Product Description

347 and 347H stainless steels are exceptional heat-resistant chromium-nickel steels. 347 is a stabilized austenitic stainless steel that builds upon the performance of 304 by incorporating a niobium addition (with 347H being its high-carbon variant). The inclusion of niobium and tantalum not only refines the internal grain structure but also effectively resists intergranular corrosion and promotes age hardening. Therefore, this material is an ideal solution for environments with intermittent heating between 800°F and 1650°F, and is particularly suitable for welding scenarios where post-weld heat treatment is not feasible.

Core Advantages: More Than Stainless Steel – A Heat-Resistant Alloy

Under extreme operating conditions ranging from 427°C to 816°C, ordinary stainless steels often fail due to intergranular corrosion caused by chromium carbide precipitation. 347/347H stainless steel, stabilized with niobium (Nb) , maintains excellent resistance to intergranular corrosion even at elevated temperatures. Whether it's 347 (0Cr18Ni11Nb) or the high-carbon variant 347H, we deliver not just pipes but safety and stability for your high-temperature environments.

Why Choose 347/347H?

1、Superior High-Temperature Strength: Compared to 304 stainless steel, 347/347H offers better ductility and stress rupture resistance. Under continuous high-temperature and high-pressure conditions, it effectively resists creep, extending equipment service life.

2、Stable Corrosion Resistance: In demanding acidic, alkaline, and polythionic acid environments, even in seawater and chloride media, the 347 series demonstrates better general and pitting corrosion resistance than 316L.

3、Excellent Weldability and Processability: The niobium-stabilized composition eliminates sensitization tendencies after welding, maintaining good mechanical properties without complex post-weld heat treatment. This makes it widely applicable in the fabrication of boilers and pressure vessels.

Key Application Areas

· Power Generation: High-temperature superheaters, reheaters, and steam lines in supercritical and subcritical power station boilers.

· Petrochemical Industry: Petroleum cracking units, chemical reactor heat exchanger tubes, coal-to-liquid industrial pipelines.

· New Energy: Molten salt storage tanks and high-temperature medium transfer pipes in CSP plants (excellent resistance to molten salt corrosion).

· Aerospace: Aircraft engine exhaust manifolds, turbine compressor hot gas lines (suitable for components operating up to 850°C).

Technical Specifications

Why Choose Us?

Full Quality Control: Strict hydrostatic testing, ultrasonic inspection, and intergranular corrosion testing ensure defect-free pipes.

Ample Stock: Regular inventory of 347/347H seamless pipes in various specifications; material certificates and third-party test reports available.

Custom Services: Support for non-standard lengths, bright annealing, and precision polishing.

Conclusion: Under the dual challenges of high temperature and corrosion, 347/347H stainless steel pipes are the strongest line of defense for your industrial systems. Contact us today for your tailored material solution!

Note: The main difference between 347 and 347H lies in carbon content. 347H (high carbon) offers higher high-temperature strength and is suitable for pressure-bearing components above 650°C, while 347 is more appropriate for moderate-temperature environments where welding performance is critical. Please select the appropriate grade based on your actual operating temperature.