Equipment often found in refineries may be enveloped in insulation and weathering jackets to maintain internal processing temperatures. In many cases moisture from the environment will penetrate the weathering jacket and infiltrate the insulation, leaching corrosive ions to the surface of metal equipment, effectively creating a corrosion cell. The goal of this project is to investigate different insulating materials for their ability to inhibit corrosion under insulation (CUI). The inhibiting mechanism utilizes water ingress that leaches ions from the insulator to bond with the surface metal and create a passive layer, inhibiting any further corrosion. This study will follow ASTM C1617-15 in order to examine the corrosion mitigating effects of three insulators. Insulators are ground down and boiled to extract leachable ions. The leachant is filtered to remove solids and then introduced to heated carbon steel coupons in a drip wise fashion over a span of four days. Insulators are ranked quantitatively on their ability to prevent corrosion based on gravimetric analysis. The mass loss corrosion rate of the insulators were: Sproule WR1200® (4.595 mils/yr), Thermo-12® Gold (5.523 mils/yr), and Pyrogel® XT-E (24.767 mils/yr).