Incoloy 028, also called Alloy 28, Sanicro 28, UNS N08028 or EN 1.4563, is a high alloy austenitic stainless steel engineered for aggressive sulfuric and phosphoric acid service that ordinary stainless grades cannot withstand. Its 27% chromium and 3.5% molybdenum content targets sulfuric and phosphoric acid specifically, not general atmospheric corrosion. XTD supplies it within its broader incoloy seamless tube range, alongside Incoloy 825, Incoloy 800 and Incoloy 925 grades.
Incoloy 028 Seamless Tube Manufacturer in China
Zhejiang Xintongda Special Steel (XTD) has produced nickel and stainless alloy tubes in Songyang County, Zhejiang, since 1985. The company is certified to ISO 9001, 14001, and 45001, and now has an annual production capacity of over 25,000 tons of nickel and stainless steel pipe and tube. Alloy 028, also known as UNS N08028, Alloy 28, Sanicro 28 or EN 1.4563, is a high alloy austenitic stainless steel with roughly 31% nickel, 27% chromium, 3.5% molybdenum and 1% copper. Engineers specify this incoloy tube where sulfuric and phosphoric acid rapidly attack ordinary stainless grades.
The governing standards are ASTM B668 and EN 10216-5. When you place purchase orders, refer to the following designations: UNS N08028, W.Nr. 1.4563, EN name X1NiCrMoCu31-27-4, ISO 4563-080-28-I, SS 2584, and AFNOR Z1NCDU31-27-03. XTD stocks material for dispatch within a week, production runs ship in 15 to 60 days, with a minimum order of 200 kg on non-stock sizes. Every heat is traceable back to raw material, so buyers moving off a failing 316L or 904L line get full documentation alongside the tube itself.
Product Specifications
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Standard
ASTM B668, EN 10216-5
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UNS Number
N08028
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W.Nr.
1.4563
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OD, Wall and Length
On request
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Alloy 028 Seamless Tube Manufacturing Process
Typically, billets undergo hot piercing to form the initial hollow shell, followed by cold pilgering or drawing to bring smaller diameters to the final wall thickness. Each tube then goes through solution annealing to stabilize the austenitic structure before pickling and dimensional finishing. Non-destructive testing confirms soundness ahead of packing. Visit the manufacturing process page for the complete production sequence XTD follows across its nickel alloy range.
Characteristics of Incoloy 028 Seamless Tube
UNS N08028 tube carries a low-carbon, copper-bearing composition built specifically for acid duty rather than general corrosion resistance.
- Chemical Composition: C ≤0.020%, Si ≤0.7%, Mn ≤2.0%, P ≤0.020%, S ≤0.010%, Cr 27%, Ni 31%, Mo 3.5%, Cu 1.0%, N ≤0.1%, remainder Fe.
- Corrosion Resistance: The alloy resists strong sulfuric and phosphoric acid, along with stress-corrosion cracking, intergranular attack, pitting and crevice corrosion in chloride-bearing media. This combination is why mills route the grade toward evaporators and heat exchangers where standard 316L or 904L tube reaches its limits.
- Mechanical Properties: Solution-annealed tube up to 20 mm wall gives Rp0.2 ≥220 MPa, Rp1.0 ≥250 MPa, tensile strength 550 to 750 MPa, elongation ≥40% and hardness ≤90 HRB. Above 20 mm wall, minimum Rp0.2 drops to 200 MPa and Rp1.0 to 230 MPa.
- Austenitic Structure and Stability: A stable austenitic matrix combined with carbon held below 0.020% limits sensitization risk, and every tube ships in the solution-annealed condition.
- Workability and Weldability: The grade forms and welds well with matched filler metal when handled in the solution-annealed state.
ASTM B668 Nickel Alloy Seamless Tube Tolerance
Dimensional tolerance on UNS N08028 tube follows ASTM B668 and the general requirements set out in ASTM B829, covering outside diameter, wall thickness, and straightness limits.
| Nominal outside diameter | OD tolerance | Wall thickness (to nominal wall) |
| up to 10 mm (0.400 in.) | ±0.10 mm (0.004 in.) | ±15% |
| over 10 to 16 mm (5/8 in.) | ±0.13 mm (0.005 in.) | ±15% |
| 16 to 38 mm (1½ in.) | ±0.19 mm (0.0075 in.) | ±10% |
| over 38 to 76 mm (3 in.) | ±0.25 mm (0.010 in.) | ±10% |
| over 76 to 114 mm (4½ in.) | ±0.38 mm (0.015 in.) | ±10% |
| over 114 to 152 mm (6 in.) | ±0.51 mm (0.020 in.) | ±12.5% |
| over 152 to 168 mm (6⅝ in.) | ±0.64 mm (0.025 in.) | ±12.5% |
| over 168 to 219 mm (8⅝ in.) | ±0.79 mm (0.031 in.) | ±12.5% |
| over 219 to 356 mm (14 in.) | +1.57 mm over, 0.79 mm under | +15% over, 12.5% under |
| over 356 to 610 mm (24 in.) | +3.18 mm over, 0.79 mm under | +15% over, 12.5% under |
Incoloy 028 (UNS N08028) Equivalent Material
UNS N08028 sits alongside several regional and mill designations for the same chemistry. EN 1.4563, EN name X1NiCrMoCu31-27-4, ISO 4563-080-28-I, SS 2584 and AFNOR Z1NCDU31-27-03 all describe this alloy 028 equivalent grade, alongside the trade names Alloy 28 and Sanicro 28.
| System | Designation |
| UNS | N08028 |
| EN / Werkstoff No. | 1.4563 |
| EN name | X1NiCrMoCu31-27-4 |
| DIN name | X1NiCrMoCuN31-27-4 |
| ISO | 4563-080-28-I |
| Swedish (SS) | 2584 |
| AFNOR (France) | Z1NCDU31-27-03 |
| Common trade names | Alloy 28, Sanicro 28 |
| Seamless pipe & tube standard | ASTM B668; EN 10216-5 |
Difference Between Incoloy 825 and Incoloy 028 (Alloy 28)
Both grades resist acid attack, yet their chemistries pull in different directions. Alloy 825 carries 1.5 to 3.0% copper against 1.0% in Alloy 28, while Alloy 28 runs higher in chromium and was developed specifically for wet-process phosphoric acid duty. The two grades differ across several elements, since 825 also carries more nickel and copper, so the better choice depends on the specific acid and operating conditions. Mechanical figures are not directly comparable either. N08028 values reflect specification minima, while N08825 figures reflect typical mill data, so neither grade should be called stronger on that basis alone. See the incoloy 825 seamless tube page for the full composition and property comparison.
| Property | Alloy 28 / Sanicro 28 (UNS N08028) | Incoloy 825 (UNS N08825) |
| UNS | N08028 | N08825 |
| EN / Werkstoff No. | 1.4563 | 2.4858 |
| Seamless tube standard | ASTM B668 | ASTM B423 / B163 |
| Density | 8.0 g/cm3 | 8.14 g/cm3 |
| Nickel | 31 | 38.0 to 46.0 |
| Chromium | 27 | 19.5 to 23.5 |
| Molybdenum | 3.5 | 2.5 to 3.5 |
| Copper | 1.0 | 1.5 to 3.0 |
| Iron | Balance | 22.0 min |
| Titanium | Not added | 0.6 to 1.2 |
| Carbon | 0.020 max | 0.05 max |
| Tensile strength Rm | 550 to 750 MPa (spec minimum basis) | 772 MPa (typical, annealed tubing) |
| 0.2% proof / yield | 220 MPa min | 441 MPa (typical) |
| Elongation | 40% min | 36% (typical) |
| Corrosion niche | Mill-developed for wet process phosphoric acid, also sulfuric acid | Reducing acids via high Ni and Cu, broad service plus oil and gas |
| Oil and gas | Sour (H2S), chloride service | Listed in NACE MR0175 |
Material Certification and Inspection Package
Every Incoloy 028 tube order ships with a documented inspection trail, giving buyers traceability from raw material through final dispatch.
- EN 10204 3.1 / 3.1B / 3.2 Material Test Certificates
- Raw Materials Certificate
- 100% Radiography Test Report
- 100% PMI (Positive Material Identification)
- Heat Treatment Charts
- Third Party Inspection Report
- Surface Roughness and Size Measurement Report
- Manufacturer Test Certificate covering impact, flattening, spin, curve, hardness, intergranular corrosion, pitting corrosion, grain size, ET, UT and HT
- Laboratory Test Certificate from a Government-Approved Lab
Application of Incoloy 028 Tube
Incoloy 028 tube earns its place in some of the harshest acid environments in process industries, replacing lower-alloy stainless where acid concentration or temperature pushes past their working limits.
Phosphoric Acid Evaporator Tubes
Alleima, the originator of the alloy, names N08028 among the most widely used metallic materials for evaporator tubes in wet-process phosphoric acid production.
Heat Exchangers and Condensers
Tube bundles handle aggressive acid and chloride media in condenser and heat exchanger service.
Sulfuric Acid Service
Cooling coils and process tubing run in sulfuric acid plants and mixed-acid duty. See our petrochemical application page.
Seawater and Chloride-Cooling Systems
Seawater-cooled exchangers benefit from the resistance of the grade to stress-corrosion cracking, pitting, and crevice attack. See our desalination application page.
Nuclear Power Heat Exchangers
Heat-exchanger tubing draws on the stress-corrosion cracking resistance of the alloy in nuclear applications. See our nuclear power application page.
Frequently Asked Questions
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What is Incoloy 028 (UNS N08028)?
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Can Xintongda Special Steel supply custom sizes of Incoloy 028 seamless tube?Zhejiang Xintongda Special Steel Manufacturing Co., Ltd produces N08028 tube outside its standard stock range on request. Incoloy 028 tube custom size orders cover non-standard outside diameter, wall thickness, and cut length beyond catalog dimensions, subject to a 200 kg minimum on production runs. Share your OD, WT, and length requirement, and the engineering team at XTD will confirm feasibility and lead time before quoting.
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Where can I buy Incoloy 028 tube?XTD sells Incoloy 028 tube directly from its Songyang County, Zhejiang facility, shipping worldwide with mill test certificates and full inspection documentation on every order. Incoloy 028 tube price depends on diameter, wall thickness, quantity, testing package, and delivery condition, so no fixed rate applies here. Send your specification and required standard to the sales team at XTD for a formal quote.
- Alloy 028 Seamless Tube Manufacturing Process
- Characteristics of Incoloy 028 Seamless Tube
- ASTM B668 Nickel Alloy Seamless Tube Tolerance
- Incoloy 028 (UNS N08028) Equivalent Material
- Difference Between Incoloy 825 and Incoloy 028 (Alloy 28)
- Material Certification and Inspection Package
- Application of Incoloy 028 Tube
- Frequently Asked Questions