Valve Material Reference
ASTM B425 / UNS N08825 (Incoloy 825) Valve
Incoloy 825Incoloy 825 (UNS N08825) is a nickel-iron-chromium alloy with additions of molybdenum, copper, and titanium that provides excellent resistance to both oxidising and reducing acids, pitting, crevice, and intergranular corrosion.
Form
Both
Max Temp
+450°C (+840°F)
Min Temp
−196°C (−321°F)
Category
Nickel Alloy
Chemical Composition — ASTM B425 / UNS N08825 (Incoloy 825)
Temperature Range
−196°C to +450°C (−321°F to +840°F)
Maximum Temperature
+450°C (+840°F)
Minimum Temperature
−196°C (−321°F)
Equivalent Grades — ASTM B425 / UNS N08825 (Incoloy 825)
| Standard | Equivalent Grade |
|---|---|
| UNS | N08825 |
| ASTM | B425 (bar), B424 (plate), B564 (forged fittings) |
| EN | NiCr21Mo / 2.4858 |
Suitable Services
Sulphuric acid (weak to moderate concentrations)
Phosphoric acid and phosphate fertiliser plants
Polluted seawater and produced water containing H₂S
Nuclear fuel reprocessing (nitric acid + radiation)
Caustic soda (NaOH) at elevated temperature
Oil and gas downhole (NACE MR0175 qualified grades)
Not Suitable For
Concentrated sulphuric acid — use Alloy 20 or Alloy C-276
Concentrated hydrofluoric acid — use Monel 400
Temperatures above 450°C
Valve Body Applications
Chemical plant valve bodies for mixed acid and salt solution service
Phosphoric acid and wet-process phosphoric acid plant valves
Sulphuric acid service (moderate concentrations)
Oil and gas sour service (H₂S + CO₂ environments)
Trim Applications
Ball valve balls and seats for acid service
Globe valve stems and discs for chemical plant
Typical Valve Types in ASTM B425 / UNS N08825 (Incoloy 825)
Ball valves: chemical plant, Class 150–600
Globe valves: acid service, control valves
Gate valves: phosphoric acid plant isolation
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