UNS N10665 Pipes

UNS N10665 pipes, commonly recognized as Alloy B2, is the workhorse grade for pure hydrochloric acid (HCl) service at all concentrations and temperatures up to 70 °C. With 65% nickel and 28% molybdenum as the primary alloying elements, B2 is essentially immune to HCl attack in the reducing conditions that destroy C276 and C22. HT PIPE is a astm b622 uns n10665 supplier with 15+ export experience. Contact us for more information and quotes for free!

 

Primary applications:

• HCl alkylation units in oil refineries (the most common B2 service in petrochemical)

• Acetic acid and acetic anhydride reactors

• Sulphuric acid at low concentration (below 60%) without oxidising contaminants

• Phosphoric acid evaporator tubes (below 60% concentration)

• Vinyl chloride monomer (VCM) production

 

IMPORTANT service limitations: B2 must NOT be used in ferric or cupric chloride solutions, or in any environment with oxidising contaminants. In these conditions, B2 suffers rapid pitting and stress corrosion cracking - use C276 or C22 instead.

 

Supplied to ASTM B622 (seamless), B619 (welded), B626 (welded, light wall). Solution-annealed at 1065 °C min, water quenched. Stock size OD 1/4 in to 8 in, Sch 5S to XXH. EN 10204 3.1 mill test certificate included.

 

Hastelloy alloy B2 Chemical Composition

Ni	Mo	Fe	C	Co	Cr	Mn	Si	P	S
Balance	26.0-30.0	2.0 max	0.02 max	1.0 max	1.0 max	1.0 max	0.10 max	0.040 max	0.030 max

 

Hastelloy Alloy B2 Pipe Mechanical Properties

Density	Melting Point	Tensile Strength	Yield Strength (0.2%Offset)	Elongation
9.2 g/cm3	1370 °C (2550 °F)	Psi – 1,15,000 , MPa –760	Psi – 52,000 , MPa – 350	40%

 

Manufacturing and Procurement Specifications

Procuring UNS N10665 pipes requires compliance with rigorous international standards to ensure the material's structural integrity and uniform chemistry.

ASTM B622 / ASME SB622: Dictates the manufacturing, dimensional tolerances, and testing protocols for seamless nickel and nickel-alloy pipes. Seamless configurations are preferred for high-pressure, critical-containment lines where longitudinal weld lines pose an unacceptable risk.

ASTM B619 / ASME SB619: Covers welded pipe options. These require precise automated gas tungsten arc welding (GTAW) or plasma arc welding (PAW) without the addition of filler metal, ensuring the weld seam remains chemically identical to the base metal.

ASTM B462 / ASME SB462: Specifies the standards for forged or rolled pipe flanges, forged fittings, and valves intended for high-temperature, corrosive service.

 

Key Performance Benefits in Industrial Applications

1. Resistance to Pure Reducing Acids

The primary reason for selecting UNS N10665 is its ability to handle pure reducing chemistries. Standard chromium-based passive films easily dissolve in hot hydrochloric, phosphoric, or sulfuric acid environments. Because Alloy B-2 does not rely on an oxide film for protection, it maintains a low corrosion rate even at boiling temperatures.

 

2. Resistance to Chloride-Induced Stress Corrosion Cracking

Chloride ions frequently cause premature failures in standard 300-series stainless steels via Stress Corrosion Cracking (SCC). The nickel-rich matrix of UNS N10665 makes it virtually immune to chloride-induced SCC, enabling safe operation under high tensile loads and elevated temperatures.

 

3. Protection Against Localized Pitting

The high concentration of molybdenum significantly improves the alloy's resistance to pitting and crevice corrosion in reducing halide environments, preventing localized wall thinning that can lead to catastrophic pressure boundary breaches.

 

 

 

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