347 Stainless Steel is a chromium nickel stainless steel which has been modified by the addition of columbium and tantalum. The main advantage of this is an excellent resistance to intergranular corrosion which is common to other austenitic stainless steels following exposure to temperatures of 800° to 1500°F

347 is generally used where corrosive conditions are severe, such as aircraft exhaust stacks, manifolds and ring collectors. Type 347 is also used for heavy welded assemblies which cannot be annealed after welding or where the operating conditions cause exposure within the temperature range between 800° to 1500°F.