Final answer:
Flashing is a piece of metal installed on roofing to prevent water seepage and damage. Galvanization, using a zinc coating, provides both prophylactic and cathodic protection, sacrificing the zinc to save the underlying structure from corrosion.
Step-by-step explanation:
A piece of metal that protects against water seepage and must be installed carefully to prevent water from getting behind the roofing is known as flashing or a similar waterproofing component. When installing roofing, it's crucial that the flashing is not compromised; otherwise, water might penetrate, leading to water damage and the need for repairs. To safeguard metal roofing elements from corrosion, and to ensure their longevity, methods like galvanization or applying cathodic protection are employed.
Galvanization involves coating the underlying iron or steel with a layer of zinc. This process not only acts as a prophylactic protection to prevent oxygen and water from accessing the steel but also serves as cathodic protection. When exposed, zinc corrodes preferentially to the iron, effectively sacrificing itself to keep the structure beneath intact. Over time, if this zinc layer is damaged from corrosion or mechanical means, the underlayer may still be protected due to the galvanic properties of zinc as it continues to corrode in place of the iron.
Applying different materials that form protective oxide coatings, such as chromium and tin, can also serve to prevent corrosion, as these coatings can hinder the access of oxygen and water. Such methods are frequently used not only in roofing but across various industries to lengthen the life span of metallic structures in aggressive environments, like automobile parts and canned foods.