Alloy 20 Forged Fittings are made to ASTM B462 / ASME SB462 UNS N08020 for sulphuric acid service. Socket weld and threaded fittings are dimensioned to ASME B16.11 for small-bore Alloy 20 piping.
Raaj Fittings manufactures Alloy 20 forged fittings in-house at our two plants in India, from ⅛" to 4" in Class 2000 to 9000, 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 standard | ASME B16.11; MSS SP-79, SP-83, SP-95 and SP-97 |
| Size range | ⅛" to 4" NPS |
| Pressure class | Socket weld: Class 3000, 6000, 9000. Threaded: Class 2000, 3000, 6000 |
| Threads | NPT to ASME B1.20.1; BSPT / BSPP to BS 21 / ISO 7-1 |
| 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 |
In small-bore lines, the crevices of socket welds and threads are where corrosion starts. Alloy 20 forged fittings keep the same corrosion resistance as the run pipe at those points. Use matching filler for socket welds and an anti-seize sealant on threads, as nickel alloys gall easily.
| Pipe | Socket weld class | Threaded class |
|---|---|---|
| SCH 80 / XS | 3000 | 2000 |
| SCH 160 | 6000 | 3000 |
| XXS | 9000 | 6000 |
Every heat is PMI-verified and its chemistry and mechanical properties are confirmed against the material specification before the forged fittings 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.
Class 3000 socket weld fittings match SCH 80 pipe, Class 6000 matches SCH 160 and Class 9000 matches XXS. For threaded fittings, the matching classes are 2000, 3000 and 6000.
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.