Sooner or later, if you irrigate through pipes, you will have to deal with corrosive water of one type or another.
“All water is corrosive to metal pipe – it’s just a matter of degrees of corrosiveness,” said Tim Wilson, Irrigation Engineering Manager at Lindsay Corporation. “The good news is that there are solutions.”
Wilson said growers should keep the following in mind when considering the best solution for their irrigation systems:
- Under normal conditions, a galvanized pipe might last 20 – 30 years without significant water corrosion issues.
- Electrical conductivity or pH alone won’t tell you if water is corrosive. Other factors, such as chlorides, sulfates, bacteria and hardness, and their relationship to each other, are far better indicators. It’s always best to get a water sample tested for corrosive properties.
- Hard water is our friend. While it might not be pleasant to drink or bathe in, hard water provides protection against corrosive elements in the water by laying down a protective scale. Many times, this scale is better than galvanization in protecting the pipe.
- Different pipe types offer protections against varying types of corrosive elements. Many people think that different pipe types are sequential in the amount of protection they offer - with galvanized at the bottom followed by aluminum, stainless steel and finally poly pipe at the top. That’s not the case. For some types of corrosive water, galvanized might actually be better than aluminum or stainless steel.
- In almost all cases, galvanized pipe offers the same, or better, protection from corrosive water than weathering steel (sometimes referred to as Cor-Ten™). If you see weathering steel being used for pivot irrigation, most of the times it’s painted. It is the paint that is providing the extra corrosion protections – not the steel.
- Poly pipe always offers the best level of protection against corrosive water.
- Brown is not always bad. Many times the brown that you see on the pivot structure is not rust – it’s staining from high levels of iron in the water.
Zimmatic offers a wide array of pipe options to meet every grower’s needs. Talk to your local dealer to about testing your water and evaluating the best solution to effectively and economically deal with corrosive water conditions