Why Is Scale Forming in My Industrial Boiler? Water Testing Guide Malaysia
Meta Description: Discover why boiler scale forms and how pH, conductivity, TDS, hardness and temperature testing support industrial boiler-water maintenance in Malaysia.
Boiler scale forms when dissolved minerals and other substances deposit on heat-transfer surfaces.
The deposits can reduce heat transfer, increase fuel consumption and cause localised overheating. Severe scale may contribute to tube damage, unstable operation and unplanned shutdowns.
Scale is usually a water-treatment and operating-condition problem rather than something that can be solved by cleaning alone.
Common Causes of Boiler Scale
The most common causes include:
Excessive water hardness
Poor feedwater treatment
Softener failure
High dissolved-solids concentration
Insufficient blowdown
Incorrect chemical dosing
High pH or alkalinity conditions
Contaminated condensate return
High local heat flux
Infrequent water testing
1. Excessive Water Hardness
Hardness is commonly associated with calcium and magnesium compounds.
When boiler water is heated, these compounds may form deposits on tubes and other hot surfaces.
Possible causes include:
Untreated make-up water
Softener breakthrough
Incorrect softener regeneration
Bypass valve left open
Excessive make-up-water demand
Poor sampling
Water-treatment-system failure
Hardness normally requires a suitable test kit or laboratory method rather than an ordinary pH or TDS meter.
2. Softener Failure
A water softener may stop performing correctly because of:
Insufficient salt
Incorrect regeneration
Resin deterioration
Channeling
Valve problem
Excessive flow
High incoming hardness
Bypass leakage
Test both:
Raw incoming water
Softened water after treatment
Testing only boiler water may delay identification of the source.
3. High Conductivity
Conductivity indicates how well water carries electrical current and generally increases as the concentration of dissolved ions increases.
High boiler-water conductivity may suggest that dissolved substances are concentrating as water turns into steam.
A conductivity meter can support:
Feedwater checks
Boiler-water checks
Condensate-return checks
Blowdown control
Trend monitoring
Conductivity does not identify the specific dissolved substance.
4. High Total Dissolved Solids
TDS describes the estimated concentration of dissolved material in water.
Many portable TDS meters estimate TDS from conductivity.
High TDS can contribute to:
Deposits
Foaming
Carryover
Unstable water conditions
Reduced boiler performance
TDS and conductivity should be interpreted according to the boiler-water treatment programme.
5. Insufficient Blowdown
Blowdown removes concentrated boiler water and replaces it with treated feedwater.
Insufficient blowdown may allow:
Conductivity to rise
TDS to increase
Suspended material to accumulate
Water chemistry to move outside the required range
Excessive blowdown wastes heat, water and treatment chemicals.
Blowdown settings should follow the approved boiler-water programme.
6. Incorrect pH
pH affects corrosion, deposition and chemical-treatment performance.
A pH reading that is too low or too high may indicate:
Incorrect chemical dosing
Contamination
Poor feedwater treatment
Sampling problems
Condensate-return issues
Instrument or electrode problems
Acceptable pH depends on the boiler system and treatment programme.
There is no single pH target suitable for every industrial boiler.
7. Incorrect Chemical Dosing
Treatment chemicals may be used to:
Control hardness
Reduce scale formation
Control oxygen
Adjust pH
Manage alkalinity
Disperse deposits
Problems may result from:
Empty chemical tank
Failed dosing pump
Blocked injection point
Incorrect concentration
Poor mixing
Incorrect control setting
Unverified test results
Water measurements should be connected to an approved dosing and treatment procedure.
8. Contaminated Condensate Return
Condensate return can reduce make-up-water and energy requirements, but contamination may introduce:
Oil
Process chemicals
Corrosion products
Dissolved solids
Suspended material
Compare the condensate return with feedwater and make-up water.
Conductivity, pH, turbidity and other application-specific tests may help identify a change.
9. High Make-Up-Water Consumption
High make-up-water demand can introduce more hardness and dissolved solids into the system.
Possible causes include:
Steam leakage
Condensate not returned
Faulty steam traps
Water leakage
Excessive blowdown
Process losses
Investigating water loss can be as important as adjusting chemical treatment.
10. High Heat-Transfer Surface Temperature
Scale acts as insulation.
As deposits become thicker, the metal surface may become hotter even when steam output remains similar.
A thermal imaging camera may help identify abnormal external temperature patterns on accessible components.
However, it cannot see internal scale directly through metal.
Important Boiler-Water Measurements
Depending on the system and treatment programme, measurements may include:
pH
Conductivity
TDS
Hardness
Alkalinity
Dissolved oxygen
Phosphate
Sulphite
Silica
Chloride
Turbidity
Temperature
Not every parameter can be measured using one portable electronic meter.
pH Meter
A portable pH meter measures acidity or alkalinity.
MTM Precision offers options including:
AZ Instrument AE8601
Benetech GM765
Benetech GM766
Before selecting a model, confirm the expected range, sample temperature, electrode type and required testing procedure.
Conductivity and TDS Meter
A conductivity or TDS meter supports rapid checks of:
Make-up water
Softened water
Feedwater
Boiler water
Condensate
Record the measurement unit because conductivity and TDS results can be displayed in different units.
Turbidity Meter
Turbidity indicates how cloudy a water sample is because of suspended particles.
The AZ Instrument AE86065 is one option for turbidity measurement.
Turbidity does not directly measure hardness or dissolved solids.
Water Temperature
pH and conductivity can change with temperature.
Use:
Automatic temperature compensation where appropriate
A separate suitable thermometer
Consistent sample cooling and handling procedures
A hot sample may be unsafe and may exceed the instrument or electrode’s allowable temperature.
How to Collect a Useful Boiler-Water Sample
Step 1: Identify the Sampling Point
Know whether the sample is raw water, softened water, feedwater, boiler water or condensate.
Step 2: Follow the Approved Sampling Procedure
Boiler water may be hot and pressurised.
Step 3: Use a Clean Sample Container
Contaminated containers can change the result.
Step 4: Measure at the Required Temperature
Allow appropriate cooling where necessary.
Step 5: Test Promptly
Some water parameters change after sampling.
Step 6: Record the Result
Document the location, temperature, unit, date and operating condition.
Basic Boiler Scale Investigation
Step 1: Confirm the Deposit
Determine whether the material is scale, corrosion product or another contaminant.
Step 2: Test Raw and Softened Water
Check whether hardness is passing through the treatment system.
Step 3: Measure Feedwater and Boiler-Water Conductivity
Look for unusual concentration or trend changes.
Step 4: Measure pH
Compare the result with the approved treatment range.
Step 5: Review Blowdown Operation
Check settings, valves and operating history.
Step 6: Inspect Chemical Dosing
Confirm tank level, pump operation and injection condition.
Step 7: Check Condensate Return
Investigate contamination and loss.
Step 8: Review Make-Up-Water Consumption
Identify leakage or excessive water replacement.
Creating a Boiler-Water Trend Record
A useful record may include:
DateSample PointpHConductivityTDSHardnessTemperatureObservationTest 1Softened waterRecordedRecordedRecordedRecordedRecordedBaselineTest 2FeedwaterRecordedRecordedRecordedRecordedRecordedNormalTest 3Boiler waterRecordedRecordedRecordedRecordedRecordedReview trend
Actual parameters and limits should follow the treatment programme.
Scale vs Corrosion
Scale
Deposited material builds up on the surface.
Corrosion
Base metal is lost through chemical or electrochemical processes.
Both may occur in the same system.
An ultrasonic thickness gauge can monitor remaining metal thickness, but it does not directly identify water chemistry or scale composition.
Recommended Boiler-Water Instruments
What to CheckRecommended InstrumentpHPortable pH meterConductivityConductivity meterTDSTDS meterHardnessSuitable hardness test kitTurbidityTurbidity meterWater temperatureContact or immersion thermometerMetal wall thicknessUltrasonic thickness gaugeExternal temperature patternThermal imaging camera
Common Boiler-Water Testing Mistakes
Avoid:
Testing only boiler water
Ignoring raw and softened water
Assuming TDS equals hardness
Assuming turbidity equals dissolved solids
Testing a sample that is too hot
Using a dirty sample container
Recording results without units
Ignoring electrode condition
Changing chemical dosing from one unverified reading
Cleaning scale without correcting the water problem
Sampling hot pressurised water without the correct procedure
Using one general meter for every parameter
Important Safety Reminder
Boiler water and steam can be hot and pressurised.
Sampling, inspection and chemical-treatment adjustments should only be performed by trained personnel following:
Site safety procedures
Boiler manufacturer instructions
Approved sampling methods
Water-treatment programme
Appropriate PPE
Applicable operating requirements
Boiler Water Testing Instruments Supplier in Malaysia
MTM Precision supplies instruments for investigating boiler scale, water-treatment performance, conductivity, TDS, pH, turbidity and metal wall thickness.
Our range includes AZ Instrument AE8601 pH meters, Benetech GM765 and GM766 pH meters, AZ Instrument AE86065 turbidity meters, conductivity and TDS meters, ultrasonic thickness gauges and thermal imaging cameras.
Contact MTM Precision
MTM Precision Sdn. Bhd.
Showroom & Service Centre
No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia
🌐 Website: www.mtmpre.com.my
📧 Email: mtmpre@yahoo.com
📱 WhatsApp: +6016-660 7346
31 Aug 2026
