Common Ultrasonic Thickness Gauge Measurement Errors and Troubleshooting Malaysia

Common Ultrasonic Thickness Gauge Measurement Errors and Troubleshooting Malaysia

Introduction

Ultrasonic thickness gauges are widely used in Malaysia for measuring steel plates, metal pipelines, storage tanks and industrial equipment.

These instruments allow technicians to measure material thickness from one accessible side without cutting or damaging suitable components.

However, operators may occasionally experience incorrect thickness readings, unstable measurements, missing readings, calibration problems or poor ultrasonic coupling.

Understanding these problems is important for factory maintenance teams, engineering contractors and industrial inspection personnel.

The Benetech GM100 Plus and Benetech GM130 Ultrasonic Thickness Gauges are portable instruments used for general industrial thickness measurement.

This guide explains common ultrasonic thickness measurement problems, their possible causes and practical troubleshooting methods.

1. How Does an Ultrasonic Thickness Gauge Work?

An ultrasonic thickness gauge measures material thickness using high-frequency ultrasonic sound waves.

The instrument transmits ultrasonic energy into the material through a probe.

When the sound reaches a suitable reflecting boundary, part of the energy returns to the probe.

The instrument calculates thickness using the sound velocity and ultrasonic travel time.

Basic Formula

Thickness = Sound Velocity × Echo Travel Time / 2

Accurate measurement depends on several factors:

Correct Sound Velocity

Proper Probe Contact

Suitable Coupling Agent

Appropriate Probe Selection

Correct Instrument Settings

Suitable Material Properties

Proper Calibration and Verification

Problems with any of these factors may produce inaccurate or unstable thickness readings.

2. Benetech GM100 Plus and GM130 Specifications

The Benetech GM100 Plus and Benetech GM130 are designed for general ultrasonic thickness measurement applications.

SpecificationGM100 PlusGM130Measuring Range on Steel1.2–300 mm1.0–300 mmWorking Frequency5 MHz5 MHzSound Velocity Range1000–9999 m/s1000–9999 m/sAutomatic CalibrationYesYesLinear Automatic CompensationYesNoThickness Value StorageYesYesCoupling Status IndicationYesYesUpper and Lower Thickness AlarmNoYesMeasurement Mode SelectionNoYesMetric and Imperial ConversionNoYes6 mm Probe SupportNoYes10 mm Probe SupportYesYes

Important: Actual measurement capability depends on the material, probe, surface condition and inspection geometry.

3. Problem 1 - Ultrasonic Thickness Gauge Shows No Reading

One of the most common problems is when the ultrasonic thickness gauge does not display a thickness value.

The instrument may be switched on, but the thickness reading remains unavailable or unstable.

Possible Causes

Insufficient Coupling Gel

Ultrasonic sound does not transmit efficiently through an air gap between the probe and measurement surface.

Poor Probe Contact

An uneven or curved surface may prevent reliable ultrasonic coupling.

Incorrect Instrument Settings

Incorrect sound velocity or measurement settings may prevent reliable measurement.

Unsuitable Material

Some materials may not provide a suitable ultrasonic response for the selected instrument and probe.

Probe Connection Problems

A loose or damaged probe connection may interrupt measurement.

Troubleshooting Steps

Check the probe connection.

Clean the measurement surface.

Apply suitable ultrasonic coupling gel.

Position the probe firmly against the material.

Verify the instrument settings.

Test the instrument using a suitable reference sample.

If the instrument works on a reference block but not on the component, the problem may be related to the material or measurement conditions.

4. Problem 2 - Thickness Reading Is Unstable

An unstable reading occurs when the displayed thickness changes significantly even though the probe remains near the same measurement location.

For example, a technician may observe readings changing between 5.2 mm, 6.1 mm and 4.8 mm.

Possible Causes

Rough Metal Surface

Insufficient Coupling Agent

Inconsistent Probe Pressure

Curved Measurement Surface

Corrosion or Pitting

Material Irregularities

Incorrect Probe Positioning

Recommended Solutions

Improve Surface Preparation

Remove loose rust, dirt and scale that interfere with probe contact.

Use Suitable Coupling Gel

Ensure that the probe and material have sufficient ultrasonic coupling.

Maintain Stable Probe Contact

Avoid unnecessary movement during measurement.

Verify the Measurement Location

Repeat readings at the same defined inspection point.

Check the Probe

Confirm that the selected probe is suitable for the material and surface geometry.

If readings remain unstable, the application may require a different probe, instrument or inspection method.

5. Problem 3 - Ultrasonic Thickness Gauge Shows Incorrect Thickness

Incorrect thickness measurement is a serious concern because it may lead to misleading maintenance records.

For example, a steel plate known to be approximately 10 mm thick may display a significantly different value.

Common Causes

Incorrect Sound Velocity

Different materials transmit ultrasonic waves at different speeds.

Calibration Problems

Incorrect calibration or verification procedures may affect measurement results.

Surface Coatings

Paint or protective coatings may influence readings from conventional ultrasonic thickness gauges.

Material Differences

Different alloys or material structures may require different measurement settings.

Incorrect Probe Selection

The probe may not be suitable for the material thickness or surface geometry.

Troubleshooting Procedure

Step 1 - Confirm the Material

Identify whether the component is carbon steel, stainless steel, aluminium or another compatible material.

Step 2 - Verify Sound Velocity

Use an appropriate sound velocity setting for the material.

Step 3 - Check the Instrument

Verify the gauge using a suitable known-thickness reference.

Step 4 - Check the Surface

Inspect for coatings, roughness and corrosion.

Step 5 - Repeat the Measurement

Take repeated readings using a consistent procedure.

Important: Do not assume that a displayed thickness is accurate simply because the instrument produces a stable reading.

6. Problem 4 - Poor Ultrasonic Coupling

Ultrasonic coupling is essential for reliable thickness measurement.

Air gaps between the probe and material can prevent ultrasonic sound from entering the component effectively.

Signs of Poor Coupling

No thickness reading

Intermittent readings

Unstable measurements

Missing or inconsistent coupling indication

Common Causes

Insufficient coupling gel

Dirty measurement surface

Rough or uneven material

Incorrect probe positioning

Unsuitable probe contact geometry

Recommended Solutions

Apply a suitable amount of ultrasonic coupling gel.

Ensure that the measurement surface is clean and appropriate for the probe.

Position the probe correctly and maintain consistent contact.

For curved surfaces, confirm that the probe and measurement technique are suitable.

Can Water Replace Ultrasonic Coupling Gel?

Water may provide ultrasonic coupling in some controlled applications, but it is not always suitable.

A proper coupling agent is generally recommended for routine industrial thickness measurement.

The selected coupling agent should be compatible with the material, surface temperature and inspection environment.

7. Problem 5 - Ultrasonic Thickness Gauge Calibration Errors

Instrument calibration and verification are important for reliable thickness measurement.

A thickness gauge may produce incorrect readings if its settings or calibration condition are unsuitable.

Common Calibration-Related Problems

Incorrect reference thickness

Wrong material sound velocity

Unsuitable reference sample

Incorrect probe configuration

Improper calibration procedure

Recommended Verification Procedure

Step 1 - Prepare a Suitable Reference

Use a reference sample with known thickness and suitable material properties.

Step 2 - Check the Probe

Ensure that the probe is connected and functioning correctly.

Step 3 - Configure the Instrument

Set the appropriate sound velocity and other required parameters.

Step 4 - Apply Coupling Agent

Ensure reliable coupling between the probe and reference.

Step 5 - Compare the Reading

Compare the displayed thickness with the reference value.

Step 6 - Investigate Significant Differences

If the reading is outside the permitted tolerance, stop relying on the instrument for critical measurements until the cause has been resolved.

Calibration vs Verification

Verification confirms whether an instrument meets specified performance requirements at the time of checking.

Calibration establishes the relationship between instrument indications and reference values under documented conditions.

A built-in automatic calibration function does not automatically replace periodic laboratory calibration or documented traceability requirements.

8. Problem 6 - Difficulty Measuring Thin Steel

Thin metal components may be challenging for some ultrasonic thickness gauges.

The Benetech GM100 Plus has a manufacturer-specified steel measuring range beginning at 1.2 mm.

The Benetech GM130 has a specified steel measuring range beginning at 1.0 mm, subject to the applicable probe and reference conditions.

Possible Causes of Measurement Difficulty

Thickness below the suitable measurement limit

Incorrect probe selection

Surface curvature

Material irregularities

Poor ultrasonic coupling

Incorrect settings

Recommended Solution

Confirm the expected material thickness and verify that the instrument and probe are suitable.

For measurements close to the minimum specified range, use an appropriate reference sample to confirm performance.

Do not assume that every component with a thickness of 1.0 mm can be measured reliably under all conditions.

9. Problem 7 - Difficulty Measuring Small-Diameter Pipes

Small-diameter pipes may create measurement difficulties because of surface curvature.

A flat probe contact surface may not couple effectively with a highly curved pipe.

Common Problems

Unstable thickness readings

Poor coupling

Inconsistent probe positioning

Limited contact area

GM100 Plus vs GM130 Probe Options

The GM100 Plus supports a 10 mm probe.

The GM130 supports compatible 6 mm and 10 mm probe options.

A smaller probe may offer better physical access to certain restricted measurement areas.

However, smaller probe diameter does not automatically guarantee accurate measurement on every curved pipe.

Recommended Approach

Confirm the pipe diameter, expected wall thickness, probe compatibility and required measurement accuracy.

Where necessary, use a suitable specialized probe or alternative inspection method.

10. Problem 8 - Incorrect Readings on Painted Steel

Many industrial pipelines, storage tanks and steel structures have protective paint or coatings.

These coatings may affect conventional ultrasonic thickness measurements.

Why Can Paint Cause Problems?

A conventional ultrasonic thickness gauge may not automatically separate the coating contribution from the metal substrate thickness.

As a result, readings may be misleading when the instrument is used on painted surfaces.

Recommended Solution

Do not assume that Benetech GM100 Plus or GM130 provides specialized through-coating thickness measurement.

If the inspection requires measuring steel thickness without removing paint, consider an instrument specifically designed for through-coating applications.

Where permitted, coating removal at approved inspection points may be necessary.

11. Problem 9 - Different Readings at Nearby Locations

Technicians may notice different thickness readings at measurement points only a short distance apart.

For example:

Inspection PointThickness ReadingA6.0 mmB5.8 mmC5.1 mmD5.9 mm

Illustrative readings only.

The lower reading at Point C may indicate local thickness variation or possible material loss.

However, other factors may also contribute.

Possible Causes

Localized corrosion

Original manufacturing thickness variation

Surface irregularities

Probe positioning

Measurement uncertainty

Material differences

Recommended Action

Repeat the measurement at the same location and verify the instrument settings.

Where significant differences remain, conduct additional inspection according to an appropriate procedure.

A single low reading should be investigated rather than automatically accepted as proof of corrosion.

12. Problem 10 - GM130 Thickness Alarm Activates Unexpectedly

The Benetech GM130 includes upper and lower thickness alarm settings.

This function helps technicians screen measurements against predefined limits.

Possible Causes of Unexpected Alarm Activation

Incorrect alarm limit settings

Incorrect measurement units

Unstable thickness reading

Incorrect sound velocity

Actual thickness outside the configured range

Troubleshooting Steps

Check the configured alarm limits.

Verify the selected measurement units.

Confirm the instrument settings.

Repeat the thickness measurement.

Compare the reading with an appropriate reference.

Investigate any confirmed out-of-range result.

Important: Thickness alarm limits must be established according to relevant engineering or inspection requirements.

An alarm indication alone does not determine whether equipment is safe or unsafe.

13. Ultrasonic Thickness Gauge Troubleshooting Checklist

Use the following checklist when measurements are unreliable.

ProblemPossible CauseRecommended ActionNo ReadingPoor couplingApply suitable coupling gelUnstable ReadingRough surfaceImprove surface preparationIncorrect ThicknessWrong sound velocityVerify material settingsCalibration ErrorUnsuitable referenceCheck using a proper referenceThin Material ProblemProbe limitationConfirm measurement capabilitySmall Pipe ProblemSurface curvatureCheck probe suitabilityPainted Surface ErrorCoating interferenceUse an appropriate methodUnexpected AlarmIncorrect alarm settingsVerify limits and readingsIntermittent MeasurementProbe connectionCheck probe and cable

If measurement problems remain unresolved, do not use questionable readings for critical equipment acceptance decisions.

14. Preventive Maintenance Tips for Ultrasonic Thickness Gauges

Proper instrument care can help maintain reliable performance.

Clean the Probe

Remove residual coupling gel after use.

Follow the manufacturer's cleaning recommendations.

Inspect the Probe Cable

Check for visible cable damage, loose connections or excessive wear.

Store the Instrument Properly

Keep the instrument in a suitable protective case when not in use.

Avoid unnecessary exposure to moisture, impact and extreme temperatures.

Check the Batteries

Replace weak batteries when necessary.

Verify Measurement Performance

Check the instrument using a suitable reference before important inspection work.

Arrange Calibration When Required

Follow the organization's quality system, inspection procedure or applicable calibration requirements.

Regular instrument verification and proper handling are important for dependable thickness measurements.

15. Benetech GM100 Plus vs GM130 - Which Model Should You Choose?

Both models are suitable for general ultrasonic thickness measurement.

Choose Benetech GM100 Plus If:

You need routine steel plate thickness measurement.

You inspect suitable metal pipelines.

You perform general factory maintenance.

You do not require configurable thickness alarms.

You mainly work with standard measurement surfaces.

Choose Benetech GM130 If:

You require upper and lower thickness alarms.

You need metric and imperial unit conversion.

You want additional measurement mode options.

You require compatible 6 mm and 10 mm probe options.

You perform varied industrial thickness inspection tasks.

The GM130 offers additional operating features, while the GM100 Plus remains suitable for many general thickness measurement applications.

16. Ultrasonic Thickness Gauge Applications in Malaysia

The Benetech GM100 Plus and GM130 are relevant to industrial inspection and maintenance applications across Malaysia.

Selangor and Kuala Lumpur

Factory maintenance, mechanical engineering and industrial equipment inspection.

Johor

Manufacturing plants, steel fabrication workshops and pipeline maintenance.

Penang and Kedah

Industrial manufacturing, machinery maintenance and metal thickness inspection.

Melaka and Negeri Sembilan

Engineering workshops, industrial facilities and preventive maintenance.

Perak and Pahang

Industrial processing plants, metal equipment and maintenance contractors.

Terengganu and Kelantan

Suitable industrial piping and equipment thickness measurement.

Sabah and Sarawak

Industrial facilities, storage tanks and mechanical maintenance applications.

The instruments may also be useful for engineering customers in Perlis.

17. Frequently Asked Questions

Q1. Why is my ultrasonic thickness gauge showing no reading?

Common causes include poor coupling, insufficient coupling gel, incorrect settings, unsuitable material or probe connection problems.

Q2. Why does my ultrasonic thickness gauge show incorrect thickness?

Incorrect sound velocity, calibration problems, surface coatings and unsuitable measurement conditions may affect readings.

Q3. Why does the thickness reading keep changing?

Unstable readings may result from rough surfaces, poor probe contact, material irregularities or inconsistent measurement technique.

Q4. Does an ultrasonic thickness gauge need coupling gel?

Yes. Suitable ultrasonic coupling agent is normally required for reliable measurement.

Q5. Can GM100 Plus measure thin steel?

The manufacturer specifies a steel measuring range beginning at 1.2 mm, subject to suitable measurement conditions.

Q6. Can GM130 measure 1.0 mm steel?

The manufacturer specifies a minimum steel measuring range of 1.0 mm under the applicable reference conditions.

Actual performance depends on the probe, material and inspection geometry.

Q7. Can GM130 measure through paint?

Do not assume that GM130 provides specialized through-coating thickness measurement.

Q8. What is the difference between calibration and verification?

Calibration establishes the relationship between instrument readings and reference values.

Verification checks whether the instrument meets specified requirements.

Q9. Does GM130 have a thickness alarm?

Yes. The GM130 supports upper and lower thickness alarm settings.

Q10. Where can I buy Benetech Ultrasonic Thickness Gauges in Malaysia?

MTM Precision Sdn Bhd supplies Benetech GM100 Plus and GM130 Ultrasonic Thickness Gauges for industrial testing and maintenance applications in Malaysia.

18. Buy Benetech GM100 Plus and GM130 Ultrasonic Thickness Gauge Malaysia

Looking for a reliable Ultrasonic Thickness Gauge Supplier in Malaysia?

MTM Precision Sdn Bhd supplies industrial testing and measuring instruments for manufacturing factories, engineering contractors, maintenance departments and inspection applications.

We supply:

Benetech GM100 Plus Ultrasonic Thickness Gauge

Suitable for general steel plate, metal pipe and industrial component thickness measurement.

Benetech GM130 Ultrasonic Thickness Gauge

Offers additional thickness alarm settings, measurement mode selection and compatible probe options.

Need Help Selecting an Ultrasonic Thickness Gauge?

Please provide:

Material Type

Expected Thickness Range

Pipe Diameter or Component Dimensions

Surface Condition

Measurement Application

Probe Requirements

Special Inspection Requirements

Customers may send photographs of their equipment or measurement application through WhatsApp for preliminary product selection assistance.

Contact MTM Precision Sdn Bhd

MTM PRECISION SDN BHD

Showroom & Service Centre:

No. 29-1 & 29-2, Jalan Bandar 18, Pusat Bandar Puchong, 47160 Puchong, Selangor, Malaysia.

Tel: 03-8080 7172

WhatsApp: +6016-660 7346

Email: mtmpre@yahoo.com

Website: www.mtmpre.com.my

Contact MTM Precision today for Benetech GM100 Plus and GM130 Ultrasonic Thickness Gauge enquiries, product availability and quotations in Malaysia.