347 stainless steel is an austenitic stainless steel stabilized by additions of columbium (plus tantalum) and has slightly improved corrosion resistance over type 321 stainless steel in strongly oxidizing environments. It is preferable for aqueous and low-temperature environments due to its good resistance to intergranular attack. Both 347 and 321 offer good resistance to polythionic acid stress corrosion cracking, encountered in oil refineries.