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Technician running an encoded ultrasonic scanner around a large-diameter pipeline girth weld

UT Quality/Technology & insights/AUT vs radiography

AUT vs radiography — the right method, weld by weld.

UT Quality runs RT, DR and CR crews as well as automated ultrasonics. Credibility means telling you where radiography still beats ultrasonics — and where AUT/PAUT should carry the mainline. Here is the actual decision.

Where radiography is still the right call.

Work down the questions. Any “yes” points to radiography for that weld; if none apply — which is the usual case on mainline production — automated ultrasonics is the primary method.

Method-selection flow — RT vs AUT/PAUT

Weld inspection method decision flow Starting from a girth weld: if code mandates RT film, if the weld is volumetric-dominant, if geometry blocks the scanner path (radiography or semi-automated PAUT), or if surface prep is impossible, radiography is chosen. Otherwise automated ultrasonics is the primary method. Girth weld to inspect 01 Code or spec mandates RT film? YES RT — we shoot it and can pair it with PAUT NO 02 Volumetric-dominant weld? thin-wall / shop welds — porosity & slag YES RT / DR porosity & slag image beautifully NO 03 Geometry blocks the scanner path? fittings, bends — no clean band path YES RT or semi-auto PAUT encoded PAUT where a band won’t fit NO 04 Surface prep impossible? YES RT may be it or qualify UT for the surface condition NO AUT / PAUT — primary method mainline production, incl. heavy-wall lands here Weld inspection method decision flow Starting from a girth weld: if code mandates RT film, if the weld is volumetric-dominant, if geometry blocks the scanner path (radiography or semi-automated PAUT), or if surface prep is impossible, radiography is chosen. Otherwise automated ultrasonics is the primary method. Girth weld to inspect 01 Code or spec mandates RT film? YES RT — we shoot it and can pair it with PAUT NO 02 Volumetric-dominant weld? thin-wall / shop welds — porosity & slag YES RT / DR porosity & slag image beautifully NO 03 Geometry blocks the scanner path? fittings, bends — no clean band path YES RT or semi-auto PAUT encoded PAUT where a band won’t fit NO 04 Surface prep impossible? YES RT may be it or qualify UT for the surface condition NO AUT / PAUT — primary method mainline production, incl. heavy-wall lands here
UT Quality runs both. A 48-inch, over-one-inch-wall mainline typically hits none of the “yes” branches on production welds — which is exactly why AUT/PAUT is the right primary method, with RT held in reserve for the exceptions.

The strengths, side by side.

AUT / PAUT is strong on

Mainline production rate, planar-flaw detection and through-wall sizing, heavy wall, immediate encoded results, and a defensible digital record — the usual answer on pipeline girth welds.

Radiography is strong on

Code-mandated film, volumetric-dominant thin-wall and shop welds where porosity and slag image well, fittings with no clean scan path (where semi-automated PAUT is the ultrasonic alternative), and cases where a scanner band simply will not couple.

Credibility is the point. The right method is the one the weld calls for — and UT Quality fields crews for both, so the recommendation is never limited by what we can run.

Questions.

When is radiography still the right method for a pipeline girth weld?

Radiography is the right call when code or spec mandates RT film, when the weld is volumetric-dominant (thin-wall or shop welds where porosity and slag image well), when fittings or geometry leave no clean scan-band path (semi-automated PAUT is also an option there), or when surface prep is impossible. When none of these apply, which is the usual case on mainline production, automated ultrasonics is the primary method.

When should automated ultrasonics (AUT/PAUT) be the primary weld-inspection method?

On mainline production welds, including heavy wall, that trigger none of the radiography exceptions. AUT/PAUT is strong on production rate, planar-flaw detection and through-wall sizing, immediate encoded results, and a defensible digital record, which is the usual answer on pipeline girth welds.

Does UT Quality run both radiography and automated ultrasonics?

Yes. UT Quality fields RT, DR and CR crews as well as automated ultrasonics, so the recommended method is never limited by what UT Quality can run. The method chosen is the one the weld calls for.

Related resources.

Automated ultrasonic testing →

How AUT reads a weld, zone by zone.

Heavy-wall weld inspection →

Where ultrasonics pull ahead on thick wall.

Digital vs conventional RT →

Exposure and development time compared.

Not sure which method your weld needs?

Tell us the scope — UT Quality will recommend RT, AUT/PAUT, or both, and field the crew for it.

Request a crew

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