Products Description
Product Specifications
| Standards | ASTM B704 / ASME SB-704 |
| Steel Grades | UNS N06625, UNS N06219, UNS N08825 |
| Equivalent Standards | ASTM B423 / B163 / B705;DIN 17751 / ISO 15156 |
| Outer Diameter (OD) | 3.18 mm – 127 mm(1/8″ – 5″) |
| Wall Thickness (WT) | 0.38 mm – 12.70 mm(0.015″ – 0.500″) |
| Length | 6 / 12 m |
| Surface Treatment | Pickled & annealed, bright annealed |
| Production Process | TIG / GTAW |
| Condition |
Annealed / solution annealed |
In UNS N08825 nickel alloy tubes, the 0.6–1.2% titanium (Ti) content serves to preferentially bind carbon into titanium carbides. This ensures resistance to intergranular corrosion in the as-welded condition, maintaining excellent corrosion resistance at the weld joints without the need for post-weld stabilizing annealing.
In the solution-annealed condition, N08825 tubes comply with the NACE MR0175 / ISO 15156-3 standard for use in sour gas service environments-where temperatures do not exceed 232°C and the partial pressure of H₂S does not exceed 200 kPa-making them suitable for sulfur-containing, corrosive environments encountered in the oil, gas, and chemical industries.
Customized Services
- Custom Sizing: Non-standard dimensions are available upon request, with maximum outer diameters reaching 12" or larger.
- Heat Treatment Customization: In addition to the standard solution-annealed condition, bright annealing is available. For components requiring stress relief following cold working, stress-relief annealing can be performed to specification.
- End and Connection Customization: Options include beveled, plain, flared, or flanged ends (socket-weld, butt-weld, or threaded). We also offer pre-welding services for flanges, end caps, and elbows.
Chemical Composition
| Element | Ni | Cr | Fe | Mo | Cu | Ti | Mn | Si | C | Al | S |
|---|---|---|---|---|---|---|---|---|---|---|---|
| UNS N08825 (Alloy 825) | 38.0–46.0 | 19.5–23.5 | ≥22.0 | 2.5–3.5 | 1.5–3.0 | 0.6–1.2 | ≤1.0 | ≤0.50 | ≤0.05 | ≤0.20 | ≤0.03 |
Mechanical Properties
| Property | Tensile Strength, min. | Yield Strength (0.2% Offset), min. | Elongation, min. | Hardness |
|---|---|---|---|---|
| UNS N08825 (Alloy 825) | 586 MPa (85 ksi) | 240 MPa (35 ksi) | 30% | As specified |
Possible Alternative Grades
- Alloy 20 is a specialized high-nickel alloy designed for sulfuric acid service. It is similar to N08825 but stabilized with niobium; it offers slightly better corrosion resistance in hot sulfuric acid than N08825, though at a higher material cost.
- Inconel 625 provides superior resistance to pitting and crevice corrosion, as well as higher high-temperature strength, compared to N08825. It is suitable for applications such as flue-gas desulfurization, deep-sea marine environments, and high-temperature corrosive conditions, though it also comes at a higher cost.
- Incoloy 800 / 800H serve as alternatives to N08825 for low-temperature and high-temperature applications, respectively. They offer excellent high-temperature strength, as well as resistance to carburization and oxidation, at a lower price point.
application areas
- Sulfuric and phosphoric acid production systems: heat exchangers, evaporators, heating coils, reactors, towers, and piping.
- Flue-gas desulfurization (FGD) and pollution control: scrubbers, condensers, reheater tube bundles, and piping for acidic condensates.
- Sour gas (H₂S) service: surface pipelines in oil and gas fields, injection well piping, and sour gas coolers.
- Organic acid and caustic alkali media: processing of fatty acids and organic acids, as well as pipelines for the transport of sodium hydroxide (NaOH) or potassium hydroxide (KOH) solutions.
Products Show
Testing Equipment
Factory Equipment
Pickling equipment
Products Package
FAQ
Q: Can N08825 be welded? How should filler materials be selected?
A: It has good weldability; GTAW or GMAW processes are recommended. Suitable filler materials include AWS ERNiFeCr-1 (for matching the N08825 base metal) or ENiCrFe-1 (for manual arc welding). No preheating is required before welding. Post-weld solution annealing is recommended to restore corrosion resistance.
Q: What is the maximum service temperature for N08825?
A: The upper limit for long-term service is approximately 550°C; it retains good toughness at cryogenic temperatures down to -196°C. Long-term exposure above 550°C can lead to the precipitation of the sigma (σ) phase, which reduces both corrosion resistance and toughness. In such cases, Incoloy 800H or Inconel 625 is recommended instead.
Q: Can N08825 be used in seawater environments?
A: It can be used in applications such as seawater-cooled heat exchangers. However, it is important to note its limitations: with a Pitting Resistance Equivalent Number (PREN) of approximately 31–35-lower than that of 254SMO or Inconel 625-it is not suitable for environments prone to severe pitting or crevice corrosion, such as those involving high flow velocities, significant sediment deposition, or warm seawater.
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