ICC-ES AC358 addresses the corrosion protection of steel helical piles by establishing specific mandates for material thickness and coatings based on three distinct soil corrosivity categories. These requirements ensure the structural integrity and long-term durability of the foundation in various environmental conditions.

The protection strategies for each category include:

1. Non-aggressive Soils: These are baseline conditions with moderate pH levels. The criteria require a minimum steel thickness of 0.25 inches (6.4 mm). Galvanizing is not required, and standard paint is considered acceptable.
2. Aggressive Soils: Characterized by high chloride content or acidic conditions, these require a minimum steel thickness of 0.375 inches (9.5 mm). They must be hot-dip galvanized per ASTM A123. Additional protection, such as an epoxy coating or a sacrificial anode, may also be used.
3. Extremely Aggressive Soils: These require the highest level of defense, including a minimum steel thickness of 0.5 inches (12.7 mm). In addition to hot-dip galvanizing, an extra protective layer is required, and cathodic protection is recommended.

By following these thresholds, the AC358 standard ensures that helical piers resist section loss over time, preserving the load path from the structure to the bearing stratum.