Influence of Initial Ovality on Local Buckling Under External Pressure (Collapse) of Oil Industry Tubulars - Experimental Results

摘要

An important load which can consider-ably affect the resistance capacity of oil industry tubulars (mainly casing and tubing in high pressure wells, and submarine pipelines installed in deep waters) is the external pressure, causing the pipe collapse phenomenon. Some of the factors with the greatest influence on pipe collapse behaviour are its geometrical imperfections (ovality, eccentricity, etc.). This paper presents the results of research activities aimed to investigate the influence of the pipe initial ovality on the external pressure collapse phenomenon by performing some tests on small scale models, based on the similitude law, in order to define design methodologies and criteria for assessing the external pressure resistance capacity of oil industry tubulars. The test results have been compared with the calculation formulas usually used to assess pipe collapse resistance capacity considering the influence of initial ovality.