Corrosion Inhibition and Scale Control Strategy for Recirculating Cooling Water

1. Why Corrosion Inhibition and Scale Control Are Essential for Recirculating Cooling Water

Recirculating cooling water is the “blood” of industrial plants (refining, chemical, power generation, central air conditioning), but once water circulates, two problems arise:

• Corrosion: uniform and pitting corrosion of carbon steel (most common in piping/heat exchangers), pitting and dezincification of copper/copper alloys (tube bundles), chloride-induced pitting/stress corrosion of stainless steel, corrosion of aluminum and its alloys;
• Scaling: calcium carbonate scale (most common), calcium sulfate scale, silica scale, slime/biofouling — scaling not only reduces heat transfer efficiency but also causes under-deposit corrosion (low oxygen concentration under the scale, forming an oxygen concentration cell that accelerates perforation).

The core trade-off: corrosion inhibition protects metals, scale control prevents deposits. Both need balance — single chemicals often fail to address both simultaneously; integrated formulations are the standard practice in industrial cooling water.

2. Mechanisms: How Corrosion and Scaling Occur

In short: The essence of corrosion inhibition and scale control in cooling water is “within allowable water quality limits, using chemicals to suppress both corrosion rate and scaling tendency to acceptable levels” — formulations must be adjusted dynamically according to water quality.

3. Vanconol® Cooling Water Solutions

Vanconol® corrosion inhibitor portfolio covers water treatment directions (specific parameters based on TDS):

Selection path:

Three monitoring items (routine for cooling water acceptance):

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

2. Scale analysis: composition analysis of scales from heat exchanger maintenance (calcium carbonate/calcium sulfate/slime ratios);

3. Water quality monitoring: pH, conductivity, hardness, alkalinity, Cl⁻, concentration cycles tracked daily.

4. Common Pitfalls

• Adding only corrosion inhibitor without controlling water quality: excessive concentration cycles, hardness exceedance — no corrosion inhibitor can suppress scaling alone; chemicals and water quality management must go hand in hand;
• Treating copper systems the same as carbon steel systems: copper heat exchangers require dedicated copper corrosion inhibitors in the formulation; general formulations provide inadequate copper protection, leading to pitting/dezincification;
• Dosing by experience without monitoring: cooling water quality varies with season/load; dosing must be dynamically adjusted based on water quality and coupon data;
• Ignoring slime/microbes: slime is a breeding ground for under-deposit corrosion — biocidal treatment must accompany corrosion inhibition and scale control.

Frequently Asked Questions (FAQ)

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

A: Depends on system makeup water volume and concentration cycles. Generally added continuously or intermittently based on system hold-up volume and makeup water, following TDS recommendations and results of corrosion coupons/water quality monitoring — not fixed on a rigid schedule.

Q2: How to select chemicals when carbon steel and copper are present in the same system?

A: Choose a combination of “corrosion inhibitor + copper corrosion inhibitor” to address both materials (copper corrosion inhibitor direction can refer to Vanconol CPI series, per TDS). Use separate coupons for carbon steel and copper for acceptance testing.

Q3: What to do when scaling is severe?

A: First perform scale analysis to confirm scale type (calcium carbonate/calcium sulfate/silica scale), then select a reinforced scale inhibitor/dispersant formulation while checking if concentration cycles are too high or makeup water quality is inadequate.

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

A: Vanconol® official positioning is water treatment corrosion inhibitor (scale/corrosion control for both cooling water and boiler water). System matching and dosage should follow the corresponding TDS. For boiler water, additional boiler water parameters (alkalinity, hardness, blowdown) must be considered.

Key Conclusions

The core of corrosion inhibition and scale control in recirculating cooling water consists of three pillars: “integrated corrosion inhibition + scale control + water quality management + dynamic monitoring”. Select the formulation direction based on system materials (carbon steel/copper considered separately), adjust dosing program according to water quality conditions (starting with Vanconol® ET-103, based on TDS), and verify performance with corrosion coupons and scale analysis. Chemicals are the tool, water quality management is the prerequisite, and monitoring closes the loop.

Data Note: Performance data and product characteristics described herein are based on the Vanconol® official website (www.hipfer.com) and corresponding product TDS. Where specific values are not stated, no assumptions are made. Corrosion rate limits follow enterprise standards or industry specifications.

*Related reading: Principles and applications of copper corrosion inhibitors｜Corrosion protection in refining units｜Vanconol® corrosion inhibitor product line (www.hipfer.com)*