ISO 17640:2018

Overview

ISO 17640:2018 - "Non-destructive testing of welds - Ultrasonic testing - Techniques, testing levels, and assessment" defines standard manual ultrasonic testing (UT) methods for fusion-welded joints in metallic materials. It is intended primarily for full‑penetration ferritic welds of thickness ≥ 8 mm and object temperatures between 0 °C and 60 °C. Where material‑dependent ultrasonic values are given, the standard references sound velocities of (5 920 ± 50) m/s (longitudinal) and (3 255 ± 30) m/s (transverse).

ISO 17640:2018 standardizes testing techniques, probe parameters, sensitivity/range setting, evaluation criteria and reporting - enabling consistent weld inspection and objective assessment of discontinuities for acceptance.

Key topics and technical requirements

• Scope and applicability: Manual ultrasonic testing of low‑attenuation metallic welds (ferritic), thickness ≥ 8 mm; special applications covered by testing level D.
• Testing levels: Four levels (A, B, C, D) corresponding to different probabilities of detection. Guidance for selecting A–C is in Annex A; Level D is for special applications and used only when specified.
• Evaluation methods:
  • Based primarily on discontinuity length and echo amplitude, or
  • Based on characterization and sizing using probe movement techniques.
• Probe and equipment parameters: Test frequency, angles of incidence, transducer size, adaptation for curved surfaces, and coupling media are specified to ensure repeatable results.
• Sensitivity & range setting: Procedures for reference setting, transfer correction and signal‑to‑noise ratio control are included.
• Testing techniques & scan paths: Manual scan paths, testing for discontinuities perpendicular to the surface, and rules for locating and sizing indications.
• Personnel & competence: Operators must be qualified per ISO 9712 (or equivalent); familiarity with welded joint types is required.
• Documentation: Requirements for pre‑test information, written test procedures (when required), and test reporting.

Practical applications - who uses ISO 17640:2018

• NDT technicians and supervisors performing ultrasonic weld inspection in fabrication, pressure vessels, pipeline, structural and heavy engineering industries.
• Quality managers and inspectors defining acceptance levels and inspection scopes.
• Engineers specifying contract requirements for weld testing at manufacture or in‑service inspection where consistent probability of detection and repeatable assessment are required.
• Training and certification bodies aligning procedures with recognized international practice.

Related standards

• ISO 11666 - Acceptance levels for ultrasonic testing of welds
• ISO 23279 - Characterization of discontinuities in welds
• ISO 16810 / ISO 16811 / ISO 16826 - UT general principles, sensitivity/range setting, and examination techniques
• ISO 9712 - Qualification and certification of NDT personnel

Keywords: ISO 17640:2018, ultrasonic testing, non‑destructive testing of welds, weld inspection, testing levels, ferritic steel, NDT personnel qualification, sensitivity setting, discontinuity evaluation.