ISO 16809:2025

Overview

ISO 16809:2025 - Non-destructive testing - Ultrasonic thickness determination specifies the principles for determining the thickness of metallic and non‑metallic materials using ultrasonic time‑of‑flight measurements. The standard covers both the contact technique and the immersion technique, and is focused on thickness determination based solely on the measured travel time of ultrasonic pulses. This is the third edition and includes terminology updates and alignment with related ultrasonic equipment standards.

Key topics and requirements

ISO 16809:2025 defines technical topics and requirements essential for reliable ultrasonic thickness determination, including:

• Modes of determination: measurement based on one‑way, two‑way or multiple pulse traversals and calculation of thickness from sound velocity × time of flight.
• Equipment and components:
  • Ultrasonic instruments (including A‑scan instruments conforming to ISO 22232‑1)
  • Probes and probe selection guidance (see ISO 22232‑2)
  • Couplant and reference blocks
• General requirements: test object preparation, reference blocks, and qualification of test personnel.
• Application guidance: surface condition and preparation, techniques for manufacturing checks and in‑service residual wall thickness determination.
• Instrument setting and verification: methods for setting instruments (numerical displays and A‑scan), and checks of settings.
• Accuracy considerations: influence of operational conditions (surface, temperature, coatings, geometry), equipment parameters (resolution, range), and methods to evaluate accuracy.
• Material influences: effects of inhomogeneity, anisotropy and sound attenuation.
• Test reporting: required general information and how to present test results.
• Informative annexes on corrosion in vessels/piping, instrument settings, parameters influencing accuracy, and technique selection.

Applications and users

ISO 16809:2025 is practical for organizations and professionals involved in ultrasonic thickness measurement:

• NDT technicians and inspectors performing routine thickness checks
• Fabrication quality control and acceptance testing during manufacture
• Maintenance and inspection teams monitoring corrosion and residual wall thickness in piping, pressure vessels, tanks and structural components
• Asset integrity and reliability engineers in oil & gas, petrochemical, power generation, shipbuilding, aerospace and manufacturing
• Certification bodies and laboratories verifying instrument performance and personnel competence

Related standards (if applicable)

• ISO 5577 - Ultrasonic testing vocabulary
• ISO 16831 - Characterization and verification of ultrasonic equipment for thickness determination
• ISO 22232‑1 / ISO 22232‑2 - Characterization and verification of ultrasonic instruments and probes

Keywords: ISO 16809:2025, ultrasonic thickness determination, non‑destructive testing, time of flight, contact technique, immersion technique, thickness measurement, probe selection, instrument settings, corrosion monitoring.