AL 29-4C® alloy is a superferritic stainless steel developed by ATI Allegheny Ludlum for extreme resistance to chloride ion pitting, crevice corrosion and stress corrosion cracking (SCC), as well as general corrosion in oxidizing and moderately reducing environments. The alloy was developed in the early 1980s for welded condenser tubing to be used in seawater and brackish water by the power generation industry. It is this extreme resistance to pitting and crevice corrosion that has led to the installation of over 2000 miles of AL 29-4C tubing in power plant condensers and heat exchangers.

The superferritic stainless steel AL 29-4C alloy shows excellent resistance to chloride ion pitting, crevice corrosion and stress corrosion cracking (SCC). This resistance makes it an ideal choice for battling the corrosive condensate of partially and fully condensing natural gas and propane burning appliances (except for high sulfur fuel sources). Its low alloy content, compared to other high-performance alloys, makes it an economical choice as well.