Analysis of Nozzle of Pressure Vessel under Complex Loadings

Abstract

Pressure vessels and heat exchangers are widely used in oil and gas refineries in which nozzle connection to main vessel is critical component of pressure vessel design. Nozzle attachment calculations are based on Welding Research Council Bulletin No.107 for determining stresses under influence of complex loading on nozzle for its durability and sustainability to withstand complex loadings. Since, 1965, the Welding Research Council's Bulletin No.107 has been the guideline for finding maximum stress values for after applying loads to an external nozzle on an imperforated shell. It was based on Professor P.P.Bijlaard's theoretical and some experiment work on the subject. The assumptions made by the professor give rise to issues regarding failure of nozzle attachment and when nozzle thickness with respect to shell thickness ratio exceeds the curves which are present in WRC. Under such circumstances WRC No.107 can not predict stresses induced in the nozzle attachment. The focus of this report is to calculate the maximum stresses by considering Prof.P.P.Bijlaard's assumptions on the major axis locations. In the major cases of multiple complex loadings are applied, these values of stresses can be un-conservative. The analytical calculations are present in this report is based on Prof.P.P.Bijlaard's assumptions. To compare the results from WRC No.107 calculation finite element analysis is performed, such that error percentage can be determined in the stress values. To find stresses induced in nozzle attachment when nozzle to shell thickness ratios are exceeding the curve limit curves are extrapolated but that method is un-conservative. Also Fatigue analysis is also performed for life assessment by using guidelines of ASME Div VIII Sec 2 part 5.