Choosing the right NDT equipment depends on your inspection goals, environment, and frequency of use. This practical guide walks you through the NDT equipment selection process—from ACFM and UT to MPI and corrosion monitoring—whether you’re buying or renting.
Key Takeaways
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Match Methods to Goals: Start by identifying what you’re inspecting — cracks, coatings, corrosion — and select the NDT method that best fits (e.g., ACFM for welds, UT for thickness).
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Select Equipment Based on Environment & Usage: Whether it’s ROV-deployable gear for subsea or portable tools for field audits, choose equipment suited to your conditions and frequency of use.
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Bundle for Efficiency & Compliance: Unique Group offers complete NDT kits with calibration tools and accessories to ensure your inspection setup is compliant, traceable, and ready to deploy.
Introduction
Ensuring safety and maintaining quality across modern industries depends heavily on non-destructive testing (NDT). The right NDT equipment helps detect flaws, measure thickness, and assess coatings, without damaging the test material.
A wide range of advanced NDT accessories is available, offering sophisticated solutions tailored to various inspection requirements across industries.
This guide will help you assess your needs, choose the right method, and select non-destructive testing equipment that aligns with your goals, whether you’re renting or buying.
Non-Destructive Testing as a Strategic Approach
Unlike destructive testing, which requires damaging or destroying the test piece to analyse its properties, Non-Destructive Testing (NDT) offers a safer, more cost-effective alternative.
Techniques such as ultrasonic testing, eddy current testing, and magnetic particle inspection enable the detection of surface and subsurface flaws without harming the material.
This means that valuable assets can be thoroughly inspected and assessed for quality and reliability while remaining fully operational and intact.
By using non-destructive testing equipment and methods, industries can perform predictive maintenance, ensuring that potential issues are identified and addressed before they lead to failure. This enhances safety and quality control, minimises downtime and reduces the need for costly repairs or replacements.
Step One: Define Your Operational Needs
The first step is defining what exactly needs to be tested, under what conditions, and by whom. This ensures your NDT equipment aligns with both field conditions and internal quality assurance (QA) standards.
Inspection Goals
- Detect cracks, corrosion, porosity, or voids
- Measure material thickness and structural integrity
- Verify coatings and detect pinholes or leaks
- Identify flaws that could lead to failure
Asset Types
- Pipelines, tanks, and pressure vessels
- Offshore structures and subsea jackets
- Industrial infrastructure and buildings
- Manufacturing components, metals, and welds
Inspection Environment
- Subsea, ROV-diver operated, or topside
- Confined spaces or high-voltage zones
Frequency of Use
- Project-based NDT testing (seasonal or third-party inspections)
- Continuous in-house QA and destructive testing, NDT equipment comparison
Stakeholders
- Engineers, inspection teams: Define inspection requirements and interpret test data to guide maintenance strategies.
- Remote vehicle operators, Divers: Deploy NDT equipment in subsea or confined spaces, requiring compact, rugged, and depth-rated tools.
- Quality assurance professionals: Conduct field testing and ensure compliance using certified, reliable NDT tools.
Output from this step: A complete picture of your inspection goals, environment, and usage profile, essential for selecting equipment that performs reliably in the field.
Step Two: Map Needs to the Right NDT Methods
Each NDT method is suited to specific applications. Here’s a quick matrix to help you match needs with techniques:
| Inspection Goal | Recommended NDT Method |
|---|---|
| Surface cracks (weld) | ACFM, Magnetic Particle Inspection (MPI/MT) |
| Internal corrosion/thinning | Ultrasonic Testing (UT) |
| Coating flaws or leaks | High-voltage spark testing, Pinhole detection |
| Subsea corrosion tracking | Cathodic Protection (CP), Corrosion probes |
| Weld inspection (deep flaws) | Phased array UT, Eddy Current Testing |
| Flaw detection in pipelines and tubular structures | Tube inspection |
Keep in mind: Whichever method you choose, it must comply with standards like ASME, ISO, or DNVGL.
Tube inspection is especially recommended for pipelines and tubular structures. It relies on electromagnetic-based techniques to identify cracks, defects, and structural inconsistencies, without causing damage. This helps maintain the structural integrity of pipes and tubes, especially in sectors like manufacturing and oil & gas.
Step Three: Choose the Right NDT Equipment for Each Method
With your inspection method finalised, it’s time to select the most suitable equipment. Non-destructive testing is necessary for underwater inspections, as it helps detect flaws, corrosion, and cracks in subsea structures and equipment.
Unique Group offers a wide array of non-destructive testing equipment tailored for offshore, subsea, and onshore applications.
Below, we explore each category along with detailed use cases and equipment options available through Unique Group.
1. Alternating Current Field Measurement (ACFM)
Use Case:
ACFM is ideal for detecting surface-breaking cracks in conductive materials, especially welds. Unlike conventional MPI, ACFM can operate through paint and coatings without removing them, preserving asset integrity. It is particularly valuable in critical infrastructure such as offshore rigs, FPSOs, and ship hulls, where weld failures can lead to catastrophic outcomes.
Best For:
This method is widely used in environments where remote or subsea inspections are necessary, especially when diver access is limited. ACFM’s ability to quantify crack length and depth also supports predictive maintenance planning.
Equipment Options from Unique Group:
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- TSC AMIGO™: A compact, portable ACFM unit perfect for topside inspection campaigns. It offers quick setup, an intuitive interface, and reliable results in harsh conditions.
- TSC U31D™: Purpose-built for subsea deployment, this unit is compatible with ROV operations and delivers accurate weld inspection data even in deepwater settings.
2. Magnetic Particle Inspection (MPI/MT)
Use Case:
Magnetic Particle Inspection (MPI) is a proven technique used to reveal surface-level and slightly subsurface defects in ferromagnetic metals. It involves magnetising the test area and applying magnetic particles that accumulate around defects, making cracks, voids, and inclusions visible.
Best For:
This method is widely used in industries where weld quality is important, such as pressure vessel manufacturing, structural steel fabrication, and rail or crane inspections. MPI is cost-effective, fast, and highly sensitive when deployed correctly.
Equipment Options from Unique Group:
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- ASAMS System 3: A robust unit with stainless steel casing, continuous ink agitation, and the ability to perform both AC and DC magnetisation. It’s engineered for lab and field conditions alike.
- SCUMPI: A highly portable MPI system designed for quick on-site assessments. Ideal for shutdown campaigns or mobile inspection units.
- UG UFM7/UPRS6:These dual magnetic field meters help inspectors confirm field strength and uniformity, needed for consistent results and passing audit
3. Ultrasonic Thickness Gauging (UT)
Use Case:
Ultrasonic testing (UT) gauges use high-frequency sound waves to measure the remaining wall thickness of materials, without cutting, grinding, or exposing the internal surface.
Wall thickness and flaw detection are accurately measured using modern ultrasonic testing equipment. This makes UT ideal for corrosion monitoring and condition assessment in live systems.
Best For:
UT is used across industries such as oil and gas, marine, and power generation. It’s especially beneficial for measuring wall thinning in pipes, risers, tanks, and other components exposed to erosive or corrosive environments.
Equipment Options from Unique Group:
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- Cygnus Range: Includes a broad spectrum of UT gauges, from general-purpose models (Cygnus 4/4+) to advanced options like the Cygnus 6+ PRO with data logging and multiple echo capabilities.
- Diver and ROV Models: Cygnus DIVE, Underwater, G1, S1, and W1 are specially engineered for deepwater operations. These devices provide live data capture during inspections, whether operated by divers or integrated with ROVs.
- Mini ROV-Mountable Gauges: For confined spaces or ultra-light ROV platforms, these compact units provide accurate readings without compromising manoeuvrability.
4. High-voltage Spark Testing & Leak Detection
Use Case:
Spark testing verifies coating integrity on conductive substrates. It detects pinholes, porosity, and micro-cracks that can lead to moisture ingress or corrosion. For leak detection in flat roofs, membranes, and geomembranes, spark testers offer rapid, reliable results.
Best For:
Industries involved in storage tank construction, waterproofing, pipeline coating, and roofing systems depend on this method for quality assurance. It’s also used in liner inspections during containment pond construction.
Equipment Options from Unique Group in partnership with Buckleys:
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- PST-100 Kits: Available in various configurations (Basic, Standard, Complete), these spark testers are field-ready and offer voltage flexibility for different materials.
- ST-AC Pro: Built for precision in challenging environments, this tester features safety interlocks and intuitive controls to support accurate, risk-aware inspections.
- Pro2 Series: The PHD Pro2, DCCT Pro2, Lab Pro2, Roof Pro2, and Geo Pro2 are engineered to handle a wide range of leak detection tasks with precision and built-in compliance safeguards.
5. Subsea Corrosion Monitoring (Cathodic Protection)
Use Case:
Structures like risers, piles, and jackets face continuous exposure to harsh marine conditions that speed up the corrosion process. Cathodic protection (CP) systems help mitigate this, but they must be regularly validated through in-situ voltage measurements and corrosion profiling.
Best For:
This equipment is essential for offshore asset owners in oil and gas, marine renewables, and shipping. Regular cathodic protection checks reduce the risk of sudden failures and help maintain alignment with ISO and DNV regulations.
Equipment Options from Unique Group in partnership with Buckleys:
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- BathyCorrometer® Pro Mk7: A widely relied-upon device for accurately measuring electrical potentials in underwater environments. Available in Basic, Standard, and Complete kits to suit different inspection scopes.
- UCP1A/B CP Probes: Offered in both contact and proximity versions, these probes adapt easily to various inspection setups and deployment conditions. Calibration kits ensure traceable results.
- Long-reach flexible Probes & Reference Cells: Designed for deepwater use where diver access is limited, these probes reach awkward geometries and deliver precise readings for better corrosion mapping.
Step Four: Equip the Full Kit – Accessories, Calibration & Compatibility
Selecting the right test equipment is only the beginning. To ensure smooth deployment, your testing process must account for compatible accessories and supporting tools that uphold data integrity and operational safety.
Major considerations:
- Accessories: Couplants, wedges, cases, cables, often overlooked but essential
- Calibration kits: Ensure compliance and traceability under ISO or ASME standards
- Bundled solutions: Save time, simplify logistics, and reduce setup issues
Unique Group supports clients with pre-configured kits tailored to exact inspection needs, reducing guesswork and deployment delays.
These packages often include sample holders, strain gauges, and measurement calibration standards to enhance flaw detection and material assessment.
Step Five: Rent or Buy? Finding the Right NDT Equipment Strategy
Both routes have merit. It all depends on your project goals, frequency of use, and budget. For example, short-term needs like weld inspection or one-off quality control tests may benefit from rentals.
On the other hand, destructive testing or long-term campaigns may require dedicated ownership.
When to Rent:
- Short-term or seasonal inspections
- Trialling a new NDT method or vendor
- Budget constraints for capital expenditure
When to Buy:
- In-house QA or production-line checks
- Long-term monitoring (e.g. marine corrosion)
- Frequent use and need for fast turnaround
Unique Group’s advantage is the immediate rentals from regional locations across project hubs, with expert technical setup support and full compliance documentation.
Final Checklist for Procurement Teams
Before placing an order, ensure the following:
- Does the equipment match your selected NDT method?
- Is it ROV-rated, subsea-capable, or offshore certified as required?
- Are calibration tools included or available?
- Are accessories compatible and field-ready?
- Can you meet your inspection timelines, whether renting or buying?
This checklist simplifies procurement and helps QA managers, engineers, and safety teams stay aligned while reducing procurement errors.
Conclusion
Non-destructive testing forms the foundation of today’s industrial reliability and maintenance practices. The right combination of systems, testing process, and methods can save time, ensure structural integrity, and uphold safety.
At Unique Group, we offer guidance, training, and technical support to help you make the right decision every step of the way. Our wide array of non-destructive testing products ensures operational excellence across sectors.
Need help selecting the right system? Talk to our NDT experts and build a reliable, compliant inspection strategy tailored to your operations.
Frequently Asked Questions (FAQs)
Do Unique Group’s Cygnus gauges come pre-calibrated?
Yes. All non-destructive testing equipment in the Cygnus range, including diver-deployable models, comes pre-calibrated with valid certificates. These are tested to meet the highest industry standards and are ready for use in any testing process involving wall thickness measurement or corrosion monitoring.
What’s the delivery time for a complete MPI inspection kit?
Standard NDT equipment packages like the ASAMS System 3 are available for rapid dispatch from our global hubs. Each kit includes all essential components, ensuring a smooth and compliant testing process from day one.
What are the essential tools for corrosion monitoring?
Our equipment for non-destructive testing of corrosion includes Buckleys BathyCorrometer® kits, calibrated UCP probes, and reference cells. These are typically used to monitor subsea structures without damaging the test material, preserving coating and structural integrity.
Are Buckleys leak detectors suitable for field use?
Absolutely. Buckleys spark and leak detection kits are field-ready, compact, and engineered for high accuracy. Whether you’re testing coatings, membranes, or lined structures, these non-destructive testing tools are optimised for rugged on-site deployment.
What’s the rental process for ultrasonic gauges?
Simply share your inspection scope, asset type, and environment with our team. We’ll configure a turnkey rental kit, including NDT equipment, calibrated thickness gauges, couplants, and probes, designed for your testing process. All rentals come with setup support and documentation for fast deployment.
