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Manage Pipeline Integrity by Predicting and Mitigating HVAC Interference

Published: 20100314 by NACE International
Author(s): Sorin Segall
Co-Author(s): Leslie Bortels - Elsyca, Jacques Parlongue - Elsyca, Wolfgang Fieltsch - Corrosion Service Company

Sharing of common corridors by gas pipelines and overhead power transmission lines is becoming quite common. However, electrical energy can be transferred from power transmission lines to pipelines through inductive, conductive and capacitive coupling. When a power transmission line runs in parallel with a pipeline for a considerable length, induced AC voltages may appear on the pipeline.

While there are significant benefits in sharing a corridor between pipelines and power transmission lines, e.g. joint land use, there are also many concerns. The main ones are safety considerations for operation and maintenance personnel on pipelines, direct effects on the pipeline, such as corrosion and coating damage and effects on the electrical devices associated with the pipeline related to cathodic protection, metering and monitoring. AC induced corrosion is a significant threat to the integrity of buried pipelines, due to its very high localized corrosion rate which can and has resulted in metal loss of more than 1 mm per year. AC corrosion mainly occurs at small coating holidays on well coated pipelines when the pipeline suffers from induced ac voltages.

In this paper, a simulation software suite will be presented that is able to model both resistive (“close field”) as inductive (“far field”) interference in right of way’s (ROW’s) with pipeline and power transmission networks of any complexity.

Practical results of simulations on two different configurations will be presented. The first one deals with a pipeline and powerline crossing in a two-layer very high resistivity soil. The second one studies induced steady state voltages on a gathering piping system located in several powerline corridors.