347 / 347H Stainless Steel Pipe

Type 347 / 347H stainless steel is an austenitic grade of chromium steel, which contains columbium as a stabilizing element. Tantalum can also be added for achieving stabilization. This eliminates the carbide precipitation, as well as intergranular corrosion in steel pipes. Type 347 / 347H stainless steel pipes offer higher creep and stress rupture properties than grade 304 and 304L. This makes them suitable for exposures to sensitization and intergranular corrosion. Moreover, the inclusion of columbium allows 347 pipes to have excellent corrosion resistance, even superior to that of 321 stainless steel pipes. However, 347H steel is the higher carbon composition substitute of stainless steel pipe grade 347. Therefore, 347H steel pipes offer improved high temperature and creep properties.

347 / 347H Stainless Steel Pipe Properties

Following are the properties of 347 / 347H stainless steel pipes offered by Arch City Steel & Alloy:

 

Corrosion Resistance:

 

  • Exhibits oxidation resistance similar to other austenitic stainless steels
  • Preferred over grade 321 for aqueous and other low temperature environments
  • Better high temperature properties than 304 or 304L
  • Good resistance to sensitization in high temperature environments
  • Suited for heavy welded equipment that cannot be annealed
  • Used for equipment operated between 800 to 150°F (427 TO 816°C)

 

Weldability:

 

  • 347 / 347H austenitic stainless steel pipes are considered to be the most weldable among all high grade steels pipes

  • They can be welded by all commercial processes

 

Heat Treatment:

 

  • 347 / 347H stainless steel pipes offer an annealing temperature range of 1800 to 2000°F

  • They can be stress relief annealed without any danger of subsequent intergranular corrosion within the carbide precipitation range of 800 to 1500°F

  • Cannot be hardened by heat treatment

 

Applications:

 

347 / 347H pipes are frequently used for fabrication of equipment that ought to be used under severe corrosive conditions. Also, they are commonly used in petroleum refining industries. Major applications include:

 

  • High temperature chemical processes
  • Heat exchanger tubes
  • High pressure steam pipes
  • High temperature steam and boiler pipes/tubes
  • Heavy duty exhaust systems
  • Radiant superheaters
  • General refinery piping

 

CHEMICAL COMPOSITION

 

Typical Chemical Composition % (max values, unless noted)
Grade C Cr Mn Ni P S Si Cb/Ta
347 0.08 max min: 17.0
max: 20.0
2.0 max min: 9.0
max: 13.0
0.04 max 0.30 max 0.75 max min:10x C
max: 1.0
347H min: 0.04
max: 0.10
min: 17.0
max: 20.0
2.0 max min: 9.0
max: 13.0
0.03 max 0.30 max 0.75 max min:10x C
max: 1.0

 

MECHANICAL PROPERTIES

 

Typical Room Temperature Mechanical Properties
Grade Tensile StrengthKSI (MPA) Yield Strength 0.2% KSI offset KSI (MPA) Elongation (% in 2ʺ(50.8 mm) Hardness (Brinell) MAX Hardness (Rockwell B) MAX
347/347H 75 (515) 30 (205) 40 201 95

 

Arch City Steel & Alloy is one of the leading stainless steel pipe and tube distributors. We offer an extensive inventory that allows us to meet stainless steel specifications, dimensions and sizes required by the customer.

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