Phonon Diagnostic Technique (PDT)
Precision Without Compromise. Insight Without Interruption.
Phonon Diagnostic Technique (PDT)
Advanced In-Service Screening for Active Degradation
A passive, in-service screening technique for detecting active corrosion, pitting, cracking and leakage across pipelines, risers, storage tanks, pressure vessels and process piping.
Vector Integrity is the authorized representative for PDT across the Americas.
What is Phonon Diagnostic Technique?
Phonon Diagnostic Technique (PDT) is a passive, in-service screening technique that detects elastic activity generated by active degradation within stressed materials, known as phonon emissions.
PDT detects active corrosion and pitting, surface and sub-surface cracking, and leaks in pressurized systems. It can be applied to pipelines, risers, storage tanks, pressure vessels and process piping, including assets that are above ground, buried or submerged.
Externally mounted sensors monitor the required section while the asset remains in operation, allowing inspection resources to be focused on areas showing active degradation.
KEY BENEFITS
Screen More. Disrupt Less.
PDT provides a way to screen large monitored areas while assets remain in service.
Inspection During Normal Operation
PDT allows monitoring while the asset remains in operation.
Large-Area Coverage
A limited sensor array can monitor large areas of an operating asset within a short data-acquisition window.
Minimal Preparatory Work
Surface preparation is localized to the selected sensor locations.
Difficult-to-Access Areas
PDT can support inspection where continuous surface access, excavation, rope access or divers may be impractical or costly.
100% Coverage of the Monitored Area
The technology provides coverage of the defined monitored area while focusing attention on active indications.
Targeted Follow-Up NDT
Conventional or advanced NDT can be used selectively for verification or additional engineering assessment where required.
HOW PDT WORKS
How Phonon Diagnostic Technique Works
Active degradation within a stressed material, such as corrosion, cracking or leakage, generates a detectable phonon-emission signature.
Externally mounted phonon-emission transducers capture the signal at each mounting point. The emitted energy travels through the structure and is detected across multiple sensors, allowing the source to be localized.
PDT software processes and maps the signal source, while proprietary calibration and processing are used to locate, size and classify active degradation.
01 — Sensors Detect
Phonon-emission transducers capture the signal at each mounting point.
02 — Software Localizes
PDT software processes and maps the signal source.
03 — Findings Identified
The inspection identifies the quantity, location, size, type and severity of indications.
DEPLOYMENT
Designed for In-Service Inspection
Sensors are positioned externally to create the required monitored zone. Localized bright-metal preparation to ST3 is required only at sensor locations.
Once sensors are installed and calibrated, monitoring is typically completed in approximately 2 hours, with all channels acquiring data simultaneously across the monitored area.
PDT requires a minimum operating pressure of 14.5 psi (1 barg) and has an operating temperature range of −148°F to 716°F, while the asset remains in service.
Highlight:
~2 hours
Typical monitoring period once installed and calibrated.
APPLICATIONS
Where Can PDT Be Used?
PDT can be applied across a range of operating assets where active degradation needs to be screened.
Pipelines
Rapid in-service screening of aboveground, buried and submerged pipelines.
PDT enables linear coverage of up to 1 km between sensor locations, requiring access only at selected sensor locations. It can support screening where ILI, excavation or continuous surface access is impractical.
Operational advantage: Screens up to 1 km of pipeline with limited access, reducing excavation, preparation and inspection costs.
Risers
In-service screening of risers with limited access requirements.
PDT is suitable for topside, splash-zone and difficult-to-access riser sections. It can monitor up to 400 m of riser from a single sensor location, extending approximately 200 m in each direction in planar mode.
It can help avoid costly diver, rope-access or shutdown campaigns.
Pressure Vessels
Full-volume screening of pressure vessels while they remain in operation.
External sensors monitor vessel shells, heads, nozzles and weld regions. PDT screens for active corrosion, cracking, leakage and other degradation activity, with targeted NDT available for verification or additional assessment where required.
Operational advantage: Minimizes shutdowns, vessel entry and extensive access requirements, reducing preparation, downtime and overall inspection costs.
Storage Tanks
In-service tank screening without emptying or full internal access.
PDT is applicable to aboveground single- and double-wall tanks and can screen tank shell, floor/wall regions and internal/external degradation activity.
Once installed and calibrated, monitoring is typically completed in approximately 2 hours.
Operational advantage: Reduces tank emptying, cleaning, gas-freeing, confined-space entry and extended out-of-service inspection.
WHY PDT?
The Value of PDT
PDT provides a different approach to inspection by focusing on active degradation rather than simply the presence of an existing defect.
It can provide:
- Inspection during normal operation
- Reduced shutdown-related inspection costs
- Minimal preparatory work
- Inspection of difficult-to-access areas
- 100% coverage of the monitored area
- Detection, localization and characterization of active degradation
- Targeted conventional and advanced NDT for verification
APPROPRIATE USE & LIMITATIONS
When PDT Is Appropriate
PDT detects active, growing degradation that is generating measurable phonon emissions under operating stress.
It can detect, locate and size active degradation. Documented piping applications report defect-depth measurement error of approximately 0.1t and defect-location accuracy of approximately ±1 m, with phonon-active areas below 10% of nominal wall thickness excluded from the reported defect list.
The asset must be under sufficient operating stress during monitoring, with a minimum pressure requirement of 14.5 psi (1 barg). PDT is intended for materials with a crystalline structure, and suitability should be confirmed during pre-inspection review.
Selected sensor locations require local access and surface preparation to bright metal for transducer installation. Conventional NDT can be used selectively for independent verification or additional engineering assessment.
CALIBRATION & SIGNAL INTERPRETATION
From Signal to Actionable Findings
Before monitoring, calibration establishes the normal mechanical, process and environmental background activity and confirms sensor coupling, sensitivity and signal transmission.
During analysis, responses are compared across sensors to identify localized active sources. Noise discrimination separates operational noise from degradation-related activity, while proprietary processing determines the location, type, size and severity of indications.
Signal Baseline
Establishes normal mechanical, process and environmental background activity.
Sensor Calibration
Confirms coupling, sensitivity and signal transmission before monitoring.
Noise Discrimination
Separates operational noise from degradation-related activity.
Signal Correlation
Compares response across sensors to identify localized active sources.
Defect Classification
Determines location, type, size and severity.
Storage Tanks
In-service tank screening without emptying or full internal access.
PDT is applicable to aboveground single- and double-wall tanks and can screen tank shell, floor/wall regions and internal/external degradation activity.
Once installed and calibrated, monitoring is typically completed in approximately 2 hours.
Operational advantage: Reduces tank emptying, cleaning, gas-freeing, confined-space entry and extended out-of-service inspection.
SUCCESS STORY
PDT Vessel Campaign: Validation to Adoption
A vessel validation program progressed into broader PDT use for shutdown-critical equipment.
Validation Basis
PDT was validated across 5 vessels alongside corrosion mapping and advanced NDT.
Technical Result
Results aligned sufficiently with advanced NDT for the operator to accept PDT where conditions apply.
Adoption
The operator proceeded with PDT for the wider 22-vessel shutdown inspection scope.
Commercial Impact
PDT reduced POB demand and inspection duration, with 13 days onsite plus 12 days reporting estimated for the campaign.
Key Outcome
The inspection strategy was transformed from shutdown-dependent vessel inspection to rapid, non-intrusive assessment with lower POB demand, full coverage and major production-risk reduction.
$97M
Operator-estimated deferred-production exposure avoided
The campaign comparison in the presentation also records PDT at 100% coverage, compared with 50% for the advanced NDT example and 80–90% for invasive inspection.
VALIDATION & INDUSTRY RECOGNITION
Independently Assessed. Field Proven.
PDT has been independently assessed by Bureau Veritas for the detection and characterization of active degradation, including corrosion, pitting, and surface and subsurface cracking.
The technology has also been reviewed or recognized by organizations including the Maritime Register of Shipping and the Vietnam Register, supporting its application within industrial and marine integrity programs.
PDT services are delivered within established quality and competency frameworks, supported by internationally recognized ISO standards and ILAC-accredited certification where applicable.
The technology has progressed beyond laboratory validation into operational deployment on pipelines, risers, vessels and tanks in live-service environments.
DELIVERABLES
What You Receive
PDT Final Report
The final PDT report provides a detailed record of detected activity, including defect location, type, size and severity, together with engineering assessment to support continued operation and integrity decisions.
The report can include:
- PDT inspection scheme and sensor layout
- Monitoring results and processed inspection data
- Defect list with location, type, size and severity
- Wall-thickness gauging results
- 3D defect mapping / asset visualization
- MAWP calculation
- Remaining life evaluation
- Conclusions on current technical condition
- Recommendations for continued operation
VECTOR INTEGRITY FOLLOW-UP
From Screening to Integrity Decisions
Following the PDT inspection, Vector Integrity can provide further engineering evaluation and integrity management support, including:
- Targeted conventional and advanced NDT for verification
- Anomaly / defect report creation and management
- Engineering review of PDT and NDT findings
- API 579 Fitness-for-Service (FFS) and remaining life assessments
- Defect prioritization and risk ranking
- Repair, monitoring and reinspection recommendations
- Integration into the client’s integrity management and inspection program
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