SB-423 Table 2)
| Condition | Tensile Strength min, ksi (MPa) | Yield Strength (0.2% Offset) min, ksi (MPa) | Elongation in 2 in. or 50 mm (4D) min, % |
|---|---|---|---|
| Hot-finished annealed | 75 (517) | 25 (172) | 30 |
| Cold-worked annealed | 85 (586) | 35 (241) | 30 |
Size Range and Condition
SB-423 covers seamless pipe and tube produced in hot-finished annealed, cold-worked annealed, and hot-forming quality conditions. Wall thickness and outside diameter tolerances follow ASME B829. For fabricated spool pieces and matched pairs with fittings, supply the outside diameter, wall thickness, and length so that end preparation and bevel can be confirmed before production.
Applications
Incoloy 825 seamless pipe is specified in sulphuric acid and hydrochloric acid pickling lines, copper and nickel electrowinning and refining circuits, pulp and paper bleaching equipment, and general chemical process piping where both oxidising and reducing acid resistance are required. The same alloy appears in downhole and completion equipment for sour gas service when the specification calls for a copper-bearing nickel alloy.
Certification and Inspection
Material is supplied with a mill test certificate to ASME SB-423 showing heat number, chemical analysis, mechanical properties, heat treatment condition, and dimensions. Available supplementary inspection includes hydrostatic or nondestructive electric testing, eddy current examination, and intergranular corrosion testing. Third-party inspection by an approved inspection body can be arranged on request.
Ordering Information
Please include the following when requesting a quotation: product form (seamless pipe or seamless tube), UNS number (N08825 or N08221), outside diameter and wall thickness or schedule, length, delivery condition (hot-finished annealed or cold-worked annealed), quantity, destination port, and any required certification or third-party inspection. We will respond with current availability, production lead time, and FOB pricing for Hefei, China.
Related specifications and products. Incoloy 825 is also supplied as butt weld fittings and as plate, sheet and strip. See our nickel alloy round pipe supply Incoloy 825 butt weld fitting range Incoloy 825 plate and strip for the dimensional and material basis behind this page.
