The best material for irrigation pipe depends on what kind of water you have. John Davis, Reinke Irrigation company vice president of engineering, says chloride, sulfate and pH level are the three most influential elements in determining how corrosive water is. The amount of effluent in water is the other key factor in determining the most appropriate pipe.
Galvanized steel provides good corrosion protection under most conditions. “However,” Davis says, “low pH can be problematic for this type of pipe. A pH below six will dissolve the zinc, leaving unprotected bare steel.”
In this case, Davis suggests aluminum pipe for pH values below seven and no lower than five. In situations of extreme high or primarily low pH values, he says stainless steel is the best choice.
Stainless steel is also appropriate for water conditions that vary considerably. “For example, pH levels in food processing effluent can go from low to high frequently, and the materials in the water change as the process changes,” Davis says. Concentrations of certain salts, oxygen content and temperatures are some other factors that can affect corrosion rates. Davis recommends growers test their water before purchasing a system.