Tesco Steel & Engineering manufactures Hastelloy B3 flanges (UNS N10675 / W.Nr. 2.4600) — the improved nickel-molybdenum alloy with ~65% Ni and ~28.5% molybdenum. B3 keeps the outstanding hydrochloric-acid and reducing-acid resistance of B2 but adds far greater thermal stability — it strongly resists the intermetallic (Ni-Mo phase) precipitation that can embrittle B2 during welding and intermediate-temperature exposure, giving much better fabricability and weldability. Available in weld neck, slip-on, blind, socket-weld, threaded, lap-joint, spectacle and orifice types to ASTM B564 / ASME B16.5. Class 150 to 2500, NPS 1/2″ to 24″, PN6 to PN400. ISO 9001:2015 certified. Made in India.
Hastelloy B3 (UNS N10675) Flanges
Hastelloy B3 Threaded Flange (Polished)
Tesco Steel & Engineering manufactures B3 flanges in all types from weld neck to orifice, Class 150 to 2500 — supplied with EN 10204 3.1 / 3.2 certification, PMI and third-party inspection on request. Explore the wider Hastelloy flange range, the predecessor Hastelloy B2 flanges, the oxidizing-service Hastelloy C276 flanges, and the flange dimension charts.
| Hastelloy B3 flanges are available in the following specifications: | |
|---|---|
| Material Grade | Hastelloy B3 / UNS N10675 / W.Nr. 2.4600 |
| Alloy Type | Nickel-molybdenum alloy (Ni-Mo), thermally stable reducing-acid grade |
| Size | 1/2″ NB to 24″ NB (DN 15 to DN 600); larger to ASME B16.47 |
| Class / Rating | 150#, 300#, 600#, 900#, 1500#, 2500# · 3000#, 6000#, 9000# (socket-weld / threaded) |
| Pressure Ratings | PN 6 – PN 400 (PN6, 10, 16, 25, 40, 64, 100, 160, 250, 320, 400) |
| Material Standards | ASTM B564, ASME SB564; EN designation 2.4600 |
| Dimensional Standards | ASME B16.5, ASME B16.47 (Series A & B), MSS SP-44, DIN EN 1092-1 |
| Flange Types | Weld Neck (WNRF), Slip-On (SORF), Blind, Socket Weld (SWRF), Lap Joint, Threaded / Screwed, Spectacle Blind, Long Weld Neck, Orifice, Plate |
| Flange Faces | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Tongue & Groove (T&G) |
| Weld Filler | ERNiMo-10 / ENiMo-10 (AWS A5.14 / A5.11) |
| Testing | PMI, hydrostatic, UT, MT/PT per spec; EN 10204 3.1 / 3.2 |
B3 retains B2's ~28% molybdenum for reducing-acid resistance, but its minor elements are carefully balanced to suppress the intermetallic precipitation that embrittles B2 — the source of its improved thermal stability and fabricability. Low carbon (0.01% max) further limits grain-boundary precipitation.
| Element | Hastelloy B3 (UNS N10675) |
|---|---|
| Nickel (Ni) | Balance (~65%) |
| Molybdenum (Mo) | 27.0 – 32.0% |
| Chromium (Cr) | 1.0 – 3.0% |
| Iron (Fe) | 1.0 – 3.0% |
| Cobalt (Co) | 3.0% max |
| Manganese (Mn) | 3.0% max |
| Carbon (C) | 0.01% max |
| Silicon (Si) | 0.10% max |
| Mechanical Property (solution annealed, typical) | Hastelloy B3 |
|---|---|
| Tensile Strength | 760 – 840 MPa (110–122 ksi) |
| Yield Strength 0.2% | 350 – 415 MPa (51–60 ksi) |
| Elongation | 40 – 55% |
| Hardness | ≤ 100 HRB |
| Density | 9.22 g/cm³ |
| Melting Range | 1370 – 1418 °C |
| Standard | Hastelloy B3 Designation |
|---|---|
| UNS (USA) | N10675 |
| Werkstoff (Germany) | 2.4600 |
| ASTM / ASME | B564 / SB564 (forgings); B333, B335, B619, B622 (other forms) |
| Common names | Hastelloy B-3, Alloy B3, Alloy B-3 |
B3 Weld Neck Flange (WNRF)
B3 Slip-On Flange (SORF)
B3 Blind Flange
| Flange Type | Description & B3-Specific Use |
|---|---|
| Weld Neck (WNRF) | Tapered hub butt-welded to pipe for high-integrity HCl and reducing-acid service; welds more readily than B2 with ERNiMo-10 filler. |
| Slip-On (SORF) | Fillet-welded over the pipe; used in hydrochloric and reducing-acid piping at moderate pressure. |
| Blind | Seals pipe ends and vessel nozzles in HCl reactors and acid systems. |
| Socket Weld (SWRF) | Small-bore (1/2″–2″) instrument and branch connections in reducing-acid service. |
| Lap Joint (LJRF) | Used with a B3 stub end where frequent dismantling is required; economizes on alloy in the backing ring. |
| Threaded (TRFF) | Internal NPT/BSP threads for non-welded low-pressure connections. |
| Spectacle Blind / Long Weld Neck / Orifice | Isolation spades, nozzle/long-neck and flow-metering flanges in B3 for HCl and reducing-acid duty. |
| Property | B3 (N10675) | B2 (N10665) | C276 (N10276) |
|---|---|---|---|
| Molybdenum | ~28.5% | ~28% | ~16% |
| Chromium | ~1-3% (low) | ~1% (none) | ~16% |
| Hydrochloric-acid resistance | Excellent | Excellent | Good |
| Thermal stability / weldability | Improved (best of B-series) | Limited | Excellent |
| Oxidizing-media use | Not suitable | Not suitable | Suitable |
| Typical role | Modern HCl grade, welded fabrications | HCl / reducing acids (predecessor) | Reducing & oxidizing workhorse |
~28.5% Mo with low chromium gives the best HCl resistance class across all concentrations up to boiling.
Engineered to resist the intermetallic precipitation that embrittles B2 — stays ductile after thermal exposure.
Far more forgiving to weld and fabricate than B2, so it is the preferred modern B-series grade.
Excellent in hot sulphuric, phosphoric and organic acids under reducing conditions.
| Industry | Typical Application |
|---|---|
| Hydrochloric Acid Plants | HCl production, handling and storage line and welded-equipment flanges |
| Chemical & Petrochemical | Reducing-acid reactor, column and piping flanges, especially welded fabrications |
| Pharmaceutical & Agrochemical | Corrosion-critical reducing-acid process flanged joints |
| Acetic / Organic Acid Plants | Acetic, formic and other organic acid line flanges |
| Sulphuric & Phosphoric Acid | Hot mineral-acid line and equipment flanges in reducing conditions |
| Pickling & Acid Recovery | Hydrochloric pickling and acid-recovery plant flanges |
Made from certified B3 with PMI verification of the ~28.5% Mo and balanced minor elements — full chemistry on the MTC.
Manufactured to ASTM B564 / ASME B16.5 in the solution-annealed condition for full corrosion resistance and stability.
WNRF, SORF, blind, socket-weld, threaded, lap-joint, spectacle, LWN, orifice and plate — in RF, FF, RTJ and T&G.
EN 10204 3.1 / 3.2 MTC, heat/lot traceability, hydrostatic and third-party inspection on request.
B3 flange prices reflect the high nickel and very high molybdenum content plus forging and machining — it is a premium alloy for the most demanding hydrochloric and reducing-acid service, especially welded fabrications. Tesco Steel & Engineering offers competitive ex-works pricing from Mumbai with full export documentation and material traceability. Click Ask for Quote or message us on WhatsApp at +91 92233 66922 with flange type, size (NB), pressure class, quantity and documentation requirements.
Q1. What is a Hastelloy B3 flange?
A Hastelloy B3 flange is a pipe flange made from the improved nickel-molybdenum alloy UNS N10675 (W.Nr. 2.4600) — about 65% nickel with ~28.5% molybdenum and low chromium and iron. B3 keeps the outstanding hydrochloric-acid and reducing-acid resistance of B2 but adds far greater thermal stability, strongly resisting the intermetallic precipitation that can embrittle B2. Flanges are forged to ASTM B564 and machined to ASME B16.5 / B16.47 dimensions.
Q2. What is the chemical composition of Hastelloy B3?
Hastelloy B3 (UNS N10675) nominal composition: nickel balance (~65%), molybdenum 27–32%, chromium 1–3%, iron 1–3%, cobalt 3% max, manganese 3% max, with very low carbon (0.01% max) and silicon (0.10% max). The carefully balanced minor elements are what give B3 its improved thermal stability over B2 while preserving the high-molybdenum reducing-acid resistance.
Q3. What is the difference between Hastelloy B3 and B2?
Both are ~28% molybdenum Ni-Mo alloys with the same outstanding resistance to hydrochloric acid and reducing media. The difference is thermal stability: B2 is prone to intermetallic (Ni-Mo phase) precipitation that can embrittle it during welding or intermediate-temperature exposure, whereas B3 was specifically developed to resist this. B3 therefore has much better fabricability, weldability and ductility retention, and is the preferred modern grade — B2 is its predecessor.
Q4. Why is Hastelloy B3 used for hydrochloric acid?
Like B2, the ~28.5% molybdenum content of B3 with very little chromium gives outstanding resistance to hydrochloric acid across all concentrations and up to boiling temperatures, plus hot sulphuric, phosphoric and organic acids. B3 delivers this same reducing-acid performance with the added benefit of thermal stability, making it ideal for welded HCl equipment and fabrications.
Q5. Can Hastelloy B3 be used in oxidizing media?
No. Like B2, Hastelloy B3 has very low chromium, so it is not suitable for oxidizing media such as nitric acid, ferric or cupric salts, or aerated/oxidizing chloride solutions, which rapidly attack it. B3 must be reserved for reducing environments. Where oxidizing or mixed oxidizing/reducing conditions occur, a Hastelloy C grade (C276, C22 or C2000) should be used instead.
Q6. What standards apply to Hastelloy B3 flanges?
Hastelloy B3 flanges are forged to ASTM B564 (UNS N10675) and machined to ASME B16.5 (1/2 inch to 24 inch) or ASME B16.47 / MSS SP-44 for larger sizes, with EN 1092-1 for PN-rated flanges. The European designation is W.Nr. 2.4600. Material is supplied with EN 10204 3.1 / 3.2 certification.
Q7. Can Hastelloy B3 flanges be welded?
Yes, and more easily than B2. Hastelloy B3 is welded by GTAW (TIG), GMAW and SMAW using matching ERNiMo-10 / ENiMo-10 filler. Its improved thermal stability means it resists the intermediate-temperature embrittlement that complicates B2 welding, so it is much more forgiving to fabricate, though good practice (clean joints, controlled heat input) still applies.
Q8. What are the mechanical properties of Hastelloy B3?
Typical Hastelloy B3 properties in the solution-annealed condition: tensile strength about 760–840 MPa (110–122 ksi), yield strength about 350–415 MPa (51–60 ksi), elongation about 40–55%, density 9.22 g/cm³. It combines high strength with good ductility that it retains better than B2 after thermal exposure.
Q9. What industries use Hastelloy B3 flanges?
Hastelloy B3 flanges are used in hydrochloric acid production and handling, chemical and petrochemical processing involving reducing acids, pharmaceutical and agrochemical plants, acetic and other organic acid plants, and equipment handling hot sulphuric and phosphoric acids — especially for welded fabrications where B2's embrittlement risk must be avoided.
Q10. Are Hastelloy B3 flanges supplied with material test certificates?
Yes. Every Hastelloy B3 flange is supplied with EN 10204 3.1 (or 3.2) mill test certificates confirming chemistry, mechanical properties and heat/lot traceability, with PMI, hydrostatic testing and third-party inspection on request. Tesco Steel & Engineering is an ISO 9001:2015 certified manufacturer and exporter from Mumbai, India.