Austenitic SS 321 Fittings and Flanges

Austenitic SS 321 Fittings and Flanges

321 stainless steel flange and 321 stainless steel fittings is titanium stabilized austenitic stainless steel with good general corrosion resistance. Stainless Steel 321 Flanges is developed to provide an 18-8 type alloy with improved inter-granular-corrosion resistance.

Chemical Properties

GRADE   Cr Ni C Mn P Si Ti Fe S N
SS 321 MIN % 17 9 5x(C+N)
MAX % 19 12 0.08 2 0.045 0.75 0.7 BALANCE 0.03 0.1

SS 321 flanges or UNS S32100 can be used for extended periods at elevated temperatures without compromising its corrosion resistance. 321 has equivalent corrosion resistance to sensitization as the low carbon version 317L. SS 321 austenitic structure also gives these grades excellent toughness, even down to cryogenic temperatures.

Physical Properties

Grade Density (g/cm3) Melting Point Elastic Modulus (GPa) Mean Co-eff of Thermal Expansion (μm/m/°C) Thermal Conductivity (W/m.K) Specific Heat (J/Kg.K) Electrical Resistivity (nΩ.m)
0-100°C 0-315°C 0-538°C at 100°C 0-100°C
SS 321 8 1400-1450 °C 190-210 16.6 17.2 18.6 16.1 500 720

Specification of Flange

The specified ASTM Standard Specification for Wrought Austenitic Stainless Steel Flanges is ASTM A182 with manufacturing standard such as ANSI/ASME B16.5, B16.48, BS4504, B 16.47 Series A & B, BS 10, EN-1092, DIN, etc.

Mechanical Properties of Flange

Grade Tensile Strength Yield Strength Elongation Reduction of area
[MPA] [MPA] (% in 50mm) min min %
SS 321/321H 515 205 30 50

According to application and uses in pipes and tubes 321 flanges are broadly grouped into different sort, for example, SS 321 Welding Neck Flange(WNF) & Long Welding Neck Flange(LWNF), Slip-on Flange(SOF), Lap Joint Flange(LJW), Blind Flange, Socket Welding Flange (SWF), Threaded Flange(THW), Plate Flange.

SS 321 Flange for the most part has different face type, for example, Flat Face (FF), Raised Face (RF), Ring Type Joint (RTJ), blind flange, with various class rating as 50 LBS, 300 LBS, 600 LBS, 900 LBS, 1500 LBS, 2500 LBS, DIN Standard ND-6,10, 16,din 2.4856 , 25, 40 & ANSI B16.5.

Specification of Fittings

The Specification for Wrought Austenitic SS 321 fittings is ASTM A403, having Specific
manufacturing Standards as ASME/ANSI B16.9, ASME B16.28, MSS-SP-43.

Mechanical Properties of Fittings

Grade Tensile Strength Yield Strength
SS 321/321H 515 205

SS 321 Fittings that are categorically available are Elbow, Reducer, Tee, Coupling, Bend, Stub End, Cap, Nipple, Washer, Cross, Union etc. which are available in different types such as Welded, Seamless and Fabricated having thickness range from 5s, 10s, 40s, 80s, 10, 20, 40, STD, 60, 80, XS, 100, 120, 140, 160, XXS available with NACE MR 01-75.


SS 321 Flange and Fittings with specific corrosion resistance properties and Sensitization properties it is widely in following industries such as:

  • Seawater Cooling Devices
  • Architectural railings
  • Wiring In Electrostatic Precipitators
  • Oil Refinery
  • Gas Scrubbing Plants
  • Pulp and Paper Processing Industries
  • Acetic, Phosphoric and Sulphuric Acid Processing Plants.