Stainless Valve Company (North Carolina, USA) has supplied two of its 48″ Big Knife valves for flue gas application, made in duplex stainless steel 2205. This material has higher strength and corrosion resistance than the austenitic stainless steels. When solids accumulate in the valve cavity, the bottom of the valve can be opened so that the valve cavity can be cleaned out without taking the valve out of the line. This saves much time and keeps the plant working for a longer time. There is the possibility that sticky substances may deposit. To prevent any problems the valve automatically closes to a predetermined percentage of opening every 24 hours and then opens again completely.