Overview
EN ISO 5577:2025 - Non-destructive testing - Ultrasonic testing - Vocabulary is the ISO/CEN vocabulary standard that defines the terms used in ultrasonic non‑destructive testing (NDT). Published as the third edition in 2025 and adopted by CEN as EN ISO 5577:2025, it supersedes the 2017 edition and provides a common, authoritative terminology for standards, technical documentation and general use across Europe and internationally. The document explicitly excludes array‑specific terminology (see Related Standards).
Key topics
This vocabulary standard organizes and defines terms across the full scope of ultrasonic NDT. Major topic areas include:
- Frequencies, waves and pulses - frequency, nominal/test/peak frequency, bandwidth, centre frequency, amplitude spectrum, and the general definition that ultrasonic waves are above the audible range (generally > 20 kHz).
- Waves and pulse characteristics - wavelength, wavefront, pulse, pulse amplitude, pulse rise time, pulse duration, pulse shape, pulse envelope and pulse energy.
- Sound generation and propagation - definitions related to sound production, reception and loss of sound pressure; ultrasonic wave interaction at interfaces.
- Test equipment and probes - instrument, probe terminology, combined equipment, reference and test blocks, delay paths.
- Testing techniques and test object concepts - probe coupling, types of ultrasonic waves (including the replacement of “plate wave” by Lamb wave), reflectors, indications, presentations (A‑scan etc.), time‑of‑flight (TOF) and evaluation of indications.
- New and revised terms (2025 edition) - additions such as pulse overshoot, main lobe, main beam, side lobe, diffraction, contact surface, echo amplitude, signal amplitude, and full screen height; several definitions and figures updated.
Practical applications and users
EN ISO 5577:2025 is a foundational reference for anyone working with ultrasonic NDT terminology:
- NDT engineers and inspectors who write procedures, record results and evaluate ultrasonic inspections.
- Standards authors and technical committees aligning test methods and normative documents.
- Manufacturers of ultrasonic equipment and probes ensuring consistent product documentation and specifications.
- Training organizations and certification bodies developing syllabi and examination material.
- Quality managers and asset owners who require clear, unambiguous reporting language for inspections.
Using a harmonized vocabulary reduces ambiguity in procedures, reports and technical specifications and supports regulatory compliance and international trade.
Related standards
- ISO 23243 - terms specific to ultrasonic testing with arrays (array‑specific vocabulary is excluded from ISO 5577).
