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