Alloy 825 Lined Stainless Steel Pipes

Superior Sulfuric and Phosphoric Acid Resistance: 

Outstanding performance in H₂SO₄ (all concentrations up to moderate temperature), H₃PO₄, and mixed acids – premier lined pipe 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 localized corrosion resistance.

Titanium Stabilization:

Titanium addition (0.6-1.2%) stabilizes the alloy against intergranular corrosion after welding – no PWHT required.

Cost-Effective Alternative to Solid Alloy 825: 

Reduces material cost by 50-70% compared to solid Alloy 825 pipe while providing equivalent internal corrosion protection.

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.

Weldable End Preparation: 

Available with weld overlay transition (butter layer) using matching filler metals at pipe ends.

Full Range of Sizes: 

Available from 2″ to 48″ (DN50 to DN1200) with lining thickness from 2mm to 6mm.

International Certifications: 

Lined pipes can be certified by ABS, BV, DNV, LR, and comply with NORSOK M-650, NACE MR0175, and ASME standards.

Alloy 825 is a nickel-iron-chromium alloy with controlled additions of molybdenum and copper for enhanced corrosion resistance in sulfuric acid service. The copper content (1.5-3.0%) provides exceptional resistance to sulfuric acid, while molybdenum (2.5-3.5%) enhances pitting resistance. Titanium stabilization prevents sensitization and intergranular corrosion after welding.

Comparison of Acid Resistance for Lining Materials:

Base Pipe Selection: 

Carbon steel, low-temperature steel, or alloy steel base pipe selected based on service pressure, temperature, and mechanical requirements.

Base Pipe Preparation: 

Base pipe is cleaned (shot blasting to SA 2.5), inspected, and prepared for lining application.

Lining Tube Fabrication: 

Alloy 825 nickel alloy sheet is rolled and welded into a tube slightly smaller than the base pipe ID using matching filler metal (ERNiCrMo-3 or ERNiCrMo-10).

Lining Insertion: 

The Alloy 825 lining tube is inserted into the base pipe.

Hydraulic Expansion: 

High-pressure water (up to 5000 psi) expands the lining tube against the base pipe inner wall, creating a tight mechanical bond.

Solution Annealing: 

Lining material is in solution annealed condition (925–1040°C) for optimal corrosion resistance.

Titanium Stabilization Verification: 

ASTM G28 intergranular corrosion test performed to verify stabilization.

Weld Overlay (Butter Layer): 

Pipe ends are prepared with Alloy 825 weld overlay using ERNiCrMo-3 or ERNiCrMo-10 filler metal.

Hydrostatic Testing: 

Each lined pipe is hydrostatically tested to verify bond integrity and pressure rating.

NDT Inspection: 

Ultrasonic testing (UT) and eddy current testing (ECT) verify lining thickness and bond quality.

End Finishing: 

Pipe ends are beveled per ASME B16.25 and prepared for field welding.

Marking & Coating: 

Pipes are marked with grade, size, lining thickness, heat number, and standard. External coating applied upon request.

Base Pipe Inspection: 

Chemical analysis, mechanical testing, dimensional check, hardness test.

Lining Material Verification: 

PMI 100% for Alloy 825 lining material – verification of 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).

Bond Integrity Testing: 

Ultrasonic test (UT) to verify bond between lining and base pipe – 100% coverage.

Lining Thickness Check: 

Ultrasonic thickness measurement at multiple points.

Hydrostatic Test: 

Each pipe tested at 1.5× design pressure.

Surface Inspection: 

Internal and external surface inspection.

Dimensional Check: 

OD, ID, wall thickness, length, straightness.

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 Plants: 

Sulfuric acid transfer lines, acid cooler piping, oleum lines, spent acid recovery lines, acid storage tank connections.

Phosphoric Acid Production: 

Wet-process phosphoric acid (WPA) transfer lines, evaporator inlet/outlet piping, reaction vessel connections, gypsum slurry lines.

Pickling Plants (Stainless Steel): 

Pickling acid lines, acid recovery system piping, spent acid transfer lines, rinse water return lines.

Offshore Chemical Injection: 

Methanol injection lines, glycol injection piping, MEG (monoethylene glycol) transfer lines (NORSOK M-650 qualified).

Sour Gas Service (H₂S): 

Amine regenerator piping, sour water stripper lines, glycol dehydration unit piping (NACE MR0175 compliant).

Fertilizer Production: 

DAP/MAP (diammonium phosphate/monoammonium phosphate) slurry lines, phosphoric acid feed lines.

Oil & Gas Produced Water: 

Produced water transfer lines, water injection piping, separation vessel connections.

Hydrometallurgy: 

Solvent extraction (SX) piping, electrowinning solution transfer lines, pregnant leach solution (PLS) lines.

Pharmaceutical: 

High-purity acid transfer lines, API reactor connections, sterile process piping.

Heat Exchanger Interconnecting Piping: 

Connecting piping for acid service heat exchangers.

1. How does Alloy 825 lined pipe compare to 316L lined pipe for acid service?
Alloy 825 lined pipe offers significantly better resistance to sulfuric acid (H₂SO₄), phosphoric acid (H₃PO₄), and sour gas (H₂S). For acid plant piping where 316L would corrode rapidly, Alloy 825 lined pipe is required. The cost premium over 316L lined pipe is justified by the extended service life in aggressive acid environments.

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 lined pipes.

3. Can Alloy 825 lined pipes be welded in the field?
Yes, with proper weld overlay (buttering) at pipe ends using ERNiCrMo-3 (Alloy 625) filler metal. Titanium stabilization eliminates the need for PWHT. Qualified welding procedures are available.

4. What is the maximum service temperature for Alloy 825 lined pipes?
400°C (752°F) for general corrosive service. For sulfuric acid service specifically, limit to 150°C (302°F) depending on acid concentration. Base pipe can handle higher temperatures with appropriate material selection.

5. Are Alloy 825 lined pipes suitable for sour service (H₂S)?
Yes, with proper hardness control. Alloy 825 lined pipes can be NACE MR0175 / ISO 15156 compliant for sour service. HIC and SSC test reports available upon request.

6. What base pipe material is recommended for high-temperature acid service?
ASTM A335 Grade P11 (1.25Cr-0.5Mo) or P22 (2.25Cr-1Mo) is recommended for high-temperature acid service where base pipe temperatures exceed 400°C.

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

Cost-Effective:

60-80% cost savings compared to solid Alloy 825 pipe

Full Traceability: 

Heat number on each pipe – traceable to original mill certificate

Complete Size Range: 

2″ to 48″ (DN50 to DN1200) – standard and custom sizes

Multiple Base Pipe Grades: 

API 5L X42-X65, A106 Gr B, A333 Gr 6, A335 P11/P22

Lining Thickness Options: 

2mm to 6mm – tailored to your acid concentration and temperature

Weld Overlay Ready: 

Pipe ends prepared with ERNiCrMo-3 butter layer for field welding

NORSOK M-650 Qualified: 

Complete offshore documentation packages

Third-Party Inspection: 

SGS, BV, DNV, TUV, LR, ABS available

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 Lined Pipes – A106 Gr B Base – 3mm Lining – Weld Overlay Ends – Acid Service):

Stock Examples (Alloy 825 Lined Pipes – API 5L X52 Base – 4mm Lining – Weld Overlay Ends – NACE MR0175 – Sour Gas Service):

Stock Examples (Alloy 825 Lined Pipes – A333 Gr 6 Base – Low Temperature – 4mm Lining – Arctic Sour Service):

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