CASE STUDY

Steel Structure Cyclical Assessment Program

A utility in Southeast, US initiated a pilot assessment project to determine the below-grade condition of their transmission system.

The Situation

Operating and maintaining transmission systems requires regular intervals of vigilant observation to maintain the safety and reliability of all structures. A commonly overlooked concern with steel structures is detecting any below-grade corrosion activity and the rate at which it occurs. When active corrosion is present and rapidly occurring, it can put large transmission systems at risk and significantly reduce reliability.

A utility in the Southeast initiated a pilot assessment project to determine the below-grade condition of their transmission system, which included more than 40,000 steel structures. This pilot assessment included the excavation of 240 towers, which revealed evidence of below-grade corrosion far more severe than anticipated. It was determined that one-third of the towers displayed heavy corrosion and would require restoration. The utility decided that a cyclical, comprehensive inspection program would provide the greatest long-term protection and extend the service life of the assets. The cyclical inspection program included a full excavation of each tower’s foundation and the application of protective coatings.

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