Overview
ISO 2400:2012 defines the specification for calibration block No. 1 used in ultrasonic non‑destructive testing (NDT). It specifies the block’s material, dimensions, manufacture, inspection and marking requirements so that ultrasonic test equipment used in manual testing can be reliably calibrated. The standard replaces ISO 2400:1972 and adds clauses on manufacture, sound velocities, marking, modifications and velocity determination.
Key topics and technical requirements
- Material: Block shall be manufactured from steel grade S355J0 (or equivalent) per EN 10025‑2.
- Pre‑machined dimensions: Rough‑machined to 320 mm × 120 mm × 30 mm before heat treatment; final dimensions and detailed geometry shown in the standard’s figures and tables.
- Heat treatment: Austenitizing at 920 °C for 30 min, rapid quench in water, tempering at 650 °C for 3 h, then cooling in still air.
- Surface finish: All external surfaces machined to Ra ≤ 0.8 µm.
- Internal quality check: Ultrasonic examination after heat treatment using a longitudinal probe of ≥ 10 MHz and transducer diameter 10–15 mm; no echoes above grain scatter noise level.
- Wave velocities: Determined per Annex A with maximum permissible error ±0.2%. Target mean values:
- Longitudinal velocity (vl): 5 920 m/s ± 30 m/s
- Transverse velocity (vt): 3 255 m/s ± 15 m/s
- Velocity measurement: Annex A describes time‑of‑flight measurements, probe frequencies (longitudinal ≥5 MHz; transverse 4–5 MHz), polarization checks and required temperature range (17–23 °C).
- Marking and documentation: Blocks must be permanently marked with ISO 2400 and the manufacturer’s serial number/trademark. Manufacturer must issue a declaration of conformity including mean measured vl and vt.
- Allowed modifications: Optionally add two zero‑point slots or a circular reflector for angle‑beam calibration; thicker blocks permitted. Existing blocks may be acceptable if meeting velocity and dimensional requirements.
Applications and users
ISO 2400 is used for ultrasonic calibration of manual inspection equipment in sectors requiring reliable NDT-such as oil & gas, pressure vessels, shipbuilding, and structural steel inspection. Primary users:
- NDT technicians and inspectors
- Calibration laboratories and QA/QC teams
- Manufacturers of ultrasonic calibration blocks and probes
- Standards and compliance officers
Keywords: ISO 2400, ultrasonic testing, calibration block No. 1, NDT calibration, longitudinal wave velocity, transverse wave velocity, S355J0.
Related standards
- ISO 5577 - Ultrasonic inspection vocabulary
- EN 1330‑4 - Terminology for ultrasonic testing
- EN 10025‑2 - Technical delivery conditions for S355J0 structural steel