Inconel 625 forged fittings are socket weld and threaded fittings forged from Alloy 625 (UNS N06625) to ASTM B564 / ASME SB564 and machined to ASME B16.11. In small-bore lines, the crevices of socket welds and threads are where corrosion starts first; Alloy 625's very high resistance to pitting and crevice corrosion makes it the material of choice for instrument connections, drains and injection points in seawater, sour gas and acid service.
Raaj Fittings forges Alloy 625 elbows, tees, couplings, caps, plugs, bushings, unions and nipples in-house at our two plants in India, from ⅛" to 4" and in Class 2000 to 9000, for offshore, chemical and refinery projects across the Middle East, Europe and the Americas.
| Material specification | ASTM B564 / ASME SB564 UNS N06625 |
|---|---|
| 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 |
| Element, % | UNS N06625 |
|---|---|
| Nickel (Ni) | 58.0 min |
| Chromium (Cr) | 20.0 – 23.0 |
| Molybdenum (Mo) | 8.0 – 10.0 |
| Niobium + tantalum (Nb + Ta) | 3.15 – 4.15 |
| Iron (Fe) | 5.0 max |
| Carbon (C) | 0.10 max |
| Manganese (Mn) | 0.50 max |
| Silicon (Si) | 0.50 max |
| Phosphorus (P) | 0.015 max |
| Sulphur (S) | 0.015 max |
| Aluminium (Al) | 0.40 max |
| Titanium (Ti) | 0.40 max |
| Cobalt (Co) | 1.0 max |
| Property (min.), annealed | UNS N06625 |
|---|---|
| Tensile strength | 827 MPa (120 ksi) |
| Yield strength (0.2% offset) | 414 MPa (60 ksi) |
| Elongation | 30% |
| Grade | UNS | Werkstoff Nr. | EN / DIN designation | Common names |
|---|---|---|---|---|
| Alloy 625 | N06625 | 2.4856 | NiCr22Mo9Nb | Inconel® 625 |
Socket weld joints leave a small crevice between the pipe end and the socket, and threaded joints have crevices along every thread. In seawater or chloride service those crevices are where stainless and even duplex steels start to corrode. Alloy 625, with about 9% molybdenum and 21% chromium, resists crevice corrosion in ambient seawater, so 625 fittings are often specified for the small-bore branches of super duplex and 625-clad piping systems, and for chemical injection quills and sampling points.
| 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 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.
The material is forged to ASTM B564 / ASME SB564, UNS N06625, and the fittings are dimensioned and rated to ASME B16.11 for socket weld and threaded ends.
Socket welds and threads create crevices that trap fluid. In chloride or sour service, 316L and even duplex can corrode in those crevices, whereas Alloy 625 resists crevice corrosion in ambient seawater.
From ⅛" to 4" NPS to ASME B16.11, in socket weld Class 3000, 6000 and 9000 and threaded Class 2000, 3000 and 6000.
Yes. Alloy 625 is widely used in sour oil and gas service and can be supplied to NACE MR0175 / ISO 15156 when specified.