Inconel 625 (Alloy 625 / UNS N06625) Instrumentation Fittings, Valves & Tubing
Inconel 625 is a nickel-chromium-molybdenum-niobium solid-solution superalloy. It's a corrosion-resistant alloy, prized for high strength and deep resistance to pitting, crevice attack and chloride stress-corrosion cracking. It holds up from cryogenic temperatures right through to elevated service. Crestflo supplies it strictly in instrumentation fluid-system forms: compression tube fittings, ferrules, instrumentation valves, manifolds and tubing.
Confirm the grade for your media below. Then request the exact components you need.
Inconel 625, in this context, refers specifically to the nickel-alloy grade used in instrumentation fluid systems: tube fittings, ferrules, valves and tubing. It doesn't cover welding filler (ERNiCrMo-3), aerospace sheet, or structural plate. Crestflo doesn't supply bar, sheet, plate, or other mill forms.
Crestflo operates as the instrumentation division within an export house that's been in business for four decades, carrying Government of India recognition and a long track record of delivery across the Middle East. Reviewed by the Crestflo Engineering Team.
What Inconel 625 Is: Alloy 625 / UNS N06625 Defined
Inconel 625 is a single-phase nickel alloy strengthened by solid solution rather than aging. Molybdenum and niobium do the hardening work here, locking into the nickel-chromium matrix without any separate heat treatment step. The result is broad resistance across oxidising and reducing conditions alike, strong fatigue and thermal-fatigue performance, and toughness that doesn't give out in sour or marine service. Few corrosion-resistant alloys match its range, which is why it turns up so often in offshore, subsea and high-integrity chemical instrumentation specs.
This grade comes in two standard conditions. Grade 1 (annealed) covers general-purpose use up to roughly 1,100 °F (593 °C). Grade 2 (solution-annealed) is the one to choose when higher-temperature strength and creep resistance matter most.
Also Known As: UNS N06625, Werkstoff 2.4856 & Trade Equivalents
Specifiers use several interchangeable names for this grade. "Inconel 625" and "Alloy 625" both refer to the same UNS N06625 material; European drawings list it as Werkstoff (W.-Nr.) 2.4856. You'll also see it written as Ni-Cr-Mo-Nb alloy, "625", or with the words flipped around as "625 Inconel" and "N06625 Inconel". Producers sell the same grade under trade names like Nicrofer 6020, Chronin 625, Nickelvac 625 and Haynes 625.
| Designation type | Value |
|---|---|
| Common names | Inconel 625, Alloy 625, "625" |
| UNS number | N06625 |
| Werkstoff / EN number | 2.4856 |
| Alloy family | Nickel-chromium-molybdenum-niobium (Ni-Cr-Mo-Nb) CRA superalloy |
| Conditions / tempers | Grade 1 (annealed) · Grade 2 (solution-annealed) |
| Trade equivalents | Nicrofer 6020, Chronin 625, Nickelvac 625, Haynes 625 |
| Governing product-form specs | ASTM B446/B444/B366/B564 · ASME SB-mirror |
Inconel® is a registered trademark of Special Metals Corporation. Crestflo isn't affiliated with Special Metals; it supplies the grade under its generic designations, Alloy 625 and UNS N06625. Any trade equivalents named above remain the property of their respective owners.
Inconel 625 Chemical Composition (UNS N06625, wt %)
Alloy 625 is built on a nickel base, with heavy additions of chromium and molybdenum, plus niobium (columbium) thrown in. The table lists the standard published limits for UNS N06625. These values come straight from the applicable ASTM/ASME specification, and each one gets confirmed on the material test certificate.
| Element | wt % (min–max) |
|---|---|
| Nickel (Ni) | ≥ 58.0 |
| 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) | ≤ 1.0 |
| Manganese (Mn) | ≤ 0.5 |
| Silicon (Si) | ≤ 0.5 |
| Aluminum (Al) | ≤ 0.4 |
| Titanium (Ti) | ≤ 0.4 |
| Carbon (C) | ≤ 0.10 |
| Phosphorus (P) | ≤ 0.015 |
| Sulfur (S) | ≤ 0.015 |
Inconel 625 Mechanical & Physical Properties
Alloy 625 pairs high tensile and yield strength with excellent ductility and fatigue life, and it holds onto its toughness even at cryogenic temperatures. The figures below are standard published minimums for annealed material. Values follow the applicable standard and can be customized to your requirement and product form.
| Property | Value (SI) | Value (imperial) | Condition |
|---|---|---|---|
| Tensile strength | ≥ 827 MPa | ≥ 120 ksi | Annealed (typical min) |
| Yield strength (0.2 %) | ≥ 414 MPa | ≥ 60 ksi | Annealed (typical min) |
| Elongation | ≥ 30 % | ≥ 30 % | Annealed (typical min) |
| Hardness | ~ 220 HB | ≤ ~ HRC 35 | Annealed |
| Density | 8.44 g/cm³ | 0.305 lb/in³ | — |
| Melting range | 1290–1350 °C | 2350–2460 °F | — |
| Cryogenic toughness | Retained | Retained | To LNG/cryogenic temperatures |
In sour service applications, hardness has to stay within the limits set by NACE MR0175 / ISO 15156. Inconel 625 work-hardens fast, and it's a tougher material to machine than stainless steel. That's why Crestflo keeps the work in-house, running it through CNC, VMC and EDM equipment to hold the tight tolerances instrumentation demands.
Inconel 625 Corrosion Resistance, PREN & Sour-Service Suitability
Inconel 625 stands up to a wide range of harsh conditions: seawater, chlorides, both oxidising and reducing acids, and sour H2S environments. It resists pitting and crevice attack well, and it holds firm against chloride stress-corrosion cracking. Its calculated pitting resistance equivalent number comes in high.
Apply the standard formula, PREN = %Cr + 3.3 × %Mo, and nitrogen barely matters for this grade. Take the mid-range values, 21.5 % Cr and 9 % Mo, and the PREN of Inconel 625 comes out at roughly 51. That's well above the super-austenitic and duplex stainless grades. It's the reason engineers favor this alloy for offshore and subsea work, where chloride exposure is a constant concern.
| Environment / media | Alloy 625 behavior | Note |
|---|---|---|
| Seawater / chlorides | Excellent | High PREN (~51); resists pitting & crevice attack |
| Sour gas / H2S | Accepted CRA | Per NACE MR0175 / ISO 15156, annealed within hardness limits |
| Oxidising acids | Very good | Cr provides oxidising resistance |
| Reducing acids | Very good | Mo provides reducing-acid resistance |
| Chloride SCC | Highly resistant | Nickel content resists chloride SCC |
| Cryogenic / LNG | Suitable | Retains toughness at low temperature |
Under NACE MR0175 / ISO 15156, Alloy 625 is accepted as a corrosion-resistant alloy for H2S and sour service. It's typically supplied in the annealed condition, within the specified hardness limits. Crestflo confirms the condition per order. See ISO 15156 as well for the metallurgical requirements that govern sour service.
Inconel 625 Product Forms We Supply
Crestflo supplies Inconel 625 only in instrumentation forms: the fluid-system components listed below. No pipe fittings, no bar, no sheet, no plate, no mill product. That means plate and sheet specifications like ASTM B443 don't apply here. Standard items sit in ready stock. Specials get made to order, and delivery takes 6-8 weeks.
| Form | Crestflo scope | Reference standard | Page |
|---|---|---|---|
| Compression tube fittings | Single & double ferrule, up to 2" / 50 mm OD | Tested to ASTM F1387; NACE-compliant | Inconel 625 tube fittings |
| Ferrules | Hardened & non-hardened | Per fitting qualification | Tube-fitting ferrules |
| Instrumentation valves & manifolds | Needle, ball, check, 2/3/5-way manifolds, 1/16"–1" | ASME B16.34 / API (valve basis) | Inconel 625 instrumentation valves |
| Tubing | Seamless & welded instrumentation tubing | ASTM B444 (seamless) / B751-B775 (welded) | Inconel 625 tubing |
Compression tube fittings come in single-ferrule and double-ferrule designs, sized in both imperial and metric. Check the tube-fitting size chart for the full range. Crestflo's valve lineup includes needle valves, ball valves and check valves, along with 2/3/5-way manifolds spanning 1/16" to 1". Tubing is available in two constructions: seamless and welded.
End connections cover tube-fitting ends, NPT (ASME B1.20.1), NPTF, BSPT, BSPP, ISO parallel, JIC 37° flare and SAE-ORB, along with socket-weld and butt-weld. Finishes range from material finish and electropolish to passivation, silver anti-galling plating and oxygen-clean. Our engineering team can supply ordering-code and part-number series details on request. Values follow the applicable standard and can be customized to requirement.
Where Inconel 625 Is Used
Inconel 625 gets specified anywhere an instrumentation fluid system has to stand up to both corrosion and extreme temperatures. You'll find it in offshore and subsea oil and gas work, sour service with H2S, hydrogen systems, LNG and cryogenic applications, carbon capture, petrochemical processing, and marine and power generation projects. It shows up as tube fittings, valves, manifolds and tubing on hydraulic lines, chemical-injection lines, sampling lines and instrument-air lines.
Take a look at the core industries we work across: oil & gas, offshore, subsea, hydrogen, LNG / cryogenic and carbon capture (CCS).
Inconel 625 vs Inconel 825, Hastelloy C-276, 316L & Monel 400
Picking 625 usually comes down to weighing chloride and acid resistance, strength and cost against the alloys around it. The table lays out those trade-offs. Follow the links for the full grade pages.
| Alloy | Key strength vs 625 | Choose when | Page |
|---|---|---|---|
| 316 / 316L | Lower cost, general service | Chloride/sour exposure is mild | 316 / 316L |
| Inconel 825 | Higher Fe, economical acid resistance | Sulfuric/phosphoric acid economy matters | Inconel 825 |
| Hastelloy C-276 | Higher Mo, severe reducing acids | Hot HCl / harshest reducing media | Hastelloy C-276 |
| Monel 400 | Cu-Ni, HF & seawater | Hydrofluoric acid or seawater specifics | Monel 400 |
| Inconel 718 | Age-hardened, higher strength | Very high mechanical load is the driver | Inconel 718 |
Alloy 625 carries more molybdenum and niobium than Inconel 825. More of both. That extra alloying gives it higher strength and wider resistance to acids and chlorides. Inconel 825, a higher-iron Incoloy grade, isn't as heavily alloyed, but it's often the better economic choice where sulfuric acid is the main concern. For a closer look, see Inconel 625 vs 825 and Hastelloy vs Inconel.
Why Source Inconel 625 Instrumentation Components from Crestflo
Crestflo builds Inconel 625 instrumentation fittings and valves, designed as drop-in replacements for the major brands. Every unit comes with genuine qualification data and full traceability behind it.
- Drop-in interchange, compression tube fittings are tested to ASTM F1387 performance qualification; instrumentation valves meet the applicable ASME B16.34 or API valve standards.
- Lead time of 6-8 weeks, standard items ship from ready stock, and specials are made to order, with delivery in 6-8 weeks. The majors often run 20-plus weeks. See lead time.
- Traceability, every part carries a heat/lot number. Add to that EN 10204 MTC 3.1 standard, with 3.2 available on request, plus PMI material verification. Destructive testing goes out to ISO/IEC 17025-accredited labs, and third-party inspection can be arranged on request. See testing & inspection.
- Certified quality system, ISO 9001 / 14001 / 45001 & PED certified.
- Small MOQ + private label: Crestflo keeps minimum order quantities low and offers private-label programs for OEMs and distributors, in both imperial and metric.
- Honest origin: material is Indian in origin. US and European melt is available on request, and full material traceability comes standard. Crestflo serves the US market as a supplier and manufacturer of Inconel 625 instrumentation components, shipping nationwide from a Houston, TX sales contact. So if you're searching for an Inconel 625 supplier near me, you'll land on a domestic point of contact. Details are here: US-origin & compliance.
Datasheets and CAD models are ready for customers who ask. Need to swap out an existing Swagelok®, Parker®, Hoke® or Hy-Lok® line for Alloy 625? Request your cross-reference from our engineering team.
Get in touch: sales@crestflousa.com · +1 346 594 9005 (Houston, TX). Ask for a quote here: Request a quote, or grab a sample here: request a sample.
Inconel 625 FAQ
Are Alloy 625 and Inconel 625 the same?
Yes. "Alloy 625" and "UNS N06625" name the same nickel-chromium-molybdenum-niobium grade; they're just two labels for one material. Special Metals Corporation holds "Inconel®" as a registered trademark. Crestflo supplies this grade as Alloy 625 / UNS N06625, and the company has no affiliation with Special Metals.
What is Inconel 625 used for?
Engineers specify it for instrumentation fluid systems where corrosion resistance and temperature performance can't be compromised. Offshore and subsea oil and gas. Sour service involving H2S. Hydrogen, LNG and cryogenic lines, carbon capture, petrochemical plants, marine environments. It's supplied as tube fittings, valves, manifolds and tubing.
What is the difference between Inconel 625 and Inconel 825?
Both alloys fall into the nickel-chromium-molybdenum CRA family. Alloy 625 carries more molybdenum and niobium, which gives it greater strength and wider resistance to acids and chlorides. Inconel 825, a higher-iron Incoloy grade, often gets the nod instead when the job's about economical resistance to sulfuric and phosphoric acid. For more detail, see the Inconel 825 page.
Is Inconel 625 hard to machine?
Yes. It hardens fast under stress and cuts tougher than stainless steel, which is why Crestflo machines it in-house on CNC, VMC and EDM equipment to hold instrumentation tolerances.
Is Inconel 625 NACE MR0175 / ISO 15156 compliant for sour service?
Alloy 625 holds up well in H2S / sour service and is accepted under NACE MR0175 / ISO 15156 for corrosion resistance. It's normally supplied in the annealed condition, within the specified hardness limits. Crestflo confirms the supplied condition against each order.
What is the PREN of Inconel 625?
PREN comes out to roughly 51, derived from PREN = %Cr + 3.3 × %Mo with about 21.5 % chromium and 9 % molybdenum feeding into the equation. That's a strong number. It translates into excellent resistance to pitting and crevice corrosion in chloride environments.
What is the UNS and Werkstoff number for Inconel 625?
The UNS number is N06625. Under the Werkstoff, or EN material, designation, it's 2.4856.
What sizes and product forms does Crestflo offer in Inconel 625?
The lineup includes compression tube fittings, both single and double ferrule, up to 2 inches (50 mm) OD, plus ferrules sold on their own. Instrumentation valves and manifolds run from 1/16 inch to 1 inch. Tubing comes in seamless and welded forms, in imperial and metric. Crestflo sticks to instrumentation forms; bar, sheet, plate and pipe aren't part of what they carry.
What certifications and traceability come with Inconel 625 parts?
Crestflo holds ISO 9001, 14001, and 45001 certification, and it's PED certified too. Compression fittings are tested to ASTM F1387. Material gets verified by PMI. Each part is stamped with a heat and lot number, documented under EN 10204 MTC 3.1, with 3.2 available on request.
Where is Crestflo's Inconel 625 made, and can I get US or European melt?
Crestflo's standard product comes from India. If you need US or European melt, that's available on request, with full material traceability included. Crestflo serves US customers and keeps a sales contact in Houston, TX. TAA and DFARS requirements? Those are covered on the US-origin & compliance page.
What is the lead time for Inconel 625 fittings and valves?
Ready stock covers standard items. Specials get made to order. Delivery runs 6 to 8 weeks, compared with the 20-plus weeks typical of the major brands.
Can I get Inconel 625 fittings as a drop-in replacement for Swagelok or Parker?
Yes. Dimensional interchange in Alloy 625, backed by ASTM F1387 performance qualification for fittings and ASME B16.34 / API for valves. Ask our engineering team for your cross-reference. Crestflo isn't affiliated with those brands; their marks belong to their owners.