The Kentucky Transportation Research Program conducted an extended 10- month evaluation of the Acoustic Emission Weld Monitor (AEWM) in a bridge fabrication shop. That device was used to detect welding flaws during typical production of butt-welds on flanges and webs used in steel bridges. A total of 153 welds were monitored.

AEWM test results were compared with visual inspection and double- blind results of conventional nondestructive testing routinely conducted on the welds. The AEWM did not miss any flaws detected visually or by nondestructive testing. Three AEWM flaw indications were confirmed by conventional nondestructive testing (radiography).

A large number of AEWM indications were not related to any detected flaws (228 of 263 indications). Those were attributed to AE noise that occurs away from the weld and small flaws that were either missed or overlooked by visual and nondestructive inspection or were removed prior to inspection by normal fabrication procedures.

The AEWM has shown the sensitivity to detect AWS code-rejectable defects. In part, the high number of overcalls was caused by use of excessive system sensitivity. Due to the success of the unit in detecting flaws, further development is warranted. Specific recommendations for further research are provided.

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