Advanced NDT

Automated Ultrasonic Testing (AUT) of girth welds

Automated ultrasonic testing replaces film radiography on pipeline and piping girth welds where production speed, radiation-free working and an encoded, auditable record matter. A motorised scanner carries phased-array and TOFD probes around the weld on a band, records every channel against position, and the result is judged against acceptance criteria that were set before the first weld was shot.

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How AUT works on a girth weld

The weld cross-section is divided into zones that follow the bevel geometry: root, hot pass, fill passes and cap. Each zone is covered by a dedicated phased-array focal law (zonal discrimination), so an indication is reported by zone, height and length rather than as a single amplitude. TOFD channels run alongside to size through-wall extent and catch volumetric flaws, and mapping channels record lack of fusion that runs along the bevel face.

Before production starts, the system is set up on a calibration block machined from the project pipe with reflectors at each zone. The setup is then qualified, often by comparing AUT results with macro sections of deliberately flawed welds, so the sizing error the acceptance criteria rely on is known rather than assumed.

Where AUT earns its place

  • Cross-country and offshore pipeline spreads, where AUT keeps pace with mechanised welding and gives feedback to the weld crew within minutes.
  • Plant piping where radiography would clear the area and stop other trades working nearby.
  • Thick-wall welds where film radiography struggles with planar flaws such as lack of sidewall fusion.
  • Projects that use engineering critical assessment (ECA) acceptance criteria, which need flaw height as well as length.

What to plan for

  • Scanner access: a clear band either side of the weld and a straight run for the guide band.
  • Bevel design and pipe dimensions are fixed before the setup is built; a change means a new calibration block.
  • Procedure qualification takes time at the start of a project and must be scheduled ahead of the first production welds.

How we deliver it

Automated UT (AUT) of girth welds is carried out to a written procedure approved for the scope, naming the code and edition, the equipment and calibration, the coverage and the acceptance criteria. The procedure and each technician’s certification are submitted for the client’s review before mobilisation.

Work is planned and supervised by ASNT Level III personnel; our founder holds ASNT NDT Level III in UT, RT, MT, PT and VT. Reports state the coverage achieved and any limitations, so the engineer reading them knows what was examined and what was not, and any reportable finding is raised the same day.

Governing codes and standards

  • ASTM E1961 (mechanized UT of girth welds using zonal discrimination)
  • API 1104 (welding of pipelines; AUT acceptance criteria)
  • DNV-ST-F101 (submarine pipeline systems; AUT annex)
  • ASME B31.3 para. 344.6 and ASME Code Cases for UT in lieu of RT
  • ASME Section V, Article 4 (ultrasonic examination of welds)

What you receive

  • Qualified AUT procedure and calibration block drawing
  • Encoded scan file for every weld, retained for audit
  • Weld-by-weld accept/reject report with zone, height and length of each indication
  • Daily repair-rate feedback to the welding team

Industries served

  • Oil and gas pipelines
  • Offshore and subsea
  • Refining and petrochemical piping
  • Power generation

Frequently asked questions

Can AUT replace radiography on a pipeline?

Yes, where the governing code allows it and the AUT procedure is qualified. API 1104 and DNV-ST-F101 both provide for automated ultrasonic examination of girth welds, and ASME B31.3 allows UT in place of RT under defined conditions.

What is zonal discrimination?

It is a setup in which the weld is divided into depth zones that follow the bevel, each covered by its own focal law. Indications are reported zone by zone, which supports height-based acceptance criteria.

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Send the equipment list or drawings, the inspection you need and your timing. Quotes are prepared for each scope and region.

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Tell us the asset, the method, where it is, the governing code, your dates, the size of the job and the report you need. We reply with questions or a quote. Affordable, accessible, fully customizable — no published pricing.












Or email the same details to info@atlantisndt.com. Mobilisation: North America; confirm your location in your RFQ.

Speak to an ASNT NDT Level III

Atlantis NDT provides ASNT Level III consulting, NDT training to ASNT SNT-TC-1A, inspection management software and independent report validation. Request a free consultation and we will return a tailored quote — affordable, accessible and fully customizable to your programme.