Inconel 625 Tube Fittings (UNS N06625)
Inconel 625 tube fittings are mechanical-grip compression fittings, machined from nickel alloy 625 (UNS N06625). One or two ferrules swage onto the tube's outside diameter, producing a leak-tight, gas-tight seal along with a firm grip on the tube itself. That combination suits aggressive, sour, and high-temperature instrumentation work. Crestflo carries these fittings from 1/8-inch up through 2-inch (50 mm) tube OD, in both single and double (twin) ferrule versions. They're qualified to ASTM F1387 and offered to NACE MR0175 / ISO 15156 for sour service applications. Standard items ship from stock; specials are built to order, with delivery running 6-8 weeks. Request a quote to price out your configuration.
What Inconel 625 Compression Tube Fittings Are
An Inconel 625 compression tube fitting is built for fluid-system instrumentation work: a body, a nut, and one or two ferrules that bite into the tube's outer diameter as the nut gets torqued down. What results is a joint you can take apart and reassemble without losing integrity. No flaring, no welding, no rubber seal needed. The seal itself is metal-to-metal, so the joint's temperature ceiling comes from the alloy, not from some O-ring giving out first.
Let's be clear on scope. These are instrumentation compression tube fittings in alloy 625, not plumbing pipe fittings, and not electrical wire ferrules. They tie into small-bore instrument tubing on analyzers, transmitters, sample lines, hydraulic controls, and process taps, wherever corrosion, H₂S, or temperature push standard stainless steel out of the running.
Also Known As: Alloy 625, N06625, Werkstoff 2.4856
Buyers and specifiers use several names for this alloy, but they all point to the same Ni-Cr-Mo-Nb material. "Inconel® 625" is a trademarked designation. "Alloy 625" and "625" are the common generic forms. The material is registered as UNS N06625 and Werkstoff 2.4856 (NiCr22Mo9Nb). You'll also see it under trade names like Nicrofer 6020, Chronin 625, and Altemp 625. Its wrought feedstock forms fall under the nickel-alloy specifications ASTM/ASME B446 (bar and rod) and B443 (plate, sheet, and strip).
| Designation type | Value |
|---|---|
| Common names | Inconel 625, Alloy 625, 625 |
| UNS number | N06625 |
| Werkstoff / EN | 2.4856 (NiCr22Mo9Nb) |
| Other trade names | Nicrofer 6020, Chronin 625, Altemp 625 |
| Wrought feedstock specifications | ASTM/ASME B446 (bar), B443 (plate) |
Because these names all point to the same product, asking for "alloy 625 tube fittings," "N06625 fittings," or "2.4856 fittings" gets you exactly what's described on this page. The terms are interchangeable.
Why Choose Inconel 625 for Instrumentation Tube Fittings
Inconel 625 is a nickel-chromium-molybdenum alloy strengthened through solid solution, with niobium added to the mix. Molybdenum and chromium content run high, and that's what gives the material strong resistance to chloride-ion pitting, crevice corrosion, and stress-corrosion cracking. The nickel base, meanwhile, holds up against reducing acids and sulfide, or sour, environments. Strength doesn't drop off much at elevated temperature either. That combination is why engineers specify 625 for seawater and marine hardware, flue-gas and scrubber service, subsea and offshore controls, and sour hydrocarbon systems, cases where 316 stainless simply isn't enough.
For the full metallurgical picture, composition, mechanical properties, PREN, corrosion-by-media data, and grade selection, see the Inconel 625 alloy grade page. We've summarized the reference composition below for convenience when writing specs. The values follow the applicable alloy standard, and Crestflo can customize them to your requirement.
| Element | Nominal % (UNS N06625) |
|---|---|
| Nickel (Ni) | ≥ 58 |
| Chromium (Cr) | 20.0–23.0 |
| Molybdenum (Mo) | 8.0–10.0 |
| Niobium + Tantalum (Nb+Ta) | 3.15–4.15 |
| Iron (Fe) | ≤ 5.0 |
| Cobalt (Co), balance | ≤ 1.0, plus minor elements |
Inconel 625 Tube Fitting Sizes (1/8-inch to 2-inch OD): Imperial & Metric
Crestflo machines Inconel 625 tube fittings in both imperial fractional and metric tube-OD series, with end connections up to 2-inch (50 mm) OD. The size chart below covers the standard imperial and metric range. Working pressure for any given fitting depends on size, wall thickness, and temperature. It comes from standard tube-fitting pressure data for the tube OD and wall, following ASTM/ASME practice, and the exact rated pressure for your configuration gets confirmed on the quotation. Values follow the applicable standard and can be customized to requirement.
| Tube OD, imperial | Tube OD, metric | Availability |
|---|---|---|
| 1/8", 1/4", 3/8", 1/2" | 6 mm, 8 mm, 10 mm, 12 mm | Standard range |
| 5/8", 3/4", 1" | 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 25 mm | Standard range |
| up to 2" (50 mm) | up to 50 mm | Made-to-order |
Inconel 625 Tube Fitting End & Thread Connections: NPT, BSPP, JIC & Weld
Fittings come with tube-OD compression ends, tapered or parallel threads, or weld ends. All fittings are available in national, international, and custom thread types.
| End type | Thread / connection standards |
|---|---|
| Tube-OD (compression) | Fractional inch and metric OD |
| Male / female tapered thread | NPT, NPTF, BSPT |
| Male / female parallel thread | BSPP, ISO parallel, SAE ORB |
| Flare / port | JIC 37°, SAE ORB |
| Weld end | Socket-weld, butt-weld, orbital |
Single vs Double Ferrule & Hardened vs Non-Hardened Options
Inconel 625 fittings come in single-ferrule and double (twin) ferrule designs, and hardened or non-hardened ferrules are supplied depending on what the job calls for. This choice shapes gripping action, vibration resistance, and how many times the fitting can be reused.
| Configuration | Description | When it is used |
|---|---|---|
| Double (twin) ferrule | Front ferrule seals, back ferrule grips | General instrumentation, vibration, gas-tight service |
| Single ferrule | One ferrule seals and grips | Simpler assemblies, certain hydraulic and OEM designs |
| Hardened ferrule | Case-hardened grip surface | Harder tube materials, maximum hold |
| Non-hardened ferrule | Softer grip surface | Thin-wall or softer tubing |
For guidance on making the right choice, see single vs double vs ferrule-less fittings and hardened vs non-hardened ferrules. Replacement nuts and ferrules are stocked separately, and so are single-ferrule fittings.
Available Inconel 625 Fitting Shapes & Connectors
Alloy 625 covers the full geometry range. That means you can build a complete instrument run in a single material:
- Union, elbow, tee, cross, and reducer fittings
- Male connectors, female connectors, and adapters for joining mismatched threads
- Bulkhead unions, port connectors, caps, and plugs for sealing off unused lines
- Weld connector (socket, butt, and orbital)
625 comes in related forms too, including 37° JIC flare fittings and DIN 2353 bite-type fittings.
Standards, Testing & NACE MR0175 Sour-Service Compliance
Crestflo qualifies its compression tube fittings to ASTM F1387, the performance standard for mechanically attached fittings. That's the basis for dimensional interchange and mechanical-integrity claims. For sour service, alloy 625 fittings are offered to NACE MR0175 / ISO 15156. We hold the standard approvals that apply to instrumentation tube fittings.
| Standard / certification | Scope | Applies here |
|---|---|---|
| ASTM F1387 | Mechanically attached fitting performance | Yes |
| NACE MR0175 / ISO 15156 | Sour-service materials | Yes |
| EN 10204 MTC 3.1 / 3.2 | Material test certification | Yes |
| ASTM/ASME B446 / B443 | Nickel-alloy bar & plate feedstock forms | As applicable |
| ISO 9001 / 14001 / 45001 & PED | Quality, environmental, safety, pressure | Certified |
These fittings go through a wide battery of tests. Hydraulic proof, burst, and impulse come first. Then there's pneumatic, flexure-fatigue, rotary-flex, vibration, and thermal-cycling work, plus pull-out and vacuum checks. Positive material identification (PMI) confirms the alloy on every piece. NDT is standard and done in-house. Destructive testing, though, goes out to labs accredited under ISO/IEC 17025. Third-party inspection? Available on request. For more detail, see our testing and inspection capability.
Material Traceability & Certification
Every Inconel 625 part is marked with its own heat/lot number. Each shipment comes standard with an EN 10204 MTC 3.1 certificate, and 3.2 is available on request. PMI confirms grade at the part level, every time. That's the kind of documentation that backs solid audit trails for offshore, subsea, and sour-service work. See material traceability for more.
Drop-In Interchange with Swagelok, Parker & Hy-Lok
Crestflo Inconel 625 fittings are built as dimensional interchange / equivalent fittings for the major instrumentation brands, and that claim rests on ASTM F1387 performance qualification, not on marketing language. These aren't "compatible" or "intermix" parts. Brand names such as Swagelok®, Parker®, and Hy-Lok® remain trademarks of their respective owners. We don't publish a part-number table. Instead, we prepare interchange references per project: request your cross-reference, and our engineering team will map your existing part numbers to Crestflo equivalents.
Origin & US-Serving Positioning
Crestflo manufactures for the US market. Standard product comes from India; US or European melt is available on request, with full material traceability. Parts are engineered as US drop-in replacements and ship in 6-8 weeks. TAA/DFARS and domestic-melt requirements get handled straight, no hedging, on our US-origin compliance page. If a project calls for a specific melt origin, just specify it on the RFQ.
Why Crestflo for Inconel 625 Tube Fittings
Crestflo operates as the instrumentation division of an export house with four decades behind it and formal recognition from the Government of India. That parent company has a proven record of delivery across the Middle East. Its backing isn't incidental; it grounds a new, focused instrumentation brand built on a handful of clear advantages:
- Lead time of 6–8 weeks versus 20+ weeks typical of the majors, see lead time.
- ASTM F1387 drop-in interchange proof that mill and trading suppliers rarely publish.
- Small MOQ and private label for distributors and OEMs.
- Both imperial and metric on every fitting, single or double ferrule, hardened or non-hardened.
- Heat-number marking plus MTC 3.1/3.2 on every order, PMI-confirmed.
- Cost-competitive after US duties and tariffs, ISO 9001 / 14001 / 45001 & PED certified.
We Engineer Confidence.
Request a Quote for Inconel 625 Fittings
Give us the details: size, shape, ferrule, thread, and quantity. We'll price it out and get your order scheduled:
- Request a quote, the fastest path to pricing and lead time.
- Request a sample for qualification.
- Become a distributor for line-card and stocking programs.
Datasheets and CAD models are available to customers on request. Reach Crestflo's US sales desk at sales@crestflousa.com or +1 346 594 9005 (Houston, TX). Round out your system with the related Inconel 625 instrumentation valves and Inconel 625 tubing, or check the tube-fittings product hub for ferrule design and geometry.
Crestflo's Engineering Team reviews every specification, standard, and material data point shown on this page. Certifications cover ISO 9001, 14001, and 45001, plus PED.
Frequently Asked Questions
Are Alloy 625 and Inconel 625 the same?
Yes. "Alloy 625" and "Inconel 625" both point to the same material: UNS N06625, also listed as Werkstoff 2.4856, a nickel-chromium-molybdenum-niobium alloy. Inconel® is simply a trademarked brand name. Alloy 625 and 625 aren't different alloys at all; they're the generic designations for that same material.
What is the difference between Inconel 625 and Inconel 825 tube fittings?
Inconel 625 carries more strength than Incoloy 825, and it brings broader chloride resistance, better sour-service performance, and higher-temperature capability, all thanks to its Ni-Cr-Mo-Nb composition. Incoloy 825, a Ni-Fe-Cr alloy, tends to get picked for sulfuric and phosphoric acid service instead, and it costs less. For the full rundown, see Crestflo's comparison at Inconel 625 vs 825.
How much do Inconel 625 tube fittings cost?
As a high-nickel alloy, 625 fittings run more than stainless steel does, and the price shifts with size, shape, ferrule type, and quantity ordered. Crestflo stays cost-competitive even after US duties and tariffs, but it quotes per configuration. There's no live pricing posted anywhere. Request a quote to get a firm number.
What are Inconel 625 tube fittings used for?
They handle corrosion-critical instrumentation lines in oil and gas settings (sour, offshore, and subsea). You'll also find them in petrochemical and chemical plants, seawater and marine systems, and flue-gas or scrubber service. Wherever chloride pitting, H₂S, or high heat take stainless off the table, Crestflo steps in.
Are Crestflo Inconel 625 fittings NACE-compliant?
Yes. Crestflo offers them to NACE MR0175 / ISO 15156 for sour-service applications, with material traceability backing project qualification. For the method, see sour-service selection.
Do they interchange with Swagelok, Parker, or Hy-Lok fittings?
They're built as dimensional interchange and equivalent fittings, with performance backed by ASTM F1387 qualification. We don't call them "compatible" or "intermix," and every brand name mentioned belongs to its respective owner. Send us your cross-reference request and we'll map your part numbers.
What sizes are available?
Tube-OD sizes run from 1/8-inch up to 2-inch (50 mm), covering both imperial fractional and metric series, and come in single or double ferrule. Standard sizes span 1/8" to 1" and 6 mm to 25 mm; anything larger is made to order.
Are single and double ferrule versions both offered?
Yes. Both single-ferrule and double, or twin, ferrule designs are available, with hardened or non-hardened ferrules supplied depending on what's required.
What material certification comes with the fittings?
Standard practice is an EN 10204 MTC 3.1 certificate, though 3.2's available if you ask for it. Every part gets a heat/lot number stamped on it. PMI confirms the alloy.
Are these made in the USA?
Crestflo manufactures for the US market. Standard product comes from India, though US or European melt is available on request, complete with full material traceability. It's engineered for a US drop-in fit and ships in 6-8 weeks. For TAA and origin specifics, see the US-origin compliance page.
What thread and end connections are available?
Tube-OD compression ends come standard, alongside NPT, NPTF, BSPT, BSPP, and ISO parallel threads. JIC 37° and SAE ORB fittings round out the lineup, and weld ends are available in socket, butt, and orbital styles. National, international, or custom thread, they're all supported.
What is the minimum order and lead time?
Small minimum order quantities apply, and lead time for US orders runs 6 to 8 weeks. Standard items ship from ready stock; specials are made to order. Private-label and custom or made-to-print options are also available.