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Inconel 625 Butt Weld Fittings | UNS N06625 SB-564
Inconel 625 butt weld fittings to ASME SB-564 and B16.9. UNS N06625 forged elbows, tees, reducers, caps and stub ends. DN15-DN600, seamless or plate-welded, EN 10204 3.1 MTC.
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Inconel 625 butt weld fittings (UNS N06625) are forged to ASME SB-564 and dimensioned to ASME B16.9. They are the standard high-strength, high-chloride-resistance fitting for offshore topside piping, subsea connectors, chemical injection lines and sour gas service, where 316L and even Duplex 2205 fall short on chloride pitting margin.
This page covers the alloy dimension. For the full range of butt weld fitting forms in any nickel alloy, see our nickel alloy butt weld fittings overview.
Specification
| Designation | Value |
|---|---|
| UNS number | N06625 |
| Material specification | ASME SB-564 (Nickel Alloy Forgings) |
| Dimensional standard | ASME B16.9 (butt welding fittings) |
| Material class | Nickel-chromium-molybdenum-columbium |
| Available grades | Grade 1 annealed / Grade 2 solution annealed |
Note on specifications: SB-564 is the correct ASME Section II specification for forged nickel alloy fittings. SA-182 covers low alloy and stainless steel only and does not include any nickel alloy grades.
Product Range
| Fitting | Types |
|---|---|
| Butt weld elbow | 45°, 90°, 180° / reducing |
| Butt weld tee | Equal and reducing, straight and branch |
| Butt weld cross | Equal and reducing |
| Butt weld reducer | Concentric and eccentric |
| Butt weld cap | Equal, standard and heavy |
| Stub end | For lap joint and RTJ flanges |
Dimensional Range
| Parameter | Range |
|---|---|
| Nominal size | DN15 – DN600 (NPS 1/2" – 24") |
| Wall thickness | SCH 5S, 10S, 40S, 80S, 160, XXS |
| Angle | 45° and 90° as standard; 11.25°/22.5°/135° on enquiry |
| Forming route | Seamless pushing (DN ≤ 600) or plate forming/welding (DN > 600 or non-standard) |
| Ends | Bevelled to ASME B16.25, plain ends optional |
Chemical Composition (ASME SB-564)
| Element | Composition, % | Element | Composition, % |
|---|---|---|---|
| Nickel | Remainder | Carbon | 0.10 max |
| Chromium | 21.5 min | Manganese | 0.50 max |
| Molybdenum | 8.0 min | Silicon | 0.50 max |
| Niobium (Cb) | 3.15 – 4.15 | Phosphorus | 0.015 max |
| Iron | 5.0 max | Sulfur | 0.015 max |
| Aluminium | 0.40 max | Cobalt (if determined) | 1.0 max |
Composition consistent with the N06625 limits of ASME SB-444 Table 2, which defines the same alloy.
Heat Treatment and Properties
| Condition | Tensile, min ksi (MPa) | Yield (0.2%), min ksi (MPa) | Elongation, min % |
|---|---|---|---|
| Grade 1, annealed | 120 (827) | 60 (414) | 30 |
| Grade 2, solution annealed | 100 (690) | 40 (276) | 30 |
Grade 1 is annealed at 871°C minimum; Grade 2 is solution annealed at 1093°C minimum, optionally followed by a stabilisation anneal at 982°C minimum to improve resistance to sensitisation. Grade 2 is normally used above 593°C where creep resistance is required.
Quality Control
- EN 10204 3.1 mill test certificate on every fitting
- Full chemical analysis by XRF or OES, actual heat values on the certificate
- Dye penetrant inspection on every fitting; ultrasonic testing on heavy wall and forgings
- Intergranular corrosion testing to ASTM G28 available on request
- Dimensional inspection against ASME B16.9, including wall thickness and centre-to-end dimensions
- Third-party inspection by Lloyd’s, BV, DNV, SGS or TUV on request
Surface, Marking and Packing
Fittings are supplied solution annealed and pickled, with a bright annealed or pickled surface as required. Each fitting carries heat number, grade, standard, size, heat treatment condition and our works mark. Export packing in wooden cases or steel pallets with plastic end caps; caps can be replaced on request.
Applications
- Offshore and subsea production piping, risers and flowline connectors
- Seawater lift, firewater and cooling water systems
- Chemical injection and hydraulic lines
- Sour gas gathering, amine and acid gas systems
- Chemical and pharmaceutical process piping
- Spray nozzles and downhole equipment
Related Products
- Nickel alloy butt weld fittings — all forms, all alloys
- Nickel alloy socket weld fittings — for small bore and high pressure
- Nickel alloy flanges — raised face, flat face and RTJ
- Nickel alloy pipe and tube — to match this fitting range
Technical Enquiries
Send the grade (1 or 2), fitting type, nominal size, schedule, quantity and any third-party inspection requirement to our technical sales desk. We will confirm dimensional tolerance, delivery condition and the applicable ASME line item, and quote FOB Shanghai or Ningbo.
Frequently Asked Questions
What is the difference between Grade 1 and Grade 2 fittings?
Grade 1 is annealed at 871°C or above with higher strength (120 ksi tensile, 60 ksi yield) and is generally used up to about 593°C. Grade 2 is solution annealed at 1093°C or above with lower strength but better creep and rupture resistance, normally used above 593°C.
Are these fittings suitable for sour service?
Yes. With 9% molybdenum and niobium stabilisation, 625 performs well in H2S-bearing environments. For very severe sour service we recommend confirming the requirement against NACE MR0175 / ISO 15156 hardness limits, which we can supply on request.
Are the fittings seamless or welded?
Both. DN15 to DN600 are normally supplied seamless, formed by pushing and pressing from seamless pipe or forged billet. Above DN600, or for non-standard sizes, we supply plate-formed and welded fittings to the same grade and heat treatment.
Can you supply fittings with NACE-compliant hardness?
Yes. We can supply hardness records and, where required, control hardness to the NACE MR0175 limits. State this on your enquiry so we quote the correct condition.
Do you supply EN 10204 3.1 certificates?
Yes, as standard on every fitting. Third-party inspection can be arranged with release applied before shipment.
