OK Flux 231 is an active, bonded flux designed for fillet and butt welding of carbon steel plate. It provides excellent tolerance of rust and mill scale so joint preparation can be minimized. This flux will produce horizontal fillets up to 3/8" (9.5 mm) leg size without undercut or rollover. The slag peeling is excellent. OK Flux 231 can be used for multipass welding, but because Mn and Si buildup is possible, welding voltage should be kept to a minimum and plate thickness should be limited to 1" (25 mm). OK Flux 231 is suitable for DC single and parallel wire welding at currents up to 1000 A. It is used for welding rail cars, water heater tanks, ship plates, and structural steel.