CP For Buried Piping, Structures & Tanks

The design verification of CP systems applied to underground facilities including storage tanks, buried piping, equipment bases, grounding systems, reinforced concrete and other underground structures is complex challenge. Space limitations may restrict installation of anodes in certain areas and shielding effects from buried structures may affect the distribution of the protective current. Modelling provides a tool to ensure adequate protection by evaluating ground bed design options and locations to mitigate the effect of interference and shielding.

A recent study investigated the impact of interference between nearby storage tanks and pipelines on the performance of the CP system and the potentials achieved.

The modelling study aimed to verify the protection provided including the interference between the CP systems for the underground infrastructure comprising three tank bases, pipelines with different quality coatings, ICCP Anodes, grounding rods, tank bottom ICCP Grid and sacrificial anodes.

 Tank Farm micro mailing Jan 2013

The study demonstrated the ability of the model to predict the protection provided by the CP systems to the structures including the interference and shielding caused by the array of complex underground structures. Changes in the coating performance and the degradation of the CP anodes over the life of the asset can also be simulated to predict the "whole life" protection provided by the CP system.

While the initial design is important the monitoring of the system performance over its life is essential to ensure adequate protection is maintained. Standard survey methods can be difficult to apply and interpret due to the variation in the depth of the piping and interference from nearby structures. Modelling provides a tool to interpret the potentials obtained during surveys in these complex situations.

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