Advanced NDT — PAUT & TOFD

Multi-element ultrasonic examination producing sectorial and encoded imaging of the weld volume, with recordable data for review.

Working Principle

An array of elements is pulsed with controlled time delays to steer and focus the beam electronically, allowing a range of angles to be applied from a single probe position.

Typical Indications

• Lack of fusion
• Lack of penetration
• Cracks
• Slag and porosity
• Root defects

Applications

• Pipeline and process piping girth welds
• Pressure vessel and nozzle welds
• Structural and heavy-wall welds
• Corrosion mapping where applicable

Equipment

Portable phased array instruments with encoders, wedges and calibration blocks appropriate to the scope.

Reporting

Encoded data files with sectorial/S-scan and C-scan imaging, indication sizing and evaluation against acceptance criteria.

Application as an alternative to radiography is subject to client approval and the governing code or specification.

Ultrasonic technique using diffracted energy from discontinuity tips, providing accurate through-wall height sizing across the weld volume.

Working Principle

A transmitter and receiver pair straddle the weld. Diffracted signals from the extremities of a discontinuity are timed, allowing through-wall position and height to be determined.

Typical Indications

• Embedded planar flaws
• Crack height growth
• Lack of fusion
• Through-wall sizing of known indications

Applications

• Heavy-wall vessel and piping welds
• In-service crack growth monitoring
• Weld overlay and clad component examination where applicable

Equipment

TOFD-capable instrumentation with encoded scanners and matched probe pairs.

Reporting

Encoded B-scan/D-scan imaging with through-wall sizing and evaluation records.

TOFD is frequently combined with PAUT to compensate for near-surface and lateral wave limitations.