Fusion-Bonded Epoxy (FBEs) coatings are a durable, dependable approach to corrosion-prevention for both inner-diameter and outer-diameter pipeline coatings. One attribute of an FBE that plays a significant role in the coating performance and operating temperature is the glass transition temperature (Tg). However, when a coating is subject to environmental conditions (water, chemicals, UV ((Ultraviolet) light, elevated temperatures, etc.) the glass transition temperature can be depressed from its applied state. This paper explores how to monitor the glass transition temperature depression after exposure via DSC (Differential Scanning Calorimetry). The depressed Tg can be described as the coating’s “Wet Tg”. In addition, the mechanical properties of the coatings will be observed via DMA (Dynamic Mechanical Analysis). Moisture Content will be observed by use of TGA (Thermogravimetric Analysis) and EIS (Electro-Impedance Spectroscopy). This paper will also correlate the change in glass transition temperature and physical properties to real world performance: adhesion and flexibility. The experimental procedures described in this study will demonstrate how to differentiate two coatings with different glass transition temperatures and barrier properties. Using these methods, we can improve future coating formulations and improve their ability to control corrosion.