SS 321 Forged Fittings are made to ASTM A182 / ASME SA182 F321 for high-temperature refinery service. Socket weld and threaded fittings are dimensioned to ASME B16.11 for small-bore SS 321 piping.
Raaj Fittings manufactures SS 321 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 A182 / ASME SA182 F321 |
|---|---|
| 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 |
SS 321 is an 18-8 stainless steel stabilised with titanium. The titanium ties up carbon as titanium carbides, so chromium carbides cannot form at the grain boundaries when the steel is held between about 425 °C and 815 °C, the range where ordinary 304 becomes sensitised.
| Element, % | S32100 |
|---|---|
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 17.0 – 19.0 |
| Nickel (Ni) | 9.0 – 12.0 |
| Titanium (Ti) | 5 × (C + N) min, 0.70 max |
| Nitrogen (N) | 0.10 max |
| Property | SS 321 |
|---|---|
| Tensile strength, min. | 515 MPa (75 ksi) |
| Yield strength (0.2%), min. | 205 MPa (30 ksi) |
| Elongation in 50 mm, min. | 30% |
| Reduction of area, min. | 50% |
| UNS | Werkstoff Nr. | EN / DIN | Other |
|---|---|---|---|
| S32100 | 1.4541 | X6CrNiTi18-10 | SUS 321 |
SS 321 socket weld and threaded fittings are forged from bar or billet, solution annealed and CNC machined. Use filler metal matched to the grade for socket welds, and an anti-seize sealant on stainless threads to prevent galling.
| 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.
Both are stabilised 18-8 grades: 321 uses titanium and 347 uses niobium (columbium). 347 is often preferred for welding because niobium is not lost in the arc, and 347 filler is used for both.
321 is chosen for long service between about 425 °C and 815 °C, where 304L would lose strength and 304 would sensitise. For ambient-temperature corrosion service, 304L is normally enough.
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 A182 F321. EN 10204 3.2 certification and inspection by your nominated third-party agency are available on request.