Tesco Steel & Engineering forges Inconel 625 weld neck flanges — UNS N06625, Werkstoff Nr. 2.4856, the nickel-chromium alloy with 8–10% molybdenum and 3.15–4.15% niobium — to ASTM B564, from 1/2″ NB to 56″ NB in ASME B16.5 Class 150–2500 and European PN patterns. The molybdenum makes it immune to seawater pitting and crevice attack; the niobium stiffens the matrix to 827 MPa minimums with no heat treatment; and NACE MR0175 lists it among the most capable sour-service materials — the alloy of subsea manifolds, offshore risers, sour gas and hot-acid plants, mating B444 pipe, welded with the famous ERNiCrMo-3. Supplied with PMI and EN 10204 3.1/3.2 on request. ISO 9001:2015, made in Mumbai, India — exported worldwide.
Inconel 625 · UNS N06625 · 2.4856Cr 20–23% · Mo 8–10% · Nb 3.15–4.15%ASTM B564 / ASME SB-564Seawater Immune · NACE MR0175827 MPa Min · No Heat Treatment1/2″ – 56″ NB · Class 150–2500ISO 9001:2015 · Exported Worldwide
Inconel 625 (UNS N06625 / 2.4856) is the family's heavyweight: onto the Ni-Cr base it adds 8–10% molybdenum — genuine immunity to seawater pitting and crevice corrosion, PREN beyond 50 — and 3.15–4.15% niobium, which stiffens the solid solution to 827 MPa tensile minimums with no heat treatment. An Inconel 625 weld neck flange pairs that certificate with a long tapered hub butt-welded to the pipe, forged to ASTM B564 — corrosion immunity and double-stainless strength in one joint.
The family splits by mission: 600 and 601 are the heat-first alloys for furnace and hot-gas duty; 625 is corrosion-and-strength-first — subsea manifolds, offshore risers, sour gas (NACE MR0175 listed) and hot-acid chemistry. Its weld metal, ERNiCrMo-3, is famously the consumable that welds half the exotic-alloy world, cladding carbon-steel wellheads and over-alloying 6-Mo and super duplex joints.
Also searched as: Alloy 625 flange, UNS N06625 flange, 2.4856 flange, NiCr22Mo9Nb flange, subsea flange, sour service nickel alloy flange — all refer to the product on this page; see also our Inconel 625 flanges overview.
Chemical Composition of Inconel 625
C
Mn
Si
S
Cu
Fe
Ni
Cr
0.10 max
0.50 max
0.50 max
0.015 max
-
5.00 max
58.00 min
20.00-23.00
Values in weight %. N06625 additionally requires the grade's defining molybdenum 8.0–10.0% and niobium (+ tantalum) 3.15–4.15% — the two additions that deliver the pitting immunity and the solid-solution strength respectively.
Mechanical Properties of Inconel 625
Tensile Strength, MPa
Yield Strength, Min, MPa
Elongation % min.
930
517
42.5
Typical annealed values per our supply practice; the governing ASTM B564 Grade 1 minimums are 827 MPa (120 ksi) tensile, 414 MPa (60 ksi) yield and 30% elongation — roughly double an annealed stainless, with no hardening heat treatment. Grade 2 (solution annealed) serves creep-range designs above 593 °C.
Equivalent Grades of Inconel 625
Standard
Werkstoff Nr.
UNS
JIS
BS
GOST
AFNOR
EN
Inconel 625
2.4856
N06625
NCF 625
NA 21
ХН75МБТЮ
NC22DNB4M
NiCr22Mo9Nb
System partners: ASTM B444 seamless pipe, B366 butt-weld fittings, B443 plate and B564 forgings. Family siblings: Inconel 600 and Inconel 601.
Inconel 625 Weld Neck Flange Specifications
Inconel 625 Weld Neck Flanges are available in the following specifications:
Size
1/2"NB to 56"NB
Class
150#, 300#, 400#, 600#, 900#, 1500#, 2500#
Sch (Schedule)
XS, XXS, STD & Schedule 20, 40, 80, 160
Pressure Ratings
PN 2.5 - PN 400
Standards
ASTM B564 / ASME SB-564 (Grade 1 & Grade 2); ASME B16.5, ASME B16.47, EN 1092-1, DIN 2631–2635, BS 4504
Condition
Annealed (Grade 1) or Solution Annealed (Grade 2, for service above 593 °C)
PREN beyond 50 removes the pitting and crevice conversation — stagnant, fouled or flowing, the alloy simply does not corrode in seawater.
Strength Without Heat Treatment
Niobium stiffens the solid solution to 827 MPa minimums as-supplied — double an annealed stainless, with full cryogenic toughness.
NACE MR0175 Listed
Among the most capable sour-service materials in ISO 15156 — H2S, chlorides and temperature combinations that exclude stainless entirely.
The Universal Weld Metal
ERNiCrMo-3 clads wellheads and over-alloys 6-Mo and duplex joints industry-wide — a 625 flange welds into any exotic system natively.
600, 601 & 625 From One Forge
The full Inconel flange family in production — whichever member the service picks, the bevels and certificates arrive matched.
Welding Inconel 625 — The Consumable Everyone Knows
Alloy 625 welds with matching ERNiCrMo-3 / ENiCrMo-3 filler — famously the consumable that welds half the exotic-alloy world — and nickel discipline: sulphur-free cleanliness, low heat input, no preheat, no PWHT. The weld metal carries the same pitting immunity and strength class as the base, which is why it also serves as the standard over-alloy filler for 6-Mo and super duplex joints.
Hot-end notes: long exposure at 600–800 °C slowly age-hardens the alloy (strength up, ductility down), and B564 Grade 2 is the code-correct supply condition above 593 °C. For dry furnace duty, 601 is the economical specialist.
Where Inconel 625 Weld Neck Flanges Are Used
Subsea and offshore lead: manifolds, wellhead and riser hardware, injection lines and splash-zone piping — the world that standardised on 625. Sour gas processing follows under NACE MR0175, then chemical plants running hot acids and chlorides, flue gas desulphurisation, aerospace and gas-turbine ducting, and nuclear auxiliaries. Our nickel-alloy production below:
Inconel 625 weld neck flanges share their dimensions with every other material in the same class — OD, thickness, hub, bore, bolt circle and bolting per the standard tables. Full ASME B16.5 charts:
625 pricing tracks nickel and molybdenum plus the testing scope, so we quote live with a stated validity rather than publish a static list. To get a firm quotation, usually within 24 hours:
1
List your requirement — size (NB), class or PN, standard (ASME B16.5 / B16.47 / EN / DIN / BS), grade (Inconel 625 / N06625, Grade 1 or Grade 2), pipe schedule or bore, and quantity.
2
State the service & testing scope — seawater, sour (NACE MR0175), or hot service above 593 °C (it picks the supply grade), plus 3.2 witness, PMI or project specifications.
3
Send it across — via the inquiry form, WhatsApp, or email to sales@tescosteel.com — and we reply with price, delivery and stock position.
It is a weld neck flange forged from Inconel 625 — the nickel-chromium-molybdenum-niobium alloy of 58% nickel minimum, 20-23% chromium, 8-10% molybdenum and 3.15-4.15% niobium, UNS N06625 / 2.4856 — to ASTM B564. The long tapered hub is butt-welded to the pipe with the bore matched to the pipe schedule, giving a radiographable joint in the family's heavyweight: seawater, sour service and hot acids at 827 MPa minimum strength.
What makes Inconel 625 the heavyweight of the family?
Two additions working together. The 9% molybdenum drives pitting and crevice resistance beyond anything chlorides can organise — 625 serves raw seawater indefinitely, without the caveats even super alloys carry. The niobium stiffens the solid solution to 827 MPa tensile minimums with no heat treatment at all — double an annealed stainless — while keeping full toughness from cryogenic up. Corrosion immunity plus strength in one certificate is why subsea engineering standardised on it.
What is the difference between Inconel 625 and Inconel 600/601?
The mission. 600 and 601 are heat-first alloys — chromia and alumina scales for furnace and hot-gas duty to 1093 and 1250 °C. 625 is corrosion-and-strength-first: molybdenum and niobium give it seawater immunity, sour-service listing and double the strength, at a working ceiling near 980 °C for oxidation but typically specified far cooler and wetter. Furnace loops pick 600/601; subsea, offshore and acid plants pick 625.
Is Inconel 625 suitable for seawater service?
Definitively — it is one of the few engineering alloys with genuine immunity to seawater pitting and crevice corrosion, stagnant or flowing, fouled or clean. Where super duplex and 6-Mo grades carry design caveats, 625's PREN beyond 50 removes the conversation. Subsea manifolds, splash-zone components, seawater injection systems and desalination high-pressure trains specify it exactly for that certainty.
Is Inconel 625 suitable for sour service (NACE MR0175)?
Yes — N06625 is listed in ISO 15156 / NACE MR0175 among the most capable materials for H2S service, serving sour wells and processing at combinations of H2S, chlorides and temperature that exclude stainless families entirely. State the sour-service requirement in the enquiry and the certification follows.
What are the equivalent designations for Inconel 625?
UNS N06625; Werkstoff Nr. 2.4856; EN NiCr22Mo9Nb; JIS NCF 625; BS NA 21; GOST ХН75МБТЮ; AFNOR NC22DNB4M; and the trade names Inconel 625 or Alloy 625. System partners: ASTM B444 seamless pipe, B366 butt-weld fittings, B443 plate and B564 forgings. An enquiry in any of these designations is quoted as the same material.
What is the chemical composition of Inconel 625?
Per ASTM B564: nickel 58.00% minimum, chromium 20.00 to 23.00%, iron 5.00% max, with residuals capped at carbon 0.10%, manganese 0.50%, silicon 0.50% and sulphur 0.015% — plus the grade's defining additions of molybdenum 8.0 to 10.0% and niobium (plus tantalum) 3.15 to 4.15%, which deliver the pitting immunity and the solid-solution strength respectively.
What are the mechanical properties of Inconel 625 flanges?
Typical annealed properties run 930 MPa tensile, 517 MPa yield and 42.5% elongation; the governing ASTM B564 Grade 1 minimums are 827 MPa (120 ksi) tensile, 414 MPa (60 ksi) yield and 30% elongation, demonstrated on every certificate — roughly double an annealed stainless, achieved without any hardening heat treatment. Grade 2 (solution annealed) serves creep-range designs above 593 °C.
Which pipe and fittings do Inconel 625 weld neck flanges mate with?
ASTM B444 seamless Inconel 625 pipe is the standard partner, with B366 butt-weld fittings and B443 plate completing the system. The weld neck bore is machined to the pipe schedule you state, so the bore runs flush through the joint and the bevel arrives ready for a matched-chemistry butt weld.
How are Inconel 625 flanges welded to pipe?
With matching ERNiCrMo-3 / ENiCrMo-3 filler — famously the consumable that welds half the exotic-alloy world — and nickel discipline: sulphur-free cleanliness, low heat input, no preheat, no PWHT. The weld metal carries the same pitting immunity and strength class as the base, which is precisely why 625 filler is also the standard over-alloy consumable for 6-Mo and super duplex joints.
What temperature range can Inconel 625 flanges be used in?
From cryogenic — strength and toughness both hold at liquefied-gas temperatures — through wet corrosive duty, up to roughly 980 °C for oxidation resistance. Two notes steer the hot end: long exposure at 600 to 800 °C slowly age-hardens the alloy (useful strength, reduced ductility), and B564 Grade 2 material is the code-correct choice above 593 °C. Most 625 flanges, though, are bought for the wet end of that range.
Why is Inconel 625 used subsea and offshore?
Because it removes two conversations at once: corrosion allowance (seawater immunity means none) and strength (827 MPa minimums shrink components). Subsea manifolds, wellhead and riser hardware, umbilical fittings and splash-zone piping standardised on 625 — and its weld metal clads carbon-steel Christmas trees and pipelines industry-wide. A flanged joint in that world is a 625 flange by default.
Is Inconel 625 resistant to chloride stress corrosion cracking?
Completely — the high-nickel matrix sits far beyond the SCC threshold, and with pitting and crevice attack also off the table, chlorides simply have no route into the alloy. That triple immunity, held from stagnant seawater to hot brines, is the certainty offshore specifications pay for.
What testing and certification do you supply with Inconel 625 flanges?
Every lot ships with EN 10204 3.1 mill test certificates covering chemical analysis — demonstrating the molybdenum and niobium windows — mechanical properties and heat-treatment condition (Grade 1 or 2), with 3.2 certification witnessed by Lloyd's, DNV, BV or TÜV on request. We also offer PMI verification, NACE MR0175 compliance documentation, hydrostatic testing and dye-penetrant examination, with full heat-number traceability.
Where are Inconel 625 weld neck flanges used?
Subsea and offshore systems above all — manifolds, risers, injection lines, splash-zone piping — plus sour gas processing, chemical plants running hot acids and chlorides, flue gas desulphurisation, aerospace and gas-turbine ducting, and nuclear auxiliaries. Wherever the specification wants corrosion immunity and strength on one certificate, 625 is the named answer.
What sizes and standards do you manufacture Inconel 625 weld neck flanges in?
From 1/2 inch NB to 56 inch NB: ASME B16.5 Class 150 to 2500 up to 24 inch, ASME B16.47 above, and European PN 2.5 to PN 400 patterns to EN 1092-1, DIN and BS 4504. Raised face is standard, ring joint for high-class offshore service on request, and every bore is machined to the mating pipe schedule from Sch 10 through XXS.
Do you keep Inconel 625 weld neck flanges in stock? What is the lead time?
625 moves in project quantities, so common offshore and chemical-plant sizes in Class 150 to 600 rotate through production with popular items often available, while larger diameters, higher classes and witness-tested lots are forged to order — typically 4 to 6 weeks. Prices track nickel and molybdenum, so quotations carry a validity period.
Do you export Inconel 625 flanges outside India?
Yes. Tesco Steel & Engineering is an ISO 9001:2015 certified manufacturer based in Mumbai, and Inconel 625 flanges ship to offshore, sour-gas and chemical projects across the Middle East, Europe, Africa, Southeast Asia and the Americas. Flanges travel face-protected and seaworthy-packed, with full heat-number and test traceability.
