Womic Stainless Steel Co., Ltd
Superior Sulfuric and Phosphoric Acid Resistance: Outstanding performance in H₂SO₄ (all concentrations up to moderate temperature), H₃PO₄, and mixed acids, making Alloy 825 the premier flat bar material for fertilizer and chemical processing facilities.
NACE MR0175 / ISO 15156 Compliant: Fully qualified for sour service (H₂S) up to 232°C (450°F), with documented HIC and SSC test reports available.
Excellent Chloride SCC Resistance: High nickel content (38-46%) provides outstanding resistance to chloride-induced SCC, outperforming all austenitic and duplex stainless steel grades.
Good Pitting and Crevice Corrosion Resistance: Molybdenum (2.5-3.5%) and chromium (19.5-23.5%) provide enhanced resistance to localized corrosion in chloride-containing environments.
Titanium Stabilization: Titanium addition (0.6-1.2%) stabilizes the alloy against intergranular corrosion after welding or high-temperature exposure, eliminating the need for post-weld heat treatment.
Good Weldability: Nickel-iron-chromium alloy offers good weldability with matching filler metals (ERNiCrMo-3 or ERNiCrMo-10). No preheat required for most applications.
Excellent Resistance to Reducing and Oxidizing Acids: Performs well in both reducing acids (sulfuric, hydrochloric, phosphoric) and oxidizing acids (nitric, chromic), as well as mixed acid environments.
Good High-Temperature Strength: Maintains excellent mechanical properties up to 540°C (1000°F) in non-oxidizing environments.
Square Edges: Precision-rolled square edges for accurate fitting and welding.
International Certifications: Flat bars can be certified by ABS, BV, DNV, LR, and comply with NORSOK M-650, NACE MR0175, and ASME standards.
|
Standard |
Description |
Corresponding Alloy 825 Grade |
|
ASTM B425 |
Standard specification for nickel-iron-chromium alloy bar and wire |
UNS N08825 |
|
ASTM B906 |
General requirements for nickel alloy plate, sheet, and strip |
UNS N08825 |
|
ASME SB425 |
ASME specification for nickel-iron-chromium alloy bars |
UNS N08825 |
|
EN 10058 |
European standard for hot-rolled flat steel bars |
2.4858 (NiCr21Mo) |
|
EN 10088-3 |
European standard for stainless steel bars for general purposes |
2.4858 |
|
JIS G4303 |
Japanese standard for stainless steel bars |
NW4825 |
|
JIS G4318 |
Japanese standard for cold-finished stainless steel bars |
NW4825 |
|
GB/T 1220 |
Chinese standard for stainless steel bars |
NS825 |
|
NORSOK M-650 |
Offshore material qualification |
Alloy 825 |
|
NACE MR0175 / ISO 15156 |
Sour service compliance |
Alloy 825 |
|
Element |
Ni |
Cr |
Fe |
Mo |
Cu |
Ti |
C |
Mn |
P |
S |
Si |
Al |
|
Alloy 825 |
38.0–46.0 |
19.5–23.5 |
≥22.0 |
2.5–3.5 |
1.5–3.0 |
0.6–1.2 |
≤0.05 |
≤1.0 |
≤0.03 |
≤0.03 |
≤0.5 |
≤0.2 |
Alloy 825 is a nickel-iron-chromium alloy with controlled additions of molybdenum and copper for enhanced corrosion resistance in reducing acid environments. The copper content (1.5-3.0%) provides exceptional resistance to sulfuric acid, while molybdenum (2.5-3.5%) enhances pitting resistance. Titanium stabilization (0.6-1.2%) prevents sensitization and intergranular corrosion after welding.
Comparison of Acid Resistance:
|
Grade |
Nickel (%) |
Copper (%) |
Sulfuric Acid (H₂SO₄) |
Phosphoric Acid (H₃PO₄) |
Sour Gas (H₂S) |
|
316/316L |
10-14 |
— |
Poor |
Fair |
Poor |
|
Duplex 2205 |
4.5-6.5 |
— |
Good |
Good |
Good |
|
Super Duplex 2507 |
6-8 |
— |
Good |
Good |
Excellent |
|
Alloy 825 |
38-46 |
1.5-3.0 |
Excellent |
Excellent |
Excellent |
|
Property |
Unit |
Alloy 825 (Annealed) |
|
Tensile Strength |
MPa |
≥585 |
|
Yield Strength (0.2% offset) |
MPa |
≥240 |
|
Elongation |
% |
≥30 |
|
Reduction of Area |
% |
≥40 |
|
Hardness (Brinell) |
HBW |
≤200 |
|
Density |
g/cm³ |
8.14 |
|
Melting Range |
°C |
1370–1400 |
|
Modulus of Elasticity |
GPa |
195 |
|
Thermal Conductivity (20°C) |
W/m·K |
11.1 |
|
Coefficient of Thermal Expansion (20–100°C) |
μm/m·K |
14.0 |
High-Temperature Tensile Properties (Typical Values):
|
Temperature (°C) |
Tensile Strength (MPa) |
Yield Strength (MPa) |
|
20 |
620-750 |
280-380 |
|
100 |
600-720 |
260-350 |
|
200 |
580-700 |
250-340 |
|
300 |
560-680 |
240-330 |
|
400 |
540-650 |
230-320 |
|
500 |
500-600 |
220-300 |
|
540 |
460-550 |
200-270 |
Maximum Recommended Service Temperatures:
|
Service Type |
Maximum Temperature |
|
Continuous Service (Sulfuric Acid) |
150°C (302°F) |
|
Continuous Service (General Corrosive) |
400°C (752°F) |
|
Sour Service (NACE MR0175) |
232°C (450°F) |
|
Minimum Service Temperature |
-196°C (-321°F) |
Critical Note: Alloy 825 is titanium-stabilized, which prevents sensitization and intergranular corrosion after welding. Unlike many stainless steels, Alloy 825 can be used in the as-welded condition without post-weld heat treatment for most corrosive environments.
Heat Treatment Condition:
All Alloy 825 flat bars are solution annealed at 925–1040°C followed
by rapid cooling (water quenching or rapid air cooling).
Delivery Condition Options:
Pickled: Acid-treated, oxide-free, matte silver finish – standard for alloy 825
Passivated: Chemically treated for enhanced corrosion protection
Grit Blasted: Matte, uniform surface texture
Standard Thickness Ranges:
|
Thickness (mm) |
Width Range (mm) |
Tolerance (mm) |
|
5 – 10 |
20 – 150 |
±0.3 |
|
10 – 20 |
30 – 200 |
±0.4 |
|
20 – 30 |
40 – 250 |
±0.5 |
|
30 – 40 |
50 – 250 |
±0.7 |
Standard Width Ranges:
|
Width (mm) |
Tolerance (mm) |
|
20 – 50 |
±0.5 |
|
50 – 100 |
±0.8 |
|
100 – 200 |
±1.0 |
|
200 – 250 |
±1.5 |
Standard Lengths:
3000mm (3 meters)
6000mm (6 meters)
Custom lengths available upon request
Straightness Tolerances:
Standard: 2mm per meter
Precision: 1mm per meter (upon request)
|
Dimensions (mm) |
Weight (kg/m) |
Dimensions (mm) |
Weight (kg/m) |
|
20 x 5 |
0.81 |
60 x 10 |
4.88 |
|
25 x 5 |
1.02 |
60 x 12 |
5.86 |
|
25 x 6 |
1.22 |
65 x 10 |
5.29 |
|
30 x 5 |
1.22 |
70 x 10 |
5.70 |
|
30 x 6 |
1.46 |
75 x 10 |
6.11 |
|
30 x 8 |
1.95 |
80 x 10 |
6.51 |
|
40 x 5 |
1.63 |
80 x 12 |
7.81 |
|
40 x 6 |
1.95 |
100 x 10 |
8.14 |
|
40 x 8 |
2.60 |
100 x 12 |
9.77 |
|
40 x 10 |
3.26 |
100 x 15 |
12.21 |
|
50 x 6 |
2.44 |
120 x 10 |
9.77 |
|
50 x 8 |
3.26 |
120 x 12 |
11.72 |
|
50 x 10 |
4.07 |
120 x 15 |
14.65 |
|
50 x 12 |
4.88 |
150 x 12 |
14.65 |
|
60 x 8 |
3.91 |
150 x 15 |
18.32 |
*Formula: Weight (kg/m) = Width (mm) × Thickness (mm) × 0.00814*
|
Surface Finish |
Code |
Description |
Typical Chemical/Offshore Applications |
|
Pickled |
P |
Acid-treated, oxide-free, matte silver finish |
Sulfuric acid plant supports, chemical reactor frames |
|
Passivated |
PA |
Chemically treated for enhanced corrosion protection |
Critical acid service, sour gas platforms |
|
Grit Blasted |
GB |
Matte, uniform surface texture |
Offshore topside structures requiring paint |
|
Polished |
PL |
Mechanically polished, smooth finish |
Pharmaceutical equipment, cleanroom applications |
Chemical Analysis: PMI verification for Ni (38-46%), Cr (19.5-23.5%), Mo (2.5-3.5%), Cu (1.5-3.0%), Ti (0.6-1.2%).
Intergranular Corrosion Test: ASTM G28 – validates resistance to intergranular corrosion (mandatory for stabilized grades).
Mechanical Testing: Tensile (≥585 MPa), yield (≥240 MPa), elongation (≥30%), hardness (≤200 HBW).
Dimensional Inspection: Thickness, width, length, straightness, squareness.
Surface Inspection: Visual check for defects, cracks, seams.
Ultrasonic Testing (UT): Upon request.
Sour Service Qualification (upon request): HIC per NACE TM0284, SSC per NACE TM0177.
Third-Party Inspection: SGS, BV, DNV, TUV, LR, ABS available.
Sulfuric Acid Plant Supports: Acid storage tank stiffeners, heat exchanger support brackets, piping rack supports, acid cooler structural frames.
Phosphoric Acid Evaporator Brackets: Evaporator shell stiffeners, agitator support brackets, platform structures, maintenance walkway supports.
Chemical Reactor Equipment Frameworks: Reactor vessel support rings, agitator mounting brackets, instrument platform supports, catalyst handling equipment frames.
Pickling Line Stiffeners: Pickling tank stiffeners, acid recovery system supports, rinse tank frames, conveyor support brackets.
Heat Exchanger Components: Heat exchanger support bars, baffle supports, channel cover stiffeners, tie rod brackets.
Offshore Chemical Injection Skids: Methanol injection skid frames, glycol unit supports, chemical tank mounting brackets (NORSOK M-650 qualified).
Sour Gas Platform Frameworks: Amine unit platform supports, sour water stripper brackets, glycol regeneration unit frames (NACE MR0175 compliant).
Pharmaceutical Equipment (High-Purity): Cleanroom equipment frames, sterile process supports, instrument mounting brackets.
Fertilizer Production Equipment: DAP/MAP production unit supports, granulator frames, conveyor structure stiffeners.
Heat Exchanger Tie Rods: Tie rods, spacer bars, support bars for heat exchanger bundles in corrosive service.
1. How does Alloy 825 compare to
316L for flat bar applications in acid service?
Alloy 825 offers significantly better resistance to sulfuric acid (H₂SO₄),
phosphoric acid (H₃PO₄), and sour gas (H₂S). For acid plant supports, chemical
reactor frames, and pickling line structures where 316L would corrode rapidly,
Alloy 825 is required.
2. Is Alloy 825 resistant to
hydrochloric acid (HCl)?
Limited. Alloy 825 has fair resistance to dilute HCl but is not recommended for
concentrated or aerated HCl. For hydrochloric acid service, consider Hastelloy
C276 flat bars.
3. Can Alloy 825 flat bars be welded
without post-weld heat treatment?
Yes. Titanium stabilization prevents sensitization, and PWHT is not required
for most corrosive environments. This is a major advantage for field
fabrication.
4. Are Alloy 825 flat bars suitable
for sour service (H₂S)?
Yes, with proper hardness control. Alloy 825 can be NACE MR0175 / ISO 15156
compliant for sour service. HIC/SSC test reports available upon request.
5. What is the maximum service
temperature for Alloy 825 flat bars?
400°C (752°F) for general corrosive service. For sulfuric acid service
specifically, limit to 150°C (302°F) depending on acid concentration.
6. What surface finish is
recommended for acid plant applications?
Pickled finish is standard for acid plant applications, providing a clean,
oxide-free surface. Passivated finish is recommended for critical acid service
where maximum corrosion protection is required.
Premier Acid Service Material: Excellent resistance to H₂SO₄, H₃PO₄, and sour gas – ideal for chemical processing and fertilizer production
NACE MR0175 / ISO 15156 Compliant: Full sour service documentation
Titanium Stabilized: ASTM G28 intergranular corrosion tested – no PWHT required
Square Edges: Precision-rolled for accurate fabrication
Full Traceability: Heat number on each bundle – traceable to original mill certificate
Complete Size Range: Thickness from 5mm to 40mm – standard and custom sizes
Global Delivery: Exported to major chemical plants, acid facilities, and offshore projects worldwide
Website: www.womicstainless.com
E-mail: info@womicstainless.com
Tel / WhatsApp / WeChat
Victor: +86 15575100681
Jack: +86 18390957568
Womic Steel – Your reliable partner for high‑quality stainless steel products, precision machined components, and custom solutions for corrosion‑resistant applications.
Stock Examples (Alloy 825 Stainless Steel Flat Bars – Pickled Finish – Acid Service Grade):
|
Dimensions (mm) |
Length |
Weight (kg/m) |
Typical Application |
|
30 x 6 |
6000mm |
1.46 |
Acid plant light brackets |
|
40 x 10 |
6000mm |
3.26 |
Heat exchanger supports |
|
50 x 10 |
6000mm |
4.07 |
Chemical reactor frames |
|
60 x 10 |
6000mm |
4.88 |
Pickling tank stiffeners |
|
80 x 12 |
6000mm |
7.81 |
Sulfuric acid tank supports |
|
100 x 12 |
6000mm |
9.77 |
Heavy acid plant structures |
|
120 x 15 |
6000mm |
14.65 |
Reactor platform supports |
Stock Examples (Alloy 825 Stainless Steel Flat Bars – Passivated Finish – Critical Acid Service):
|
Length |
Weight (kg/m) |
Typical Application |
|
|
40 x 8 |
6000mm |
2.60 |
Phosphoric acid evaporator brackets |
|
50 x 12 |
6000mm |
4.88 |
Sour gas platform frames |
|
65 x 10 |
6000mm |
5.29 |
Offshore chemical injection skids |
|
80 x 10 |
6000mm |
6.51 |
Pharmaceutical equipment frames |
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