Stress Concentrations Around Circular Holes in Perforated Drainage Pipes

Stress concentrations around circular holes in perforated buried pipes obtained from three-dimensional elastic finite element analysis are presented. The maximum stresses around the perforation were found to depend on the thickness and diameter of the pipe, the diameter of the perforation, the circumferential location of the perforation, and the axial and circumferential spacing between perforations. It was found that a stress concentration of 3.0, based on the simple hole in a plate solution, may be conservatively used for most perforated pipes. Better estimates of stress concentration factors derived from finite element analysis are presented. Guidelines are provided for specifying the location, size, and spacing of perforations that minimize the stress concentrations. Two example calculations are presented to illustrate the proposed procedure for estimating the maximum stresses around the perforations.