Corrosion assessment and repair of existing OHL supports, anchors and foundations

Moderator: Pierre Van Dyke

Speakers: João BGF da Silva, Rob Meijers, George Florea, Christian Johnsson and Denis Mondière

This workshop aims to communicate the essence of two CIGRE Technical Brochures, namely “Assessment of Existing Overhead Line Supports” (TB 230 – already published), and “Detection, Prevention and Repair of Sub-Surface Corrosion in Overhead Line Supports, Anchors and Foundations” recently completed and to be published soon.

Starting with the TB 230, with the participation of over 60 utilities from around the world, it has become clear that the most critical issue regarding the life of existing OHL supports is corrosion. Different corrosion protection and repair practices and methods were collected and discussed, within the framework of current refurbishment procedures.

Many different type of structural foundations have been used throughout the world. The choice of a specific foundation solution, in all case, is made based on several considerations or constraints such as environmental impact, soil type, accessibility, costs, availability of materials and equipment, etc. The most well-known and used type is the concrete foundation (with different types of design), but directly embedded steel solutions such as grillages, piles and anchors are also increasingly used.

Although these types of foundation, which result in direct contact of the steel with the soil, have been successfully installed in several regions, there are many cases where the severity of sub-surface corrosion has made such applications unsuitable.

The new SC B2 WG B2.65 Technical Brochure aims to address the full complexity associated with this issue.

Therefore, based on the TBs mentioned above, this Workshop will focus on:

1 - Assessment of existing OHL supports:

• Inspection philosophies,
• Risk management,
• Methods for refurbishing and repairing corrosion on existing OHL supports.

2 - Corrosion mechanisms:

• Different soils and types of corrosion,
• Steel foundations in soil (grillage, piles and anchors),
• Prevention of corrosion of steel in the ground,
• Corrosion above foundation steel at ground level.

3 – Corrosion of steel in concrete foundations:

• Corrosion in concrete,
• Mechanisms of steel corrosion in concrete foundations,
• Prevent corrosion of steel in concrete foundations,
• Refurbishment of steel corrosion in concrete foundation.

4 - Inspection and detection methods for corrosion:

• Visual inspection,
• Soil samples and soil tests,
• Non-destructive tests,
• Destructive and non-destructive methods for determining the required reinforcement of corroded steel in concrete.

5 - Case Studies:

• Different practical examples of corrosion and repairs in steel and concrete foundations.

Speakers

Joao Baptista
da Silva