Ni Alloy 31 Pipe

Ni Alloy 31 (1.4562)-a nitrogen-fortified iron-nickel-chromium-molybdenum alloy-effectively bridges the performance gap between super-austenitic stainless steels and expensive nickel-based alloys. Our manufacturers can produce astm b622 uns n08031 seamless and welded pipes to meet industry requirements. Contact us market@htpipe.com for more information and a free quote!

Core Chemical Attributes: Why Alloy 31 is Irreplaceable

Element	Content (Typical %)	Core Function
Chromium (Cr)	26.0 - 28.0	Provides extreme resistance to oxidizing acids (e.g., Nitric Acid).
Nickel (Ni)	30.0 - 32.0	Stabilizes the austenite structure; resists Stress Corrosion Cracking (SCC).
Molybdenum (Mo)	6.0 - 7.0	Significantly enhances resistance to pitting and crevice corrosion.
Nitrogen (N)	0.15 - 0.25	Increases mechanical strength and inhibits intermetallic phase precipitation.
Copper (Cu)	1.0 - 1.4	The key element for stability in Sulfuric Acid environments.

 

Alloy 31 Pipe Tube Specifications

Specifications	ASTM B622, ASTM B626, ASTM B619
Standard Size	1/8"NB TO 30" NB IN
Alloy 31 Seamless Pipes	1/2" NB - 16" NB
SS Alloy 31 ERW Pipe	1/2" NB - 24" NB
SS Alloy 31 EFW Pipe	6" NB - 100" NB
Outer Diameter	6.00 mm OD up to 914.4 mm OD, Sizes up to 24" NB
Thickness	0.3 - 50 mm, SCH 5, SCH10, SCH 40, SCH 80, SCH 80S, SCH 160, SCH XXS, SCH XS, LSAW, SSAW, HSAW
Manufacturing techniques	Seamless / ERW / Welded / Fabricated / CDW / EFW
Shape	Round, Half Round, Square, Rectangular or Custom
Length	Single Random, Double Random & Custom Length
Pipe End	Plain End, Beveled End, Treaded
Test Certificate	EN 10204 3.1 B
Alloy 31 round pipes
Size range	Wall thickness: 1mm- 150mm (SCH10-XXS)
	Outer diameter: 6mm- 2500mm (3/8"-100")
Nickel Alloy N08031 square pipe
Size range	Wall thickness: 1mm- 150mm (SCH10-XXS)
	Outer diameter: 4mm*4mm- 800mm*800mm
Alloy 31 UNS N08031 rectangular pipes
Size range	Wall thickness: 1mm-150mm (SCH10-XXS)
	Outer diameter: 6mm-2500mm (3/8"-100")
	Length: 4000mm, 5800mm, 6000mm, 12000mm, or as required.

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Exceptional PREN Value

The Pitting Resistance Equivalent Number (PREN) for Alloy 31 is typically ≥ 48. This ensures the alloy prevents localized pitting when handling hot seawater, acidic oil/gas wells, or bleaching equipment.

 

Unique Stability in Sulfuric Acid

Most stainless steels fail rapidly in sulfuric acid concentrations between 20% and 80%. Thanks to the addition of Copper (Cu), Alloy 31 piping maintains an incredibly low corrosion rate across a wide range of concentrations and temperatures, making it the premier choice for acid recovery systems.

 

Resistance to Stress Corrosion Cracking (SCC)

High nickel content ensures that the pipeline will not suffer sudden brittle fracture due to stress factors in harsh process streams containing chloride ions.

 

Typical Application Scenarios for Alloy 31 Pipe

Flue Gas Desulfurization (FGD): Handling scrubbers with high chloride concentrations and waste acids.

Phosphoric Acid Production: Coping with impurities in concentrated acid during the "wet process."

Pulp and Paper Industry: Bleaching equipment using chlorine dioxide environments.

Fine Chemicals: Reactor and transfer lines involving halide catalysts.

 

Selection Guide: Seamless vs. Welded Pipes

Alloy 31 Seamless Pipe: Best for high-pressure, mission-critical environments. It offers a more uniform metallurgical structure without weld-zone vulnerabilities. Reference Standard: ASTM B622.

Alloy 31 Welded Pipe: More cost-effective for large-diameter transport. Modern automated welding combined with solution annealing ensures weld performance closely matches the base metal. Reference Standard: ASTM B619 / B626.

 

 

 

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