Can you use galvanized pipe underground if the pipe threads are protected?

Using galvanized pipe underground is generally not recommended due to the potential for corrosion. While it may seem logical that protecting the threads could prevent immediate issues, the entire exposed surfaces of the pipe still interact with moisture and soil, leading to long-term degradation. Galvanized pipes are coated with zinc to resist rust when exposed to air, but this protective layer can wear away over time, especially in underground environments where moisture levels can vary and soil chemistry can be more aggressive.

Corrosion is further influenced by factors like the type of soil, presence of moisture, and any electrical activity in the area, which could accelerate the degradation process. Therefore, despite any protective measures taken at the threaded joints, the main body of the galvanized pipe remains susceptible to corrosion over its lifespan when buried. Using pipe specifically designed for underground applications, such as PVC or HDPE, is preferred because these materials are resistant to corrosion and are better suited to the conditions found underground.