ISO 23279:2017

Overview

ISO 23279:2017 - “Non-destructive testing of welds - Ultrasonic testing - Characterization of discontinuities in welds” defines a standardized procedure to characterize ultrasonic indications in welds. The standard classifies indications as originating from planar or non‑planar embedded discontinuities and is also applicable to discontinuities that become surface‑breaking after removal of weld reinforcement. It provides a flowchart procedure (Annex A) and supporting guidance (Annex B and C) for consistent ultrasonic testing (UT) interpretation.

Key topics and requirements

• Classification parameters: considers welding technique, geometric position, maximum echo amplitude, directional reflectivity, echo static pattern (A‑scan) and echo dynamic pattern (envelope).
• Five‑stage flowchart procedure: standardized stages to filter and classify indications:
  • Stage 1: exclude very low amplitude echoes (evaluation level per ISO 11666).
  • Stage 2: designate high‑amplitude echoes (reference level +6 dB) as planar.
  • Stage 3: directional reflectivity (applicable when indication length exceeds specified limits); requires probe angle differences ≥ 10° and amplitude imbalance thresholds (9 dB for transverse waves, 15 dB when comparing transverse vs longitudinal).
  • Stage 4: static A‑scan pattern comparison against a 3 mm side‑drilled hole reference to identify non‑planar reflectors.
  • Stage 5: transverse echo dynamic pattern analysis (envelope) to distinguish cracks, inclusions or clusters.
• Practical probe guidance: recommendation to use the same probes for detection and classification; when mixing probe types select frequencies that yield similar wavelengths (example: 4 MHz longitudinal ≈ 2 MHz transverse for steel).
• Complementary testing: where ambiguous, additional UT angles, probe scans, parallel dynamic scans or other NDT methods (e.g., radiography) are advised.

Applications and users

ISO 23279:2017 is intended for NDT technicians, welding inspectors, QA/QC engineers and integrity specialists who perform ultrasonic testing of welded joints. It is used to:

• Provide consistent interpretation of weld indications for acceptance, repair, or further examination.
• Support inspection procedures in sectors requiring weld integrity such as pressure equipment, pipelines, power generation, petrochemical and shipbuilding.
• Standardize reporting and decision criteria for indications like lack of fusion, inclusions and cracks.

Related standards

• ISO 11666 - Ultrasonic testing - Acceptance levels (evaluation level reference).
• ISO 17640 - Ultrasonic testing - Techniques, testing levels and assessment (testing procedures and dynamic pattern scanning).

Keywords: ISO 23279:2017, ultrasonic testing, NDT of welds, characterization of discontinuities, planar/non‑planar, A‑scan, directional reflectivity, echo dynamic pattern.