Using the new QNix® 9500 Paint Thickness Gauge to measure Galvanize coatings / Duplex coating systems.

We all know the damages the different types of corrosion cause on steel metal structures every year if preventive measures are not taken. One such preventive measure is galvanizing.

Galvanic corrosion occurs when two non-similar metals with physical or electrical contact come in with a common electrolyte such as saltwater. The more active metal – also known as the anode corrodes faster than the more noble metal – the cathode. Corrosion experts use several methods to prevent corrosion, among others, the use of a sacrificial anode to provide a cathodic protection system. For example, a sacrificial anode layer of zinc is applied to the surface of a fabricated steel part, providing corrosion protection, with the thickness of the galvanized coating having a direct correlation to the life span – service life of the steel structure. A layer of paint or powder coating is also added to the zinc layer, making a duplex system. The inspection of both coating thicknesses is believed to be the most important step to determine the degree of metal degradation.

To comply with international standards including ASTM D7091, ASTM A123, and ISO 2808, an electronic, non-destructive, simple, fast, and easy-to-use device is used to simultaneously measure duplex coating Thickness – with a single measurement. The QNix® 9500 premium plus Paint Thickness Gauge. Simply check the zero on the uncoated substrate/part and adjust, if need be. Also, use the measuring shims provided to check the accuracy of the Paint thickness gauge on the uncoated substrate. Thereafter, take a reading and both paint and zinc coating thicknesses will be displayed. It is important to note that every spot reading will be slightly different, due to the surface roughness of both steel and zinc. Best results can be obtained by taking a series of readings and averaging them, according to ASTM A123. The ASTM A123 Excerpts of Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products: using a Paint thickness gauge to measure, a specimen of coating thickness shall be an average of a minimum of 5 readings at widely dispersed points, with that average value not being less than one coating thickness grade lower than the value listed in the appropriate specification. And, the thickness should be in the range of 1.4 and 3.9 mils, depending on the coating grade.

About TestCoat:

For many years, TestCoat has been a trustworthy partner and leader in the supply and distribution of inspection equipment, laboratory & physical test equipment for the coatings and paint industries. We supply non-destructive quality control and testing instruments such as Paint thickness Mil Gauges, Gloss meters, portable and benchtop metal hardness testers, laboratory mixersviscometers, film applicatorsdrying time recorder, cupping testers, Wet scrub abrasion testers, Coating inspection kits with advanced technology, and of the highest standards.

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