Field-Testing Procedures on a Metallic Pipeline Collocated with an HVDC Powerline

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Development of this strategy began after a steel pipeline, coated with Fusion Bonded Epoxy (FBE), was constructed in a collocated right-of-way (ROW) with a high voltage direct current (HVDC) Powerline. Area Cathodic Protection (CP) Technicians reported challenges in recording stable DC Pipe-to-Soil (P/S) Potentials due to rapid fluctuations observed in the DC waveform. In addition, CP technicians recorded DC line current concurrently with P/S potentials and found that there was a correlation between the two.

Product Number: 51323-19035-SG

Author: Andrew Mackey, Alex Ristow

Publication Date: 2023

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Effective assessment of risk to pipeline integrity requires confidence in data and engineering analysis. The current body of literature on high voltage direct current (HVDC) influence on pipelines during steady state operation is limited. This paper presents an approach for data gathering and field-testing when a metallic pipeline is collocated with a suspended HVDC electric power transmission line to determine if influence seen is from the transmission line, as well as to aid in analysis of risk to pipeline integrity.

This paper identifies challenges and practices for data gathering, test planning, and data processing. Repeating these testing procedures as the HVDC powerline is in normal operation, monopole, and shutdown modes offers the opportunity to develop a complete dataset, providing information regarding cathodic protection (CP) efficacy during all HVDC conditions. Placement of testing equipment is determined by proximity of HVDC and pipeline system installations, HVDC grounding locations, and soil/terrain conditions. Synchronization of the time stamps from the resulting field-testing data with the HVDC operational load data is a critical component of the data processing step. Further engineering analysis is required to determine if additional monitoring or further investigation should be performed to determine any risk to pipeline integrity or if the influence is a measurement error concern.