Inconel 600/601 has been the envelope material of choice since the introduction of high temperature IFLs nearly 30 years ago. Inconel 600/601 is a widely 
available high temperature material, which is compatible with Cesium, Potassium and Sodium and has adequate oxidation resistance and reasonable high temperature creep strength.
ACT’s Inconel/Sodium IFLs are rated to 1,100°C for up to 1,000 hours of operation (based on creep strength). It should be noted that Inconel is limited to 1000°C. Haynes allows for setpoints up to 100°C beyond that.
Experience gained from operating IFLs in a variety of applications, coupled with a growing desire to operate IFLs for longer than 1,000 hours at 1,100°C, has indicated a need for more robust, longer life IFLs specifically for use in the range of 1,000 to 1,100°C.
ACT recently introduced a new line of Haynes/Sodium IFLs that can meet this demanding application requirement. The stresses in typical IFLs are in the range of 0.3 to 0.6ksi at 1,100°C (depending on the diameter).
The figure and table below show Haynes 230 has significantly greater creep resistance than Inconel 600/601. While life expectancy is dependent on each application, the data indicates that life expectancy at 982°C based on table below is 5x or more compared to Inconel 600/601.
ACT’s UHT-IFLs are available in all the standard IFL sizes. Custom sizes are also available upon request.