ULTRASONIC TEST (UT)

Ultrasonic Inspection (UT) is a highly reliable non-destructive testing method used to assess the internal quality of welded joints. By transmitting high-frequency sound waves into the material, it becomes possible to detect internal imperfections without causing any damage to the structure. This makes ultrasonic testing an essential tool for ensuring the integrity and safety of critical welds.

In the marine industry, where structural strength and reliability are of utmost importance, weld quality plays a decisive role in overall vessel safety. Ultrasonic inspection allows hidden defects such as cracks, lack of fusion, porosity, and slag inclusions to be identified at an early stage. Detecting these imperfections before they develop into serious failures helps prevent costly repairs and operational risks.

In the marine industry, where structural strength, fatigue resistance, and long-term reliability are of utmost importance, weld quality plays a decisive role in overall vessel safety. Welded joints are continuously exposed to cyclic loading, dynamic stresses, vibration, and harsh environmental conditions such as corrosion and temperature variations. For this reason, even minor weld imperfections can develop into critical defects over time if not properly detected and evaluated.

Ultrasonic weld inspection is widely applied to critical areas such as hull structures, longitudinal and transverse members, deck connections, tank boundaries, and other load-bearing components. It is particularly effective in identifying internal discontinuities that cannot be detected by visual inspection methods.

In shipbuilding, repair, and conversion projects, ultrasonic testing is used both during fabrication and as part of in-service inspections. It ensures that welding activities meet required quality standards and that any defects are identified before the structure is subjected to operational loads.

Furthermore, ultrasonic inspection plays a key role in supporting classification society surveys by providing reliable and traceable data on weld integrity. This contributes directly to maintaining compliance with class rules and enhances the overall safety and service life of the vessel.

The inspection process is carried out using calibrated ultrasonic flaw detectors in combination with angle beam probes, typically ranging between 45°, 60°, and 70°, depending on the weld geometry and inspection requirements. Sound waves introduced into the material are reflected at interfaces where acoustic impedance changes occur, allowing discontinuities to be accurately located and sized. Evaluation of indications is performed based on amplitude, sound path distance, and signal characteristics, supported by A-scan interpretation.

All inspections are conducted in accordance with applicable international standards such as ISO 17640, ISO 23279, and relevant classification society requirements including ABS, DNV, BV, and LR rules. Calibration and sensitivity settings are verified using reference blocks (e.g., IIW or V1 blocks), ensuring traceability and measurement accuracy throughout the inspection process.

Depending on the project requirements, welds are assessed against specified acceptance criteria, and all relevant indications are recorded and evaluated by certified NDT personnel. Particular attention is given to critical zones such as weld root, fusion faces, and heat-affected zones (HAZ), where defects are most likely to occur.

Thanks to its precision and efficiency, ultrasonic weld inspection is widely preferred as a practical and dependable alternative to radiographic testing, especially for thicker sections and situations where radiation-based methods are not feasible. It enables immediate on-site evaluation and minimizes operational delays while maintaining a high level of inspection reliability.

All inspections are documented through detailed and structured reporting, including scan plans, calibration records, indication mapping, and evaluation results. Reports can be submitted in full compliance with classification society formats and project specifications, supporting survey processes and certification requirements.