1. Product Attributes
| Grade |
Alloy 28 / INCOLOY 028 |
| UNS Designation |
N08028 |
| W.Nr. |
1.4563 |
| Common Trade Names |
Nic28, NiCro 31/27 |
| Type |
Seamless Pipe |
| Standards |
ASTM B668, ASME SB668, EN 10216-5 |
| Dimensional Standards |
ANSI B36.10 / B36.19 |
| Outer Diameter Range |
6 mm – 914 mm (24-inch NB) |
| Wall Thickness |
SCH 5, SCH 10, SCH 40, SCH 80, SCH 160 |
2. Material Overview
Alloy 28 (UNS N08028 / W.Nr. 1.4563) is a highly alloyed austenitic stainless steel specifically engineered for severely corrosive environments. Commonly marketed under trade names such as NiCro 31/27, this super-austenitic grade offers an exceptional combination of corrosion resistance and mechanical strength. The alloy features a high nickel content (30-34%) combined with substantial chromium (26-28%) and molybdenum (3-4%) additions, delivering outstanding resistance to strong oxidizing and reducing acids including sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, and formic acid. Alloy 28 seamless pipes are the preferred choice for high-pressure, leak-proof applications where welded alternatives cannot meet the required reliability standards.
3. Chemical Composition
| Element |
Content (wt%) |
| Nickel (Ni) |
30.0 – 34.0 |
| Chromium (Cr) |
26.0 – 28.0 |
| Molybdenum (Mo) |
3.0 – 4.0 |
| Copper (Cu) |
0.6 – 1.4 |
| Manganese (Mn) |
2.5 max |
| Silicon (Si) |
1.0 max |
| Carbon (C) |
0.03 max |
| Phosphorus (P) |
0.03 max |
| Sulfur (S) |
0.03 max |
| Iron (Fe) |
Remainder |
4. Physical Properties
| Property |
Value |
| Density |
8.0 g/cm³ |
| Melting Range |
1350°C – 1400°C (2462°F – 2552°F) |
| Specific Heat (20°C) |
~500 J/kg·K |
| Thermal Conductivity (20°C) |
~12.0 W/m·K |
| Electrical Resistivity (20°C) |
~1.0 μΩ·m |
| Modulus of Elasticity (20°C) |
~200 GPa |
| Magnetic Permeability |
< 1.01 (non-magnetic) |
5. Mechanical Properties
| Property |
Value (Annealed Condition) |
| Tensile Strength (Rm) |
500 MPa min |
| Yield Strength (Rp0.2) |
214 MPa min |
| Elongation (A%) |
40% min |
| Reduction of Area (Z%) |
50% min |
| Hardness |
HRC 33 max / HBW 300 max |
| Impact Toughness (Charpy-V, RT) |
≥ 100 J |
| Note: Alloy 28 may also be supplied in the cold-worked condition with yield strength exceeding 125 ksi (862 MPa) for demanding applications. |
6. Corrosion Resistance Comparison (CPT / CCT)
| Alloy Grade |
UNS |
PREN |
CPT (°C)* |
CCT (°C)** |
| Alloy 28 |
N08028 |
38 – 39 |
40 – 50 |
25 – 35 |
| 316L |
S31603 |
24 – 26 |
15 – 20 |
< 0 |
| 317L |
S31703 |
28 – 32 |
20 – 25 |
0 – 5 |
| 904L |
N08904 |
34 – 37 |
40 – 45 |
20 – 25 |
| 254 SMO |
S31254 |
42 – 44 |
70 – 80 |
40 – 50 |
| Alloy 625 |
N06625 |
46 – 52 |
> 85 |
> 60 |
| Alloy C-276 |
N10276 |
56 – 62 |
> 85 |
> 60 |
*CPT: Critical Pitting Temperature per ASTM G48 Method C (6% FeCl₃)
**CCT: Critical Crevice Temperature per ASTM G48 Method D
PREN = %Cr + 3.3(%Mo) + 16(%N) |
7. Material Characteristics
| Corrosion Resistance |
Excellent resistance to strong oxidizing and reducing acids including sulfuric, phosphoric, nitric, hydrochloric, and formic acids. Superior resistance to pitting corrosion, crevice corrosion, and stress corrosion cracking (SCC) in chloride-containing environments. Suitable for seawater piping and heat exchanger service. |
| High Temperature Resistance |
Not recommended for prolonged exposure above 593°C (1100°F) as this may result in embrittlement. Excellent oxidation resistance up to 1000°C (1832°F) under intermittent service conditions. |
| Cryogenic Performance |
Maintains excellent toughness and ductility at cryogenic temperatures. No ductile-to-brittle transition, making it suitable for LNG and low-temperature applications. |
| Heat Treatment |
Cannot be strengthened by heat treatment. Annealing performed at 1093°C – 1149°C (2000°F – 2100°F), followed by rapid cooling in water or air to achieve optimal corrosion resistance and stress corrosion cracking resistance. |
| Cold Workability |
Can be cold formed successfully. Has a moderately high work hardening rate, so intermediate annealing may be required during severe forming. Annealing after cold or hot forming is recommended to restore optimal properties. |
| Weldability |
Excellent weldability using standard processes (GTAW/TIG, GMAW/MIG, SMAW). Recommended filler metal: ERNiCrMo-3 or matching composition. Post-weld heat treatment is generally not required but may be applied for stress relief. |
| Seamless Construction Advantage |
Seamless pipe eliminates the weld seam — the weakest point in welded pipe. Provides uniform grain structure, superior pressure containment, and enhanced reliability in cyclic thermal and pressure service. The preferred choice for critical, high-pressure, and severely corrosive applications. |
8. Product Image Showcase
9. Supply Forms
| Product Form |
Specification |
| Seamless Pipe |
OD 6 mm – 914 mm, WT SCH 5 to SCH 160 |
| Seamless Tube |
OD 3 mm – 114 mm, WT 0.5 mm – 15 mm |
| Welded Pipe |
OD 12.7 mm – 2540 mm, WT 1.0 mm – 50 mm |
| 'U' Bent Tube |
Per customer specifications and TEMA standards |
| Fabricated Pipe |
Custom lengths, beveled ends, threaded ends |
| Hollow Bar |
OD 32 mm – 250 mm, for machining components |
10. Typical Applications
| Industry |
Application |
| Chemical Processing |
Acid handling systems, reactors, heat exchangers, and transfer piping for phosphoric acid, sulfuric acid, nitric acid, and mixed acid services |
| Oil & Gas |
Downhole tubing, sour service production equipment, offshore platform piping, subsea flowlines |
| Pollution Control |
Flue gas desulfurization (FGD) systems, wet scrubbers, stack liners |
| Marine Engineering |
Seawater cooling systems, desalination plants, ballast water systems, heat exchangers in high-chloride environments |
| Petrochemical |
Process piping for aggressive chemical media, catalytic reformer tubes |
| Pharmaceutical |
High-purity process piping, reactor vessels |
| Pulp & Paper |
Bleaching equipment, digesters, chemical recovery systems |
| Nuclear Power |
Component cooling water systems, auxiliary piping |
11. DINGSCO — Professional Nickel Alloy Manufacturer
DINGSCO — PROFESSIONAL NICKEL ALLOY MANUFACTURER
QUALITY ASSURANCE: Our mission is to provide our customers only with the best quality products. As an ISO 9001:2015, PED 2014/68/EC, and API 6A certified manufacturer, we enforce strict quality control at every production stage — from raw material selection and melting through forging, rolling, heat treatment, and final inspection. Each shipment is accompanied by comprehensive mill test certificates (MTC) per EN 10204 3.1, with EN 10204 3.2 upon request via third-party inspection (TUV, SGS, Bureau Veritas, Lloyd's Register).
SCIENCE AND TECHNOLOGY INNOVATION STRATEGY: We pay close attention to customer needs and implement continuous product innovation. By leveraging our full range of product types and material grades, we provide customers with one-stop service solutions. Our commitment to continuous improvement drives material, process, and equipment optimization across all production lines.
COOPERATION: We are pleased to help others and glad to extend a helping hand. We actively participate in team collaboration and support collective decision-making. We share our experience with each other and excel at cooperating with different types of colleagues and partners worldwide.
ISO 9001:2015 PED 2014/68/EC API 6A EN 10204 3.1 / 3.2
12. Material Selection — Alternative Nickel Alloy Grades
DINGSCO offers a comprehensive portfolio of nickel alloy seamless pipes and tubes. If Alloy 28 does not fully meet your specific requirements, please consider the following alternative grades:
| Alloy Grade |
UNS |
Key Feature |
Typical Application |
| Alloy 31 |
N08031 |
Higher Mo (6.0-7.0%), superior acid resistance |
FGD, phosphoric acid, chemical processing |
| Alloy 825 |
N08825 |
Good general corrosion resistance, lower cost |
Chemical processing, oil & gas, marine |
| Alloy 625 |
N06625 |
Exceptional strength and corrosion resistance |
Aerospace, marine, nuclear, chemical |
| Alloy C-276 |
N10276 |
Universal corrosion resistance, best for severe acids |
Chemical, pollution control, waste treatment |
| Alloy 400 |
N04400 |
Excellent seawater and HF acid resistance |
Marine, chemical, hydrocarbon processing |
| Alloy K-500 |
N05500 |
Age-hardenable, high strength + corrosion resistance |
Marine shafts, pump shafts, fasteners |
| 254 SMO |
S31254 |
High Mo super-austenitic, excellent pitting resistance |
Seawater, chemical, pulp & paper |
| 904L |
N08904 |
Good acid resistance, cost-effective option |
Chemical processing, heat exchangers |
13. Customized Products
At DINGSCO, we understand that every project has unique requirements. We offer extensive customization capabilities to deliver nickel alloy pipes precisely matched to your specifications:
| Customization Option |
Available Capabilities |
| Custom Dimensions |
Non-standard OD, WT, and lengths manufactured to your engineering drawings |
| End Finishes |
Plain end, beveled end (30°/37.5°), threaded end (NPT/BSP), grooved end, flanged end |
| Surface Treatments |
Pickled & passivated, bright annealed, electropolished, shot blasted |
| Special Testing |
Ultrasonic testing (UT), eddy current testing (ET), hydrostatic testing, dye penetrant (PT), radiographic testing (RT), PMI, IGC per ASTM A262, ferrite content measurement |
| Special Packaging |
Wooden crates, steel frames, seaworthy packing, individual pipe wrapping, custom labeling & marking |
| Documentation |
MTC EN 10204 3.1/3.2, material certificates, test reports, NACE MR0175/ISO 15156 compliance, dual certification |
| Value-Added Services |
Cut-to-length, 'U' bending, heat treatment, positive material identification (PMI), third-party inspection coordination |
Payment & Shipping Terms
| Minimum Order Quantity: |
Negotiable |
| Price: |
Negotiable |
| Packaging Details: |
According to Customers' Requests |
| Delivery Time: |
(Sample Order) 7 days |
| Payment Terms: |
T/T |
| Supply Ability: |
Negotiable |
Contact DINGSCO today for a competitive quote on Alloy 28 UNS N08028 seamless pipes. Our technical team is ready to assist you with material selection, technical specifications, and custom requirements.
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