Alloy 825 (UNS N08825) heat exchanger pipe is a titanium-stabilized nickel-iron-chromium-molybdenum-copper superalloy pipe with exceptional resistance to sulfuric acid, phosphoric acid, reducing acids and chloride-induced corrosion. It offers an unbeatable balance of corrosion resistance, mechanical strength and cost-effectiveness, specially engineered for heat exchanger components operating in aggressive chemical and oil & gas environments.
As the industry-standard cost-effective corrosion-resistant alloy, Alloy 825 pipe delivers 5-10x better performance than 316L stainless steel at only 30-40% higher cost, with excellent weldability, formability and long-term thermal stability. It is the ideal material for manufacturing heat exchanger tubes, tube sheets and baffles in chemical processing, oil refining and marine industries.
| Item | Details |
|---|---|
| Executive Standards | 1. International Material Standards: ASTM B423 (Seamless Pipe), ASTM B424 (Bar), ASTM B704 (Welded Pipe), ASME SB423, ASME SB424, ASME SB704, DIN 17744, EN 2.4858
2. Heat Exchanger Specific Standards: TEMA (Tubular Exchanger Manufacturers Association), HEI (Heat Exchange Institute), API 660, API 661 3. Corrosion Service Standards: NACE MR0175/ISO 15156, NACE MR0103 4. Testing Standards: ASTM E8 (Tensile), ASTM E23 (Impact), ASTM A450 (Hydrostatic), ASTM E243 (Eddy Current), ASTM A388 (Ultrasonic) 5. Quality Management Standards: ISO 9001, ISO 14001, AS9100, PED 2014/68/EU |
| Material Grade | 1. Main Grade: Alloy 825 (Nickel-Iron-Chromium-Molybdenum-Copper Alloy, Cost-Effective Corrosion-Resistant Heat Exchanger Grade)
2. International Designations: UNS N08825, W.Nr. 2.4858, Incoloy 825, NiFe30Cr21Mo3CuTi 3. Equivalent Grades: NS1402 (China), Alloy 825 (USA), Nicrofer 4221 (Germany), fully compatible with all global heat exchanger manufacturing standards 4. Special Grade: Ultra-low carbon version available for maximum weldability and resistance to intergranular corrosion in critical applications |
| Chemical Composition (Weight %) | 1. Nickel (Ni): 38.0 – 46.0 (base element for overall corrosion resistance and thermal stability)
2. Chromium (Cr): 19.5 – 23.5 (for oxidizing acid resistance and high-temperature oxidation protection) 3. Molybdenum (Mo): 2.5 – 3.5 (primary element for reducing acid resistance and crevice corrosion resistance) 4. Copper (Cu): 1.5 – 3.0 (enhances resistance to sulfuric acid and other reducing acids) 5. Titanium (Ti): 0.6 – 1.2 (stabilizes against intergranular corrosion after welding) 6. Iron (Fe): 22.0 minimum (for improved formability and cost-effectiveness) 7. Carbon (C): ≤0.05 (ultra-low content to prevent intergranular corrosion) 8. Manganese (Mn): ≤1.00 9. Silicon (Si): ≤0.50 10. Phosphorus (P): ≤0.020 11. Sulfur (S): ≤0.015 12. Aluminum (Al): ≤0.20 |
| Mechanical Properties (Annealed State) | 1. Tensile Strength (Room Temperature): 585 – 795 MPa
2. 0.2% Yield Strength (Room Temperature): ≥240 MPa 3. Elongation (δ5): ≥40% (excellent formability for complex components) 4. Reduction of Area: ≥50% 5. Hardness (HB): 130 – 190 6. Impact Toughness (Akv, Room Temperature): ≥180 J 7. Tensile Strength (300℃): ≥480 MPa 8. Tensile Strength (500℃): ≥350 MPa 9. Modulus of Elasticity: 196 GPa 10. Thermal Expansion Coefficient: 14.2 × 10⁻⁶ /℃ (20-100℃) 11. Pitting Resistance Equivalent Number (PREN): ≥30 |
| Dimensional Tolerance (Heat Exchanger Precision Grade) | 1. Outer Diameter Tolerance:
– Precision Cold Drawn (≤50mm): ±0.05mm – Standard Grade (50-100mm): ±0.10mm – Heavy Section (100-300mm): ±0.20mm – Ultra-Precision Grade available upon request: ±0.02mm 2. Wall Thickness Tolerance: ±10% of nominal wall thickness 3. Length Tolerance: – Fixed Length (1m-6m): ±0.5mm/m – Maximum Full-Length Tolerance: ≤2.0mm – Custom Length up to 12m available 4. Roundness Tolerance: ≤0.01mm (≤50mm); ≤0.02mm (50-100mm); ≤0.03mm (100-300mm) 5. Concentricity Tolerance: ≤0.02mm for precision machined pipes |
| Heat Exchanger Operating Conditions (Detailed) | 1. Chemical Processing Industry:
– Sulfuric acid production and handling: 0-98% H₂SO₄, temperatures up to 120℃. Alloy 825 outperforms 316L stainless steel by 10-20x in sulfuric acid environments, making it the material of choice for sulfuric acid coolers and evaporators. – Phosphoric acid production: Wet process phosphoric acid containing fluoride and chloride impurities, temperatures up to 150℃. Resists corrosion from common contaminants found in phosphate rock. – Nitric acid production: 0-65% HNO₃, temperatures up to 150℃. Excellent resistance to both oxidizing and reducing acid mixtures. – Pulp and paper industry: Black liquor evaporators, white liquor heaters, digester heat exchangers, temperatures up to 180℃. Resists corrosion from alkaline and acidic pulping chemicals. – Organic chemical production: Acetic acid, formic acid, solvents, pesticides, temperatures up to 250℃. 2. Oil and Gas Industry: – Sour gas processing: H₂S concentrations up to 30%, CO₂ concentrations up to 40%, chloride levels up to 100,000 ppm, temperatures up to 200℃, pressures up to 150 bar. – Refinery applications: Hydrodesulfurization units, amine scrubbers, glycol dehydration units, sour water strippers, temperatures up to 300℃. – Offshore production platforms: Seawater cooling systems, produced water treatment, crude oil processing, temperatures up to 120℃. 3. Marine Engineering Industry: – Seawater cooling systems: Fresh and saltwater, temperatures up to 120℃, pressures up to 40 bar. Excellent resistance to seawater corrosion and biofouling. – Desalination plants: Multi-effect distillation (MED) and reverse osmosis (RO) systems, brine solutions, temperatures up to 150℃. – Shipbuilding: Main engine coolers, auxiliary coolers, condenser tubes, temperatures up to 180℃. 4. Power Generation Industry: – Flue gas desulfurization (FGD) systems: Limestone slurry, sulfuric acid mist, chlorides, temperatures up to 180℃. Resists sulfuric acid dew point corrosion. – Waste-to-energy plants: Corrosive flue gases, fly ash, temperatures up to 400℃. – Nuclear power plants: Auxiliary cooling systems, spent fuel pool heat exchangers, temperatures up to 120℃. 5. Extreme Operating Conditions: – Maximum continuous operating temperature: 550℃ in oxidizing environments – Maximum continuous operating temperature: 450℃ in reducing environments – Excellent resistance to thermal cycling and thermal shock – Pressure rating: up to 200 bar depending on design and temperature |
| Heat Exchanger Tube Bundle Applications (Detailed) | 1. U-Bend Tubes:
– Application: Shell and tube heat exchangers, condensers, evaporators requiring thermal expansion compensation in sulfuric acid and sour gas environments – Technical Requirements: Minimum bend radius 1.5× tube diameter, no wall thinning >12% at bend, no cracking or wrinkling – Alloy 825 Advantage: Excellent hot and cold formability, maintains full corrosion resistance and mechanical properties after bending, no post-bend heat treatment required. Superior to stainless steels in weld heat-affected zone corrosion resistance. – Available Sizes: OD 6mm – 50mm, wall thickness 0.5mm – 5mm, bend radii 1.5D – 10D 2. Condenser Tubes: – Application: Power plant surface condensers, refinery condensers, offshore platform condensers, seawater cooling condensers – Technical Requirements: High corrosion resistance to cooling water, excellent thermal conductivity, tight dimensional tolerances, resistance to vibration-induced fatigue and erosion-corrosion – Alloy 825 Advantage: 5-10x longer service life than 316L stainless steel in polluted seawater and high-chloride cooling water, immune to biofouling and erosion-corrosion at flow velocities up to 8 m/s – Available Sizes: OD 10mm – 30mm, wall thickness 0.8mm – 3mm, lengths up to 12m 3. Evaporator Tubes: – Application: Sulfuric acid evaporators, phosphoric acid evaporators, desalination plants, food processing evaporators, brine evaporators – Technical Requirements: Resistance to fouling, excellent heat transfer properties, resistance to thermal cycling and chemical attack – Alloy 825 Advantage: Smooth surface reduces scaling and fouling, excellent thermal conductivity, withstands repeated heating and cooling cycles without deformation. Resistant to both acidic and alkaline cleaning solutions. – Available Sizes: OD 12mm – 40mm, wall thickness 1.0mm – 4mm 4. Reboiler Tubes: – Application: Distillation columns, chemical processing reboilers, refinery reboilers, sour water strippers – Technical Requirements: High-temperature strength, resistance to thermal fatigue, resistance to process fluids and fouling – Alloy 825 Advantage: Maintains strength at elevated temperatures, excellent resistance to thermal fatigue, no thermal deformation even after long-term service. Resistant to coking and fouling in hydrocarbon processing. – Available Sizes: OD 16mm – 50mm, wall thickness 1.5mm – 5mm 5. Cooler Tubes: – Application: Sulfuric acid coolers, process fluid coolers, hydraulic oil coolers, compressor intercoolers, marine engine coolers – Technical Requirements: High pressure rating, excellent corrosion resistance, tight dimensional tolerances, resistance to vibration – Alloy 825 Advantage: High strength-to-weight ratio, withstands high operating pressures, immune to corrosion from process fluids and seawater. Excellent fatigue resistance for long-term reliable operation. 6. Tube Sheets and Baffles: – Application: Structural components of high-corrosion shell and tube heat exchangers in chemical processing and offshore industries – Technical Requirements: Flatness tolerance, hole position accuracy, high-temperature strength, corrosion resistance, compatibility with tube materials – Alloy 825 Advantage: Excellent machinability, maintains dimensional stability at high temperatures, no galvanic corrosion with Alloy 825 tubes. Superior to stainless steels in weldability for large tube sheets. 7. Support Rods and Spacers: – Application: Supporting tube bundles in heat exchangers operating in corrosive environments – Technical Requirements: Straightness, corrosion resistance, mechanical strength, resistance to vibration – Alloy 825 Advantage: Excellent straightness, immune to galvanic corrosion, long service life in aggressive environments. Resistant to crevice corrosion at contact points with tubes. |
| Surface Quality Requirements (Detailed) | 1. Standard Pickled Surface (ASTM B423):
– Surface Finish: Ra ≤3.2μm – Process: Hot rolled, cold drawn, solution annealed, pickled and passivated – Appearance: Uniform silver-gray matte finish, free of scale, oxides and discoloration – Application: General purpose industrial heat exchanger components, tube sheets, baffles, supports – Defect Control: No cracks, folds, seams, pits, inclusions or other harmful defects allowed; minor surface imperfections ≤0.05mm deep acceptable 2. Mechanically Polished Surface: – Surface Finish: Ra ≤1.6μm (standard polish), Ra ≤0.8μm (fine polish) – Process: Pickled surface followed by centerless grinding or belt polishing – Appearance: Uniform bright metallic finish, smooth and reflective – Application: Heat exchanger tubes requiring reduced fouling, food processing applications, pharmaceutical industry – Defect Control: No visible surface defects, uniform surface texture, no grinding marks or chatter marks 3. Electropolished Surface: – Surface Finish: Ra ≤0.4μm (standard electropolish), Ra ≤0.2μm (ultra-fine electropolish) – Process: Mechanically polished surface followed by electrochemical polishing – Appearance: Mirror-like finish, extremely smooth and clean – Application: High-purity pharmaceutical applications, semiconductor manufacturing, ultra-clean heat exchangers – Defect Control: Absolutely no surface defects, uniform electropolishing across entire surface, no pitting or staining 4. Special Surface Treatments: – Passivation: All surfaces passivated according to ASTM A967 to enhance corrosion resistance – Shot Peening: Available for improved fatigue resistance in high-vibration applications – Anti-Fouling Coatings: Optional epoxy or PTFE coatings for severe fouling environments 5. Surface Inspection: – 100% visual inspection of all surfaces by trained inspectors – Surface roughness measurement using calibrated profilometers at multiple points along each pipe – Dye penetrant inspection available upon request for critical components |
| Straightness Requirements (Detailed) | 1. Standard Straightness (ASTM B423):
– Straightness Tolerance: ≤0.5mm/m for pipes up to 6m in length – Maximum Full-Length Straightness Error: ≤3.0mm for 6m long pipes – Application: General purpose industrial heat exchanger components, baffles, supports, tube sheets 2. Precision Straightness: – Straightness Tolerance: ≤0.25mm/m for pipes up to 6m in length – Maximum Full-Length Straightness Error: ≤1.5mm for 6m long pipes – Application: Heat exchanger tubes, tube bundle support rods, long components requiring tight alignment 3. Ultra-Precision Straightness: – Straightness Tolerance: ≤0.1mm/m for pipes up to 6m in length – Maximum Full-Length Straightness Error: ≤0.6mm for 6m long pipes – Application: High-precision heat exchangers, nuclear power applications, aerospace heat exchangers 4. Straightening Process: – All pipes undergo multi-roll straightening after solution annealing – Precision pipes undergo additional centerless grinding and straightening – Straightness verified using laser straightness measurement systems with 0.01mm accuracy 5. Importance of Straightness: – Ensures proper alignment of tube bundles, preventing tube-to-tube contact and wear – Reduces vibration and noise in operating heat exchangers – Facilitates easy assembly and installation, reducing labor costs – Prevents stress concentrations that could lead to premature fatigue failure – Ensures uniform heat transfer across the entire tube bundle |
| Eddy Current Testing (ET) (Detailed) | 1. Testing Standard: ASTM E243, ASME V Article 8, TEMA RCB-7.3
2. Testing Frequency: 100% of all heat exchanger pipes undergo eddy current testing 3. Equipment: Computerized multi-frequency eddy current testing systems with automatic defect marking and digital data recording 4. Testing Parameters: – Frequency Range: 10kHz – 2MHz depending on pipe diameter and wall thickness – Sensitivity: Calibrated to detect artificial defects of 0.3mm depth (5% of wall thickness) or smaller – Defect Types Detected: Surface cracks, subsurface cracks, pits, inclusions, seams, laps and wall thickness variations 5. Testing Procedure: – Pipes pass through encircling coils at controlled speed (1-5m/s) – System automatically records all test data and marks defective areas with paint – Defective sections are cut out and removed – Retesting performed on repaired sections to ensure compliance 6. Acceptance Criteria: – No defects exceeding 5% of wall thickness allowed – No linear defects of any length allowed – Isolated pits ≤0.3mm deep acceptable if spaced ≥50mm apart 7. Additional Testing Options: – Ultrasonic Testing (UT) according to ASTM A388 for internal defect detection – Dye Penetrant Testing (PT) according to ASTM E165 for surface defect detection – Magnetic Particle Testing (MT) not applicable as Alloy 825 is non-magnetic 8. Documentation: – Complete eddy current test report provided with each shipment – Test data stored digitally for minimum 15 years for traceability |
| Hydrostatic Pressure Testing (Detailed) | 1. Testing Standard: ASTM A450, ASME B31.3, TEMA RCB-7.2
2. Testing Frequency: 100% of all heat exchanger pipes undergo hydrostatic pressure testing 3. Test Pressure Calculation: – Standard Test Pressure: 1.5× design pressure – Minimum Test Pressure: 10 bar – Maximum Test Pressure: Limited by yield strength (≤80% of yield strength at test temperature) 4. Test Medium: – Deionized water with chloride content ≤25ppm to prevent corrosion – Optional corrosion inhibitors added for long-term storage – Water temperature maintained between 10℃ and 50℃ to prevent condensation 5. Testing Procedure: – Pipes are sealed at both ends with high-pressure hydraulic fittings – Water is pumped into the pipe until test pressure is reached – Pressure held for minimum 10 seconds (standard) or 30 seconds (critical applications) – Visual inspection for leaks, bulging or deformation during pressure holding – Pressure released and pipes drained and dried after testing 6. Acceptance Criteria: – No leakage of any kind allowed – No permanent deformation or bulging allowed – No pressure drop during holding period allowed 7. Additional Testing Options: – Pneumatic pressure testing available upon request using dry nitrogen – Burst pressure testing available for design verification – Cyclic pressure testing available for fatigue life evaluation 8. Post-Testing Processing: – Pipes are thoroughly dried internally and externally using compressed air – Ends are capped immediately to prevent moisture ingress during storage and transportation – Optional passivation performed after testing to restore corrosion resistance |
| Fixed Length Specifications (Detailed) | 1. Standard Fixed Lengths:
– 1000mm, 2000mm, 3000mm, 4000mm, 5000mm, 6000mm – Length Tolerance: ±0.5mm/m, maximum ±2.0mm for 6m lengths – Squareness of Cut: ≤0.1mm per 100mm diameter 2. Custom Fixed Lengths: – Any length from 100mm to 12000mm available upon request – Length Tolerance: ±0.3mm for lengths ≤3m, ±0.5mm for lengths >3m – Ultra-precision cutting available with tolerance ±0.1mm 3. Long Length Products: – Maximum single length: 12000mm – Ideal for large heat exchangers requiring long tubes without welded joints – Reduces number of welds, improving reliability and reducing maintenance costs 4. Cutting Methods: – Band saw cutting for standard lengths – CNC lathe cutting for precision lengths with square ends – Abrasive cutting for small diameter pipes – Water jet cutting available for sensitive materials 5. End Preparation: – All cut ends deburred and chamfered as standard – Optional end facing and turning available 6. Length Verification: – All lengths verified using calibrated measuring tapes or laser distance meters – 100% inspection of all cut lengths 7. Packaging by Length: – Pipes bundled by length to facilitate easy identification and handling – Long pipes packaged in steel frames to prevent bending during transportation |
| Tube End Processing Standards (Detailed) | 1. Plain Square End (Standard):
– Standard: ASME B16.25, TEMA RCB-7.4 – Dimensions: Ends cut square to within 0.1mm per 100mm diameter – Chamfer: 0.5×45° external chamfer to remove burrs – Application: General purpose tube-to-tubesheet welding, expansion joints 2. Beveled End for Welding: – Standard: ASME B16.25, AWS D10.9 – Bevel Angle: 30° ±2.5° (standard), 37.5° ±2.5° (heavy wall) – Root Face: 1.6mm ±0.8mm – Application: High-pressure piping, tube-to-tubesheet welding in critical applications 3. Chamfered End: – Standard: Customer specific – Chamfer Angles: 15°, 30°, 45°, 60° available – Chamfer Length: 1mm – 10mm depending on wall thickness – Application: Tube expansion, assembly into fittings 4. Expanded End: – Standard: TEMA RCB-7.5 – Expansion Ratio: Up to 15% of original diameter – Length of Expansion: 10mm – 50mm depending on tube diameter – Application: Tube-to-tubesheet expansion joints, quick connect fittings 5. Swaged End (Reduced End): – Standard: ASME B16.19 – Reduction Ratio: Up to 50% of original diameter – Length of Swage: 2× diameter minimum – Application: Connection to smaller diameter piping, nozzles 6. Flared End: – Standard: SAE J514, ISO 8434 – Flare Angle: 37° (JIC), 45° (SAE), 60° (metric) – Application: Flare fittings, hydraulic connections 7. Threaded End: – Standard: NPT, BSPP, BSPT, metric threads – Thread Class: Class 2A (external), Class 2B (internal) – Application: Threaded connections, instrumentation fittings 8. End Protection: – All tube ends protected with plastic caps during storage and transportation – Heavy-duty metal caps available for heavy wall pipes – Ends sealed to prevent moisture and contamination ingress |
| Why Choose Us (Emily PIPE) | 1. 20+ Years of Superalloy Expertise: We have been manufacturing and exporting high-performance nickel-iron-chromium alloy heat exchanger components for over 20 years, with deep understanding of the unique requirements of chemical and oil & gas industrial environments.
2. Complete International Certifications: Our production facilities are certified to ISO 9001, ISO 14001, AS9100 and PED, with all products complying with ASTM, ASME, NACE and API standards. 3. Dedicated Alloy 825 Production Line: We operate a dedicated production line for Alloy 825 products, ensuring strict control over chemical composition (especially titanium and copper content), mechanical properties and surface quality. 4. Full-Process Quality Control: We implement a comprehensive quality control system from raw material inspection to finished product testing, including 100% eddy current testing and hydrostatic testing for all heat exchanger pipes. 5. Advanced Customization Capability: We can produce custom sizes, lengths, surface finishes and end treatments according to your drawings and technical specifications, including complex U-bend tubes and large tube sheets. 6. In-House Testing Laboratory: We operate a fully equipped testing laboratory that can perform chemical analysis, mechanical testing, corrosion testing and non-destructive testing, providing third-party verified test reports. 7. Global One-Stop Service: We handle everything from material production and custom processing to international shipping and customs clearance, with reliable logistics partners ensuring on-time delivery to any industrial facility worldwide. 8. Professional Technical Support: Our team of metallurgical engineers and heat exchanger specialists provides expert guidance on material selection, design optimization and fabrication techniques. |
| Inquiry Guidance Words | 1. If you need high-quality Alloy 825 heat exchanger pipes for your chemical processing, oil and gas or marine industrial project, please send us your specific requirements including dimensions, quantity, required standards, operating conditions and delivery date, and we will provide a detailed quotation within 12 hours.
2. For any questions about material properties, sulfuric acid corrosion resistance, welding guidelines or heat exchanger design recommendations, our alloy specialists are available to assist you promptly. 3. Emily PIPE is your trusted partner for cost-effective high-performance alloy heat exchanger solutions. Contact us today to discuss how our Alloy 825 products can help you improve the reliability and service life of your heat exchangers while optimizing your total project costs. |
| Supplementary Industry Information | 1. Comprehensive Test Reports: Each batch comes with a full Material Test Report (MTR) including chemical composition analysis (with verified titanium and copper content), mechanical properties testing, heat treatment records, eddy current test results and hydrostatic test results.
2. Full Material Traceability: Every pipe comes with a unique heat number and complete traceability documentation from raw material ore to finished product, meeting the strictest industrial project requirements. 3. Value-Added Processing: We offer comprehensive value-added services including precision cutting, machining, bending, welding, end forming and assembly, providing ready-to-install heat exchanger components. 4. Professional Industrial Packaging: We use protective plastic caps on both ends, anti-corrosion wrapping, wooden crates and steel frames to prevent damage during long-distance international transportation. 5. Urgent Order Support: We maintain a large inventory of standard Alloy 825 pipe sizes, enabling us to fulfill urgent orders within 7-15 days. 6. Prototype Development Support: We support small batch prototype orders with fast turnaround times to help you accelerate product development and testing. 7. After-Sales Service: We provide lifetime technical support for all our products, including on-site assistance for fabrication, installation and troubleshooting. 8. Sustainability Commitment: All our products are manufactured using sustainable practices and are 100% recyclable, helping you meet your environmental targets. |