Ultrasonic Testing for Condition Monitoring

Understanding Ultrasonic Testing in Modern Condition Monitoring

In the demanding industrial environments of Atlantic Canada, where maritime conditions, temperature fluctuations, and operational stresses can accelerate equipment degradation, maintaining asset reliability is paramount. Ultrasonic testing (UT) has emerged as one of the most powerful non-destructive testing (NDT) methods for condition monitoring, offering engineers and maintenance professionals the ability to detect problems before they result in costly failures or dangerous situations.

Ultrasonic testing utilizes high-frequency sound waves, typically ranging from 20 kHz to 25 MHz, to evaluate the structural integrity of materials and detect anomalies that are invisible to the naked eye. For industries across Nova Scotia and the Maritime provinces—including pulp and paper, food processing, energy generation, and manufacturing—this technology represents a critical component of any comprehensive predictive maintenance programme.

At its core, ultrasonic testing works by transmitting sound waves through a material and analysing the reflected signals. When these waves encounter discontinuities such as cracks, voids, inclusions, or wall thickness variations, they reflect back to the transducer at different times and amplitudes, creating a detailed picture of the material's internal condition.

Key Applications of Ultrasonic Testing in Industrial Settings

Thickness Measurement and Corrosion Monitoring

One of the most common applications of ultrasonic testing in Atlantic Canadian industries is wall thickness measurement. This is particularly critical for:

• Pressure vessels and storage tanks operating under demanding conditions

• Piping systems carrying corrosive materials or operating at elevated temperatures

• Heat exchangers and boiler tubes subject to erosion and scaling

• Offshore and coastal structures exposed to saltwater corrosion

• Process equipment in pulp and paper facilities throughout Nova Scotia

Modern ultrasonic thickness gauges can measure material thickness with accuracy levels of ±0.01 mm, allowing engineers to track corrosion rates as low as 0.05 mm per year. This precision enables the development of accurate remaining life calculations and informed decisions about repair, replacement, or continued operation of critical assets.

Flaw Detection and Weld Inspection

Ultrasonic flaw detection is essential for identifying internal defects that could compromise structural integrity. In manufacturing and fabrication facilities across the Maritimes, UT is routinely used to inspect:

• Welded joints in pressure equipment and structural steel

• Forgings and castings for internal voids or inclusions

• Bolts and fasteners in critical applications

• Composite materials and bonded assemblies

Phased array ultrasonic testing (PAUT) has revolutionised flaw detection capabilities, offering the ability to steer and focus ultrasonic beams electronically. This technology can inspect complex geometries and provide detailed cross-sectional images of welds, significantly improving defect detection and characterisation compared to conventional single-element transducers.

Bearing and Rotating Equipment Monitoring

Airborne and structure-borne ultrasonic testing provides early warning of bearing degradation, often detecting problems weeks or months before they would be apparent through vibration analysis. When bearing defects develop, they produce ultrasonic emissions in the 20-100 kHz range that can be detected and trended over time.

For facilities operating critical rotating equipment—such as compressors, pumps, motors, and turbines—ultrasonic bearing monitoring offers several advantages:

• Detection of lubrication problems before metal-to-metal contact occurs

• Identification of early-stage bearing defects at frequencies above normal vibration monitoring ranges

• Ability to monitor slow-speed bearings (below 25 RPM) where vibration analysis is less effective

• Real-time feedback during lubrication activities to prevent over-greasing

Ultrasonic Testing Technologies and Equipment Selection

Conventional Ultrasonic Testing

Conventional UT remains the workhorse of ultrasonic inspection programmes. These systems typically operate in the 1-10 MHz frequency range and use single-element transducers in either pulse-echo or through-transmission configurations. Modern portable instruments feature digital signal processing, data logging capabilities, and connectivity options for integration with asset management systems.

When selecting conventional UT equipment for condition monitoring applications, key specifications to consider include:

• Frequency range: Higher frequencies (5-10 MHz) provide better resolution but limited penetration; lower frequencies (1-2.25 MHz) offer greater penetration for thick materials

• Pulser voltage: Typically 100-400V for adequate signal strength in attenuative materials

• Display resolution: Minimum 320 x 240 pixels for clear A-scan visualisation

• Data storage: Sufficient capacity for storing thousands of readings with location identification

• Environmental rating: IP65 or higher for reliability in Maritime industrial environments

Phased Array Ultrasonic Testing (PAUT)

Phased array technology represents a significant advancement in ultrasonic inspection capabilities. PAUT systems use multi-element transducers (typically 16-128 elements) that can be individually controlled to steer, focus, and scan ultrasonic beams without mechanical movement. This enables:

• Sector scans covering angles from -70° to +70° in a single acquisition

• Electronic focusing at multiple depths for optimised sensitivity

• Linear scans for rapid coverage of large areas

• Encoded inspections with positional accuracy of ±1 mm

For weld inspection applications common in Nova Scotia's fabrication and manufacturing sectors, PAUT can reduce inspection time by 50-80% compared to conventional methods while providing superior defect characterisation and permanent records of inspection results.

Time of Flight Diffraction (TOFD)

TOFD is a specialised ultrasonic technique that offers exceptional sensitivity for detecting and sizing planar defects such as cracks and lack of fusion in welds. This method uses two transducers—one transmitter and one receiver—positioned on either side of the weld. Defect sizing accuracy with TOFD typically achieves ±1 mm, making it invaluable for fitness-for-service assessments and remaining life calculations.

Implementing an Effective Ultrasonic Condition Monitoring Programme

Establishing Baseline Measurements

The foundation of any successful ultrasonic condition monitoring programme is accurate baseline data. Initial measurements should be taken at carefully documented locations using standardised procedures. For thickness monitoring, consider establishing a grid pattern with measurement points at intervals appropriate to the expected corrosion mechanism—typically 150-300 mm spacing for general corrosion and closer spacing (50-75 mm) in areas of localised attack.

Baseline data should include:

• Precise location identification using permanent marking or GPS coordinates

• Original material thickness from design documents or manufacturer specifications

• Initial ultrasonic readings with instrument settings documented

• Surface condition notes and any access limitations

• Reference to applicable codes and standards (CSA, ASME, API)

Determining Inspection Intervals

Inspection frequency should be based on the calculated corrosion rate and the remaining corrosion allowance. A common approach uses the following formula:

Inspection Interval = (Remaining Thickness - Minimum Required Thickness) ÷ (Corrosion Rate × Safety Factor)

Safety factors typically range from 2 to 4 depending on the consequence of failure and confidence in the corrosion rate data. For critical equipment in Nova Scotia's process industries, annual inspections are common during the initial monitoring period, transitioning to risk-based intervals once corrosion behaviour is well-characterised.

Data Management and Trending

Modern condition monitoring programmes require robust data management systems to track measurements over time and identify trends. Key features to look for in ultrasonic data management software include:

• Database storage for historical readings with full traceability

• Automated corrosion rate calculations and remaining life projections

• Colour-coded thickness mapping for visual representation of condition

• Alert generation when readings approach minimum thresholds

• Integration capabilities with CMMS and enterprise asset management systems

Industry Standards and Regulatory Considerations

Ultrasonic testing for condition monitoring in Canada must comply with various codes, standards, and regulatory requirements. Key documents governing UT applications include:

• CSA W59: Welded Steel Construction—includes requirements for ultrasonic inspection of structural welds

• ASME Section V: Nondestructive Examination—provides procedures for ultrasonic examination of pressure equipment

• API 510/570: Pressure Vessel and Piping Inspection Codes—specify requirements for in-service inspection including UT

• CAN/CGSB-48.9712: Qualification and Certification of NDT Personnel

In Nova Scotia, the Technical Safety Division of Service Nova Scotia oversees pressure equipment safety, and ultrasonic inspection reports often form part of the documentation required for registration and periodic inspection compliance. Ensuring that UT programmes meet these regulatory requirements is essential for continued safe operation of pressure equipment.

Personnel Qualification Requirements

Ultrasonic testing personnel should be qualified and certified according to CAN/CGSB-48.9712 or equivalent standards such as SNT-TC-1A or ISO 9712. Certification levels include:

• Level I: Performs specific calibrations, tests, and evaluations under supervision

• Level II: Sets up and calibrates equipment, performs tests, and evaluates results according to applicable codes

• Level III: Develops procedures, interprets codes, and provides technical direction

Integration with Automation and Industry 4.0

The evolution of ultrasonic testing technology aligns closely with broader Industry 4.0 trends, offering significant opportunities for automation and digitalisation. Forward-thinking organisations across Atlantic Canada are implementing:

Automated Ultrasonic Testing Systems

Robotic and semi-automated UT systems can perform repetitive inspections with greater consistency and speed than manual methods. Crawler-mounted systems for tank floor scanning can cover 100+ square metres per hour, while automated pipe inspection systems provide 100% coverage of circumferential welds. These technologies are particularly valuable for large-scale inspections during turnarounds and shutdowns.

Permanent Ultrasonic Sensors

Permanently installed ultrasonic sensors enable continuous or periodic monitoring without manual intervention. These sensors are particularly valuable for:

• High-temperature locations where manual access is impractical

• Insulated piping where repeated insulation removal is costly

• Remote locations difficult to access for routine inspections

• Critical equipment requiring frequent monitoring

Wireless sensor networks can transmit thickness data to central monitoring systems, enabling real-time tracking of corrosion rates across entire facilities.

Cloud-Based Data Analytics

Cloud platforms for ultrasonic data storage and analysis offer scalability, accessibility, and advanced analytics capabilities. Machine learning algorithms can analyse historical data to identify patterns, predict future degradation, and optimise inspection intervals based on actual asset behaviour rather than conservative assumptions.

Maximising Return on Investment

Implementing ultrasonic testing for condition monitoring represents a significant investment, but the returns can be substantial. Studies consistently show that predictive maintenance programmes based on condition monitoring technologies like UT deliver:

• 25-30% reduction in maintenance costs through elimination of unnecessary preventive maintenance

• 70-75% reduction in equipment failures through early detection of developing problems

• 35-45% reduction in downtime through planned repairs versus emergency shutdowns

• Extended equipment life through condition-based operation rather than arbitrary replacement schedules

For industrial facilities in Nova Scotia and throughout the Maritimes, where equipment replacement often involves lengthy lead times and significant logistics challenges, the value of extending asset life while maintaining safety is particularly significant.

Partner with Sangster Engineering Ltd. for Your Ultrasonic Testing Needs

Implementing an effective ultrasonic testing programme requires expertise in both the technology and its application to real-world industrial challenges. At Sangster Engineering Ltd., our team brings decades of experience serving industrial clients across Atlantic Canada, combining deep technical knowledge with practical understanding of the unique conditions facing Maritime industries.

Whether you're establishing a new condition monitoring programme, upgrading existing inspection capabilities, or seeking to integrate ultrasonic testing with automated systems, we can help you develop solutions that maximise asset reliability while optimising costs. Our services include programme development, procedure writing, equipment selection guidance, and integration with broader asset management strategies.

Contact Sangster Engineering Ltd. today to discuss how ultrasonic testing can enhance your condition monitoring capabilities and support your operational excellence objectives. Our Amherst, Nova Scotia office serves clients throughout the Maritime provinces, and we're committed to delivering engineering solutions that make a real difference to your operations.

Partner with Sangster Engineering

At Sangster Engineering Ltd. in Amherst, Nova Scotia, we bring decades of engineering experience to every project. Serving clients across Atlantic Canada and beyond.

Contact us today to discuss your engineering needs.