PAUT Inspection — Phased Array Ultrasonic Testing

PAUT inspection — phased array ultrasonic testing (PAUT) for welds, small bore tubing, turbine components and complex geometry across the UAE and GCC. Encoded scanning, scan plans and qualification blocks, carried out by ISO 9712 qualified technicians under ISO 17020 accreditation. Last reviewed: August 2026.

Phased array ultrasonics uses a multi-element probe to steer, focus and sweep the beam electronically, producing imaged data across the volume of a weld rather than a series of single readings. Encoded scanning records probe position with the signal, so the inspection is reproducible, reviewable after the fact, and defensible when a result is challenged.

Scan planning

Coverage is not achieved by pointing a probe at a weld. A scan plan is developed first, establishing beam angles, focal laws, probe positions and index offsets that demonstrably cover the required volume for the geometry in question. Operators develop scan plans and produce technical justification summaries accounting for the chosen parameters, and write the procedures and work instructions that make an inspection traceable and repeatable rather than operator-dependent.

Applications

• High pressure and high temperature pipingFull weld volume coverage at 1 mm scanning intervals on circumferential and seam welds between 20 mm and 75 mm wall thickness, using encoded scanning at power station sites.
• Small bore tubingInspection of tubes from 50 mm internal diameter down to 6 mm, where conventional probe access is not possible.
• Complex geometry branch weldsEncoded scanning of variable weld profiles for accurate sizing of internal defects, where a fixed-angle technique cannot achieve coverage.
• Turbine and generator componentsExamination focused on areas of high stress concentration — fir tree serrations at turbine blade roots, and geometry changes along exciter cooling fans.
• Foundation and structural boltsDetection and monitoring of corrosion wastage along wind tower foundation bolts, reliably to five times bolt diameter along the length.
• Storage tanksCorrosion inspection and wall loss mapping across tank shells and floors.
• Shafts and axlesIn-situ detection of transverse cracking in rotating and rail components for the public transport sector.
• Pipelines and pressure equipmentPipeline girth welds, pressure vessels, bifurcation lines and valve bodies, with detailed analysis reporting.
• Aerospace compositesFlat and shaped carbon fibre reinforced polymer (CFRP) components examined for delamination, porosity and disbonds.
• Qualification blocksPurpose-fabricated calibration and qualification blocks in the material and geometry being inspected — aluminium, stainless steel, low carbon steel and Inconel — to demonstrate probability of detection.

Technical development

ITMAD's PAUT personnel have worked in research and development programmes examining the technique for detection of critical discontinuities in power industry components, published conference papers on compliance with standards and the use of qualification blocks to improve probability of detection, and investigated the effects of temperature, surface condition and couplant selection on PAUT signal response beyond the ranges prescribed in the standards. That work informs how techniques are selected and justified on live inspections.

Standards applied

• ISO 13588 — ultrasonic testing of welds using automated phased array technology
• ISO 19285 — PAUT acceptance levels for welds
• ASME Boiler and Pressure Vessel Code, Section V, Article 4, with acceptance to the relevant construction code section
• ASTM E2700 — contact ultrasonic testing of welds using phased arrays
• API 1104 for pipeline girth welds
• AWS D1.1 for structural steel welding
• Client and project specifications, and manufacturer requirements where these govern

PAUT in place of radiography

PAUT is increasingly accepted where radiography was previously specified. It requires no radiation source, so there is no exclusion zone and no shutdown of surrounding work; it produces digital data immediately rather than film requiring processing; and it measures through-wall flaw height, which radiography cannot. Substitution requires the governing code to permit it and the technique to be qualified, and we will advise where the code does not allow it.

Limitations

Coverage can be constrained by geometry, surface condition and access — a scan plan will show where full volumetric coverage is not achievable, and we will report that rather than imply coverage that was not obtained. Highly attenuative or coarse-grained materials reduce penetration. Surface preparation affects coupling and therefore sensitivity. PAUT is complementary to the other NDT methods rather than a replacement for all of them, and where a different technique answers the question better we will say so.

Personnel and accreditation

PAUT is carried out by technicians qualified to ISO 9712 and ASNT SNT-TC-1A Level II with specific phased array qualification, under Level III oversight of procedure approval and technique validation. ITMAD is accredited to ISO/IEC 17020 as an inspection body, is an ADNOC approved inspection contractor, and is listed on the Abu Dhabi City Municipality register of Approved Third Party Inspection Bodies. Certificates are issued in the format required by the governing authority, including Dubai Municipality and the Dubai free zone authorities.

Coverage

PAUT inspection is carried out at power stations, refineries, fabrication yards, pipelines and offshore installations across Dubai, Abu Dhabi, Sharjah and the northern Emirates, and on mobilisation across the wider GCC. Encoded scanning suits shutdown and turnaround work where the inspection window is fixed and results are needed for a return-to-service decision.

What you receive

• The scan plan and technical justification for the parameters applied
• Encoded scan data retained and available for independent review
• Indications reported with location, length and through-wall height
• Sectorial, C-scan and B-scan imagery supporting each finding
• Assessment against the acceptance criteria of the governing code
• Calibration and qualification block records
• Technician qualification level and certification reference
• Analysis supporting a repair or continued operation decision