Why do they require asphalt paint om outside of rigid conduit?

Asphalt paint is applied to the outside of rigid conduit primarily for protection against corrosion and environmental damage. The paint creates a barrier that prevents moisture and chemicals from degrading the metal, extending the lifespan of the conduit. Additionally, it can provide a level of insulation and improve visibility for safety purposes. Overall, using asphalt paint enhances the durability and functionality of the conduit in outdoor installations.