Overview
EN ISO 16827:2025 - Non-destructive testing: Ultrasonic testing - Characterization and sizing of discontinuities defines principles and techniques for characterizing and sizing previously detected discontinuities so they can be evaluated against applicable acceptance criteria. Endorsed by CEN, this 2025 revision updates the 2014 edition and clarifies use with phased array techniques (additional verification steps may be needed). The standard applies in general terms to the materials and applications covered by ISO 16810.
Key topics and requirements
- Scope and normative references: Aligns with ISO 5577 (vocabulary), ISO 16810 (general UT principles) and ISO 16811 (sensitivity and range setting).
- Characterization principles: Defines the features required for evaluation (location, orientation, shape, signal amplitude) and surface condition requirements for reliable sizing.
- Pulse-echo techniques: Procedures for locating discontinuities, determining orientation, assessing multiple indications, classifying shape (simple and detailed), and measuring maximum echo height.
- Sizing techniques:
- Maximum echo height methods
- Probe movement sizing (including focusing probes)
- Selection criteria for appropriate sizing methods
- Use of mathematical algorithms and iterative sizing approaches (informative annexes)
- Special sizing techniques (examples provided)
- Through-transmission technique: Location, evaluation of multiple discontinuities, amplitude reduction assessment, and sizing considerations.
- Annexes: Normative and informative annexes cover analysis of multiple indications, classification of shape, detailed sizing procedures, algorithm guidance and worked examples.
Practical applications and users
EN ISO 16827:2025 is intended for professionals who need to reliably characterize and size ultrasonic discontinuities to determine conformity with acceptance criteria. Typical users include:
- NDT (non-destructive testing) technicians and ultrasonic testing specialists
- Inspection engineers and quality managers
- Asset owners, fabricators and maintenance teams who rely on ultrasonic evaluation for fitness-for-service decisions
- Certification bodies and procedure writers developing UT inspection methods
Note: The standard supports application of phased array ultrasonic testing (PAUT), but requires additional verification and steps when used with phased array systems.
Related standards
- ISO 16810 - Ultrasonic testing - General principles
- ISO 16811 - Sensitivity and range setting
- ISO 16823 - Through-transmission technique
- ISO 16826 - Testing for discontinuities perpendicular to the surface
- ISO 16828 - Time-of-flight diffraction (TOFD) technique
- ISO 5577 - UT vocabulary
Keywords: EN ISO 16827:2025, ultrasonic testing, NDT, characterization and sizing of discontinuities, pulse-echo, through-transmission, phased array, sizing techniques, acceptance criteria.
