Corrosion ControlIntermediate 14 min read

Corrosion Control: Process Control Basics

Introduces the Langelier Saturation Index and the water chemistry behind corrosivity, explains how orthophosphate, polyphosphate, and silicate inhibitors actually work, and covers routine lead/copper monitoring and troubleshooting for Class C operators.

Once you move beyond simply recognizing red water and blue stains, your job as a Class C operator is to actually predict and manage whether your water will attack pipe metal or protect it. The tool operators have used for nearly a century to make that call is the Langelier Saturation Index — and pairing it with an understanding of the phosphate and silicate inhibitors your plant may feed gives you real control over corrosion instead of just reacting to complaints after the fact. This guide walks through the LSI, the water-chemistry relationships that drive it, the major classes of corrosion inhibitors and how each actually works, and the routine monitoring operators use to confirm a corrosion control program is holding.

The Langelier Saturation Index (LSI)

The LSI, developed by Wilfred Langelier in 1936, is the most widely used tool for estimating whether water will tend to **deposi

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