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Tips for choosing the right irrigation pipe
To choose the most appropriate irrigation pipe for your
operation, consider the composition and amount of effluent of the water first.
Chloride, sulfate and pH level are the three most influential chemicals in
determining how corrosive water is, says John Davis, Reinke's vice president of
engineering. The amount of effluent in water is another key factor to consider.
Reinke, a leading mechanized irrigation systems
manufacturer, was the first pivot manufacturer to offer water pipe options on
their systems 30 years ago. Today, the company says it is still the only
manufacturer to offer a choice of four types of pipe, including aluminum, galvanized
steel, stainless steel, and chromium nickel copper alloy (CN+) steel.
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 extremely high or primarily low pH values,
stainless steel is the best choice, say Reinke experts. 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 said.
Reinke's unique CN+ water pipe, made from the same type of
steel as railroad tracks, can be affected by low pH conditions, but the
corrosion resistant properties exist in the material itself and not just in the
surface coating, making it stronger and more durable than other pipes, the
company says. This pipe is ideal for corrosive water situations because it can
withstand the effects of normal atmospheric corrosion, as well as corrosion
caused by water, chemicals and feedstuffs, they add.
Davis says concentrations of certain salts, oxygen content
and temperatures are some other factors that can affect corrosion rates and are
also important to consider when selecting the appropriate pipe.