Olivier Hamart - Vallourec
New grade P9Mod has been developed in order to improve resistance to coke deposit comparing to widely used P5 or P9 grades in refinery furnaces. Specific chemical analysis based on Cr, Si, Cu and Ni contents has been specified after laboratory testing on different heats. Thermogravimetric analysis have been performed to differentiate materials (ferritic to austenitic grades) in terms of coking level and coking rate. Alloys have been classified versus their coking resistance in the function of temperature showing the efficiency and enhanced resistance of P9Mod solution.
P9Mod tubes have been installed in European visbreaker during one year for field testing. Even if the process parameters were not the best one, results are showing the efficiency of P9Mod as coke resistant material and highest mechanical properties (thanks to alloying elements ) comparing to P9.