Hastelloy B2 / B3 Pipe Fittings
Hastelloy B2 / B3 Pipe Fittings ( UNS N10665 / UNS N10675 )
Hastelloy B2 / Hastelloy B3 Pipe Fittings are premium nickel-molybdenum alloy fittings designed for highly reducing environments containing strong acids, aggressive chemicals, and high temperatures. These fittings offer exceptional resistance to hydrogen chloride gas, sulfuric acid, acetic acid, and other severe media.
Hastelloy B2 (UNS N10665) provides excellent resistance to reducing acids, while Hastelloy B3 (UNS N10675) enhances thermal stability and offers improved tolerance to thermal cycling and fabrication stress. Both alloys are widely used in chemical processing, petrochemicals, pharmaceuticals, and pollution control equipment.
Key Features
Outstanding resistance to reducing environments such as hydrochloric, hydrogen chloride, and sulfuric acid.
Excellent thermal stability, especially in Hastelloy B3.
High resistance to stress corrosion cracking and pitting.
Superior weldability and fabricability compared to other nickel alloys.
Retains mechanical strength at elevated temperatures.
Accurate dimensional stability for reliable joining and leakage-free performance.
Specification
| Specification | Details |
|---|---|
| Grades | Hastelloy B2 (UNS N10665), Hastelloy B3 (UNS N10675) |
| Standards | ASTM B366, ASME SB366 |
| Types | Seamless, Welded, Buttweld, Forged |
| Fitting Types | Elbow, Tee, Reducer, Cap, Cross, Stub End, Coupling |
| Manufacturing Sizes | ½” to 48” (Buttweld), Custom sizes available |
| Wall Thickness | SCH 5S – SCH XXS |
| Connection Type | Butt Weld, Socket Weld, Threaded |
| Form | Long Radius & Short Radius Fittings |
| Finishing | Solution Annealed, Pickled & Passivated |
Equivalent Grades
| Alloy | UNS | Werkstoff Nr. | EN / BS |
|---|---|---|---|
| Hastelloy B2 | N10665 | 2.4617 | NiMo 28 |
| Hastelloy B3 | N10675 | 2.4600 | NiMo 29 |
Available Sizes
Buttweld Fittings: ½” to 48”
Forged Fittings: ⅛” to 4”
Socket Weld / Threaded: Class 3000, 6000, 9000
Custom sizes upon request.
Chemical Composition
Hastelloy B2
| Element | % |
|---|---|
| Nickel (Ni) | Balance |
| Molybdenum (Mo) | 26–30 |
| Iron (Fe) | ≤ 2 |
| Chromium (Cr) | ≤ 1 |
| Cobalt (Co) | ≤ 1 |
| Carbon (C) | ≤ 0.02 |
| Manganese (Mn) | ≤ 1 |
| Silicon (Si) | ≤ 0.1 |
Hastelloy B3
| Element | % |
|---|---|
| Nickel (Ni) | Balance |
| Molybdenum (Mo) | 27–32 |
| Iron (Fe) | ≤ 1.5 |
| Chromium (Cr) | ≤ 1.5 |
| Cobalt (Co) | ≤ 3 |
| Carbon (C) | ≤ 0.01 |
| Manganese (Mn) | ≤ 1 |
| Silicon (Si) | ≤ 0.1 |
Mechanical Properties
| Property | Hastelloy B2 | Hastelloy B3 |
|---|---|---|
| Tensile Strength | 760 MPa (min) | 790 MPa (min) |
| Yield Strength (0.2% offset) | 350 MPa (min) | 365 MPa (min) |
| Elongation | 40% | 40% |
| Hardness | 95 HRB | 96 HRB |
Physical Properties
| Property | B2 / B3 Value |
|---|---|
| Density | 9.22 g/cm³ |
| Melting Range | 1370–1410°C |
| Electrical Resistivity | 1.1 μΩ·m |
| Thermal Conductivity | 8.5 W/m·K |
| Modulus of Elasticity | 205 GPa |
Types of Hastelloy B2 / B3 Pipe Fittings
Elbow (45°, 90°, LR, SR)
Equal & Reducing Tee
Concentric & Eccentric Reducer
End Cap
Cross
Stub End (Short & Long)
Coupling / Union / Nipple
Customized Fabricated Fittings
Corrosion Resistance
Strong reducing acids (HCl, H₂SO₄, H₃PO₄).
Hydrogen chloride gas & pure sulfuric environments.
Pitting, crevice corrosion, and stress corrosion cracking.
Environments with halides and aggressive chemical mixtures.
Heat Resistance
Suitable for continuous service up to 540°C.
Maintains strong mechanical properties at elevated temperatures.
Excellent resistance during temperature fluctuations (especially B3).
Heat Treatment
Typically solution annealed at 1065–1120°C, followed by rapid quenching.
Eliminates internal stresses and enhances corrosion resistance.
Avoid unnecessary cold working without post-annealing (especially in B2).
Welding
Weldable using TIG, MIG, or SMAW processes.
Recommended filler metals: Hastelloy B-2 / B-3 filler wires.
Requires careful heat input to avoid carbide precipitation.
B3 has improved weldability and reduced risk of post-weld cracking.
Fabrication
Easily fabricated by forming, bending, machining, and forging.
Avoid excessive heat during forming for B2 alloy.
Both alloys need cleanliness to prevent contamination during fabrication.
Applications
Chemical processing plants
Hydrochloric acid manufacturing
Sulfuric acid reactors & equipment
Petrochemical & refinery components
Pollution control equipment
Pharmaceuticals
Vacuum furnaces & high-temperature vessels
Heat exchangers, piping systems & reactors