The difference between Alloy B2 and B3 is B3's superior thermal stability. This stability significantly reduces the possibility of brittle and unwanted phases when exposed to high temperatures, like during welding. Due to this the B3 offers significantly greater ductility after welding and superior long-term reliability in demanding service environments compared to B2.
ASTM B622 Alloy B3 Seamless Pipe Manufacturer
We are Zhejiang Xintongda Special Steel (XTD), a leading manufacturer and worldwide supplier of Alloy B3 seamless pipes. This pipe is a high-performance nickel-molybdenum alloy that comprises nickel (around 65%), molybdenum (around 28%), chromium (1.0–3.0%), and controlled amounts of iron, manganese, tungsten, and cobalt. We manufacture this pipe as per the ASTM B622 standard. It is known for its ability to resist strong reducing acids such as pure hydrochloric, hydrobromic, and sulfuric acids. It is also widely recognised for its resistance against knife-line attacks in heat-affected zones. Alloy B3 seamless pipe is preferred over other B-type alloys due to its improved structural stability and fabricability. This pipe is used in chemical and petrochemical processing, pharmaceutical manufacturing, power generation and pulp & paper production. We are a multiple international certified supplier and have a production capacity of 25000 tons. We also provide custom Alloy B3 pipes as per customer requirements.
Our ASTM B622 pipes follow these specifications:
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Standard ASTM B622 -
OD Range 6-457 mm 
Thickness 1-65 mm 
Length ≤ 18 m
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Technical Data
Technical Data
Alloy B-3 Seamless Pipe Manufacturing Process
The manufacturing process of seamless pipe of Alloy B3 involves using a solid billet of high-grade nickel and molybdenum alloy. This is followed by forming through extrusion or rolling. We then heat-treat (solution annealing) it for improved microstructure. We use cold drawing for enhanced precision and conduct multiple testing & Quality Control methods before the final surface treatment and inspection.
Key Features of Alloy B3 Seamless Pipe
ASTM B622 pipes have 7 important characteristics. These include corrosion resistance in strong reducing acids, resistance to pitting and knife-line corrosion, high mechanical strength under pressure and temperature stress, thermal stability, workability, elevated temperature resistance and heat treatment.
- Excellent Corrosion Resistance in Strong Reducing Acids: This pipe offers extremely high resistance to pure hydrochloric, hydrobromic, and sulfuric acids due to its nickel-molybdenum composition. This resistance makes it suitable for manufacturing reaction vessels and piping in the chemical process industry.
- Superior Resistance to Pitting and Knife-line Corrosion: ASTM B622 pipes resist localised attacks like pitting and corrosion (due to the nickel-rich, low-carbon alloy chemistry) at the heat affected zone of welds. This is known as knife-line attack. This quality ensures the pipe maintains its structural integrity and leak-proof performance over a long duration.
- High Mechanical Strength under Pressure and Temperature Stress: Due to its chemical properties, the pipe has high tensile and yield strength. This allows it to handle high internal pressure and mechanical loads, making it a preferred choice for critical industrial applications and high-pressure service.
- Thermal Stability: This pipe has improved structural stability compared to other B-type alloys due to its controlled amounts of iron (~1-3%) and carbon (≤0.01%). This prevents undesirable brittle phases. This stability simplifies fabrication processes and ensures long-term reliability in high-temperature service.
- Workability: Alloy B3 pipe is ductile and can be readily formed, machined and welded using standard processes. Its good workability simplifies the manufacturing and installation of complex piping systems.
- Elevated Temperature Resistance: The pipe maintains its corrosion resistance in reducing environments at continuous operating temperatures up to 800°F (427°C). For applications requiring only mechanical strength retention without active corrosive media, service temperatures up to 1600°F (870°C) are achievable.
- Heat Treatment: The pipe typically undergoes a final solution annealing (heat treatment) at 1950°F (1066°C) followed by rapid water quenching during manufacturing. This optimises the alloy's microstructure. It also maximises its corrosion resistance and mechanical ductility before deployment.
B3 Seamless Nickel Alloy Pipe Equivalent Material
The equivalent designation of B3 seamless nickel alloy pipe is UNS N10675. Some of the other equivalent materials include the German designation, Werkstoff Nr. 2.4600. The table below mentions the other equivalent materials.
| GRADE | UNS | GB | JIS | ISO | DIN/EN | GOST | |
| ISC | NEW | ||||||
| Alloy B3 | N10675 | — | — | — | — | 2.4600 | — |
100% Certified Testing & Documentation
- EN 10204 3.1 and EN 10204 3.2 Material Test Certificates (MTC)
- Raw Materials Certificate
- 100% PMI
- Heat Treatment Charts
- Third-Party Inspection Report
- Surface roughness and size measurement
- Manufacturer Test Certificate (Impact Testing, Flattening, Flare, Bend, Hardness, Intergranular, Pitting Corrosion, Grain size, ET, UT, HT)
- Laboratory Test Certificate from the Government-Approved Lab
ASTM B622 UNS N10675 Seamless Pipe Industrial Applications
ASTM B622 UNS N10675 seamless pipes have 6 industrial applications. These include:
Chemical Processing
This pipe is used for constructing reaction vessels and handling systems containing concentrated hydrochloric and sulfuric acids. Its superior resistance to reducing acids makes it suitable for critical, highly corrosive media transfer lines.
Oil & Gas
The pipes are used for tubular components in various processing facilities. Its strength and resistance to stress corrosion cracking make it reliable for aggressive and pressurised environments.
Petrochemical
UNS N10675 seamless pipes form important components like heat exchangers and reactor piping systems in petrochemical plants. It effectively resists harsh chemicals used in the synthesis of various petroleum-derived products.
Power Generation
The pipe is used in power generation equipment and for steam piping and heat exchangers. It maintains structural integrity and doesn't corrode in systems that use high-purity water and high temperatures. They are also used in waste incinerators and combustion chambers.
High-Temperature Systems
ASTM B622 pipe is used for manufacturing heat-treating fixtures, furnace parts, and apparatus that operate typically above corrosive temperature limits. Its thermal stability ensures reliable performance and structural integrity at elevated temperatures.
Pharmaceutical
These seamless pipes are used for process piping and high-purity equipment. The strong resistance to corrosion prevents metal ions from escaping and medications from getting contaminated during production.
Frequently Asked Questions
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What is the difference between Alloy B2 and B3?
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What is the maximum service temperature for Alloy B3?Alloy B-3 supports a maximum service temperature of approximately 870 °C (1600 °F) in oxidizing-free, reducing environments. The nickel-molybdenum matrix maintains strength and corrosion resistance up to this limit under controlled atmospheres.
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What is the corrosion resistance of Alloy B3 seamless pipes?Alloy B-3 seamless pipes resist hydrochloric acid across a wide range of concentrations at temperatures below boiling. The nickel-molybdenum composition prevents pitting, crevice corrosion, and stress corrosion cracking in reducing acids.