Alloy 20 Pipe & Tube | UNS N08020 Sulfuric Acid Grade

Alloy 20 (UNS N08020) Pipe & Tube is a niobium stabilised nickel iron chromium alloy which has been developed for sulfuric acid service where 304 and 316 stainless steel corrode too rapidly to be economic. The addition of niobium locks carbon and prevents intergranular attack, which would occur after welding, and resistance for a broad range of concentrations and temperatures is achieved in sulfuric acid with a composition of about 34 per cent nickel, 3 to 4 per cent copper and 2 to 3 per cent molybdenum. It is delivered in the “stabilize annealed” condition with a minimum tensile strength of 551 MPa (80 ksi) and a minimum yield of 241 MPa (35 ksi). USA Piping Solution offers Alloy 20 seamless pipe and tube, welded pipe to ASTM B464 and welded tube to ASTM B468 with each heat delivered with an EN 10204 3.1 mill test certificate and ASTM A262 Practice E intergranular corrosion test.

Request a Quote on Alloy 20 (UNS N08020) Pipe & Tube →

Specifications of Alloy 20 UNS N08020 Pipes & Tubes

Specification Feature	Technical Details & Standard Compliance
Material Grade	Alloy 20 / UNS N08020 / W.Nr. 2.4660 / Carpenter 20 / 20Cb-3
Governing Specifications	• Seamless Pipe & Tube: ASTM B729 / ASME SB729 • Welded Pipe: ASTM B464 / ASME SB464 • Welded Tube: ASTM B468 / ASME SB468 • Flanges & Forged Fittings: ASTM B462 / ASME SB462 • Wrought Fittings: ASTM B366 / ASME SB366
Applicable Standards	ASTM, ASME, EN, DIN, ISO
Supply / Heat Treat Condition	Stabilized annealed at 1700 °F to 1850 °F (927 °C to 1010 °C) followed by rapid cooling in air or water
Manufacturing Types	• Seamless: Cold drawn, cold worked, and stabilized annealed • Welded: Automatic electric arc welded, cold worked to size, and stabilized annealed
Pipe Size Range	1/8 in NB to 12 in NB (Outside Diameter: 10.29 mm to 323.8 mm)
Tube Size Range	1/8 in OD to 4 in OD (Outside Diameter: 3.18 mm to 101.6 mm)
Tube Wall Thickness	0.028 in to 0.220 in (0.71 mm to 5.58 mm) / SWG 22 to SWG 10 (Custom heavy wall thicknesses available)
Pipe Schedule Range	SCH 5S, SCH 10S, SCH 40S (STD), SCH 80S (XS), SCH 160, SCH XXS (per ASME B36.19M / B36.10M)
Density (for Weight Calculations)	8.08 g/cm³ (0.292 lb/in³) — Note: Do not use carbon steel multiplier (7.85 g/cm³)
Available Product Forms	Round Straight Pipes/Tubes, U-Bend Heat Exchanger Tubes, Coiled Tubing, Pancake Coils
Pipe & Tube End Finish	Plain End (PE), Beveled End (BE for welding), Threaded (NPT / BSPT)
Surface Finish Conditions	Annealed & Pickled (AP), Bright Annealed (BA), Mechanical Polish (180 / 240 / 320 Grit ID & OD)
Length Options	Single Random (5 m to 7 m), Double Random (11 m to 13 m), Cut-to-Length
Mandatory ASTM B729 Tests	• Non-Destructive: Eddy Current Testing or Hydrostatic Testing • Mechanical: Tensile Test, Flattening Test, Flaring Test • Metallurgical: Grain size determination, Intergranular corrosion test (ASTM A262 Practice E)
Quality & Test Certificates	• EN 10204 3.1 Mill Test Certificate (MTC) • EN 10204 3.2 Third-Party Inspection (TPI) Report (SGS, BV, TÜV on request) • Positive Material Identification (PMI) Report • 100% Radiography Test Report (for welded pipes) • Raw Material Melt Origin Certificate
Specialized Product Scope	Shell & Tube Heat Exchanger Tubes, Condenser Tubes, Instrumentation Tubing, Heavy Wall Sulfuric Acid Transfer Piping

Chemical Compositions of Alloy 20 UNS N08020 Pipes & Tubes

Element	Nickel (Ni)	Chromium (Cr)	Copper (Cu)	Molybdenum (Mo)	Niobium (Cb)+Ta	Carbon (C)	Manganese (Mn)	Silicon (Si)	Phosphorus (P)	Sulfur (S)	Iron (Fe)
Composition (%)	32.00–38.00	19.00–21.00	3.00–4.00	2.00–3.00	8×C min – 1.00 max	0.07 max	2.00 max	1.00 max	0.045 max	0.035 max	29.50 min (Bal)

Alloy 20 UNS N08020 Pipes & Tubes Mechanical Properties

Property	Tensile Strength, min	Yield Strength (0.2% Offset), min	Elongation in 50 mm, min	Hardness (Typical)	Supply Condition
Value	551 MPa (80 ksi)	241 MPa (35 ksi)	30.0%	80–90 HRB	Stabilize Annealed

Physical Properties of UNS N08020 Pipes & Tubes

System	Density	Melting Range	Specific Heat (70°F/21°C)	Electrical Resistivity	Thermal Conductivity (70°F/21°C)	Modulus of Elasticity (Tension)	Poisson's Ratio
Imperial	0.292 lb/in³	2600 °F - 2630 °F	0.12 Btu/lb⋅°F	650 Ohm-cir mil/ft	8.4 Btu⋅ft/ft²⋅h⋅°F	28.0 × 10⁶ psi	0.31
Metric	8.08 g/cm³	1427 °C - 1443 °C	502 J/kg⋅°C	1.08 µΩ⋅m	14.5 W/m⋅K	193 GPa	0.31

Equivalent Grades of Alloy 20 UNS N08020 Pipes & Tubes

UNS	W.Nr.	DIN / EN Designation	Common Trade Names
N08020	2.4660	NiCr20CuMo	Alloy 20 / Carpenter 20 / 20Cb-3

Dimensions Chart of Alloy 20 UNS N08020 Pipes & Tubes

Nominal Pipe Size (NPS)	Outside Diameter (OD)	SCH 10S Wall (in / mm)	SCH 10S Weight (lb/ft / kg/m)	SCH 40S Wall (in / mm)	SCH 40S Weight (lb/ft / kg/m)	SCH 80S Wall (in / mm)	SCH 80S Weight (lb/ft / kg/m)
1/2"	0.840" (21.3 mm)	0.083" (2.11 mm)	0.67 lb/ft (1.00 kg/m)	0.109" (2.77 mm)	0.85 lb/ft (1.27 kg/m)	0.147" (3.73 mm)	1.09 lb/ft (1.62 kg/m)
3/4"	1.050" (26.7 mm)	0.083" (2.11 mm)	0.86 lb/ft (1.28 kg/m)	0.113" (2.87 mm)	1.13 lb/ft (1.69 kg/m)	0.154" (3.91 mm)	1.48 lb/ft (2.20 kg/m)
1"	1.315" (33.4 mm)	0.109" (2.77 mm)	1.41 lb/ft (2.10 kg/m)	0.133" (3.38 mm)	1.68 lb/ft (2.50 kg/m)	0.179" (4.55 mm)	2.17 lb/ft (3.23 kg/m)
1-1/4"	1.660" (42.2 mm)	0.109" (2.77 mm)	1.81 lb/ft (2.70 kg/m)	0.140" (3.56 mm)	2.28 lb/ft (3.40 kg/m)	0.191" (4.85 mm)	3.00 lb/ft (4.47 kg/m)
1-1/2"	1.900" (48.3 mm)	0.109" (2.77 mm)	2.09 lb/ft (3.11 kg/m)	0.145" (3.68 mm)	2.72 lb/ft (4.05 kg/m)	0.200" (5.08 mm)	3.63 lb/ft (5.41 kg/m)
2"	2.375" (60.3 mm)	0.109" (2.77 mm)	2.64 lb/ft (3.93 kg/m)	0.154" (3.91 mm)	3.66 lb/ft (5.45 kg/m)	0.218" (5.54 mm)	5.03 lb/ft (7.48 kg/m)
2-1/2"	2.875" (73.0 mm)	0.120" (3.05 mm)	3.53 lb/ft (5.26 kg/m)	0.203" (5.16 mm)	5.80 lb/ft (8.63 kg/m)	0.276" (7.01 mm)	7.67 lb/ft (11.41 kg/m)
3"	3.500" (88.9 mm)	0.120" (3.05 mm)	4.33 lb/ft (6.45 kg/m)	0.216" (5.49 mm)	7.58 lb/ft (11.28 kg/m)	0.300" (7.62 mm)	10.26 lb/ft (15.27 kg/m)
4"	4.500" (114.3 mm)	0.120" (3.05 mm)	5.61 lb/ft (8.36 kg/m)	0.237" (6.02 mm)	10.81 lb/ft (16.08 kg/m)	0.337" (8.56 mm)	14.99 lb/ft (22.31 kg/m)
6"	6.625" (168.3 mm)	0.134" (3.40 mm)	9.29 lb/ft (13.83 kg/m)	0.280" (7.11 mm)	19.01 lb/ft (28.29 kg/m)	0.432" (10.97 mm)	28.59 lb/ft (42.55 kg/m)
8"	8.625" (219.1 mm)	0.148" (3.76 mm)	13.38 lb/ft (19.92 kg/m)	0.322" (8.18 mm)	28.58 lb/ft (42.53 kg/m)	0.500" (12.70 mm)	43.43 lb/ft (64.63 kg/m)

Applications and Industrial Uses of Alloy 20 UNS N08020 Pipes & Tubes

Chemical Processing Industry
Fertilizer Manufacturing Plants
Petrochemical Industry
Pharmaceutical Industry
Food & Beverage Processing Industry
Heat Exchanger and Condenser Systems
Pulp & Paper Industry
Marine & Offshore Processing Systems

Frequently Asked Questions

1. What are Alloy 20 UNS N08020 Pipes & Tubes?

Alloy 20 UNS N08020 Pipes & Tubes are nickel-iron-chromium alloy products designed to provide excellent resistance to sulfuric acid, chlorides, and other corrosive chemicals.

2. What is Alloy 20 UNS N08020 used for?

They are widely used in chemical processing, fertilizer plants, pharmaceutical manufacturing, food processing, petrochemical industries, and heat exchangers.

3. What is the difference between Alloy 20 and Stainless Steel 316L?

Alloy 20 offers better resistance to sulfuric acid, chlorides, and stress corrosion cracking than Stainless Steel 316L, making it suitable for more aggressive chemical environments.

4. Is Alloy 20 resistant to sulfuric acid?

Yes. Alloy 20 is specifically developed to provide excellent resistance to sulfuric acid across a wide range of concentrations.

5. Can Alloy 20 Pipes & Tubes be welded?

Yes. Alloy 20 Pipes & Tubes have good weldability and can be welded using standard welding procedures with compatible filler metals.

6. What is the maximum operating temperature of Alloy 20 Pipes & Tubes?

Alloy 20 is generally used at temperatures up to approximately 540°C (1000°F), depending on the application and service conditions.

7. Why is Alloy 20 stabilized with niobium?

Niobium binds carbon during welding, preventing chromium carbide formation and reducing the risk of intergranular corrosion. ASTM B729 requires niobium plus tantalum to be at least eight times the carbon content, with corrosion resistance verified by ASTM A262 Practice E testing.

Alloy 20 (UNS N08020) Pipe & Tube | ASTM B729 / ASME SB729 Supplier