Alloy 20 Pipes & Pipe Fitting

Alloy 20 Pipes & Pipe Fittings Supplier in Mumbai, India

Nicorex Alloys is an ISO 9001 and ISO 14001 certified supplier, importer, stockist, and trading company for Alloy 20 pipes and pipe fittings based in Mumbai, India. We supply seamless and welded pipes with matching buttweld fittings manufactured to ASTM B729, B464, B468, and B366.

Alloy 20 (UNS N08020 / 2.4660), also known as Carpenter 20 or Incoloy 20, is a nickel-iron-chromium austenitic alloy designed for sulfuric acid environments. Alloy 20 has a nickel content of 32-38%, a chromium content of 19-21%, a copper content of 3-4%, and a molybdenum content of 2-3%. In addition, the niobium stabilisation contains a minimum of 8%C up to 1.0%. This exceeds the composition requirements for conventional stainless steels. Copper content up to 4% helps form a protective film, while niobium stabilisation helps inhibit chromium carbide (Cr₂₃C₆) precipitation, which ensures resistance to intergranular corrosion in the as-welded condition. Alloy 20 has 32-38% nickel, which helps in reducing stress corrosion cracking in environments with chloride ions. The maximum tensile strength of this alloy is 551 MPa, i.e., 80 ksi, with a maximum yield strength of 241 MPa, i.e., 35 ksi, along with an elongation of 30% before failure. In addition, the non-magnetic properties provide toughness at subzero temperatures, with the ability to be used up to 315°C (600°F) in aqueous environments.

Seamless pipes are available to ASTM B729, welded pipes to B464/B775, tubes to B468, and fittings to B366 (buttweld). Alloy 20 exhibits excellent corrosion resistance. Mumbai’s stock of Alloy 20 comes with full EN 10204/3.1 certification to guarantee metallurgical integrity.

Specifications of Alloy 20 Pipes & Fittings

Alloy 20 pipe specifications are given in the following table that includes seamless and welded pipes and tubes, sizes, conditions and other required information:

Alloy 20 pipe specifications
Field	Details
Pipe & Tube Standards	ASTM B729, B464, B468 / ASME SB729, SB464, SB468
Size Range	NPS 1/2″ to 12″; OD 6.35-323.85 mm
Wall / Schedule	SCH 5S, 10S, 40S, 40, 80S, 80, 120, 160, XXS
Alloy 20 fitting specifications:
Field	Details
Fittings Standards	Buttweld Fittings: ASTM B366 / ASME SB366
Dimensions	ASME B16.9
Size	BW Size: NPS 1/2″ to 48″

Chemical Composition of Alloy 20 Pipe & Fitting

Refer to the table provided below for the composition of Alloy 20 (UNS Number N08020) as per ASTM B729, including the niobium stabilisation and copper additions.

Material / Element	Nickel (Ni)	Chromium (Cr)	Copper (Cu)	Molybdenum (Mo)	Niobium + Tantalum (Nb+Ta)	Carbon (C)	Manganese (Mn)	Silicon (Si)	Phosphorus (P)	Sulfur (S)	Iron (Fe)
Alloy 20 (N08020) %	32.0-38.0	19.0-21.0	3.0-4.0	2.0-3.0	8×C min to 1.00	0.07 max	2.00 max	1.00 max	0.045 max	0.035 max	Balance

Copper (3-4%) is the primary driver of sulfuric acid resistance, forming a protective copper sulphate film in H₂SO₄. Niobium stabilises carbon, preventing Cr₂₃C₆ precipitation at grain boundaries during welding. This feature maintains intergranular corrosion resistance when welded. High nickel content significantly improves resistance to chloride stress corrosion cracking compared to austenitic stainless steels such as 316L. Chromium (19-21%) covers oxidising acid (HNO₃) resistance. Molybdenum (2-3%) adds pitting and crevice corrosion protection.

Mechanical Properties of Alloy 20 Pipes & Fittings

Please refer to the mechanical properties of Alloy 20 pipe and fitting materials as per ASTM B729, specifically for the stabilised annealed condition.

Property	Tensile Strength (min)	Yield Strength 0.2% (min)	Elongation (min)	Hardness
Value	551 MPa (80 ksi)	241 MPa (35 ksi)	30%	≤95 HRB

Alloy 20 is fully austenitic and non-magnetic. Impact toughness remains excellent at sub-zero temperatures. The 30% elongation gives good formability for pipe bending and fitting fabrication.

Alloy 20 Equivalent Grades

Please refer to the table provided below to ensure compliance with international equivalent designations of Alloy 20 to be utilised for your project.

Property	UNS	Werkstoff Nr.	EN
Designation	S32760	1.4501	X2CrNiMoCuWN25-7-4

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Types of Alloy 20 Pipes & Fittings

Alloy 20 pipes are manufactured for piping systems handling sulfuric acid, mixed acids, and chloride-bearing chemical environments where austenitic stainless steels fail from SCC or acid attack.

Alloy 20 Seamless Pipe (ASTM B729)

Alloy 20 Welded Pipe (ASTM B464 / B775)

Alloy 20 Welded Tube (ASTM B468)

Alloy 20 ERW/EFW Pipe

Alloy 20 Elbow (45° / 90° / 180°)

Alloy 20 Tee (Equal / Reducing)

Alloy 20 Reducer (Concentric / Eccentric)

Alloy 20 Cap & Stub End

Industries Using Alloy 20 Pipes & Fittings

Alloy 20 is used widely in the following industries:

Storage tanks, pipes, heat exchangers, acid concentrators, dilution systems, and transfer lines for H₂SO₄. From contact process towers to distribution, they are used in sulphuric acid manufacturing.
Wet phosphoric acid piping, superphosphate production equipment, and ammonium sulphate process lines.
Mixed acid piping, organic chemical synthesis, and pharmaceutical reactors. Chloride-containing process streams eliminate the risk of SCC in 316L.
Acid gas scrubbing, amine treating, and sour water strippers.
Production of synthetic fibres (nylon, polyester) involves sulfuric acid and mixed acids.
Organic acid handling and food-grade piping for acidic food processing environments.
FGD scrubber piping and condensate piping in acid environments.

How to Order Alloy 20 Pipes & Fittings from Nicorex Alloys

To ensure a complete technical procurement request for Alloy 20, follow this numbered checklist:

Grade: (UNS N08020)
Size: (NPS or OD in mm)
Schedule: (Wall thickness or SCH rating)
Standard: (ASTM B729 for seamless or B464 for welded)
Length: (Single Random, Double Random, or Fixed)
Condition: (Stabilized-annealed)
Testing: (Hydrostatic, Eddy Current, or Ultrasonic)
Certification: (EN 10204 3.1 or 3.2)

Specify stabilised-annealed condition to confirm niobium has performed its carbide-stabilisation function. This is critical for welded acid piping where intergranular corrosion resistance must be guaranteed.

Frequently Asked Questions

What is Alloy 20 Pipe Used For?

Alloy 20 was designed for sulfuric acid service. It’s used in H₂SO₄ piping, phosphoric acid production, mixed acid chemical processing, pharmaceutical reactors, and any application requiring combined sulfuric acid resistance and chloride SCC immunity.

What is the Difference Between Alloy 20 and 904L Pipe?

Alloy 20 has higher Ni (32-38% vs 23-28%), higher Cu (3-4% vs 1-2%), and is Nb-stabilised. 904L is non-stabilised and lower cost. Alloy 20 is preferred for welded acid piping where Nb stabilisation eliminates PWHT need and higher nickel provides SCC immunity.

Why is Alloy 20 Pipe also called Carpenter 20 Pipe?

Alloy 20 was originally developed by Carpenter Technology Corporation for sulfuric acid service. The name Carpenter 20 persists as a common trade designation alongside the official UNS N08020.

What is the ASTM Standard for Alloy 20 Seamless Pipe?

ASTM B729 / ASME SB729 covers seamless N08020 pipe. Welded pipe: ASTM B464. Tube: B468. Fittings: B366.

What is the Maximum Temperature for Alloy 20 Pipe Fittings?

Alloy 20 is primarily designed for aqueous corrosion service at moderate temperatures, up to ~315°C (600°F). For continuous high-temperature service above 593°C, Incoloy 800H/HT or Inconel 600 are more appropriate.

What is the Price of Alloy 20 Pipe in India?

Alloy 20 is a premium alloy with a higher cost than 904L due to its greater nickel content. Contact Nicorex Alloys for current pricing and availability from Mumbai stock.