Alloy 20 Pipes & Tubes
ASTM B729 UNS N08020 Seamless and Welded Pipes for Sulfuric Acid Service
Stellar Alloys is the reliable manufacturer and supplier of the Alloy 20 pipe and offers pipes composed of ASTM B729 seamless and ASTM B464 welded pipes in the usage of the corrosive and acid service. Alloy 20 or UNS N08020 (commonly carpenter 20) is an alloy of nickel iron chromium that was designed to resist sulfuric acid environments.
Alloy 20 pipes and tubes are popular in chemical processing, fertilizer plants, pharmaceutical equipment, and petrochemical systems where pitting resistance, stress corrosion cracking, and intergranular attack are of high concern. We provide both seamless and welded Alloy 20 piping to all commonly used schedules and unusual sizes as needed in the project.
Having established sourcing, stringent quality control, and exporting strength worldwide, Stellar Alloys can serve as a good ally to industrial customers in need of quality Alloy 20 pipe products to serve in the challenging operating environments.
Table of Contents
- Alloy 20 Pipe Specification
- Product Range
- Alloy 20 Pipe Sizes & Dimensions
- Types of Alloy 20 Pipes
- Specification Chart of Alloy 20 Pipe
- Chemical Composition (UNS N08020)
- Mechanical Properties (ASTM B729 / B464)
- ASTM Scheduled Sizes & Dimensions
- Tolerance on Alloy 20 Pipes
- Alloy 20 Pipe Weight Chart (SCH 40)
- Ready Stock of Alloy 20 (UNS N08020) Tubing
- Industries & Applications
- Inspection & Test Reports
- Alloy 20 Pipe Price List
- Equivalent Material Grades
- Why Choose Stellar Alloys?
- Frequently Asked Questions for Alloy 20
Alloy 20 Pipe Specification
Parameter | Specification Details |
Product Material | Alloy 20 / Carpenter 20 |
UNS Number | UNS N08020 |
Werkstoff Number | 2.4660 |
Manufacturing Standards | ASTM B729 (Seamless), ASTM B464 (Welded), ASTM B468 (Tubing) |
ASME Standards | ASME SB 729, ASME SB 464, ASME SB 468 |
Product Forms | Seamless Pipe, Welded Pipe (ERW / EFW), Tubes, U-Tubes |
Size Range Seamless | 1/2″ NB to 12″ NB |
Size Range Welded | 1/2″ NB to 48″ NB |
Outside Diameter | 6.00 mm OD up to 914.40 mm OD |
Wall Thickness | 0.5 mm to 50 mm |
Schedules | SCH 5, SCH 10, SCH 40, SCH 80, SCH 80S, SCH 160, SCH XXS |
Length | Single Random, Double Random, Cut Length |
End Finish | Plain End, Beveled End, Threaded |
Surface Finish | Annealed & Pickled, Polished, Electropolished |
Dimensional Standards | ANSI B36.10, ANSI B36.19 |
Testing & Inspection | PMI, IGC, Hydrostatic, Eddy Current, Ultrasonic |
Certification | EN 10204 3.1 / 3.2, NACE MR0175 (on request) |
Typical Applications | Sulfuric Acid Processing, Chemical Plants, Fertilizer Units, Pharmaceutical Equipment |
Product Range
| Product Form | Specification | OD Range | Thickness |
| Alloy 20 Seamless Pipe | ASTM B729 / ASME SB 729 | 1/2″ NB to 12″ NB | SCH 10S to SCH XXS |
| Alloy 20 Welded Pipe | ASTM B464 / ASME SB 464 | 1/2″ NB to 48″ NB | SCH 5S to SCH 80S |
| Alloy 20 Welded Tube | ASTM B468 / ASME SB 468 | 6.35mm OD to 219mm OD | 0.5mm to 12.7mm |
| Alloy 20 Heat Exchanger Tube | ASTM B729 / B468 | 15.88mm to 50.8mm OD | 1mm to 3mm |
Alloy 20 Pipe Sizes & Dimensions
We offer a comprehensive range of dimensions in Alloy 20, adhering to ANSI/ASME B36.19 and B36.10 standards.
Seamless Pipe Sizes
| Product | Type |
| Size Range | 1/2″ NB to 12″ NB |
| Specifications | ASTM B729 / ASME SB 729 |
| Schedules | SCH 10, SCH 40, SCH 80, SCH 160, SCH XXS |
Welded (ERW/EFW) Pipe Sizes
| Size Range | 1/2″ NB to 48″ NB |
| Specifications | ASTM B464 / ASME SB 464 |
| Schedules | SCH 5S, SCH 10S, SCH 40S, SCH 80S |
U-Tube & Heat Exchanger Sizes
| Size Range | 1/2″ NB to 48″ NB |
|
OD Range |
15.88mm to 50.8mm |
|
Length |
Up to 30 Meters (Straight or U-Bend) |
Types of Alloy 20 Pipes
Our inventory includes a vast array of configurations to meet specific process requirements:
Alloy 20 Seamless Pipe
Alloy 20 Seamless Tubes
Alloy 20 Welded Pipes
Alloy 20 Welded Tubes
Alloy 20 ERW Pipes
Alloy 20 ERW Tubes
Specification Chart of Alloy 20 Pipe
| Specification | Description |
|
Thickness |
0.5mm – 50 mm, SCH 5, SCH10, SCH 40, SCH 80, SCH 80S, SCH 160, SCH XXS, SCH XS |
|
Outer Diameter |
6.00 mm OD up to 914.4 mm OD, Sizes up to 48” NB |
|
Type |
Seamless / ERW / Welded / Fabricated / CDW / LSAW |
|
Form |
Round Pipes, Square Pipes, Rectangular Pipes, Coiled Tubes, “U” Shape, Hydraulic Tubes |
|
Length |
Single Random, Double Random & Required Length |
|
End |
Plain End, Beveled End, Threaded |
|
Designation |
UNS N08020 / W.Nr. 2.4660 / Carpenter 20 |
Chemical Composition (UNS N08020)
|
Element |
Percentage (%) |
|
Nickel (Ni) |
32.0 – 38.0 |
|
Chromium (Cr) |
19.0 – 21.0 |
|
Iron (Fe) |
Balance |
|
Copper (Cu) |
3.0 – 4.0 |
|
Molybdenum (Mo) |
2.0 – 3.0 |
|
Niobium (Nb) + Tantalum (Ta) |
8 x Carbon – 1.0 |
|
Manganese (Mn) |
2.0 max |
|
Silicon (Si) |
1.0 max |
|
Carbon (C) |
0.07 max |
Mechanical Properties (ASTM B729 / B464)
|
Property |
Metric Units |
Imperial Units |
|
Tensile Strength (min) |
551 MPa |
80,000 psi |
|
Yield Strength 0.2% (min) |
241 MPa |
35,000 psi |
|
Elongation (min) |
30% |
30% |
|
Hardness (max) |
95 HRB |
– |
ASTM Scheduled Sizes & Dimensions
Dimensions and Wall Thickness for Alloy 20 Seamless Pipes acc. to ANSI B36.10 / B36.19.
|
Nominal Size (Inches) |
OD (mm) |
Wall Thickness (mm) |
|||
|
SCH 10S |
SCH 40S (Std) |
SCH 80S (XS) |
SCH 160 |
||
|
1/2″ |
21.34 |
2.11 |
2.77 |
3.73 |
4.78 |
|
3/4″ |
26.67 |
2.11 |
2.87 |
3.91 |
5.56 |
|
1″ |
33.40 |
2.77 |
3.38 |
4.55 |
6.35 |
|
1-1/4″ |
42.16 |
2.77 |
3.56 |
4.85 |
6.35 |
|
1-1/2″ |
48.26 |
2.77 |
3.68 |
5.08 |
7.14 |
|
2″ |
60.33 |
2.77 |
3.91 |
5.54 |
8.74 |
|
2-1/2″ |
73.03 |
3.05 |
5.16 |
7.01 |
9.53 |
|
3″ |
88.90 |
3.05 |
5.49 |
7.62 |
11.13 |
|
4″ |
114.30 |
3.05 |
6.02 |
8.56 |
13.49 |
|
6″ |
168.28 |
3.40 |
7.11 |
10.97 |
18.26 |
|
8″ |
219.08 |
3.76 |
8.18 |
12.70 |
23.01 |
|
10″ |
273.05 |
4.19 |
9.27 |
12.70 |
28.58 |
|
12″ |
323.85 |
4.57 |
9.53 |
12.70 |
33.32 |
Tolerance on Alloy 20 Pipes
Diameter Tolerance
NPS Size | OD Tolerance (Over) | OD Tolerance (Under) |
1/8 to 1-1/2 | 1/64″ (0.4 mm) | 1/32″ (0.8 mm) |
1-1/2 to 4 | 1/32″ (0.8 mm) | 1/32″ (0.8 mm) |
4 to 8 | 1/16″ (1.6 mm) | 1/32″ (0.8 mm) |
8 to 18 | 3/32″ (2.4 mm) | 1/32″ (0.8 mm) |
Wall Thickness Tolerance
Minimum wall thickness at any point shall not be more than 12.5% under the nominal wall thickness specified.
Alloy 20 Pipe Weight Chart (SCH 40)
Approximate weights for UNS N08020 pipe based on density of 8.08 g/cm³.
NPS Size | OD (mm) | Wall (mm) | Weight (kg/m) |
1/2″ | 21.34 | 2.77 | 1.29 |
3/4″ | 26.67 | 2.87 | 1.71 |
1″ | 33.40 | 3.38 | 2.53 |
1-1/2″ | 48.26 | 3.68 | 4.10 |
2″ | 60.33 | 3.91 | 5.51 |
3″ | 88.90 | 5.49 | 11.44 |
4″ | 114.30 | 6.02 | 16.27 |
6″ | 168.28 | 7.11 | 28.61 |
8″ | 219.08 | 8.18 | 43.08 |
10″ | 273.05 | 9.27 | 61.06 |
12″ | 323.85 | 9.53 | 74.79 |
Ready Stock of Alloy 20 (UNS N08020) Tubing
We maintain a vast inventory of common sizes for immediate dispatch.
- ASTM B729 Alloy 20 Electropolished Tubing
- Alloy 20 Square Tubing
- Werkstoff 2.4660 Tubing
- Alloy UNS N08020 12mm Tube
- UNS N08020 High Pressure Tube
- Carpenter 20 Electropolished Tubes
- Alloy 20 Hydraulic Tubing
- ASTM B468 Alloy 20 ERW Tube
- Alloy 20 Rectangular Tubing
- Alloy 20 Capillary Tubing
- Alloy 20 Seamless Pipe
- Alloy 20 Welded Pipe (ERW)
- Alloy 20 EFW Pipe
- Carpenter 20 Seamless Tube
- UNS N08020 Heat Exchanger Tube
- Alloy 20 Rectangular Pipe
- Alloy 20 Square Pipe
- Alloy 20 Instrumentation Tubing
- Alloy 20 Cold Drawn Seamless Pipe
- Alloy 20 Hot Finished Pipe
- Alloy 20 Polished Pipe
- Alloy 20 Electropolished Tube
- Alloy 20 Capillary Tube
- Alloy 20 High Pressure Pipe
- Werkstoff 2.4660 Pipe
- ASTM B729 UNS N08020 Pipe
- ASTM B468 Welded Tube
- Alloy 20 U-Tube
- Annealed & Pickled Alloy 20 Pipe
- Alloy 20 Condenser Tube
Industries & Applications
- Chemical Processing: Manufacturing of sulfuric acid, phosphoric acid, and nitric acid. Process piping for mixing tanks and heat exchangers.
- Food & Pharmaceutical: Processing equipment where contamination must be minimized. Alloy 20 is resistant to organic acids and sterilization chemicals.
- Petrochemical: Alkylation units using hydrofluoric acid (HF) and sulfuric acid catalysts. Heat exchangers and transfer piping.
- Pickling Operations: Heating coils, tanks, and racks in steel pickling baths containing sulfuric and hydrochloric acid mixtures.
Inspection & Test Reports
Stellar Alloys ensures complete transparency and quality assurance. Every Alloy 20 order is accompanied by:
- Mill Test Certificates (MTC) acc. to EN 10204 3.1
- EN 10204 3.2 Third Party Inspection Reports
- Intergranular Corrosion Test (IGC) Reports
- Positive Material Identification (PMI) Report
- Visual Inspection Reports
- Destructive Test Reports (Tensile, Hardness, Flattening, Flaring)
- Non-Destructive Test Reports (Eddy Current, Hydrostatic, Ultrasonic)
- NACE MR0175 Compliance Certificate
Nickel Alloy Pipe Price List
Prices for Alloy 20 are subject to nickel, chromium, and molybdenum market fluctuations. Below is an indicative reference.
Product | Size | Price Estimate |
Alloy 20 Seamless Pipe | 1/2″ SCH 40 | |
Carpenter 20 Welded Pipe | 2″ SCH 10 | |
UNS N08020 Tubing | 19.05mm x 1.65mm |
Equivalent Material Grades
Standard | Grade / Designation |
UNS (Unified Numbering System) | N08020 |
Werkstoff Nr. (Germany) | 2.4660 |
DIN (Germany) | NiCr20CuMo |
AFNOR (France) | Z2NCUD31-20AZ |
Common Name | Alloy 20, Carpenter 20, 20Cb-3 |
Why Choose Stellar Alloys?
Stellar Alloys is a specialist in acid-resistant piping.
- Specialized Inventory: We stock hard-to-find Alloy 20 sizes for quick turnaround.
- Quality Verified: 100% PMI and IGC testing on critical orders.
- Global Logistics: Expertise in export packaging and shipping to over 40 countries.
- Technical Support: Guidance on sulfuric acid concentration limits and temperature ranges.
Related Links
Frequently Asked Questions for Alloy 20
Alloy 20 is primarily designed for sulfuric acid service. It resists pitting and chloride corrosion and is often used in mixing tanks, heat exchangers, and process piping where 316 stainless steel fails.
It straddles the line. While technically a “super austenitic stainless steel” due to its iron content, it is often grouped with nickel alloys (like Incoloy 825) because of its high nickel (32-38%) performance characteristics.
ASTM B729 covers seamless pipe and tube, whereas ASTM B464 covers welded pipe. Seamless is preferred for high pressure; welded is cost-effective for larger diameters.
Yes, Alloy 20 has excellent weldability. The niobium stabilization prevents carbide precipitation, allowing it to be used in the as-welded condition in many environments. Matching filler metal (ER320LR) is typically used.
Carpenter 20 is a proprietary trade name for Alloy 20 (UNS N08020). They refer to the same chemical composition and material properties.
Alloy 20 is significantly superior to 316 SS in sulfuric, phosphoric, and nitric acids, and offers much better resistance to stress-corrosion cracking due to its higher nickel content.
Alloy 20 performs well up to approximately 1000°F (538°C). However, it is most commonly used for liquid phase chemical processing below 300°F (150°C).
Yes, Intergranular Corrosion (IGC) testing (ASTM A262 Practice E) is commonly performed on Alloy 20 to ensure the quality of the material, especially for welded pipes.