Collapse Analysis of Perforated Pipes Under External Pressure

Abstract

Abstract This work is a numerical, analytical and experimental study of collapse pressure of perforated pipes to evaluate the effect of lateral perforations on the radial resistance of pipes under external pressure. These types of pipes are a simple and economical technology widely used in our days as sand control meshes or perforated liners. In this work was considered a variation of geometric configurations (relation diameter/pipe thickness (OD/t)), distance between perforations, number of perforation on the circumferential and longitudinal directions and hole diameter. First, was evaluated the reduction of the radial resistance to the external pressure through the real collapse of 12 pipes of 151 mm of diameter (8 with holes and 4 without). For the analytical part was calculated the collapse pressures using the API equations (API 1999), DNV equation (DNV, 2010) and four-hinge mechanism (ABBASSIAN & PARFITT 1998). For the numerical part was developed a tridimensional model on finite elements using ABAQUS, to obtain the pipe collapse pressure and validate the numerical model through the experimental results. The experimental and numerical results shows that the D/t relationship, initial imperfections (like ovalization) and material properties have important influence on the pipes resistance, although the perforation diameter and the axial space between them are the variables with most influence on the collapse resistance of perforated tubes. In general terms, when we compared the collapse pressures of pipes with holes and pipes without holes with similar properties was found a reduction of collapse pressure close to 10%, but some geometrical parameters of holes could reduce or increase this difference.