Electromagnetic Interference with Corded Inspection Probes
A galvanizer contacted the AGA regarding a skyscraper project in Manhattan, NY where a hot-dip galvanized coating inspection was performed above the 60th floor during ongoing construction. Upon climbing to the various floors requiring inspection, the galvanizer found all the digital coating thickness inspection gauges were completely unresponsive once at the elevated job site.
The galvanizer contacted the gauge manufacturer and discovered a history of sporadic issues over the years when using digital inspection gauges at the job sites of skyscrapers (particularly in Manhattan). After being informed of the issue by the galvanizer, I reached out to the gauge manufacturer (AGA Sustaining Member DeFelsko) to learn more.
Defelsko informed us that while all of their instruments are tested for immunity to radio interference according to international standards, the radio interference at some job sites is so extreme that it occasionally causes issues with the operation of any digital gauge including DeFelsko's PosiTector 6000 model. This is especially the case when using the cabled probes because the cable acts as an antenna. Non-cabled probes are much less affected, and the issue can sometimes be overcome by wrapping the probe cable in a tight coil.
To address this issue, the DeFelsko PosiTector 6000 electronics were redesigned two years ago to be highly immune to electromagnetic interference, and well beyond the relevant industry requirements. Since then, field reports of interference issues have dropped to zero since the changes were made.
For galvanizers performing field inspections in areas where electromagnetic interference is of concern, either avoid the use of a corded probe, upgrade to a newer digital model, or utilize a manual gauge (i.e. banana gauge). Otherwise, the vast majority of our members are unlikely to experience this specific issue in the field.
© 2020 American Galvanizers Association. The material provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel. This material provides general information only and is not intended as a substitute for competent professional examination and verification as to suitability and applicability. The information provided herein is not intended as a representation or warranty on the part of the AGA. Anyone making use of this information assumes all liability arising from such use.