Alloy 20 Flanges are made to ASTM B462 / ASME SB462 UNS N08020 for sulphuric acid service. They are supplied in every common flange type and facing to ASME B16.5, B16.47 and the main EN, DIN, BS and JIS standards.
Raaj Fittings manufactures Alloy 20 flanges in-house at our two plants in India, from ½" to 60" and in Class 150 to Class 2500, and exports them to EPC contractors, fabricators and stockists across the Middle East, Europe and the Americas, with full traceability and EN 10204 certificates.
| Material specification | ASTM B462 / ASME SB462 UNS N08020 |
|---|---|
| Dimensional standards | ASME B16.5 (½" to 24"), ASME B16.47 Series A and B (26" to 60"), EN 1092-1, DIN, BS 4504, JIS B2220 |
| Pressure class | ASME Class 150, 300, 600, 900, 1500 and 2500; PN 6 to PN 400 |
| Facing | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Male & Female, Tongue & Groove |
| Certification | EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 on request |
Alloy 20 (UNS N08020) is a nickel-iron-chromium alloy with copper and molybdenum, stabilised with niobium. It was developed specifically for sulphuric acid service and is often called "Carpenter 20" or "20Cb-3".
| Element, % | N08020 |
|---|---|
| Carbon (C) | 0.07 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulphur (S) | 0.035 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 19.0 – 21.0 |
| Nickel (Ni) | 32.0 – 38.0 |
| Molybdenum (Mo) | 2.0 – 3.0 |
| Copper (Cu) | 3.0 – 4.0 |
| Niobium + tantalum (Nb + Ta) | 8 × C min, 1.00 max |
| Property | Alloy 20 |
|---|---|
| Tensile strength, min. | 551 MPa (80 ksi) |
| Yield strength (0.2%), min. | 241 MPa (35 ksi) |
| Elongation, min. | 30% |
| UNS | Werkstoff Nr. | EN / DIN | Other |
|---|---|---|---|
| N08020 | 2.4660 | NiCr20CuMo | Carpenter® 20Cb-3 |
Nickel alloy flanges are forged from certified bar or billet and machined; their high cost means flange type and facing should be chosen carefully, and lap joint flanges with Alloy 20 stub ends are sometimes used to save material.
Every heat is PMI-verified and its chemistry and mechanical properties are confirmed against the material specification before the flanges are released. Each piece is marked with grade, size, rating and heat number for traceability to its EN 10204 3.1 mill test certificate. EN 10204 3.2 certification and inspection by the buyer's nominated third-party agency are available on request, as are PED 2014/68/EU compliance for European projects and IBR certification for Indian boiler applications.
Alloy 20 was designed for sulphuric acid and is widely used in acid production, pickling, chemical and pharmaceutical plants where stainless steels would corrode.
Carpenter 20Cb-3 is a trade name for UNS N08020. Fittings are supplied to the ASTM specifications for N08020.
We make Alloy 20 Flanges from ½" to 24" to ASME B16.5 and from 26" to 60" to ASME B16.47 Series A and B, in Class 150 to 2500, and to EN 1092-1, DIN, BS and JIS standards in PN ratings.
Every order is supplied with EN 10204 3.1 mill test certificates showing heat chemistry and mechanical properties to ASTM B462 UNS N08020. EN 10204 3.2 certification and inspection by your nominated third-party agency are available on request.