Moisture barriers laminated to metal including Aluminium and stainless steel are widely used throughout the oil and gas industries to prevent galvanic corrosion of the cladding and also corrosion under insulation (CUI) from underneath. If water is present inside the system and makes contact with the metal jacketing or cladding corrosion can occur. The first barriers used were paint based, over time these evolved to using Kraft paper on polyethylene hence the name polykraft moisture barrier. Since the inception of moisture barrier they have evolved from paint to paper then Surlyn. In order to protect the metal jacket or lagging the barrier must be resistant to water and scratches and not have any pin holes that would let water through. When comparing barriers only a Surlyn/ Polyethylene barrier is able to achieve all these aims.