Alloy 347/347H

UNS S34700


Description of the Alloy 347H Pipe

We make alloy 347H stainless steel of austenitic chromium and columbium. Together, these metals deflect leftover chemicals instead of absorbing them. This prevents corrosion and makes your bars, pipes, and pipe fittings last longer. If your business needs stainless steel pipes to handle chemicals, alloy 347H may be the perfect material.

Other benefits of the Alloy 347 / 347H material include that it can withstand temperature differences of 800 ̊ to 1600 ̊ ̊ F. So if you plan on heating and cooling metal to reshape it, choose alloy 347H.

Uses of the Alloy 347H Pipe

The ability to withstand high temperatures and corrosion makes this one of our best-selling pipes. These special properties make it ideal for many industries, including the following:

  • Petroleum refining
  • Chemical processing
  • Steam service
  • Food processing
  • Pharmaceutical production
  • Waste heat recovery
  • Exhaust Systems

When you implement 347H stainless steel, make sure you adhere to tensile requirements. Yield strength is 30 KSI and tensile strength is 75 KSI.

Typical Applications

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

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.


  • 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”


  • 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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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*