UNS S34700/EN 1.4550/ASTM A269 TP347 Seamless Coiled Tubing

UNS S34700/EN 1.4550/ASTM A269 TP347 Seamless Coiled Tubing

​Shanghai Toko Tech Co., Ltd.​​ is a professional manufacturer and supplier of high-performance special alloy pipes and components. Its ​347 (UNS S34700)​​ seamless coiled tubing is a columbium (niobium)-stabilized austenitic stainless steel specifically designed to provide excellent intergranular corrosion resistance following welding or exposure to high temperatures.

​Key Features & Advantages:​​

Superior Intergranular Corrosion Resistance:​​ The addition of ​Columbium (Nb, also called Niobium)​​ stabilizes the alloy, preventing the formation of chromium carbides at grain boundaries during welding or high-temperature exposure (in the range of 800°F – 1500°F / 427°C – 816°C). This makes it ideal for applications where post-weld heat treatment is not practical.

Excellent High-Temperature Properties:​​ Offers good resistance to oxidation and maintains high strength at elevated temperatures, making it suitable for continuous service at temperatures up to 800°C (1472°F).

Good General Corrosion Resistance:​​ Provides corrosion resistance similar to 321 and 304 stainless steels in a wide range of atmospheric and mild chemical environments.

Enhanced Strength in Certain Applications:​​ The columbium stabilization can provide higher creep and stress-to-rupture strength in specific high-temperature conditions compared to unstabilized grades.

Seamless & Continuous Length:​​ The seamless structure ensures higher pressure integrity and reliability. The long coiled length simplifies installation in complex systems requiring long runs or bending.

Difference from 321:​​

While both 321 (Ti-stabilized) and 347 (Nb-stabilized) are used for similar applications, ​347 is often preferred in strong oxidizing acid environments​ and for heavy section welding. Columbium (Nb) is less reactive than Titanium (Ti) and is not as readily lost to the formation of oxides during welding, which can be an advantage in certain processes.

​Typical Specifications (Customizable):​​

​Material Grade:​​ UNS S34700 / EN 1.4550 / ASTM A269 TP347

Outer Diameter (O.D.):​​ φ3 mm ~ φ20 mm (Common range for coils)

Wall Thickness (W.T.):​​ 0.5 mm ~ 2.0 mm (Varies with O.D.)

Coil Length:​​ Several hundred meters per continuous coil (exact length depends on O.D. and W.T.)

Standard:​​ ASTM A269, ASTM A213, etc.

Primary Applications:​​

This tubing is specifically designed for welded equipment and high-temperature service in corrosive environments, including:

Aviation & Aerospace:​​ Engine exhaust systems, manifold systems, and heat exchanger tubing.

Chemical & Petrochemical Processing:​​ Vessels, piping, and tubing for processing chemicals, especially in welded assemblies exposed to corrosive media.

Oil & Gas Refining:​​ Heater tubes, heat exchangers, and piping in refinery environments.

Power Generation:​​ Boiler tubes, superheaters, and other components in fossil fuel power plants.

Food and Pharmaceutical Processing:​​ Equipment and piping where welding is required and corrosion resistance is critical.

Why Choose TOKO TECH’s 347 Coiled Tubing?​​

TOKO TECH ensures consistent quality through strict process control from material selection to final packaging. The production includes ​solution annealing​ and ​100% non-destructive testing (Eddy Current or Ultrasonic)​​ to ensure integrity. The coils are often protected with ​VCI (Vapor Corrosion Inhibitor) packaging​ or ​vacuum sealing​ to prevent corrosion during transit and storage.

​In summary,​​ TOKO TECH’s 347 seamless coiled tubing provides a robust solution for applications demanding excellent intergranular corrosion resistance after welding or high-temperature exposure. Its niobium stabilization offers distinct advantages in specific environments, and the long, continuous coil format provides significant installation efficiency for complex systems.