By Charles J. Hazouri
Thermal imaging is the use of special camera-like devices that measure thermal patterns and temperatures across the surface of an object. The image produced can detect changes in materials used and temperatures, which can identify moisture intrusion and heat loss.
The benefit of using thermal imaging is that it is non-contact, two dimensional, real time, and saves cost by reducing time spent troubleshooting a specific anomaly or deficiency.
Infrared thermography is a more informative and non-invasive inspection technique, making it the perfect tool for marine inspections of G10 as well as all fiberglass laminates.
G10 laminate was first introduced in the 1950s and is best described as a thermo-laminated continuous filament woven fiberglass sheet bonded with difunctional or trifunctional epoxy resin. It has great strength, high temperature resistance, good electrical loss and strength, low moisture absorption, is chemical resistant, and is among the most versatile laminates available.
In the marine industry, G10 laminate can be used as backing for carbon fiber sheeting, as structural frames and stiffeners, and as backing plates for various shipboard systems.
To demonstrate the value of thermographic imaging of G10 laminates, a thermal inspection and series of tests were conducted. The initial inspection involved imaging sections of a Hatteras motor yacht. The second test used two sections of G10, one of which was made with a distinctive non-conformity.
The test vessel and samples were offered and supplied by Nathan Goodwin of All Points Boats in Ft. Lauderdale. The inspection and tests were conducted in August and October using a FLIR T440BX thermal imager, which is a camera-like device capable of detecting, displaying and recording thermal patterns across the surface of an object.
The initial inspection proved that imaging of G10 laminates is comparable to imaging solid materials such as structural framing constructed of aluminium and steel. The images show that G10 has well-defined, delineated edges, and appears much darker and is distinctive from regular laminates.
In the next test, two samples were heated and then imaged using thermal infrared technology. Sample A was a standard piece of G10 with no anomalies; Sample B was a piece of G10 with an anomaly consistent with an area of delamination or a small void.
Together, the samples showed that there is a defined pattern to G10 laminates and that any non-conformity can be easily identified with thermographic inspection techniques.
Based on the evidence in these inspections and tests, qualitative and quantitative infrared thermography can clearly identify and document the thermal patterns of G10 laminates when used in the structural capacity of vessel repair and/or construction, or for product failure such as moisture intrusion, delamination, and voids. It is the perfect tool for marine inspections because it has the benefits of being both a more informative process and a non-invasive inspection technique.
Charles J. Hazouri is a certified Level III thermographer, certified marine surveyor, auditor and consultant based in New Orleans. Comments on this essay are welcome at firstname.lastname@example.org.