UNS N08925 Pipes and Tubes (also known as W.Nr. 1.4529) are 6% molybdenum super austenitic stainless steel products designed for severe chloride and acid environments. The alloy has a PREN of around 24-26% nickel, 20% chromium and a controlled nitrogen of 0.10-0.20% which gives the alloy a high PREN and therefore a good resistance to pitting and crevice corrosion. In non-oxidizing acid such as sulphuric acid and phosphoric acid, the performance is further improved by the addition of Copper. The maximum carbon level of 0.020% prevents carbide precipitation during welding and heat treatment. The seamless products are available from ASTM B677, and welded pipe/tube are made to ASTM B673 and B674. Amardeep Steel offers UNS N08925 Pipes and Tubes used in seawater, brine, chemical and acid service applications.
Specifications of UNS N08925 Pipes and Tubes
Parameter | Details |
|---|---|
Grade Designation | UNS N08925, W.Nr 1.4529, 6Mo Super Austenitic Stainless Steel |
Seamless Pipe & Tube Standard | ASTM B677 / ASME SB677 |
Welded Pipe Standard | ASTM B673 / ASME SB673 |
Welded Tube Standard | ASTM B674 / ASME SB674 |
Pipe Size Range | 1/2" to 12" NB (Seamless); Larger diameters available as Welded Pipe |
Pipe Wall Schedules | SCH 5S, SCH 10S, SCH 40S, SCH 80S |
Tube Size Range | 6.35 mm to 50.8 mm OD; Wall thickness: 0.5 mm to 3 mm |
Heat Treatment Condition | Solution annealed at 1100°C to 1150°C, followed by rapid water quenching |
Product Forms | Straight lengths, U-bend heat exchanger tubes, coiled tubing |
End Finish | Plain End (PE), Bevelled End (BE) |
Length Options | Single Random Length (SRL), Double Random Length (DRL), Cut-to-length |
Certification | EN 10204 3.1 MTC supplied as standard; 3.2 TPI available upon request |
Chemical Compositions of UNS N08925 Pipes and Tubes
Element | Specification Limit (%) |
|---|---|
Nickel (Ni) | 24.0 to 26.0 |
Chromium (Cr) | 19.0 to 21.0 |
Molybdenum (Mo) | 6.0 to 7.0 |
Copper (Cu) | 0.8 to 1.5 |
Nitrogen (N) | 0.10 to 0.20 |
Carbon (C) | 0.020 max |
Manganese (Mn) | 1.00 max |
Silicon (Si) | 0.50 max |
Phosphorus (P) | 0.045 max |
Sulphur (S) | 0.030 max |
Iron (Fe) | Balance |
UNS N08925 Pipes and Tubes Mechanical Properties
Property (ASTM B677 Solution Annealed) | Minimum Required Value |
|---|---|
Tensile Strength, min | 600 MPa (87 ksi) |
Yield Strength (0.2% offset), min | 300 MPa (43 ksi) |
Elongation in 50 mm (2 in.), min | 40% |
Solution Annealing Temperature | 1100°C to 1150°C (water quench or rapid cool) |
Physical Properties of UNS N08925 Pipes and Tubes
Property (at 20°C) | Typical Value |
|---|---|
Density | 8.1 g/cm³ |
Melting Range | 1320°C to 1390°C |
Specific Heat Capacity | 450 J/kg·K |
Thermal Conductivity | 12 W/m·K |
Mean Thermal Expansion (20°C to 100°C) | 15.8 µm/m·°C |
Modulus of Elasticity | 193 GPa |
Electrical Resistivity | 0.88 µΩ·m |
Magnetic Permeability | Non-magnetic (retains non-magnetic status after cold working) |
Equivalent Grades of UNS N08925 Pipes and Tubes
Standard / System | Grade Designation |
|---|---|
UNS Designation | N08925 |
Werkstoff Number (W.Nr) | 1.4529 |
EN Designation | X1NiCrMoCuN25-20-7 |
Common / Trade Names | 1925hMo, 6Mo Super Austenitic |
Closely Related Grades | UNS N08926 (Higher Nitrogen content, frequently dual-certified) |
ASTM Pipe / Tube Specs | ASTM B677 (Seamless), ASTM B673 (Welded Pipe), ASTM B674 (Welded Tube) |
UNS N08925 Pipe and Tubes Schedule and Weight Chart
NPS | OD (mm) | SCH 5S (Wall / Weight) | SCH 10S (Wall / Weight) | SCH 40S (Wall / Weight) | SCH 80S (Wall / Weight) |
|---|---|---|---|---|---|
1/2" | 21.34 | 1.65 mm / 0.83 kg/m | 2.11 mm / 1.03 kg/m | 2.77 mm / 1.31 kg/m | 3.73 mm / 1.67 kg/m |
3/4" | 26.67 | 1.65 mm / 1.05 kg/m | 2.11 mm / 1.32 kg/m | 2.87 mm / 1.74 kg/m | 3.91 mm / 2.26 kg/m |
1" | 33.40 | 1.65 mm / 1.33 kg/m | 2.77 mm / 2.16 kg/m | 3.38 mm / 2.58 kg/m | 4.55 mm / 3.34 kg/m |
1 1/4" | 42.16 | 1.65 mm / 1.70 kg/m | 2.77 mm / 2.78 kg/m | 3.56 mm / 3.50 kg/m | 4.85 mm / 4.60 kg/m |
1 1/2" | 48.26 | 1.65 mm / 1.96 kg/m | 2.77 mm / 3.21 kg/m | 3.68 mm / 4.17 kg/m | 5.08 mm / 5.58 kg/m |
2" | 60.33 | 1.65 mm / 2.46 kg/m | 2.77 mm / 4.06 kg/m | 3.91 mm / 5.61 kg/m | 5.54 mm / 7.72 kg/m |
2 1/2" | 73.03 | 2.11 mm / 3.81 kg/m | 3.05 mm / 5.43 kg/m | 5.16 mm / 8.91 kg/m | 7.01 mm / 11.78 kg/m |
3" | 88.90 | 2.11 mm / 4.66 kg/m | 3.05 mm / 6.66 kg/m | 5.49 mm / 11.65 kg/m | 7.62 mm / 15.76 kg/m |
4" | 114.30 | 2.11 mm / 6.02 kg/m | 3.05 mm / 8.63 kg/m | 6.02 mm / 16.59 kg/m | 8.56 mm / 23.03 kg/m |
6" | 168.28 | 2.77 mm / 11.67 kg/m | 3.40 mm / 14.27 kg/m | 7.11 mm / 29.16 kg/m | 10.97 mm / 43.91 kg/m |
8" | 219.08 | 2.77 mm / 15.25 kg/m | 3.76 mm / 20.60 kg/m | 8.18 mm / 43.90 kg/m | 12.70 mm / 66.70 kg/m |
10" | 273.05 | 3.40 mm / 23.33 kg/m | 4.19 mm / 28.67 kg/m | 9.27 mm / 62.22 kg/m | 12.70 mm / 84.14 kg/m |
12" | 323.85 | 3.96 mm / 32.24 kg/m | 4.57 mm / 37.13 kg/m | 9.53 mm / 76.23 kg/m | 12.70 mm / 100.56 kg/m |
Size Chart of UNS N08925 Pipes and Tubes
Tube OD | 20 BWG (0.89 mm) | 18 BWG (1.24 mm) | 16 BWG (1.65 mm) | 14 BWG (2.11 mm) | 12 BWG (2.77 mm) |
|---|---|---|---|---|---|
1/2" (12.70 mm) | 0.27 kg/m | 0.36 kg/m | 0.46 kg/m | 0.57 kg/m | 0.70 kg/m |
5/8" (15.88 mm) | 0.34 kg/m | 0.46 kg/m | 0.60 kg/m | 0.74 kg/m | 0.92 kg/m |
3/4" (19.05 mm) | 0.41 kg/m | 0.56 kg/m | 0.73 kg/m | 0.91 kg/m | 1.15 kg/m |
1" (25.40 mm) | 0.56 kg/m | 0.76 kg/m | 1.00 kg/m | 1.25 kg/m | 1.60 kg/m |
1 1/4" (31.75 mm) | 0.70 kg/m | 0.96 kg/m | 1.26 kg/m | 1.59 kg/m | 2.04 kg/m |
1 1/2" (38.10 mm) | 0.84 kg/m | 1.16 kg/m | 1.53 kg/m | 1.93 kg/m | 2.49 kg/m |
2" (50.80 mm) | 1.13 kg/m | 1.56 kg/m | 2.06 kg/m | 2.61 kg/m | 3.39 kg/m |
Applications and Industrial Uses of UNS N08925 Pipes and Tubes
- Seawater Desalination Plants
- Marine and Offshore Equipment
- Seawater Cooling Systems
- Chemical Processing Plants
- Sulfuric Acid Processing Equipment
- Phosphoric Acid Processing Systems
- Brine and Saltwater Handling Systems
- Flue Gas Desulfurization Equipment
Frequently Asked Questions
What are UNS N08925 Pipes and Tubes?
UNS N08925 Pipes and Tubes are 6% molybdenum super austenitic stainless steel products designed for severe corrosion-resistant applications.
What is UNS N08925 also known as?
UNS N08925 is also known as Alloy 925 or 1.4529.
What ASTM standards cover UNS N08925 Pipes and Tubes?
Seamless pipe and tube are covered by ASTM B677, while welded pipe and tube are covered by ASTM B673 and ASTM B674.
Is UNS N08925 suitable for seawater applications?
Yes. It provides excellent corrosion resistance in seawater, brine, and other chloride-rich environments.
Is UNS N08925 resistant to pitting and crevice corrosion?
Yes. Its high molybdenum and nitrogen content provides strong resistance to pitting and crevice corrosion.
Can UNS N08925 withstand chloride stress corrosion cracking?
Yes. Its high nickel and alloy content provides strong resistance to chloride stress corrosion cracking.
Is UNS N08925 suitable for sulfuric and phosphoric acid service?
Yes. Copper additions improve its resistance to non-oxidizing acids such as sulfuric and phosphoric acid.
