ISO 16809-2025 PDF

Full title and description

ISO 16809-2025 — Non‑destructive testing — Ultrasonic thickness determination. This international standard specifies the principles for determining the thickness of metallic and non‑metallic materials using ultrasonic contact or immersion techniques, based exclusively on measurement of the time‑of‑flight of ultrasonic pulses.

Abstract

The standard defines the fundamental measurement principles and measurement conditions for ultrasonic thickness determination using pulse time‑of‑flight methods (contact and immersion). It provides guidance on required instrument settings, reference velocity considerations, calibration with reference blocks and on the intended range of materials and applications for which time‑of‑flight thickness measurements are appropriate. ISO 16809:2025 replaces the 2017 edition.

General information

• Status: Published (International Standard).
• Publication date: 13 June 2025 (June 2025).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 19.100 — Non‑destructive testing.
• Edition / version: Edition 3 (2025).
• Number of pages: 34 pages (published ISO English edition; page count may vary slightly by language/format).

Scope

ISO 16809:2025 specifies principles for determination of the thickness of metallic and non‑metallic materials using either the contact technique or the immersion technique and is based solely on measurement of the time of flight of ultrasonic pulses. It is intended for applications where single‑port time‑of‑flight (pulse‑echo) measurements provide reliable thickness values and does not replace application‑specific ultrasonic inspection standards that define acceptance criteria or alternative ultrasonic techniques (for example phased‑array inspection procedures or TOFD sizing) used for flaw detection and evaluation.

Key topics and requirements

• Principles of time‑of‑flight ultrasonic thickness determination (pulse‑echo) using contact and immersion transducers.
• Calibration and use of reference blocks and determination/verification of ultrasonic velocity for the material under test.
• Instrumentation and probe selection considerations (frequency, bandwidth, couplant and probe contact/immersion requirements).
• Measurement procedure basics: signal acquisition, identification of backwall echoes, gating and timing methods.
• Factors affecting measurement accuracy and repeatability (surface condition, temperature, material anisotropy and attenuation) and recommendations to reduce uncertainty.
• Limitations of the time‑of‑flight method and relationship to other ultrasonic NDT methods and standards.

Typical use and users

Used by NDT technicians, inspection engineers, quality control personnel, laboratories and asset integrity teams across industries such as oil & gas (pipelines, pressure equipment), power generation, shipbuilding, petrochemical, aerospace, and manufacturing. Typical applications include corrosion monitoring, remaining‑life assessment, verification of plate and component thickness and routine condition surveys. Users rely on this standard for establishing consistent measurement practice and for training/qualification reference.

Related standards

ISO 16809:2025 is part of the ISO/TC 135 suite of ultrasonic and NDT standards and is referenced alongside other documents such as ISO 16810 (general principles of ultrasonic testing), ISO 16827 (characterization and sizing of discontinuities), ISO 22825 (ultrasonic testing of welds in austenitic steels), ISO 17640 (ultrasonic testing of welds — techniques and assessment) and regional implementations such as EN 14127. Users commonly consult these related standards when developing procedures that combine thickness measurement with other ultrasonic inspection requirements.

Keywords

ultrasonic thickness, non‑destructive testing, ultrasonic testing (UT), time‑of‑flight, pulse‑echo, contact technique, immersion technique, calibration, reference block, measurement uncertainty, NDT.

FAQ

Q: What is this standard?

A: ISO 16809:2025 is an international standard that defines principles and basic procedures for determining material thickness by ultrasonic time‑of‑flight methods using contact or immersion techniques.

Q: What does it cover?

A: It covers the measurement principles, calibration/velocity determination, instrumentation considerations and factors affecting accuracy for ultrasonic thickness determination based on pulse time‑of‑flight. It focuses on thickness measurement, not on detailed flaw acceptance criteria.

Q: Who typically uses it?

A: NDT technicians, inspection and integrity engineers, test laboratories, manufacturers and certification bodies that perform or specify ultrasonic thickness measurements for corrosion monitoring, quality control and regulatory inspections.

Q: Is it current or superseded?

A: Current — ISO 16809:2025 was published in June 2025 and supersedes ISO 16809:2017.

Q: Is it part of a series?

A: Yes — it is part of the ISO/TC 135 family of ultrasonic and NDT standards (the ISO 16800 series and related ISO 17000‑series documents). Practitioners commonly use it together with complementary standards such as ISO 16810, ISO 16827, ISO 22825 and ISO 17640.

Q: What are the key keywords?

A: Ultrasonic thickness, non‑destructive testing, time‑of‑flight, pulse‑echo, contact technique, immersion technique, calibration, NDT.