Alloy C-4 Seamless Pipe for High-Temperature Corrosive Environments with Corrosion Resistant and Metallurgical Stability

Alloy C-4 (UNS N06455) is a high-performance nickel-chromium-molybdenum alloy known for its exceptional metallurgical stability and corrosion resistance. It is the most microstructurally stable member of the widely used Ni-Cr-Mo alloy family, which is renowned for resistance to a wide range of aggressive chemicals, particularly hydrochloric acid, sulfuric acid, and chlorides.

This alloy features a face-centered cubic (FCC) lattice structure with an optimized chemical composition that ensures metallurgical stability and resistance to sensitization. With lower carbon, silicon, and iron content compared to earlier similar alloys such as Hastelloy C-276, Alloy C-4 delivers excellent stability at 650 °C to 1040°C and significantly improved resistance to intergranular corrosion. Under proper manufacturing conditions, it can avoid wire-cutting sensitization and corrosion in weld heat-affected zones.

The alloy's excellent corrosion resistance, high-temperature stability, and weldability make it an ideal material choice for the most demanding chemical processing, flue gas desulfurization (FGD), and high-temperature industrial applications.

*PREN = %Cr + 3.3 * %Mo + 16 * %N (Pitting Resistance Equivalent Number). Higher values indicate superior pitting corrosion resistance. Test data represents typical values and may vary with specific product form and heat treatment condition.

• Excellent Corrosion Resistance: Outstanding resistance to a wide range of aggressive acidic media including strong acids, salts, oxides, chlorides, and sulfides. The alloy resists stress corrosion cracking (SCC) and intergranular corrosion, ensuring long service life in harsh chemical conditions such as wet chlorine, hypochlorous acid, sulfuric acid, hydrochloric acid, and mixed acid environments.
• Excellent High-Temperature Stability: Maintains high ductility and mechanical integrity even after prolonged aging at elevated temperatures (649°C to 1038°C). The metallurgically stable FCC structure prevents the formation of deleterious grain boundary precipitates in the weld heat-affected zone (HAZ), typically eliminating the need for post-weld heat treatment (PWHT).
• Excellent Weldability: Easily welded using TIG (GTAW), MIG (GMAW), or SMAW techniques without fear of sensitization. The alloy's low carbon content and optimized chemistry prevent HAZ sensitization, allowing direct use after welding without additional heat treatment. Matching filler metal ERNiCrMo-7 is recommended.
• Oxidation-Reduction Mixed Corrosion Resistance: Capable of withstanding both oxidizing and non-oxidizing acids, making it versatile for complex process environments where multiple corrosive species coexist.
• Good Formability: The alloy is ductile and can be cold-formed and hot-formed using standard techniques. Hot working should be performed within 1080°C to 900°C followed by rapid cooling.

DINGSCO supplies high-quality Alloy C-4 seamless tubes with strict dimensional tolerances and superior surface finish. Please contact our sales team for detailed product photos, mill test certificates (MTC), and third-party inspection reports (SGS, BV, TUV).

• Chemical Processing Industry: Processing contaminated inorganic acids, organic acids, and chlorine gas environments; reactor vessels, heat exchangers, and piping systems in aggressive chemical plants.
• Flue Gas Desulfurization (FGD) Systems: Excellent resistance to sulfuric acid condensates and chloride-bearing scrubber solutions in coal-fired power plant emission control systems.
• Pickling and Acid Regeneration Plants: Withstands highly corrosive pickling acids (HCl, HNO₃, HF mixtures) at elevated temperatures in steel pickling and acid recovery operations.
• Acetic Acid and Chemical Product Manufacturing: Resistant to organic acid corrosion at process temperatures in pharmaceutical and fine chemical production.
• Titanium Dioxide Production (Chlorination Process): Equipment and piping requiring exceptional resistance to chlorine and chloride-containing environments at high temperatures.
• Electrolytic Cells: Components exposed to aggressive electrolyte solutions in chlor-alkali and electrochemical processing.
• Wet Chlorine Processing: Handling wet chlorine gas, hypochlorous acid, and chlorine dioxide in water treatment and bleaching operations.

DINGSCO is a leading manufacturer and supplier specializing in high-performance nickel alloy products. With decades of metallurgical expertise and state-of-the-art production facilities, we deliver premium-quality nickel alloy tubes, pipes, bars, plates, and customized components to customers worldwide.

Our mission is to provide our customers only with the best quality products. As an ISO 9001:2015, PED 2014/68/EC, and API 6A certified manufacturer, we implement strict quality control at every production stage -- from raw material inspection to final product delivery. Each shipment is accompanied by comprehensive Mill Test Certificates (MTC) per EN 10204 3.1.

We pay close attention to customer needs, implement product innovation, and further leverage the company's full range of product types and material grades to provide customers with one-stop service. Continuous improvement through material research, process optimization, and equipment upgrades is at the core of our development.

We are pleased to help others and glad to acquire the hand of others. We actively participate in team meetings and support decision-making. We share our experience with each other and excel at cooperating with different types of colleagues and partners across the global supply chain.

ISO 9001:2015 | PED 2014/68/EC | API 6A

DINGSCO offers a comprehensive portfolio of nickel alloys and special stainless steels. Our technical team is ready to assist you in selecting the optimal material for your specific application:

DINGSCO provides fully customized nickel alloy solutions to meet your exact specifications and application requirements:

• Custom Dimensions: Non-standard OD, wall thickness, and length combinations manufactured to your precise requirements.
• Custom Heat Treatment: Solution annealing, stress relieving, and aging treatments tailored to your application needs.
• Custom Surface Finish: Pickled, bright annealed, mechanically polished (up to mirror finish), and electropolished surfaces available.
• Custom Testing & Inspection: Additional NDT (UT, ET, RT, PT, MT), PMI, IGC testing per ASTM A262 / G28, corrosion testing per ASTM G48, mechanical testing, and third-party inspection (SGS, BV, TUV, Lloyd's) upon request.
• Custom Packaging: Export-grade wooden cases, plywood pallets, crates with waterproof wrapping, and end-caps for tube protection.
• Custom Machining & Fabrication: CNC machining, tube bending, cutting, beveling, and welding fabrication services available.
• Documentation: Full EN 10204 3.1 / 3.2 certification, Certificate of Origin (CO), and compliance statements provided.

for expert material selection guidance, competitive pricing, and fast delivery. Our engineering team is ready to support your project with technical expertise and reliable supply chain solutions.