When to Use PAUT vs. Conventional UT: A Guide for Key Industries

Ultrasonic Testing (UT) has long been a cornerstone of nondestructive testing (NDT). As technology has advanced, Phased Array Ultrasonic Testing (PAUT) has expanded the capabilities of conventional UT, offering higher resolution imaging, faster inspections, and improved adaptability. But the question remains: when can you use conventional UT and when is PAUT the better choice?

This guide explores the general differences between the two methods and then focuses on three critical industries—aerospace and aviation, oil & gas, and nuclear power—where the decision between PAUT and conventional UT can have significant implications.

General Guidelines: PAUT vs. Conventional UT

• Conventional UT
• Best for simple geometries and straightforward flaw detection.
• Provides single-point thickness measurements and linear scans.
• Cost-effective and widely available.
• Ideal for routine inspections, thickness checks, and weld evaluations when high-resolution imaging is not required.
• PAUT
• Employs multiple elements and electronic beam steering/focusing for detailed imaging.
• Excels in complex geometries, large areas, and critical components.
• Enables defect characterization and sizing with higher confidence.
• Reduces inspection time while increasing data quality and recordability.

Quick Comparison: Conventional UT vs. PAUT

Aerospace and Aviation

In aerospace, where safety margins are slim and materials are advanced, inspection demands precision.

• When to Use Conventional UT
• Straightforward thickness measurements on metal skins or simple welds.
• Routine inspections where high-resolution imaging is not required.
• When to Use PAUT
• Inspection of composite materials for delaminations, disbonds, and porosity.
• Detection of cracks in critical welds and fastener holes.
• Complex geometries such as turbine blades or bonded structures.
• Situations where detailed imaging and permanent digital records are required for regulatory compliance.

Oil & Gas

Pipelines, refineries, and offshore structures demand regular inspection to prevent costly failures.

• When to Use Conventional UT
• Spot thickness measurements on pipelines and storage tanks.
• Straight-line weld inspections in less critical areas.
• Low-cost, high-volume inspections where speed and simplicity are priorities.
• When to Use PAUT
• Corrosion mapping for pipelines and vessels.
• Weld inspections on high-pressure or high-temperature lines.
• Inspection of components with varying thickness or complex shapes, such as nozzles and elbows.
• Situations requiring advanced defect characterization, such as crack depth or planar flaw orientation.

Nuclear Power

Nuclear facilities are among the most regulated and safety-critical environments in the world. Inspections must be thorough, traceable, and capable of meeting stringent standards.

• When to Use Conventional UT
• Simple welds and thickness checks where component accessibility is straightforward.
• Verification tasks where advanced imaging is unnecessary.
• When to Use PAUT
• Inspections of reactor pressure vessels, piping welds, and other safety-critical components.
• Applications where permanent records are required for regulatory documentation.
• Complex geometries and materials where single-point conventional UT may miss critical flaws.
• Life extension and in-service inspection programs demanding comprehensive data and high confidence levels.

Ultimately, both PAUT and conventional UT are valuable tools in the NDT toolbox. The decision comes down to the complexity of the inspection, the criticality of the component, and the level of detail required.

• Conventional UT: Best for simple, routine, and cost-sensitive inspections.
• PAUT: Best for complex, high-value, and safety-critical inspections where imaging, accuracy, and documentation matter most.

At Vermon NDT, we design and manufacture advanced PAUT probes that deliver consistent, high-quality results across industries and over time. Whether you’re inspecting a composite wing panel, a pipeline weld, or a reactor vessel, having the right probe makes all the difference. Find the right probe for you at pautprobes.com.