Application of quantitative electromagnetic technology to asses coating integrity of pipelines in México

Abstract

There are several surface inspection methods to evaluate the integrity of the pipe coating, obtaining acceptable qualitative results in some soil types and low complexity pipeline systems. However, these methods do not determine the necessary parameters for a quantitative evaluation of coating quality. The Mexican Petroleum Institute has developed Surface Electromagnetic Pipeline Inspection (SEMPI) technology for the quantitative assessment of buried pipeline coating integrity. SEMPI is a theory-based technology that enables the development of instrumentation, field methodology, as well as data processing and interpretation techniques. The application of SEMPI consists of two stages: regional and local. The regional stage includes magnetic field, voltage and, soil resistivity (rs) measurements, where the main result is the determination of the electrical resistance of the coating (Tc) along the pipeline as an indicating parameter of the coating quality. A scale signalized from Tc data allows classifying the quality of pipe coating as good (green), fair (yellow) and poor (red). The local stage includes detailed electric field measurements of on anomalous pipeline sections (Tc < 50 Ohm.m2), locating damage in the coating with a detection accuracy of the ± 0.5 m. The equivalent unlined (holiday) area per meter of the inspected pipeline is calculated during the local stage. This work presents successful results from the implementation of regional and local stages of SEMPI technology in two pipelines located in the southeast region of Mexico.