TA large-deflection, nonlinear, static structural analysis was carried out in ANSYS. The aim of the analysis was to check the size, strength and number of bolts to see if they were adequate to withstand the new pressure.
The analysis was carried out for two values of internal pressure 90psi and 145ps.
The maximum stresses in the main structure of the model were all found to be below the specified yield of the material.
A stress intensity linearization was also carried out on a path in the main structure.
Within ANSYS, an option is available to allow a separation of stresses through a section, into membrane and bending stresses. The stress linearization option requires a path to be defined by two nodes and the results are then mapped onto that path. The stress linearization tool takes the nodal data for the complex stress pattern found along the path and breaks it down into components: Membrane, Bending and Membrane + Bending. The membrane and membrane + bending stresses have been compared with the code allowed limits.
The maximum membrane bending stress value from the analysis was found to satisfy the criteria of 1.5 x design strength. The graphics below show the defined path and a graphical representation of the linearization results.
SPX Flow Technology performed ASME code calculations for the bolts considering the internal pressure of 145psi. The required cross sectional area of the bolts was found to be less than the actual cross sectional area of the bolts, therefore the current bolt size was considered to be satisfactory under the increased internal pressure.
The thickness of the head was also found to be sufficient for the uprated pressure of 145psi.