Corrosion and Scale Inhibition Solution for Circulating Cooling Water

1. Why Corrosion and Scale Inhibition Is Essential for Circulating Cooling Water?

Circulating cooling water is the “blood” of industrial plants (refining, chemical, power plants, central air conditioning). However, once water circulates, two types of problems arise:

• Corrosion: Uniform corrosion and pitting of carbon steel (most common in pipes/heat exchangers), pitting and dezincification of copper/copper alloys (heat exchanger tubes), chloride pitting/stress corrosion of stainless steel, and corrosion of aluminum and aluminum alloys;
• Scaling: Calcium carbonate scale (most common), calcium sulfate scale, silica scale, slime/biological fouling — scale not only reduces heat exchange efficiency but also causes under-deposit corrosion (low oxygen concentration beneath scale creates an oxygen concentration cell, accelerating perforation).

Core contradiction: Corrosion inhibition aims to “protect metal,” while scale inhibition aims to “control deposition.” These two aspects must be balanced — single agents often compromise one at the expense of the other. Integrated composite formulations are the standard practice in industrial circulating water.

2. Mechanism: How Does Corrosion and Scaling Occur?

In essence: The essence of corrosion and scale inhibition in circulating water is “within the water quality limits, use chemicals to simultaneously suppress corrosion rate and scaling tendency to acceptable levels” — the formulation must be dynamically adjusted based on water quality.

3. Vanconol® Circulating Water Solutions

Vanconol® corrosion inhibitor product line covers water treatment applications (specific indicators subject to actual TDS):

Selection path:

Monitoring trio (routine acceptance for circulating water):

1. Corrosion coupons: carbon steel/copper coupons for 30 days; corrosion rate (carbon steel generally <0.075 mm/a, subject to company standards);

2. Scale analysis: composition analysis of scale samples during heat exchanger maintenance (proportion of calcium carbonate/calcium sulfate/slime);

3. Water quality monitoring: routine tracking of pH, conductivity, hardness, alkalinity, Cl⁻, and concentration cycles.

4. Common Pitfalls

• Adding corrosion inhibitor without controlling water quality: if concentration cycles are too high or hardness exceeds limits, even good corrosion inhibitors cannot suppress scaling — chemical treatment and water quality management must go hand in hand;
• Treating copper systems as carbon steel systems: copper heat exchangers require dedicated copper corrosion inhibitors in the formulation; generic formulas provide insufficient copper protection, leading to pitting/dezincification;
• Dosing based solely on experience without monitoring: circulating water quality varies with seasons/loads; dosage must be dynamically adjusted based on water quality and coupon data;
• Neglecting slime/microorganisms: slime provides a breeding ground for under-deposit corrosion; biocidal treatment (sterilization and algae removal) must be paired with corrosion and scale inhibition.

Frequently Asked Questions (FAQ)

Q1: How often should corrosion inhibitor be added to circulating cooling water?

A: It depends on system makeup water volume and concentration cycles. Typically, continuous or intermittent dosing is based on system volume and makeup rate. The dosage should follow TDS recommendations and be verified via corrosion coupons and water quality monitoring — no fixed dosing interval applies.

Q2: How to select chemicals when both carbon steel and copper materials are present in one system?

A: Choose a “corrosion inhibitor + copper corrosion inhibitor” combination formulation to protect both materials (copper corrosion inhibitor reference: Vanconol CPI series, subject to TDS). Use separate carbon steel and copper coupons during acceptance testing.

Q3: What to do if scaling is severe?

A: First perform scale analysis to confirm the type (calcium carbonate/calcium sulfate/silica scale). Then select a strengthened anti-scalant/dispersant formula accordingly. Simultaneously, check whether the concentration cycle is too high and whether makeup water quality is adequate.

Q4: Is ET-103 used in boiler water or circulating water?

A: According to Vanconol® official information, it is a water treatment corrosion inhibitor (circulating water/boiler water scale and corrosion inhibitor). Specific system matching and dosage must be based on the corresponding TDS. For boiler water, integrated judgment combining boiler water quality indicators (alkalinity, hardness, blowdown) is required.

Core Conclusion

The key to corrosion and scale inhibition in circulating cooling water is the “integrated corrosion inhibition + scale inhibition + water quality management + dynamic monitoring” package: select combination direction based on system material (carbon steel/copper considered separately), adjust dosing scheme according to water quality conditions (starting point: Vanconol® ET-103, subject to TDS), and validate via corrosion coupons and scale analysis. Chemicals are the means, water quality management is the prerequisite, and monitoring ensures closed-loop control.

Data Disclaimer: Performance data and product characteristics in this article are subject to the Vanconol® official website (www.hipfer.com) and corresponding product TDS. Where specific values are not indicated, no extrapolation is made. Corrosion rate limits are subject to company standards/industry specifications.