wilsonpipeline Stainless inventory now includes Alloy 347/347H (UNS S34700/S34709) in Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe.
General Properties
Alloy 347 is a stabilized, austenitic, chromium steel containing columbium which allows for the elimination of carbide precipitation, and, consequently, intergranualr corrosion. Alloy 347 is stabilized by the additions of chromium and tantalum and offers higher creep and stress rupture properties than alloy 304 and 304L which may also be used for exposures where sensitization and intergranualr corrosion are of concern. The addition of columbium also allows Alloy 347 to have excellent corrosion resistance, even superior to that of alloy 321. 347H is the higher carbon composition form of Alloy 347 and demonstrates improved high temperature and creep properties.
Specifications: UNS S34700 / S34709
Applications:
Alloy 347 is frequently used for the fabrication of equipment, which must be placed in service under severe corrosive conditions, and is also common to the petroleum refining industries. Applications that consistently used Alloy 347 include:
High temperature chemical processes
Heat exchanger tubes
High temperature steam service
High pressure steam pipes
Radiant superheaters
Boiler tubes
Heavy duty exhaust systems
General refinery piping
Standards:
ASTM/ASME: UNS S34700 / S34709
EURONORM: FeMi35Cr20Cu4Mo2
DIN: 2.4660
Corrosion Resistance:
Offers similar resistance to general, overall corrosion as Alloy 304
Used for applications where alloys such as Alloy 304 are vulnerable to intergranualr corrosion
Generally used for heavy welded equipment which cannot be annealed and for equipment which is operated between 800 to 150°F (427 TO 816°C)
Alloy 347 is preferred over Alloy 321 for aqueous and other low temperature environments
Primarily used in high temperature environments where resistance to sensitization is necessary, in turn preventing intergranualr corrosion at lower levels
Susceptible to stress corrosion cracking
Exhibits oxidation resistance similar to all other 18-8 austenitic stainless steels
Weldability
Austenitic stainless steels are considered to be the most weldable out of all high alloy steels
Can be welded by all fusion and resistance welding processes
Heat Treatment
Annealing temperature range is 1800 to 2000°F
May be stress relief annealed within the carbide precipitation range of 800 to 1500°F without any danger of subsequent intergranualr corrosion
Cannot be hardened by heat treatment
Chemical Properties:CCrMnNiPSSiCb/Ta3470.08 max
min: 17.0 max: 20.02.0 max
min: 9.0 max: 13.00.04 max
0.30 max
0.75 max
min:10x C max: 1.0347H
min: 0.04 max: 0.10
min: 17.0 max: 20.02.0 maxmin: 9.0 max: 13.00.03 max0.30 max0.75 maxmin:10x C max: 1.0
Mechanical Properties:Grade
Tensile Strength ksi (MPa) minYield Strength 0.2% ksi offset ksi (MPa) minElongation (% in 50mm) minHardness (Brinell) MAXHardness (Rockwell B) MAX347/347H
75 (515)
30 (205)4020195
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