Stainless Steel 347/347H

These types of stainless are austenitic chromium steels containing colubium.  They are recommended for parts fabricated by welding which cannot be subsequently annealed.  These types also are used for parts which are intermittently heated and cooled to temperatures between 800°F and 1600°F.  The addition of columbium produces a stabilied type of stainless that eliminates carbide precipitation and, consequently, intergranular corrosion.

Availability - Stainless Steel 347/347H 

Seamless Pipe 1/2" - 12"

Weld Pipe 8" - 12"

Butt-Weld Flanges 1/2" - 8"


Specifications - Stainless Steel 347/347H


A312, A403


SA312, SA403




Chemical Composition - 347/347H

C Co Cr Mn Ni P S Si Ta
Max     Max   Max Max Max  
0.08% Trace* 17% - 20% 2.0% 9% - 13% 0.04% 0.03% 0.75% Trace*


*The columbium plus tantalum content shall not be less than 10 times the carbon content and not more than 1.0%.  347H requires the columbium plus tantalum content to be not less than 8 times the carbon content and not more than 1.0%.

Design Features - Stainless Steel 347/347H

  • Superior general corrosion resistance over Type 321 due to stabilization with columbium.
  • Reduced tendencies to form continuous networks of chromium carbides at the grain boundaries.
  • Better high temperature properties than 304 or 304L.  Generally used for parts which are intermittently heated up to 1500°F.  For continuous service the maximum temperature is 1650°F.
  • Type 347 has high carbon (.04 to .10) for better high temperature creep properties.
  • Improved intergranular corrosion resistance.

Typical Applications - 347/347H

  • High temperature chemical process heat exchanger tubes
  • Refineries
  • High temperature steam service

Tensile Requirements - 347/347H

Tensile Strength (KSI): 75

Yield Strength (KSI): 30

KSI can be converted to MPA (Megapascals) by multiplying by 6.895.

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