The objective of this study is to estimate the Fatigue assessment life of inlet separator at operating conditions and to check the equivalent Von Misses stresses at designed conditions
3D modeling has been done as per available drawings. Thicknesses for shell and saddles have been considered as given in drawings. Uniform thicknesses of 22.5mm have been considered for cylindrical shell as well as dished heads With the help of finite element analysis FEA subcontractor study, actual stress distributions in different components of inlet separators and the actual behavior of separator at operating and design conditions have been determined. During ANSYS software operational service, inlet separator is subjected to cyclic or repeated stresses
Maximum Von Mises stresses for occasional wind and seismic scenario are under yield strength of material. For operating pressure and temperature loading, minimum requirement for vessel Life is 7000 Cycles to operate safely for 25 years. Minimum number of cycles required for full operation span is 12600 cycles Nozzle N1 has been analyzed for slug loads where frequency is considered to be a 20 times per hour. At the selected frequency of loading, assuming complete reversal in opposite direction of load, the fatigue life is calculated to be 2 years. However we consider that at such high frequency of slug loading, it is safe to consider only 50% reversal in load due to damping from liquid. With this consideration, the fatigue life of the nozzle N1 is 16 years. Therefore a change of nozzle neck pipe with increased thickness is recommended.