347/H

These types of stainless are austenitic chromium steels containing columbium. 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 ̊ and 1600 ̊ F. The addition of columbium produces a stabilized type of stainless that eliminates carbide precipitation, and consequently, intergranular corrosion.

Chemical Composition

C Co Cr Mn Ni P S Si Ta
Max Max Max Max Max
0.08 Trace* 17.0 – 20.0 2.0 9.0 – 13.0 0.04 0.30 0.75 Trace*

Design Features

  • 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 347H has high carbon (.04-.10) for better high temperature creep properties.
  • Improved intergranular corrosion resistance.

Typical Applications

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

<b>Specialty</b>

Availability

  • Seamless Pipe 1/2”- 12”
  • Weld Pipe 8” – 24”
  • Butt-Weld Flanges 1/2”- 24”
  • Bar 1” – 12”
  • Plate 1/8″ – 3″
  • Flanges 1/2” – 24”
  • Tubing 1/4″ – 1″
  • Pressure Fitting 1/2” – 2

Specifications

  • ASTM A312, A403, A182, A479, A276
  • ASME SA312, SA403, SA182, SA479, SA276

Tensile Requirements

Tensile Strength (KSI) 75
Yield Strength (KSI) 30
KSI can be converted to MPA (Megapascals) by multiplying by 6.895.

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