- System
- Problem
- Evidence
- Check
- Treatment
- Programme
SELECTED PROBLEM
Hardness, alkalinity & heat-transfer scale
Minerals can precipitate on hot heat-transfer surfaces as water concentrates and local conditions differ from the bulk sample.
What you may notice
Hard deposits, reduced heat transfer, higher approach temperature or increasing pressure loss.
Possible contributors
High calcium hardness or alkalinity, elevated pH, excessive cycles, high surface heat flux and interrupted treatment.
What we would review
- Assess makeup
- circulating-water hardness
- alkalinity
- pH
- temperature
- cycles
- identify deposits
- review heat duty
Treatment approach
Review cycles, blowdown, pH and pretreatment together with an inhibitor/dispersant approach suited to the operating envelope.
Mechanism, monitoring & limitations
Mechanism
Educational families include phosphonates, polyacrylates, polycarboxylates, maleic-acrylic and sulfonated polymers. Threshold inhibition, crystal modification and dispersion are different mechanisms.
Monitor
Conductivity, pH, hardness, alkalinity, treatment residual, blowdown and exchanger temperatures.
Compare deposit formation, heat-transfer performance and water balance over a representative load period.
Limitations
Confirmed adherent scale may require controlled offline cleaning after deposit and metallurgy review; inhibitors are not universal descalers.
Exact selection and operating limits require current technical documentation and site-specific review.
Why it matters & information needed
- Why it matters
- Insulating deposits can reduce duty and create under-deposit corrosion sites.
- Information needed for assessment
- Makeup/circulating analyses, recirculation and makeup flows, cycles, heat load, metallurgy and deposit records.

