Overview - ISO 5577:2025 (Ultrasonic testing vocabulary)
ISO 5577:2025 is the third edition of the international vocabulary for ultrasonic non‑destructive testing (NDT). It defines the standardized terms and definitions used across ultrasonic testing to provide a common basis for standards, inspection procedures, instrumentation, training and reporting. The document covers fundamental concepts such as frequencies, waves and pulses, sound propagation, transducers and probes, test equipment, testing techniques, coupling, reflectors, signals and evaluation of indications. It explicitly does not cover array‑specific terminology (see Related standards).
Key topics and technical scope
The standard organizes vocabulary into clear topic groups that reflect practical ultrasonic NDT workflows:
- Frequencies, waves and pulses - frequency types (nominal, test, peak), bandwidth, pulse shape, pulse rise time, pulse energy and classifications (broad/medium/narrow‑band).
- Wave types - longitudinal (compression), transverse (shear), Rayleigh (surface), creeping and Lamb waves (replaces earlier “plate wave” term).
- Sound generation and reception - transducer types (piezoelectric, piezo composite, EMAT), focusing transducers and probe nomenclature.
- Sound propagation and beam characteristics - sound field, sound beam, beam axis, beam profile, beam boundary, near‑field/far‑field descriptions.
- Test equipment and probes - instrument, probe, combined equipment, reference and test blocks, instrument settings.
- Testing techniques and evaluation - coupling media, reflector and defect terminology, signal/indication presentation (A‑scan, etc.), time‑of‑flight, echo amplitude and evaluation criteria.
- Additions in 2025 include terms such as pulse overshoot, main lobe, side lobe, diffraction, contact surface, echo amplitude, signal amplitude and full screen height.
The standard contains no normative references and is intended for universal use in standardization and general practice.
Practical applications
ISO 5577:2025 is essential for consistent communication and documentation where ultrasonic testing is used:
- Harmonizing terminology in technical specifications, inspection procedures and reports
- Training and certification curricula for NDT personnel
- Equipment specifications, calibration, software interfaces and data formats
- Supporting development and interpretation of other NDT standards and industry guidelines
- Quality assurance, procurement and cross‑border projects where consistent definitions reduce ambiguity
Who uses this standard
- NDT technicians and inspectors
- Inspection and quality engineers
- Standards committees and technical writers
- Probe and instrument manufacturers
- Training and certification bodies
- NDT software developers and data analysts
Related standards
- ISO 23243 - terms used in ultrasonic testing with arrays (array‑specific vocabulary not covered in ISO 5577:2025)
- Documents and guidance produced by ISO/TC 135 (Non‑destructive testing)
Keywords: ISO 5577:2025, ultrasonic testing, non‑destructive testing, NDT vocabulary, transducer, probe, pulse, frequency, Lamb wave, sound beam, ultrasonic NDT terminology.
