Local pressure stresses on lateral pipe-nozzle with various angles of intersection

Abstract

This paper reports the variations of local pressure stress factors (local pressure stress/internal pressure) at the juncture of a pipe-nozzle when the angle of the pipe-nozzle intersection varies from the standard 90° to the 30° lateral. These stress factors in both the circumferential and longitudinal directions at four symmetric points around the pipe-nozzle juncture are plotted as functions of the angle. The ALGOR finite element software was employed to model the true pipe-nozzle geometry. The numerical stress results come from a pipe-nozzle with geometric parameters, beta, β, (nozzle mean radius/pipe mean radius) of 0.5, and gamma, γ, (pipe thickness/pipe mean radius) of 50.0. This study shows that the 90° intersection, a standard pipe-nozzle, exhibits relatively less severe local stresses. These stresses are increasing as the angle of intersection is decreasing from 90° and become more severe when the angle of intersection is further decreasing from 45°. The circumferential stress at the inside crotch point exhibits the worst stress value. The stress factor results in pipe circumferential direction at the inside crotch points are in good agreement with the stress factor equation from the ASME boiler and pressure vessel code.