# Phased array ultrasonic testing (PAUT)

> Phased array ultrasonic testing (PAUT) uses a probe with many small elements fired with programmed time delays to steer, sweep and focus the ultrasonic beam and build an image of the inspected volume.

- Source: https://amps.global/glossary/phased-array-ultrasonic-testing/
- Type: Glossary
- Published: 2026-09-05
- Tags: NDT, ultrasonic testing, advanced NDT

## Key facts

- Probes typically have 16 to 128 elements; focal laws define the angles and focus for each firing
- Sectorial (S-scan) and linear (E-scan) views are recorded with an encoder for a permanent, auditable record
- ASME BPVC Section V Article 4 and ISO 13588 cover PAUT of welds; it is accepted as an alternative to radiography under specified conditions
- Technicians usually hold a conventional UT certificate plus a PAUT endorsement

Also known as: PAUT, phased array UT, PA.

## How it works

Instead of one crystal at a fixed angle, a phased array probe contains a row of elements. Firing them with small time delays (a focal law) shapes a wavefront that can be steered through a range of angles and focused at a chosen depth. Sweeping the angles produces a sectorial scan; stepping along the elements produces a linear scan. Combined with an encoder, the result is an image of the weld volume that can be stored, reviewed and re-analysed.

## Why inspection companies use it

PAUT covers a weld in one pass where conventional UT needs several probes and passes, gives a permanent record, and avoids the radiation, exclusion zones and shift-work constraints of radiography. It is common on pipeline girth welds, pressure vessels, storage tank shells and heavy fabrication, often paired with TOFD.

## PAUT in AMPS

In AMPS, reports are produced from your own Microsoft Word templates through the template engine: job data such as the client, purchase order number, equipment serial numbers, location and dates is filled in automatically, an AI assistant can tidy the wording, the report can be signed in AMPS, and the finished Word file is saved in the job's report folder in your OneDrive, SharePoint or Google Drive. Scan files stay in the job's document folder next to the report, and equipment calibration certificates for the PAUT instrument and probes are flagged before they expire.

## Related pages

- [Ultrasonic testing (UT)](https://amps.global/glossary/ultrasonic-testing/)
- [Time-of-flight diffraction (TOFD)](https://amps.global/glossary/time-of-flight-diffraction/)
- [Radiographic testing (RT)](https://amps.global/glossary/radiographic-testing/)
- [NDT reporting software](https://amps.global/solutions/ndt-reporting-software/)

## Sources

- [Phased array ultrasonics on Wikipedia](https://en.wikipedia.org/wiki/Phased_array_ultrasonics)
- [ASME Boiler and Pressure Vessel Code](https://www.asme.org/codes-standards/bpvc-standards)
- [BINDT - British Institute of Non-Destructive Testing](https://www.bindt.org/)