ASTM A182 F321H / UNS S32109 Stainless Steel Weld Neck Flange WNRTJ Flange

ASTM A182 F321H Stainless Steel Flange UNS S32109 Forged WNRTJ Flange

ASTM A182 F321H is a high-temperature, stabilized stainless steel grade used for Weld Neck (WN) Ring Type Joint (RTJ) flanges. Stainless steel grade F321H, part of the 321 series, stabilized with titanium (Ti) to prevent chromium carbide precipitation, enhancing resistance to intergranular corrosion. These flanges are engineered for extreme environments requiring leak-tight seals, high pressure, and thermal stability. Their titanium-stabilized composition and RTJ design make them indispensable in critical HPHT systems, such as oil and gas, petrochemical, and power generation systems. The "H" suffix indicates a higher carbon content (0.04–0.10%) for enhanced creep resistance at elevated temperatures.

Key Features

1. High-Temperature Performance:

   • Suitable for continuous service up to 800°C (1472°F).

   • Resists oxidation, scaling, and creep deformation under stress.

2. Stabilized with Titanium:

   • Prevents sensitization (chromium carbide formation) during welding or high-temperature exposure.

3. WN RTJ Design:

   • Weld Neck (WN): Tapered hub for stress distribution, ideal for high-pressure systems.

   • RTJ Face: Machined groove for metal ring gaskets (e.g., oval/octagonal), ensuring leak-proof seals in HPHT environments. 

F321 vs. F321H: F321H has higher carbon for improved high-temperature strength.

ASTM A182 F321/F321H Stainless Steel Flange Specification

Applications

• Oil & Gas: Wellhead equipment, pipelines, and refinery systems.

• Power Plants: Steam lines, boilers, and turbine connections.

• Chemical Processing: High-temperature reactors and heat exchangers.

• Aerospace: Exhaust systems and combustion components.