Automated Ultrasonic Testing for Inspection of In Service Steel Bridges

project overview

Proposed Innovation

Develop an Automated Ultrasonic Testing method that leverages advances in ultrasonic technology with innovations in automated robotics to produce a system capable of measuring weld defects in critical bridge members with greater precision and consistency than currently possible.

Early system with encoder integrated with
UT probes

Output from Phased Array Ultrasonic Testing (PAUT) system

Research Motivations

• Difficulty for bridge owners and state agencies in balancing allocation of limited resources with maintenance of safe and functioning bridge inventory.
• Opportunity for application of Fitness-for- Service (FFS) analysis to better inform these logistical and engineering decisions.
• Limitations of Traditional Ultrasonic Testing (UT) and Radiographic Testing (RT) methods in precise detection of steel weld defects

Research Overview & Accomplishments

Industry Review: Review Findings

• An exhaustive inventory of commercially available AUT Scanners was compiled to give the project team the widest possible variety of prototype systems to consider.
• Fixed-Rail scanners were selected over Rover-Style scanners as the latter rely on magnetic wheels that have stability issues.
• Features valued by industries that currently utilize AUT scanners (such as in Oil & Gas and Aerospace) were identified to inform prototype design decisions.

Fixed-Rail Scanner
(AUT Solutions)

Scanner (Olympus)

Feature Definition
• Precise X-Y-Z movement with encoded positioning system
• Computerized control of probe movement
• Universal holders for conventional UT, PAUT, and TOFD probes
• Portable data acquisition system and hardware

Prototype Development: Selection Motivation

• Advances in 3-D printers and consumer CNC machines have driven down their cost significantly while providing precise computer control of instrument motion.
• For a prototype system, modification of an XY plotting device was far more cost- efficient than use of a commercial system developed for more rugged applications.

Prototype AUT System
(based on Makeblock XY Plotter Robot Kit)

Probe Holder Control Software

Prototype Testing: Inspection Details

• A total of six [6] bridge member weld mock- ups with known void locations were evaluated by four [4] ASNT III UT Inspectors to gather data on their methods for use with the developing the AUT system scan plan.
• After inputting the developed scan plan into the robot, comparative data was collected to evaluate performance against inspectors.
• Field testing of the prototype system was completed on welds in different orientations to evaluate the effectiveness of the instrumentation outside of ideal or controlled settings.

AUT System – Vertical Mounting

AUT System – Overhead Mounting


Major Findings

• The AUT system produced results with reasonably similar quality to the results of the inspection team.
• While the AUT system was found to be effective in gathering data on the field- tested bridge, the logistical challenges associated with accessing the welds and mounting the system to accommodate those welds was found to be time- consuming and inefficient.
• Based on discussion with the expert panel, this system shows promise in providing initial survey results in controlled fabrication shop settings to allow more informed and time-efficient selection of where expert inspectors should perform more detailed scans.
• In addition, the significant amount of noise introduced by weld reinforcement indicates a general need for grinding of the weld flush with the steel to be part of the protocol for an ideal weld inspection using any kind of ultrasonic testing.

PAUT C-Scan – ASNT III Inspector

PAUT C-Scan – AUT System

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