Stainless steel 347h Flange

JN ALLOY supplies 347H SO flanges, 347H WN flanges, UNS S34709 blind flanges, 1.4961 347H plain flanges, ASTM A182 UNS S34709 SW flanges, 347H spectacle blind flanges, 347H threaded flanges, 1.4961 spacer ring,UNS S34709 paddle blind/blank, 347H bleed/test/drip ring, 347H reducing flange.

Stainless steel 347H (UNS S34709) is an upgraded material with optimized carbon content based on conventional 347 stainless steel. Its composition contains about 17-19% chromium, 9-13% nickel, and niobium (Nb) and tantalum (Ta) are added as stabilizing elements. Niobium combines with carbon to form stable niobium carbide (NbC), which effectively inhibits the precipitation of chromium carbide at the grain boundary, thereby significantly improving the resistance to intergranular corrosion, especially for conditions after welding or long-term exposure to high temperatures above 427°C. In addition, the high chromium and nickel content gives S34709 excellent oxidation resistance, which can be used for a long time in an environment below 816°C, and the short-term temperature resistance can reach 870°C. SS 347H has better creep strength and stress rupture resistance at high temperatures, and also has good low-temperature toughness (minimum -196°C) and resistance to chloride stress corrosion cracking. Jinie Technology (Jiangsu) Co., LTD supply all different types and scales of flanges. Please feel free to contact us for further product information and pricing.

Stainless steel 347h Flange manufacturing usually adopts forging or casting process. Forged flanges have higher mechanical strength and fatigue resistance due to their dense grain structure. Key processes include:

1. Solution treatment (1040-1120°C water quenching) to eliminate processing stress and homogenize the structure.

2. Precision machining to ensure that the flatness and roughness of the sealing surface (such as RF, FF, RTJ type) meet the standards.

3. Surface treatment can be optional pickling passivation or electrolytic polishing to enhance corrosion resistance.

High temperature stability: The continuous working temperature is about 50°C higher than that of 304H, and the high-temperature strength attenuation rate is low, which is suitable for pipeline systems with frequent thermal expansion;

Welding reliability: Intergranular corrosion can be avoided without annealing after welding, especially suitable for thick-walled flanges and dissimilar steel welding (such as connection with carbon steel pipelines);

Economic efficiency: By reducing downtime maintenance caused by corrosion/deformation, the equipment life cycle is extended, and the comprehensive cost is lower than that of high-end materials .

Material: ASTM A182 Standard Specification for Forged or Rolled Alloy Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High Temperature Service

Standard: ASME B16.5, ASME B16.47, DIN, EN, BS, JIS

Size: 1/2"-48", DN6-DN400

Class: 150#,300#,400#,600#,900#,1500#,2500#

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