Introduction

ASTM B690 Seamless Nickel Alloy Pipe is the standard specification for nickel-iron-chromium-molybdenum alloy seamless pipe and tube intended for general corrosive service, particularly in seawater, chemical processing, and high-chloride environments. This specification covers four primary high-performance grades: UNS N08367 (Alloy 6XN / 6Mo), UNS N08904 (904L), UNS N08028 (Alloy 28), and UNS N08031 (Alloy 31), available in cold-worked or hot-finished conditions.

These super austenitic stainless steel pipe grades are characterized by high molybdenum and nitrogen content, delivering superior pitting resistance, excellent corrosion resistance, crevice corrosion resistance, and chloride stress corrosion cracking resistance. The high molybdenum alloy pipe composition (6–7% Mo for N08367, 4–5% for N08904, 3–4% for N08028, and 6–7% for N08031) provides exceptional protection in aggressive environments where standard stainless steels fail. This corrosion resistant alloy pipe is widely used in seawater desalination, offshore platforms, chemical processing, FGD systems, and the pulp and paper industry.

Key grades covered under this specification:

• UNS N08367 (Alloy 6XN / 6Mo Pipe) – The highest molybdenum content (6–7%) with nitrogen addition, offering superior pitting resistance and seawater corrosion resistance for marine and desalination applications.

• UNS N08904 (904L Pipe) – A high alloy stainless steel pipe with excellent resistance to sulfuric acid, phosphoric acid, and chloride pitting, widely used in chemical processing and acid handling.

• UNS N08028 (Alloy 28 Pipe) – Features enhanced resistance to sulfuric and phosphoric acids, making it ideal for fertilizer production and petrochemical service.

• UNS N08031 (Alloy 31 Pipe) – Highest alloy content with 6–7% molybdenum and nitrogen, providing superior corrosion resistance in the most aggressive chemical environments.

All products meet ASME SB690 and ASTM B690 general requirements. Our range includes seamless ASTM B690 pipe from 1/2″ to 12″ NPS, with custom sizes, Schedule 40/80, heavy wall alloy pipe, large diameter alloy pipe, and cut-to-length services.

Specifications & Process Options

Applications

1. Seawater Desalination & Marine Systems

• ASTM B690 pipe for desalination plants is the preferred material for seawater handling due to its superior pitting resistance and crevice corrosion resistance. Key advantages and typical uses include:

• Seawater intake and brine handling – 6XN pipe for desalination delivers excellent resistance to warm, high-chloride brine in MSF and RO plants, preventing pitting and crevice corrosion at seals and flanges.

• High-velocity seawater service – Seawater resistant alloy pipe withstands erosion-corrosion in high-flow intake lines and pump discharge systems.

• Long service life – Alloy 6XN pipe and 904L pipe provide extended maintenance-free operation in aggressive marine environments, outperforming duplex and 316L stainless steels.

2. Chemical Processing & Acid Handling

• Chemical grade alloy pipe is essential for handling aggressive acids and corrosive process streams:

• Sulfuric and phosphoric acid resistance – Alloy 28 Pipe and Alloy 31 Pipe offer excellent resistance to hot concentrated acids, making them ideal for reactors, heat exchangers, and distillation columns.

• Mixed acid and chloride streams – Corrosion resistant pipe for chemical plants effectively handles acid mixtures containing chlorides, fluorides, and organic compounds without localized attack.

• Fertilizer industry – Alloy pipe for fertilizer industry resists corrosive attack from phosphate rock digestion and ammonium sulfate crystallization, extending equipment life.

3. Offshore Platforms & Oil and Gas

• Nickel Alloy Seamless Tube and Alloy 6XN pipe are widely used in offshore and subsea applications:

• Subsea pipelines and risers – Offshore corrosion resistant pipe withstands high chloride concentrations, high pressures, and variable temperatures in deepwater oil and gas production.

• Topsides process piping – Marine grade alloy pipe resists salt spray, splash zone corrosion, and internal process corrosion from produced water and acid gases.

• Firewater and utility systems – Corrosion resistant alloy pipe ensures reliable service in critical safety systems on offshore platforms.

4. Flue Gas Desulfurization & Environmental Systems

• ASTM B690 pipe for FGD systems delivers durability in aggressive scrubber environments:

• Scrubber liquor recirculation – Alloy 31 Pipe and 6Mo pipe withstand low-pH, high-chloride scrubber liquor in limestone-based FGD systems, resisting pitting and crevice corrosion.

• Spray header and absorber internals – Corrosion resistant pipe for scrubbers maintains structural integrity in high-temperature, high-humidity acidic environments.

• Quench nozzles and mist eliminators – Super austenitic stainless steel pipe provides long service life in demanding air pollution control equipment.

5. Pulp & Paper and Industrial Processing

• Alloy pipe for pulp and paper industry is trusted for bleach plant and chemical recovery service:

• Chlorine dioxide bleaching – 904L pipe and 6XN pipe resist corrosion in bleach plant piping, maintaining surface integrity in high-chloride, acidic conditions.

• Green liquor and liquor – Corrosion resistant pipe for bleaching systems withstands sulfidity and high-temperature caustic service in recovery boilers.

• Chemical recovery – High alloy stainless steel pipe provides reliable service in evaporators, digesters, and recovery furnace components.

Why Choose Us as Your ASTM B690 Pipe Supplier?

We are a trusted ASTM B690 pipe supplier, ASTM B690 seamless pipe supplier, and nickel alloy pipe manufacturer, China-based, serving clients worldwide. All products meet ASTM B690 / ASME SB690 with full mill test certificates and NDT.

What we offer:

• Forms: Seamless pipe, tube, hollow bar, fittings, flanges

• Sizes: 1/2″ to 6″ OD; SCH10–SCH160; custom diameters & wall thicknesses

• Grades: UNS N08367 (6XN), UNS N08904 (904L), UNS N08028 (Alloy 28), UNS N08031 (Alloy 31)

• Standards: ASTM B690 / ASME SB690; also B622, B444, B423, B163

• Customization: Cut-to-length, special bevel ends, coatings, cold-drawn/hot-finished

• Quality: EN 10204 3.1, PMI, full traceability, hydrostatic testing

• Global supply: Export to desalination, chemical, oil & gas, power, and heat exchanger industries worldwide

Contact us for size chart, pricing, or a quote on 6XN Pipe, 904L Pipe, Alloy 28 Pipe, Alloy 31 Pipe, or custom requirements.

FAQ – ASTM B690 Nickel Alloy Pipe

Q: What is the difference between UNS N08367 (6XN), N08904 (904L), N08028 (Alloy 28), and N08031 (Alloy 31)?

A: UNS N08367 (6XN/6Mo) features 6–7% molybdenum with nitrogen, offering the highest pitting resistance for seawater and desalination. UNS N08904 (904L) has 4–5% molybdenum with copper addition, providing excellent sulfuric acid resistance. UNS N08028 (Alloy 28) offers enhanced resistance to phosphoric and sulfuric acids for fertilizer and chemical service. UNS N08031 (Alloy 31) is the highest alloyed grade, offering the broadest corrosion resistance across multiple aggressive environments.

Q: What is the maximum operating temperature for this material?

A: These grades perform well up to approximately 300–400°C (570–750°F). For higher temperature applications, nickel-based alloys such as Alloy 625 or Hastelloy grades are typically recommended.

Q: Do you supply other nickel alloy grades besides the ASTM B690 family?

A: Yes. We also supply Seamless Hastelloy C276 Pipe, Hastelloy C22 Pipe, Inconel 625 Pipe, Inconel 825 Pipe, Monel 400 Pipe, Alloy 20 Pipe, and Alloy 28/31 Pipe from our inventory.

Q: Do you provide material test certificates with each shipment?

A: Yes. Every shipment includes EN 10204 Type 3.1 mill test certificates with chemical analysis, mechanical property reports, and dimensional inspection records. Additional NDT reports including hydrostatic testing, eddy current testing, and ultrasonic examination are available upon request.

XI’AN MONO TECHNOLOGY CO.,LTD. is one of ASTM B690 Seamless Nickel Alloy Pipe other Superalloy, Nickel alloy, High Temperature Alloy pipe manufacturers, suppliers, factory, company, exporter, seller, brands, import, buy, best, high-quality from China, in accordance with ASTM, ASME, DIN, ISO,JIS standard.pls contact us freely for your RFQ to info@monokj.com