Coarse Grain Weld Inspection with Advanced Ultrasonic Imaging Techniques

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Back to Core Research Programme AMorph – 4D Printing for Field Morphing Structures Automation of Composite and Hybrid Joining Process Coaxial Wire Additive Manufacturing Processes and In-Line Monitoring Tools Development of Coded Excitation Technique for Non-Metallic Pipes Inspection Development of Digital Twin technology as a demonstrator for real-time integrity assessment of crack growth in tensile specimens Development of Friction Stir Welding (FSW) for Hydrogen Fuel Storage Tanks Development of Leak-Before-Break Hydrogen Storage Composite Pressure Vessels With Polymeric Liner Establishing Assessment Methods for Determining Safe Service Limits of High-Temperature Materials in Extreme Environments Fracture toughness in aggressive environments: effect of crack monitoring techniques on test results In-process detection and non-destructive testing of electron beam weld imperfections Internal Bore Coatings for Applications in Corrosion and Hydrogen Environment Joining of Additively Manufactured Materials Long term behaviour of polymeric liner materials/coatings in hydrogen service Techniques for High Temperature Ultrasonic Inspection of Arc Welding Ultimate Leverage Fund

Project Code: 36676

Start date and planned duration: January 2026, 24 months

Objective

Conduct an independent, comparative evaluation of advanced ultrasonic array techniques (FMC/TFM, PAUT, PWI, PCI) for inspection of coarse-grained materials.
Quantify detection and characterisation performance using experimental trials.
Provide credible, evidence-based guidance for detection, characterisation and sizing of imperfections in a suitable way as a trusted industry reference for technical justifications and NDT capability statements.

Project Outline

This CRP aims to develop a best practice guide for the application of advanced ultrasonic imaging techniques to inspect coarse-grained anisotropic welds using TWI owned test pieces.

Ultrasonic inspection of welds made using austenitic stainless steels presents significant challenges for inspection of high integrity components in the nuclear power generation, fusion and decommissioning sectors. Similarly, nickel based alloys, widely used in the oil and gas pipelines transporting corrosive fluids present similar difficulties. The coarse-grained, anisotropic structure of these materials increases signal attenuation, noise, and beam skewing, reducing the probability of detection, requires multiple probes/scans and compromising defect sizing accuracy. These issues are particularly critical in the nuclear sector, where ageing infrastructure and new plant developments demand robust and reliable inspection solutions.

The adoption and standardisation of phased array ultrasonic testing (PAUT) and full matrix capture/total focusing method (FMC/TFM) have improved inspection capability. However, with a growing range of advanced techniques and standards now available, industry needs independent, high-quality evidence to guide technique selection for challenging scenarios such as coarse-grained anisotropic welds.

The CRP will deliver a best practice guide and Members report based on data from TWI owned legacy specimens. This CRP builds on Project 36079 (December 2025 completion), which demonstrated the application of advanced ultrasonic testing (UT) techniques for the inspection of austenitic cladding. The current project will extend this evaluation to coarse-grained, anisotropic welds which presents greater inspection challenges. Techniques including PAUT, TFM, phase coherence imaging (PCI) and plane wave imaging (PWI) will be assessed to generate a robust evidence base and develop practical guidance for industrial use.

Industry Sectors

- Oil and Gas

- Defence

- Nuclear

Benefits to Industry

The project addresses a longstanding challenge in ultrasonic inspection of coarse-grained, anisotropic welds, which is critical for sectors such as nuclear power and high-integrity part manufacture. The need for robust, evidence-based inspection techniques is driven by safety, regulatory, and operational requirements. The project’s outcomes will support the evolution of codes, standards, and best practice guidance. Industry is seeking independent, high-quality evidence to guide technique selection for challenging weld scenarios, and this project will deliver practical guidance and evidence to directly address these needs.