ISO 16823:2025

Overview

ISO 16823:2025 - "Non‑destructive testing - Ultrasonic testing - Through‑transmission technique" defines the principles and practical requirements for ultrasonic through‑transmission testing of flat products (e.g., plates and sheets). The standard covers use of through‑transmission to detect discontinuities and to determine sound attenuation, and it complements general ultrasonic testing principles given in ISO 16810.

Key topics and technical requirements

• Scope and purpose: Detection of discontinuities and determination of attenuation in flat or thin test objects, materials with high attenuation, or cases where direct reflection is unfavourable.
• NDT personnel: Personnel requirements reference ISO 16810 for qualification and responsibilities.
• Test equipment:
  • Instruments must comply with ISO 22232‑1.
  • Probes must meet ISO 22232‑2 and be selected based on material, thickness, geometry and expected discontinuity orientation.
  • Frequency selection (typically 1 MHz to 10 MHz) balances axial resolution and attenuation; probe size and frequency define near‑field length and beam divergence.
  • Considerations include dead zone, damping, and use of focusing probes (improved lateral resolution and SNR).
• Coupling media: Water, paste, oil, grease, etc., must be compatible with the test material, stable during verification and testing, and suitable for the operating temperature; transfer corrections are applied if conditions change (see ISO 16811).
• Reference and standard blocks: Use ISO 2400 and ISO 7963 standard blocks for equipment setting and verification. Reference blocks should match acoustic properties and surface condition of the test object where possible; otherwise apply transfer corrections (ISO 16811).
• Testing principles and techniques: Includes basic setup, scanning, sensitivity setting, evaluation of discontinuities, and methods to determine attenuation (comparative using a reference block or using the test object only).

Practical applications

• Inspection of plates, sheets and thin components in metalworking, manufacturing and quality control.
• Testing materials with high sound attenuation (composites, porous metals) where pulse‑echo is ineffective.
• Situations where discontinuity orientation is unfavourable for reflection-based techniques.
• Measurements of sound attenuation for material characterization or process monitoring.

Who uses ISO 16823:2025

• NDT engineers and technicians performing ultrasonic through‑transmission testing.
• Quality assurance and inspection teams in metallurgy, aerospace, automotive, and manufacturing.
• Test equipment manufacturers and calibration laboratories developing probes, instruments, and reference blocks.

Related standards

• ISO 16810 (general ultrasonic testing principles)
• ISO 16811 (sensitivity and range setting; transfer corrections)
• ISO 16826, ISO 16827, ISO 16828 (complementary UT techniques)
• ISO 22232‑1 / ISO 22232‑2 (equipment and probe characterization)
• ISO 2400, ISO 7963 (standard/calibration blocks)

Keywords: ISO 16823:2025, ultrasonic testing, through‑transmission, non‑destructive testing, NDT, plates and sheets, sound attenuation, probes, coupling media, reference blocks.