Ultrasonic Thickness Gauge Calibration and Accuracy Checking Guide Malaysia

Ultrasonic Thickness Gauge Calibration and Accuracy Checking Guide Malaysia

Introduction

Ultrasonic Thickness Gauge Calibration is an important consideration for manufacturing factories, quality control departments, industrial maintenance teams and non-destructive testing personnel in Malaysia.

An ultrasonic thickness gauge is used to measure the thickness of suitable materials without cutting or dismantling the component.

However, reliable measurement depends on more than switching on the instrument and placing the probe against a metal surface.

Factors such as sound velocity settings, probe condition, ultrasonic coupling, calibration references, surface preparation and measurement technique can influence the displayed thickness.

The Benetech GM100 Plus and Benetech GM130 Ultrasonic Thickness Gauges include built-in automatic calibration functions and adjustable sound velocity settings.

This guide explains how to perform basic ultrasonic thickness gauge accuracy checks, how to recognize measurement errors and how to distinguish instrument verification from formal calibration.

It also explains when a factory should consider documented calibration and traceability for its inspection equipment.

1. Why Is Ultrasonic Thickness Gauge Calibration Important?

An ultrasonic thickness gauge calculates material thickness using ultrasonic sound travel time.

If the instrument settings or measurement conditions are incorrect, the displayed thickness may be inaccurate.

Common Industrial Applications

Steel Plate Thickness Inspection

Pipe Wall Thickness Measurement

Storage Tank Wall Inspection

Industrial Corrosion Monitoring

Machinery Component Measurement

Factory Preventive Maintenance

Quality Control Inspection

Incorrect thickness measurements may affect maintenance records, material verification and engineering decisions.

Benefits of Proper Measurement Verification

Improved Measurement Confidence

Verification helps confirm that the instrument performs acceptably under defined conditions.

Reduced Measurement Errors

Appropriate checks can reveal incorrect settings or instrument problems.

Better Inspection Consistency

Standardized procedures help technicians obtain more repeatable results.

Support for Quality Management

Documented checks can support equipment control requirements.

Improved Maintenance Records

Reliable readings are more useful when comparing thickness changes over time.

For critical applications, measurement requirements should be established by the relevant engineering or quality personnel.

2. Calibration vs Verification vs Adjustment

These terms are often used interchangeably, but they have different meanings.

What Is Calibration?

Calibration establishes the relationship between the indication of a measuring instrument and reference values under specified conditions.

A formal calibration process may include:

Reference standards

Defined measurement conditions

Measurement results

Measurement uncertainty

Traceability information

Calibration documentation

Calibration itself does not necessarily involve changing instrument settings.

What Is Verification?

Verification confirms whether an instrument meets specified requirements.

For example, a technician may measure a known-thickness reference and compare the displayed reading with an established acceptance limit.

What Is Adjustment?

Adjustment changes an instrument setting or response to achieve an intended indication.

An ultrasonic thickness gauge may provide a built-in calibration or adjustment function.

Key Difference

ActivityMain PurposeCalibrationEstablish measurement relationship against referencesVerificationCheck conformity with specified requirementsAdjustmentChange settings or responseRoutine Accuracy CheckConfirm acceptable performance before or during use

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

3. How Does Ultrasonic Thickness Measurement Work?

An Ultrasonic Thickness Gauge uses ultrasonic sound pulses to measure material thickness.

The probe transmits sound into the material.

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

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

Basic Formula

Thickness = Sound Velocity × Echo Travel Time / 2

Example

Suppose a steel component has a thickness of 10 mm.

If the instrument uses an incorrect sound velocity, the calculated thickness may differ from the actual value.

Therefore, the correct sound velocity setting is essential.

Main Factors Affecting Results

Material Sound Velocity

Probe Selection

Instrument Timing and Zero Settings

Reference Standard

Surface Condition

Coupling Quality

Material Temperature

Measurement Geometry

These factors should be considered during accuracy checking and inspection.

4. Benetech GM100 Plus and GM130 Specifications

The Benetech GM100 Plus and Benetech GM130 are portable ultrasonic thickness gauges suitable for general industrial thickness measurement.

SpecificationGM100 PlusGM130Steel Measurement Range1.2–300 mm1.0–300 mmWorking Frequency5 MHz5 MHzSound Velocity Range1000–9999 m/s1000–9999 m/sAutomatic CalibrationYesYesLinear Automatic CompensationYesNoCoupling Status IndicationYesYesThickness Value StorageYesYesUpper and Lower Thickness AlarmNoYesMeasurement Mode SelectionNoYesMetric / Imperial ConversionNoYes6 mm Probe CompatibilityNoYes10 mm Probe CompatibilityYesYesPower Supply3 × 1.5 V AAA3 × 1.5 V AAA

Important: The specified measuring ranges refer to the manufacturer's steel reference conditions. Actual performance depends on the material, probe, surface condition and measurement geometry.

Both models provide functions that support routine measurement preparation and checking.

However, the operator must still follow an appropriate verification procedure.

5. Equipment Required for an Accuracy Check

Before checking an ultrasonic thickness gauge, prepare the appropriate equipment.

1. Ultrasonic Thickness Gauge

For example:

Benetech GM100 Plus or Benetech GM130.

2. Compatible Ultrasonic Probe

Use a probe suitable for the instrument and intended measurement.

3. Known-Thickness Reference

Use a suitable reference block or specimen with a reliably established thickness.

For formal calibration, the reference and its uncertainty must be appropriate for the required measurement traceability.

4. Ultrasonic Coupling Gel

Suitable coupling gel is normally required to transmit ultrasonic energy between the probe and reference surface.

5. Cleaning Materials

Use suitable cleaning materials to prepare the measurement area.

6. Inspection Record

Prepare a record for documenting the reference value, indicated reading and relevant conditions.

7. Manufacturer Instructions

Follow the applicable manufacturer's operating and calibration instructions.

Do not assume that an unverified piece of steel with an approximate nominal thickness is a suitable calibration standard.

6. Step-by-Step Ultrasonic Thickness Gauge Accuracy Checking Procedure

The following procedure describes a general routine verification approach.

It does not replace the manufacturer's instructions or an accredited laboratory calibration procedure.

Step 1 - Inspect the Instrument

Check the condition of:

Instrument housing

Display

Probe

Probe cable

Connectors

Battery

Damaged probes or cables may affect measurement performance.

Step 2 - Switch On the Instrument

Turn on the GM100 Plus or GM130.

Confirm that the display operates normally.

Step 3 - Check the Probe Connection

Ensure that the compatible ultrasonic probe is correctly connected.

Step 4 - Select the Appropriate Measurement Settings

Confirm the measurement mode where applicable.

For the GM130, ensure that the selected mode is appropriate for the inspection.

Step 5 - Confirm the Material Sound Velocity

Set the correct sound velocity for the reference material.

If the reference material differs from the inspection material, additional setting changes may be necessary before actual measurement.

Step 6 - Perform the Manufacturer's Required Calibration or Zero Procedure

Follow the model-specific instructions.

Do not assume that both models use identical button sequences or adjustment procedures.

Step 7 - Apply Coupling Gel

Apply suitable ultrasonic coupling gel to the reference surface.

Step 8 - Measure the Known-Thickness Reference

Place the probe against the reference.

Obtain a stable reading and confirm proper coupling.

Step 9 - Compare the Reading

Compare the indicated thickness with the established reference value.

Step 10 - Evaluate the Result

Determine whether the difference is acceptable according to the specified tolerance and relevant measurement uncertainty.

Step 11 - Record the Check

Document the results and relevant instrument information.

If the instrument does not meet the required acceptance criteria, investigate the cause before using it for important inspection work.

7. How to Calculate Thickness Measurement Error

A basic thickness measurement error can be calculated by comparing the displayed reading with a reference value.

Formula

Measurement Error = Indicated Thickness - Reference Thickness

Example

A suitable reference has an established thickness of 10.00 mm.

The ultrasonic thickness gauge displays 10.08 mm.

Measurement Error = 10.08 - 10.00

Measurement Error = +0.08 mm

The displayed reading is 0.08 mm higher than the reference value.

Percentage Error

Percentage Error = (Measurement Error / Reference Thickness) × 100%

Percentage Error = (0.08 / 10.00) × 100%

Percentage Error = 0.8%

Important Consideration

A calculated error does not automatically determine whether an instrument passes or fails.

Acceptance depends on:

Manufacturer specifications

Required measurement tolerance

Reference uncertainty

Test conditions

Applicable quality requirements

The examples above are illustrative and do not represent verified accuracy specifications for GM100 Plus or GM130.

8. Why Checking Only One Thickness May Be Insufficient

A single reference measurement may confirm performance at one thickness value, but it does not establish performance across the instrument's entire range.

For example, a gauge that performs acceptably near 10 mm may require additional verification before use on significantly thinner or thicker materials.

Multi-Point Checking

Depending on the application, verification may involve several reference thicknesses.

Reference ThicknessExample Indicated ReadingError2.00 mm2.03 mm+0.03 mm5.00 mm5.02 mm+0.02 mm10.00 mm10.08 mm+0.08 mm20.00 mm19.94 mm-0.06 mm

Illustrative values only, not actual GM100 Plus or GM130 test results.

Why Multi-Point Checking Matters

Thin Material Performance

Checks whether the instrument performs acceptably near the intended lower measurement range.

Mid-Range Performance

Checks performance around common operating thicknesses.

Thicker Material Performance

Checks performance at larger thickness values.

Recommended Practice

Select reference points according to the intended measurement range and inspection requirements.

Do not claim that checking a few reference points constitutes full-range calibration unless the procedure supports that conclusion.

9. Sound Velocity Setting and Measurement Accuracy

Sound Velocity Setting is one of the most important factors affecting ultrasonic thickness measurement.

Different materials transmit ultrasonic sound at different speeds.

Common Material Examples

MaterialTypical Longitudinal Sound VelocityCarbon SteelApproximately 5920 m/sStainless SteelApproximately 5740 m/sAluminiumApproximately 6320 m/sCopperApproximately 4760 m/s

These values are general illustrative references. Actual sound velocity varies with material composition, structure, temperature and other conditions.

Why Incorrect Velocity Causes Errors

Suppose an instrument is configured for carbon steel but used on another material without adjusting the sound velocity.

The displayed thickness may be systematically incorrect.

Recommended Procedure

Identify the Material

Confirm the material type where possible.

Use an Appropriate Reference

A known-thickness specimen of the same material may help establish a suitable sound velocity.

Verify the Setting

Check the instrument using the appropriate procedure.

Record the Setting

Document the sound velocity when traceable or repeatable measurements are required.

Do not assume that every steel alloy or metal component uses exactly the same sound velocity.

10. Probe Condition and Calibration Accuracy

The ultrasonic probe plays an important role in thickness measurement.

A damaged or unsuitable probe may affect measurement performance.

Common Probe Problems

Worn Probe Contact Surface

Wear may influence coupling and measurement behavior.

Damaged Cable

A damaged cable may interrupt or degrade the ultrasonic signal.

Loose Connector

An unstable connection may produce intermittent readings.

Incorrect Probe Selection

An unsuitable probe may fail to measure certain thicknesses or geometries reliably.

Poor Coupling

Insufficient coupling gel may prevent stable ultrasonic transmission.

Recommended Maintenance

Inspect the probe before use.

Check the cable and connectors.

Clean the contact surface appropriately.

Store the probe carefully.

Verify measurement performance after replacing a probe.

A probe replacement may require renewed verification or adjustment according to the manufacturer's instructions.

11. Does Surface Condition Affect Thickness Accuracy?

Yes. Surface condition can significantly affect ultrasonic thickness measurement.

Smooth Metal Surface

A clean, suitable surface generally supports better probe contact.

Rough Steel Surface

Surface irregularities may cause unstable readings.

Rusted Surface

Loose rust and scale may interfere with ultrasonic coupling.

Curved Pipe Surface

Pipe curvature can affect the probe contact area.

Painted Surface

Protective coatings may influence conventional ultrasonic thickness measurement.

Corroded Surface

Localized corrosion may create irregular reflecting surfaces and complex measurement conditions.

Recommended Practice

Prepare the surface according to the inspection procedure.

Use suitable coupling gel and verify the measurement where possible.

A stable displayed reading should not automatically be treated as proof of accurate thickness measurement.

12. Can GM100 Plus and GM130 Measure Through Paint?

Many industrial pipelines, storage tanks and steel components are painted.

However, conventional ultrasonic thickness measurement may be affected by coating layers.

The Benetech GM100 Plus and GM130 should not be assumed to provide specialized through-coating thickness measurement.

For applications requiring metal substrate measurement without removing paint, a specialized through-coating instrument may be necessary.

Where permitted, approved coating removal at selected measurement points may be required.

Important for QA and QC

If the measurement procedure requires bare-metal contact, ensure that the surface preparation is appropriate.

Document any coating-related limitations.

13. Measurement Repeatability vs Measurement Accuracy

Repeatability and accuracy are different concepts.

Measurement Repeatability

Repeatability describes how closely repeated measurements agree under specified conditions.

Measurement Accuracy

Accuracy concerns how closely a measurement result agrees with the true value, although it is not normally expressed as a single numerical quantity in formal metrology.

Example

A technician measures a suitable reference several times.

MeasurementDisplayed Thickness110.12 mm210.11 mm310.12 mm410.13 mm510.12 mm

Illustrative values only.

The readings are closely grouped.

However, if the established reference thickness is 10.00 mm, the measurements may still have a systematic error.

Important Lesson

Consistent readings do not necessarily mean accurate readings.

Both repeatability and agreement with appropriate references should be considered.

14. Ultrasonic Thickness Gauge Calibration Frequency

A common question is:

How often should an ultrasonic thickness gauge be calibrated?

There is no single calibration interval suitable for every instrument and application.

The appropriate interval depends on:

Frequency of use

Measurement criticality

Operating environment

Manufacturer recommendations

Previous calibration history

Instrument stability

Quality management requirements

Customer or regulatory requirements

Routine Pre-Use Checks

A suitable reference check before important measurements can help identify problems.

Periodic Calibration

Documented calibration may be required according to the organization's quality system.

After Repair

Calibration or verification may be necessary after instrument repair or adjustment.

After Probe Replacement

Measurement verification may be required when changing probes.

After Suspected Damage

An instrument should be checked if it has been dropped, damaged or exposed to unsuitable conditions.

Calibration intervals should be based on measurement risk and documented requirements rather than an arbitrary universal schedule.

15. Ultrasonic Thickness Gauge Calibration for ISO 9001 Quality Systems

Manufacturing factories operating under ISO 9001 may need to control monitoring and measuring resources used to verify product or service conformity.

Depending on the measurement requirements, this may involve:

Equipment identification

Suitable calibration or verification

Measurement traceability where required

Defined acceptance criteria

Equipment status records

Protection from damage

Appropriate corrective action when equipment is unsuitable

Important Distinction

ISO 9001 does not automatically require every ultrasonic thickness gauge to be calibrated by an ISO/IEC 17025-accredited laboratory.

The appropriate approach depends on the organization's requirements and the intended use of the measurement results.

When ISO/IEC 17025 Calibration May Be Relevant

An ISO/IEC 17025-accredited calibration laboratory may be appropriate when accredited calibration, defined measurement uncertainty and metrological traceability are required.

Customers should confirm that the laboratory's accreditation scope covers the relevant instrument or measurement service.

A calibration certificate should not be described as accredited unless the service is actually covered by the laboratory's accreditation.

16. Example of an Ultrasonic Thickness Gauge Verification Record

A basic verification record may include the following information.

ItemExampleInstrumentBenetech GM130Instrument IDUTG-001ProbeCompatible 10 mm ProbeReference Thickness10.00 mmIndicated Thickness10.06 mmIndication Error+0.06 mmSound VelocityRecorded According to Reference MaterialCheck Date11 October 2026OperatorQA TechnicianAcceptance CriteriaDefined by Approved ProcedureResultPending Evaluation Against Criteria

Illustrative example only.

Additional Information

For more formal records, include:

Reference identification

Reference calibration status

Measurement conditions

Instrument serial number

Procedure reference

Measurement uncertainty where required

Reviewer or approver

Do not assign a pass result until the actual acceptance criteria and relevant uncertainty have been evaluated.

17. Troubleshooting Failed Accuracy Checks

Problem 1 - Reading Is Consistently Too High

Possible causes:

Incorrect sound velocity

Incorrect adjustment

Unsuitable reference

Coating interference

Recommended Action: Verify the settings and reference, then repeat the check.

Problem 2 - Reading Is Consistently Too Low

Possible causes:

Incorrect sound velocity

Instrument setting problems

Probe-related error

Measurement geometry

Recommended Action: Confirm the reference material, settings and probe condition.

Problem 3 - Readings Change Every Time

Possible causes:

Poor coupling

Rough surface

Unstable probe contact

Damaged cable

Recommended Action: Improve coupling, inspect the probe and repeat measurements.

Problem 4 - No Reading on a Reference Block

Possible causes:

Probe connection problem

Incorrect settings

Insufficient coupling gel

Instrument fault

Recommended Action: Inspect the instrument and follow the manufacturer's troubleshooting procedure.

Problem 5 - Instrument Passes One Reference but Fails Another

Possible causes:

Range-dependent error

Incorrect procedure

Probe limitations

Reference problems

Recommended Action: Investigate the results and arrange further evaluation when necessary.

Do not use an instrument for critical acceptance decisions when its required measurement performance cannot be confirmed.

18. GM100 Plus vs GM130 for QA and QC Applications

Choose Benetech GM100 Plus If:

You need routine thickness measurement.

You mainly inspect suitable steel plates.

You perform general industrial material checks.

You do not require thickness alarm settings.

You prefer straightforward operation.

Choose Benetech GM130 If:

You require upper and lower thickness alarm settings.

You need measurement mode selection.

You want metric and imperial conversion.

You require compatible 6 mm and 10 mm probe options.

You perform varied industrial inspection tasks.

Important QA and QC Consideration

Neither model should be assumed to meet a specific accuracy, uncertainty or traceability requirement without reviewing the relevant specifications and verification results.

Choose the instrument according to the actual measurement tolerance and inspection requirements.

19. Calibration and Accuracy Checking Applications Across Malaysia

Ultrasonic Thickness Gauge Calibration and Accuracy Checking are relevant to industrial users throughout Malaysia.

Selangor and Kuala Lumpur

Manufacturing factories, QA/QC departments, engineering companies and maintenance contractors.

Johor

Industrial plants, steel fabrication workshops and pipeline inspection contractors.

Penang and Kedah

Electronics manufacturing, mechanical engineering and industrial quality control.

Melaka and Negeri Sembilan

Factory maintenance, metal fabrication and equipment inspection.

Perak and Pahang

Industrial processing plants, engineering workshops and industrial maintenance.

Terengganu and Kelantan

Suitable industrial piping, steel equipment and thickness inspection applications.

Sabah and Sarawak

Industrial facilities, maintenance contractors and engineering companies.

Customers in Perlis may also require ultrasonic thickness gauge verification and industrial measurement equipment.

20. Frequently Asked Questions

Q1. Does an ultrasonic thickness gauge need calibration?

Calibration or verification may be necessary depending on the intended use, measurement risk and applicable quality requirements.

Q2. What is the difference between calibration and verification?

Calibration establishes a measurement relationship against references, while verification checks conformity with specified requirements.

Q3. Does Benetech GM100 Plus have automatic calibration?

Yes. The GM100 Plus includes a built-in automatic calibration function.

Q4. Does Benetech GM130 have automatic calibration?

Yes. The GM130 includes a built-in automatic calibration function.

Q5. Can I check an ultrasonic thickness gauge using a steel block?

A suitable known-thickness reference may be used for routine checking.

The reference must be appropriate for the required accuracy and measurement procedure.

Q6. Why is my ultrasonic thickness gauge reading incorrect?

Possible causes include incorrect sound velocity, poor coupling, unsuitable probes, surface conditions or instrument problems.

Q7. How often should ultrasonic thickness gauges be calibrated?

The interval depends on usage, measurement criticality, instrument history and applicable quality requirements.

Q8. Is automatic calibration the same as laboratory calibration?

No. A built-in function does not automatically replace documented laboratory calibration.

Q9. Can GM100 Plus and GM130 be used for QA/QC?

They may be suitable for general thickness measurement applications when their performance meets the relevant inspection requirements.

Q10. Does ISO 9001 require ISO/IEC 17025 calibration for every thickness gauge?

Not automatically. The appropriate calibration and traceability requirements depend on the organization's measurement needs and applicable obligations.

Q11. Can an ultrasonic thickness gauge measure through paint?

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

Q12. Where can I buy an ultrasonic thickness gauge in Malaysia?

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

21. Buy Benetech Ultrasonic Thickness Gauge Malaysia

Looking for a suitable Ultrasonic Thickness Gauge Supplier in Malaysia?

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

Benetech GM100 Plus Ultrasonic Thickness Gauge

Suitable for general thickness measurement of compatible steel plates, pipelines and industrial metal components.

Benetech GM130 Ultrasonic Thickness Gauge

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

Need Help Choosing an Instrument?

Please provide:

Material Type

Expected Thickness Range

Measurement Application

Required Measurement Tolerance

Probe Requirements

Calibration or Verification Requirements

Quality System Requirements

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

For calibration-related enquiries, please provide the instrument model, required calibration scope and any specific documentation or accreditation requirements so that service suitability can be confirmed.

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 selection, calibration requirements and quotations in Malaysia.