Carbon and low-alloy steel welds represent the largest single inspection volume in any industrial NDT programme — and also the application where the capability gap between conventional UT and phased array is most commercially significant. PAUT replaces multi-probe, multi-angle conventional UT setups with a single encoded scan pass, delivering complete weld volume coverage, real-time sectorial imaging, and a permanent encoded data record that supports both code acceptance and engineering fitness-for-service assessment.
Full Volumetric Coverage in a Single Encoded Pass
A PAUT sectorial scan sweeps multiple
refracted angles simultaneously — typically from 40° to 70° shear wave in
defined increments — covering the full weld cross-section in a single scanner
pass. This eliminates the multiple probe positions, index point corrections,
and manual coverage tracking required by conventional multi-angle UT.
Real-Time Sectorial Scan Imaging
The S-scan image produced by PAUT shows the
complete weld cross-section in real time during scanning — enabling the
operator to identify reflector position, through-wall depth, and angular
response on-screen before the scan pass is complete. This image is encoded and
stored as a permanent record of every scan position.
Superior Defect Characterisation
PAUT angular response data — the variation
in signal amplitude across the focal law range — provides characterisation
information that single-angle conventional UT cannot generate. Planar defects
(lack of fusion, cracks) produce a characteristic angular peak. Volumetric
defects (porosity, slag) produce a broader, lower-amplitude response. This
information supports defect classification and sizing that improves the
reliability of accept/reject decisions.
TOFD Integration for Maximum Sizing Accuracy
For welds requiring the highest accuracy in
through-wall defect sizing — particularly for fitness-for-service assessments
under BS 7910, API 579, or equivalent Engineering Critical Assessment standards
— PAUT is deployed with simultaneous TOFD acquisition. TOFD provides direct
time-of-flight sizing accuracy that is independent of the reflector's angular
orientation.
Code-Compliant Procedures for All Major Standards
PAUT weld inspection procedures are
qualified and deployed in accordance with ASME Section V (Article 4 and Code
Cases 2235, 2600), EN ISO 13588, AWS D1.1, DNVGL-ST-F101, API 1104, and
client-specific inspection specifications. Procedure qualification includes
technique demonstration and POD validation where required by the applicable
code.
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Pipeline girth welds — onshore and offshore, all
diameters and wall thicknesses
•
Pressure vessel shell seam and head welds —
longitudinal and circumferential
•
Storage tank shell weld inspection
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Structural steelwork butt and fillet welds — bridges,
platforms, fabricated structures
•
Heat exchanger shell and tubesheet welds
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Piping spool and fabrication weld inspection
•
In-service weld inspection during planned and unplanned
shutdowns
•
Weld repair verification — post-repair acceptance
inspection
•
Fitness-for-service weld assessment — sizing input for
BS 7910 / API 579 ECA
Reports include encoded S-scan and B-scan
images at all weld inspection positions, indication tables with through-wall
position, depth from scanning surface, length, height, and classification, and
accept/reject disposition against the applicable examination code. Coverage
maps confirm that 100% of the nominated inspection volume was scanned at the
qualified probe positions.