(UNS S32100) 321 Stainless Steel

321 stainless steel, also known as UNS S32100 and Grade 321, is primarily comprised of 17% to 19% chromium, 12% nickel, .25% to 1% silicon, 2% maximum manganese, traces of phosphorus and sulfur, 5 x (c + n) .70% titanium, with the balance being iron. With regards to corrosion resistance, 321 Stainless Steel is equivalent to Grade 304 in the annealed condition and is superior if the application involves service in the 797° to 1652° F range. 321 Stainless Steel combines high strength, resistance to scaling and phase stability with resistance to subsequent aqueous corrosion.

Industries that use 321 Stainless Steel include:

• Chemical
• Food processing
• Petrochemical
• Pharmaceutical
• Power generation
• Pulp and Paper

Products partially or completely constructed of 321 Stainless Steel include:

• Expansion joints
• Furnace components
• High temperature chemical process equipment
• Refinery equipment
• Superheater and afterburner parts
• Thermal oxidizers
• Welded equipment
• Stainless Steel Flanges
• Boilers
• Aircraft exhaust stacks
• Aircraft piston engine manifolds
• Chemical processing equipment
• Compensators and expansion bellows
• Stainless Steel Tubes
• Jet engine parts
• Manifolds
• Stainless Steel Pipe Fittings
• Heat exchangers
• Outlet and inlet ductwork
• Stainless Steel Pipes
• Piping systems
• Pressure vessels
• Slurry tanks
• Stack liners
• Stainless Steel Bars
• Stainless Steel Valves

Types 321 (S32100) is stabilized stainless steel which offer as their main advantage an excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800 to 1500°F. Type 321 stainless steel is stabilized against chromium carbide formation by the addition of titanium. Type 347 is stabilized by the addition of columbium and tantalum.

While Types 321 stainless steel continues to be employed for prolonged service in the 800 to 1500°F temperature range, Type 304L has supplanted these stabilized grades for applications involving only welding or short time heating.

Types 321 stainless steel is also advantageous for high temperature service because of their good mechanical properties. Types 321 and 347 stainless steels offer higher creep and stress rupture properties than Type 304 and, particularly, Type 304L which might also be considered for exposures where sensitization and intergranular corrosion are concerns. This results in higher elevated temperature allowable stresses for these stabilized alloys for ASME Boiler and Pressure Vessel Code applications.

The Types 321 stainless steel has maximum use temperatures of 1500°F for code applications like Type 304, whereas T304L is limited to 800°F. Applications for Types 321 stainless steel includes those for welded construction and parts subjected to heating in the carbide precipitation range, aircraft collector rings, aircraft exhaust stacks, boiler casings, cabin heaters, stainless steel tubes, exhaust manifolds, fasteners, fire walls, flash boilers, flexible couplings, furnace heating elements, jet engine parts, large mufflers for stationary diesel engines, pressure vessels, stack liners, all-welded tank car for carrying chemicals, annealing box inner covers, collector rings, expansion joints, heat resistors, heavy wall welded equipment, welded tanks for storing organic chemicals, wire cloth and screens (industrial).

Types 321 stainless steel offers similar resistance to general, overall corrosion as the unstabilized chromium nickel Type 304 stainless steel. Heating for long periods of time in the chromium carbide precipitation range may affect the general resistance of Types 321 stainless steel in severe corrosive media.

321 Stainless Steel is available in the following forms at Yaang

• Stainless Steel Elbows
• Stainless Steel Angle Bars
• Stainless Steel Bars
• Stainless Steel Pipe Fittings
• Stainless Steel Tubes
• Stainless Steel Flanges (i.e. flanges, slip-ons, blinds, weld-necks, lapjoints, long welding necks, socket welds, elbows, tees, stub-ends, returns, caps, crosses, reducers, and pipe nipples)
• Stainless Steel U Tubes
• Stainless Steel Concentric Reducer
  
• Stainless Steel Pipes

Source: Yaang Pipe Industry (www.yaang.com)